Workpiece processing sheet

Abstract

To provide a work-machining sheet having superior expandability.SOLUTION: A work-machining sheet 1 has a base material 11 and a sticker layer 12. The base material 11 includes a surface layer 111, a back face layer 113 and a middle layer 112. A test piece prepared by cutting the base material 11 into rectangular slices of 15 mm in a short side shows a breaking elongation of 600% or larger in each of MD and CD directions. A ratio (R25%) of tensile stress at 25%-extention, measured in a tensile test in which the base material 11 is pulled and stretched in the MD direction to tensile stress at 25%-extention, measured in a tensile test in which the base material 11 is pulled and stretched in the CD direction is equal to or smaller than 1.3. A ratio (R50%) of tensile stress at 50%-extention, measured in a tensile test in which the base material 11 is pulled and stretched in the MD direction to tensile stress at 50%-extention, measured in a tensile test in which the base material 11 is pulled and stretched in the CD direction is equal to or smaller than 1.3.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a workpiece processing sheet used for processing workpieces such as semiconductor wafers. [Background technology]

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

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

[0004] Patent Document 1 discloses a dicing substrate film that includes a base layer and a surface layer, with the aim of providing a workpiece processing sheet with excellent expandability, and the surface layer contains a specified polystyrene resin and a specified vinyl aromatic hydrocarbon-conjugated diene hydrocarbon copolymer or a hydrogenated product thereof. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6146616 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in recent years, with the miniaturization of semiconductor devices, the chips handled by workpiece processing sheets have become increasingly smaller, and therefore workpiece processing sheets are required to have better expandability than conventional workpiece processing sheets in order to enable good pickup of such tiny chips.

[0007] The present invention has been made in view of the above circumstances, and has as its object to provide a workpiece processing sheet having excellent expandability. [Means for solving the problem]

[0008] In order to achieve the above object, first, the present invention provides a workpiece processing sheet comprising a substrate and an adhesive layer laminated on one side of the substrate, wherein the substrate has a surface layer located proximal to the adhesive layer and a surface layer located distal to the adhesive layer. Backing layer and the surface layer and the Backing layer and an intermediate layer located between the substrate and the intermediate layer, and a test piece obtained by cutting the substrate into a strip with a short side of 15 mm is subjected to a tensile test in an environment of 23°C with a chuck distance of 100 mm and a tensile speed of 200 mm / min. The breaking elongation measured when the substrate is pulled in the MD direction and the CD direction is 600% or more, and the ratio of the tensile stress at 25% elongation measured when the substrate is pulled in the MD direction to the tensile stress at 25% elongation measured when the substrate is pulled in the CD direction (R 25% ) is 1.3 or less, and the ratio of the tensile stress at 50% elongation measured when the substrate is subjected to a tensile test in which the substrate is pulled in the MD direction to the tensile stress at 50% elongation measured when the substrate is subjected to a tensile test in which the substrate is pulled in the CD direction (R 50%) is 1.3 or less (Invention 1).

[0009] The workpiece processing sheet according to the above invention (Invention 1) has a base material comprising the three layers described above, and by satisfying the conditions of the ratio of the breaking elongation and tensile stress described above, it has excellent expandability.

[0010] In the above invention (Invention 1), the surface layer, the intermediate layer and the Backing layer Each of the above contains a polyolefin resin and a thermoplastic elastomer, and the above surface layer and the above Backing layer Each of the above preferably contains an antistatic agent (Invention 2).

[0011] In the above invention (Invention 2), it is preferable that the intermediate layer does not contain the antistatic agent, or that the intermediate layer contains the antistatic agent in a content (unit: mass %) that is less than that of each of the surface layer and the back layer (Invention 3).

[0012] In the above invention (Invention 1), the surface layer, the intermediate layer and the Backing layer Each of the intermediate layer and the surface layer contains polyethylene. Backing layer It is preferable that the polyethylene contained in the polyethylene resin has a melt flow rate (MFR) measured in accordance with JIS K7210-1 that is different from that of the polyethylene contained in the polyethylene resin (Invention 4).

[0013] In the above inventions (inventions 1 to 4), a dicing sheet is preferred (invention 5). [Effects of the Invention]

[0014] The workpiece processing sheet according to the present invention has excellent expandability. [Brief explanation of the drawings]

[0015] [Figure 1]1 is a cross-sectional view of a workpiece processing sheet according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, an embodiment of the present invention will be described. A cross-sectional view of a workpiece processing sheet according to one embodiment is shown in Fig. 1. The workpiece processing sheet 1 shown in Fig. 1 includes a substrate 11 and an adhesive layer 12 laminated on one side of the substrate 11.

[0017] As shown in Figure 1, the substrate 11 comprises a surface layer 111 located proximal to the adhesive layer 12, a back layer 113 located distal to the adhesive layer 12, and an intermediate layer 112 located between the surface layer 111 and the back layer 113.

[0018] In the workpiece processing sheet 1 according to this embodiment, when a test piece is prepared by cutting the substrate 11 into strips with a short side of 15 mm and conducting a tensile test in an environment of 23°C with a chuck distance of 100 mm and a tensile speed of 200 mm / min, the breaking elongation measured is 600% or more in both the MD direction and the CD direction.

[0019] In addition, in the workpiece processing sheet 1 according to this embodiment, the ratio of the tensile stress at 25% elongation measured when a tensile test is performed in which the substrate 11 is pulled in the MD direction to the tensile stress at 25% elongation measured when a tensile test is performed in which the substrate 11 is pulled in the CD direction (R 25% ) is less than 1.3.

[0020] Furthermore, in the workpiece processing sheet 1 according to this embodiment, the ratio of the tensile stress at 50% elongation measured when a tensile test is performed in which the substrate 11 is pulled in the MD direction to the tensile stress at 50% elongation measured when a tensile test is performed in which the substrate 11 is pulled in the CD direction (R 50% ) is less than 1.3.

[0021] Generally, wafers are diced onto a workpiece processing sheet, followed by curing of the adhesive layer by ultraviolet irradiation, and then chips are picked up in the expanded state. Usually, the substrate is also cut during the dicing process. Therefore, conventional workpiece processing sheets are very prone to breaking when expanded.

[0022] However, in the workpiece processing sheet 1 according to this embodiment, since the substrate 11 satisfies the above-mentioned physical properties, even after the dicing as described above, breakage is unlikely to occur in the expanding step. In particular, the tensile stress ratio (R 25% ) and the ratio of tensile stress (R 50% ) are within the above ranges, i.e., the difference in tensile stress between when pulled in the MD direction and when pulled in the CD direction is relatively small, which prevents stress from concentrating on a part of the base material 11 and makes it less likely to break. Therefore, the workpiece processing sheet 1 according to this embodiment has excellent expandability.

[0023] Furthermore, since the substrate 11 in this embodiment has at least three layers, namely, the surface layer 111, the intermediate layer 112, and the back layer 113, it is easy to impart other desired properties to the workpiece processing sheet 1 while ensuring excellent expandability. For example, as described below, excellent antistatic properties can be imparted by adding an antistatic agent to the surface layer 111 or the back layer 113. Furthermore, by designing the surface layer 111 and the back layer 113 to have a relatively high elastic modulus, adhesion to a metal roll during film formation of the substrate 11 can be suppressed, thereby imparting high film formability.

[0024] 1. Composition of workpiece processing sheet (1) Base material As described above, the substrate 11 in this embodiment includes the surface layer 111, the intermediate layer 112, and the back surface layer 113. The compositions of these layers are not particularly limited as long as the substrate 11 satisfies the above-described physical properties.

[0025] The material for each layer constituting the substrate 11 is not particularly limited as long as it can form those layers, and it is preferable to use, for example, a resin. In particular, from the viewpoint of realizing better expandability and easily suppressing the generation of chips, it is preferable to use at least one of polyolefin resin and thermoplastic elastomer as the main material. Note that the surface layer 111 and the back layer 113 may have different compositions or may have the same composition.

[0026] (1-1) Polyolefin resin Specific examples of the polyolefin resin are not particularly limited. In this specification, the polyolefin resin refers to a homopolymer or copolymer containing an olefin as a monomer, or a copolymer containing an olefin and a molecule other than an olefin as monomers, in which the mass ratio of the portion based on the olefin unit in the polymerized resin is 1.0 mass% or more.

[0027] The polymer constituting the polyolefin resin may be linear or may have a side chain, and may also have an aromatic ring or an aliphatic ring.

[0028] Examples of olefin monomers constituting polyolefin-based resins include olefin monomers having 2 to 8 carbon atoms, α-olefin monomers having 3 to 18 carbon atoms, and olefin monomers having a cyclic structure. Examples of olefin monomers having 2 to 8 carbon atoms include ethylene, propylene, 2-butene, and octene. Examples of α-olefin monomers having 3 to 18 carbon atoms include propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, and 1-octadecene. Examples of olefin monomers having a cyclic structure include norbornene, cyclopentadiene, cyclohexadiene, dicyclopentadiene, tetracyclododecene, and derivatives thereof.

[0029] The polyolefin resins can be used singly or in combination of two or more.

[0030] Among the specific examples of the polyolefin resins mentioned above, it is preferable to use at least one of polyethylene containing ethylene as a main polymerization unit and polypropylene containing propylene as a main polymerization unit.

[0031] As the polypropylene, for example, homopolypropylene, random polypropylene, and block polypropylene are preferably used. These may be used alone or in combination of two or more. In particular, it is preferable to use a mixture of homopolypropylene and random polypropylene.

[0032] The homopolypropylene, random polypropylene, and block polypropylene may each be a commercially available product. Examples of commercially available homopolypropylenes include those manufactured by Prime Polymer Co., Ltd. under the product names "Prime Polypro E111G," "Prime Polypro E-100GV," "Prime Polypro E-100GPL," and "Prime Polypro E-200GP." Examples of commercially available random polypropylenes include those manufactured by Prime Polymer Co., Ltd. under the product names "Prime Polypro B221WA," "Prime Polypro B241," "Prime Polypro E222," and "Prime Polypro E-333GV." Examples of commercially available block polypropylenes include those manufactured by Prime Polymer Co., Ltd. under the product names "Prime Polypro E701G," "Prime Polypro E702G," and "Prime Polypro E702MG."

[0033] The polyethylene may be any one of high density polyethylene, medium density polyethylene, low density polyethylene, very low density polyethylene and linear low density polyethylene, or a mixture of two or more of these.

[0034] In particular, it is preferable to use low-density polyethylene as the polyethylene, and examples of commercially available products include "Novatec LL" manufactured by Mitsubishi Chemical Corporation, and the Neozex series and Ultraozex series manufactured by Prime Polymer Co., Ltd.

[0035] The polyethylene preferably has a melt flow rate (MFR) of 1 g / 10 min or more, more preferably 2 g / 10 min or more, and even more preferably 3 g / 10 min or more. The melt flow rate is preferably 10 g / 10 min or less, more preferably 9 g / 10 min or less, and even more preferably 8 g / 10 min or less. Having a melt flow rate within these ranges makes it easier for the workpiece processing sheet 1 according to this embodiment to achieve better expandability. The melt flow rate was measured in accordance with JIS K7210:2014 at a temperature of 190°C and a load of 2.16 kg.

[0036] When any of the layers constituting the substrate 11 contains a polyolefin resin, the content of the polyolefin resin in that layer is preferably 10% by mass or more, particularly preferably 15% by mass or more, and even more preferably 20% by mass or more. Furthermore, the content is preferably 100% by mass or less, particularly preferably 95% by mass or less, and even more preferably 90% by mass or less. By ensuring that the polyolefin resin content is within the above range, the workpiece processing sheet 1 according to this embodiment is more likely to have good expandability.

[0037] The surface layer 111, the intermediate layer 112, and Backing layer When both of the surface layer 111 and the intermediate layer 112 contain polyethylene, the polyethylene contained in the intermediate layer 112 is Backing layerIt is preferable that the melt flow rate of the polyethylene contained in the intermediate layer 112 is different from that of the polyethylene contained in the surface layer 111 and the polyethylene contained in the intermediate layer 112, as measured in accordance with JIS K7210-1. Backing layer It is preferable that the melt flow rate is larger than that of each polyethylene contained in 113. This makes it easier for the workpiece processing sheet 1 according to this embodiment to obtain better expandability.

[0038] (1-2) Thermoplastic elastomer The thermoplastic elastomer is not particularly limited as long as it is other than the polyolefin-based resin and can be used to form the substrate 11. Examples of the thermoplastic elastomer include olefin-based elastomers, rubber elastomers, urethane-based elastomers, styrene-based elastomers, acrylic-based elastomers, and vinyl chloride-based elastomers. These may be used alone or in combination of two or more.

[0039] Among the above-mentioned elastomers, olefin-based elastomers are preferred from the viewpoint of facilitating good expandability. In particular, it is preferred that at least one of the front surface layer 111 and the back surface layer 113 contains an olefin-based elastomer. In this specification, the term "olefin-based elastomer" refers to a copolymer containing structural units derived from olefin or its derivatives (olefin-based compounds), and is a material that has rubber-like elasticity and thermoplasticity in a temperature range including room temperature.

[0040] Examples of olefin-based elastomers include those containing at least one resin selected from the group consisting of ethylene-propylene copolymers, ethylene-α-olefin copolymers, propylene-α-olefin copolymers, butene-α-olefin copolymers, ethylene-propylene-α-olefin copolymers, ethylene-butene-α-olefin copolymers, propylene-butene-α-olefin copolymers, and ethylene-propylene-butene-α-olefin copolymers. Among these, ethylene-propylene copolymers are preferred.

[0041] When any of the layers constituting the substrate 11 contains an olefin-based elastomer, the content of the olefin-based elastomer in that layer is preferably 1% by mass or more, particularly preferably 10% by mass or more, and even more preferably 15% by mass or more. Furthermore, the content is preferably 90% by mass or less, particularly preferably 80% by mass or less, and even more preferably 70% by mass or less. By ensuring that the olefin-based elastomer content is within the above range, the workpiece processing sheet 1 according to this embodiment is more likely to achieve good expandability.

[0042] Furthermore, from the viewpoint of easily obtaining good expandability, it is also preferable to use a styrene-based elastomer. In particular, it is preferable that the intermediate layer 112 contains a styrene-based elastomer. In this specification, the term "styrene-based elastomer" refers to a copolymer containing structural units derived from styrene or its derivatives (styrene-based compounds), and is a material that has rubber-like elasticity and thermoplasticity in a temperature range including room temperature.

[0043] Examples of styrene-based elastomers include styrene-conjugated diene copolymers and styrene-olefin copolymers, with styrene-conjugated diene copolymers being preferred. Specific examples of styrene-conjugated diene copolymers include unhydrogenated styrene-conjugated diene copolymers such as styrene-butadiene copolymer, styrene-butadiene-styrene copolymer (SBS), styrene-butadiene-butylene-styrene copolymer, styrene-isoprene copolymer, styrene-isoprene-styrene copolymer (SIS), and styrene-ethylene-isoprene-styrene copolymer; and hydrogenated styrene-conjugated diene copolymers such as styrene-ethylene / propylene-styrene copolymer (SEPS: hydrogenated styrene-isoprene-styrene copolymer) and styrene-ethylene-butylene-styrene copolymer (SEBS: hydrogenated styrene-butadiene copolymer). The styrene-based thermoplastic elastomer may be hydrogenated or unhydrogenated, but hydrogenated products are preferred. Among the above, hydrogenated styrene-conjugated diene copolymers are preferred, and styrene-ethylene-butylene-styrene copolymers (SEBS) are particularly preferred, from the viewpoint of facilitating good expandability.

[0044] The content of structural units derived from styrene or styrene compounds in the styrene-based elastomer (styrene ratio) is preferably 1% by mass or more, particularly preferably 5% by mass or more, and even more preferably 10% by mass or more. From the viewpoint of easily achieving excellent film-forming properties, the content of the structural units is preferably 80% by mass or less, particularly preferably 70% by mass or less, and even more preferably 60% by mass or less. This makes it easier to achieve excellent expandability.

[0045] When any of the layers constituting the substrate 11 contains a styrene-based elastomer, the content of the styrene-based elastomer in that layer is preferably 1% by mass or more, particularly preferably 10% by mass or more, and even more preferably 15% by mass or more. Furthermore, the content is preferably 90% by mass or less, particularly preferably 80% by mass or less, and even more preferably 70% by mass or less. By ensuring that the content of the styrene-based elastomer is within the above range, the workpiece processing sheet 1 according to this embodiment is more likely to achieve good expandability.

[0046] (1-3) Antistatic agent Each layer constituting the base material 11 preferably contains an antistatic agent. In particular, it is preferable that the front layer 111 and the back layer 113 each contain an antistatic agent. This makes the workpiece processing sheet 1 according to this embodiment more likely to have excellent antistatic properties, and can effectively suppress peeling electrification when the release sheet or workpiece is separated from the workpiece processing sheet 1.

[0047] Although intermediate layer 112 may also contain an antistatic agent, from the viewpoint of easily suppressing the generation of chips during dicing, it is preferable that intermediate layer 112 does not contain an antistatic agent or that intermediate layer 112 contains an antistatic agent in a content (unit: mass %) that is lower than that of each of front surface layer 111 and back surface layer 113. In this way, by having intermediate layer 112 that does not contain an antistatic agent or has a low content of antistatic agent between front surface layer 111 and back surface layer 113, it is possible to effectively suppress the generation of chips from intermediate layer 112 when a dicing blade reaches intermediate layer 112 during dicing.

[0048] The antistatic agent in this embodiment is not particularly limited, and known antistatic agents can be used. Examples of the antistatic agent include low-molecular-weight antistatic agents and polymer-type antistatic agents. However, polymer-type antistatic agents are preferred because they can easily suppress the generation of cutting chips and are less likely to bleed out from the front surface layer 111 and the back surface layer 113.

[0049] Examples of polymer-type antistatic agents include copolymers having polyether units, such as polyether ester amides and polyether polyolefin block copolymers, and these copolymers may contain metal salts, such as alkali metal salts and alkaline earth metal salts, or ionic liquids.

[0050] The content of the antistatic agent in the surface layer 111 is preferably 3% by mass or more, particularly preferably 5% by mass or more, and even more preferably 10% by mass or more. When the content of the antistatic agent is 3% by mass or more, it becomes easier to exhibit good antistatic properties. Furthermore, the content of the antistatic agent in the surface layer 111 is preferably 40% by mass or less, particularly preferably 35% by mass or less, and even more preferably 30% by mass or less. When the content of the antistatic agent is 40% by mass or less, it becomes easier to suppress the generation of cutting chips.

[0051] The content of the antistatic agent in the back surface layer 113 is preferably 10% by mass or more, particularly preferably 20% by mass or more, and even more preferably 30% by mass or more. When the content of the antistatic agent is 10% by mass or more, it becomes easier to exhibit good antistatic properties. Furthermore, the content of the antistatic agent in the back surface layer 113 is preferably 50% by mass or less, particularly preferably 45% by mass or less, and even more preferably 40% by mass or less. When the content of the antistatic agent is 50% by mass or less, it becomes easier to suppress the generation of cutting chips.

[0052] As described above, it is preferable that intermediate layer 112 does not contain an antistatic agent, or that intermediate layer 112 contains an antistatic agent in a content (unit: mass %) lower than that of each of front surface layer 111 and back surface layer 113. When intermediate layer 112 contains an antistatic agent, the content thereof in intermediate layer 112 is preferably 10 mass % or less, particularly preferably 5 mass % or less, and further preferably 3 mass % or less. When the content of antistatic agent in intermediate layer 112 is 5 mass % or less, it becomes easier to suppress the generation of cuttings. It is also preferable that the lower limit of the content be, for example, 0.01 mass % or more.

[0053] (1-4) Acid-modified resin Each layer constituting the substrate 11 preferably contains an acid-modified resin. In particular, the surface layer 111 preferably contains an acid-modified resin. In this specification, "acid-modified resin" means a resin in which a structure derived from an acid component is added to a polymer chain. The structure derived from the acid component may be in the form of an acid anhydride or may have a carboxy group. When the surface layer 111 contains an acid-modified resin as described above, the adhesion between the substrate 11 and the adhesive layer 12 is improved, and it is possible to prevent the adhesive from remaining on the chip side during pick-up.

[0054] Preferred examples of the main chain of the acid-modified resin include ethylene-acrylic copolymers such as ethylene-(meth)acrylic acid copolymers and ethylene-(meth)acrylic acid ester copolymers. Such resins can easily improve the adhesion between the surface layer 111 and the pressure-sensitive adhesive layer 12. In this specification, (meth)acrylic acid refers to both acrylic acid and methacrylic acid. The same applies to other similar terms.

[0055] The (meth)acrylic acid ester is preferably a (meth)acrylic acid alkyl ester having an alkyl group with 1 to 4 carbon atoms. Preferred examples include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and n-butyl (meth)acrylate. Of these, ethyl (meth)acrylate is more preferred, and ethyl acrylate is particularly preferred.

[0056] When the surface layer 111 contains an acid-modified resin, the content of the acid-modified resin in the surface layer 111 is preferably 5% by mass or more, and particularly preferably 10% by mass or more. This further improves the adhesion between the surface layer 111 and the pressure-sensitive adhesive layer 12. Furthermore, the content is preferably 30% by mass or less, particularly preferably 25% by mass or less, and even more preferably 20% by mass or less. This makes it easier to satisfy the above-mentioned physical properties.

[0057] (1-5) Other ingredients The layers constituting the substrate 11 may contain components other than those described above. In particular, the resin composition may contain components used in the substrate of a general workpiece processing sheet.

[0058] Examples of such components include various additives such as flame retardants, plasticizers, lubricants, antioxidants, colorants, infrared absorbers, ultraviolet absorbers, ion scavengers, etc. The content of these additives is not particularly limited, but is preferably set within a range in which the substrate exhibits the desired functions.

[0059] (1-6) Surface treatment of substrate The surface of the substrate 11 on which the pressure-sensitive adhesive layer 12 is laminated may be subjected to a surface treatment such as a primer treatment, a corona treatment, a plasma treatment, or a roughening treatment (matt finish) in order to improve adhesion to the pressure-sensitive adhesive layer 12. Examples of roughening treatments include embossing and sandblasting. Of these, corona treatment is preferred.

[0060] (1-7) Manufacturing method of substrate The method for producing the substrate 11 in this embodiment is not particularly limited, and for example, melt extrusion methods such as a T-die method or a round die method, a calendar method, a solution method such as a dry method or a wet method, etc. Among these, from the viewpoint of efficiently producing the substrate, it is preferable to adopt the melt extrusion method, and it is particularly preferable to adopt the T-die method.

[0061] Furthermore, when the substrate 11 is manufactured by a melt extrusion method, the components constituting each layer are kneaded together, and then the resulting kneaded mixture is extruded directly or after pellets are first produced, using a known extruder to simultaneously extrude multiple layers to form a film.

[0062] (1-8) Physical properties of the substrate As described above, in the present embodiment, the substrate 11 is cut into strips with short sides of 15 mm, and the test pieces are subjected to a tensile test in an environment of 23°C with a chuck distance of 100 mm and a tensile speed of 200 mm / min. The measured breaking elongation is 600% or more in both the MD and CD directions.

[0063] From the viewpoint of easily achieving better expandability, the breaking elongation is preferably 650% or more, more preferably 700% or more, both when pulled in the MD direction and when pulled in the CD direction. The upper limit of the breaking elongation is not particularly limited, and may be, for example, 1000% or less, particularly 800% or less, both when pulled in the MD direction and when pulled in the CD direction.

[0064] Furthermore, from the viewpoint of easily achieving better expandability, the breaking elongation when the test piece is pulled in the MD direction is preferably 650% or more, more preferably 700% or more, and particularly preferably 800% or more. The upper limit of the breaking elongation is not particularly limited, and may be, for example, 1000% or less, particularly 800% or less.

[0065] Furthermore, from the viewpoint of easily achieving better expandability, the breaking elongation when the test piece is pulled in the CD direction is preferably 650% or more, more preferably 700% or more, and particularly preferably 800% or more. The upper limit of the breaking elongation is not particularly limited, and may be, for example, 1000% or less, particularly 800% or less.

[0066] The details of the method for measuring the breaking elongation are as described in the test examples below.

[0067] As described above, the substrate 11 in this embodiment has a ratio (R 25% ) is less than 1.3.

[0068] Here, from the viewpoint of easily achieving better expandability, the ratio of the tensile stresses (R 25% ) is preferably 1.25 or less, and particularly preferably 1.2 or less. 25% The lower limit of ) is not particularly limited, and may be, for example, 0.8 or more, particularly 0.9 or more.

[0069] As described above, the substrate 11 in this embodiment has a ratio (R 50% ) is less than 1.3.

[0070] Here, from the viewpoint of easily achieving better expandability, the ratio of the tensile stresses (R 50% ) is preferably 1.25 or less, and particularly preferably 1.2 or less. 50%The lower limit of ) is not particularly limited, and may be, for example, 0.8 or more, particularly 0.9 or more.

[0071] From the viewpoint of easily achieving even better expandability, the ratio of the tensile stress at 10% elongation measured when a tensile test is performed in which the substrate 11 is pulled in the MD direction to the tensile stress at 10% elongation measured when a tensile test is performed in which the substrate 11 is pulled in the CD direction (R 10% ) is preferably 1.5 or less, particularly preferably 1.4 or less, and further preferably 1.3 or less. 10% The lower limit of ) is not particularly limited, and may be, for example, 0.8 or more, particularly 0.9 or more.

[0072] Furthermore, the tensile stress at 10% elongation measured when a tensile test is carried out in which the substrate 11 is pulled in its MD direction is preferably 6.5 MPa or more, particularly preferably 8 MPa or more, and more preferably 10 MPa or more. Furthermore, the tensile stress is preferably 20 MPa or less, particularly preferably 15 MPa or less, and more preferably 13 MPa or less. When the tensile stress is within these ranges, the above-mentioned tensile stress ratio (R 10% ) becomes easier to satisfy.

[0073] Furthermore, the tensile stress at 25% elongation measured when a tensile test is conducted in which the substrate 11 is pulled in its MD direction is preferably 7 MPa or more, particularly preferably 9 MPa or more, and more preferably 10 MPa or more. Furthermore, the tensile stress is preferably 20 MPa or less, particularly preferably 15 MPa or less, and more preferably 13 MPa or less. When the tensile stress is within these ranges, the above-mentioned tensile stress ratio (R 25% ) becomes easier to satisfy.

[0074] Furthermore, the tensile stress at 50% elongation measured when a tensile test is conducted in which the substrate 11 is pulled in its MD direction is preferably 8 MPa or more, particularly preferably 9 MPa or more, and more preferably 10 MPa or more. Furthermore, the tensile stress is preferably 20 MPa or less, particularly preferably 15 MPa or less, and more preferably 13 MPa or less. When the tensile stress is within these ranges, the above-mentioned tensile stress ratio (R 50% ) becomes easier to satisfy.

[0075] Furthermore, the tensile stress at 10% elongation measured when a tensile test is carried out in which the substrate 11 is pulled in its CD direction is preferably 6.5 MPa or more, particularly preferably 7 MPa or more, and more preferably 10 MPa or more. Furthermore, the tensile stress is preferably 20 MPa or less, particularly preferably 15 MPa or less, and more preferably 13 MPa or less. When the tensile stress is within these ranges, the above-mentioned tensile stress ratio (R 10% ) becomes easier to satisfy.

[0076] Furthermore, the tensile stress at 25% elongation measured when a tensile test is carried out in which the substrate 11 is pulled in its CD direction is preferably 7 MPa or more, more preferably 8 MPa or more, and even more preferably 10 MPa or more. Furthermore, the tensile stress is preferably 20 MPa or less, more preferably 15 MPa or less, and even more preferably 13 MPa or less. When the tensile stress is within these ranges, the above-mentioned tensile stress ratio (R 25% ) becomes easier to satisfy.

[0077] Furthermore, the tensile stress at 50% elongation measured when a tensile test is carried out in which the substrate 11 is pulled in its CD direction is preferably 7.5 MPa or more, particularly preferably 7 MPa or more, and more preferably 10 MPa or more. Furthermore, the tensile stress is preferably 20 MPa or less, particularly preferably 15 MPa or less, and more preferably 13 MPa or less. When the tensile stress is within these ranges, the above-mentioned tensile stress ratio (R 50% ) becomes easier to satisfy.

[0078] The details of the method for measuring the tensile stress are as described in the test examples below.

[0079] (1-9) Thickness of each layer of the substrate In this embodiment, the thickness of the surface layer 111 is preferably 1 μm or more, particularly preferably 2 μm or more, and even more preferably 4 μm or more. The thickness of the surface layer 111 is preferably 10 μm or less, particularly preferably 8 μm or less, and even more preferably 4 μm or less. Having the thickness of the surface layer 111 within the above range makes it easier for the workpiece processing sheet 1 to achieve excellent expandability and to impart the desired performance to the workpiece processing sheet 1.

[0080] In this embodiment, the thickness of the intermediate layer 112 is preferably 40 μm or more, particularly preferably 50 μm or more, and even more preferably 60 μm or more. The thickness of the intermediate layer 112 is preferably 100 μm or less, particularly preferably 90 μm or less, and even more preferably 80 μm or less. Having the thickness of the intermediate layer 112 within the above range makes it easier for the workpiece processing sheet 1 to achieve excellent expandability and to impart the desired performance to the workpiece processing sheet 1.

[0081] In this embodiment, the thickness of the back surface layer 113 is preferably 2 μm or more, particularly preferably 4 μm or more, and even more preferably 8 μm or more. The thickness of the back surface layer 113 is preferably 40 μm or less, particularly preferably 30 μm or less, and even more preferably 25 μm or less. Having the thickness of the back surface layer 112 within the above range makes it easier for the workpiece processing sheet 1 to achieve excellent expandability and to impart the desired performance to the workpiece processing sheet 1.

[0082] (2) Adhesive layer The adhesive constituting the adhesive layer 12 in this embodiment is not particularly limited as long as it can exert sufficient adhesive strength to the adherend (particularly, adhesive strength to the workpiece sufficient for processing the workpiece). Examples of adhesives constituting the adhesive layer 12 include acrylic adhesives, rubber adhesives, silicone adhesives, urethane adhesives, polyester adhesives, polyvinyl ether adhesives, etc. Among these, it is preferable to use acrylic adhesives because they can easily exert the desired adhesive strength.

[0083] The adhesive constituting the adhesive layer 12 in this embodiment may be an adhesive that is not active energy ray curable, but is preferably an adhesive that is active energy ray curable (hereinafter, may be referred to as an "active energy ray curable adhesive"). When the adhesive layer 12 is composed of an active energy ray curable adhesive, the adhesive layer 12 can be cured by irradiation with active energy rays, and the adhesive strength of the workpiece processing sheet 1 to the adherend can be easily reduced. In particular, irradiation with active energy rays makes it possible to easily separate the processed workpiece from the workpiece processing sheet 1.

[0084] The active energy ray-curable adhesive constituting the adhesive layer 12 may be one whose main component is a polymer having active energy ray curability, or one whose main component is a mixture of a non-active energy ray-curable polymer (a polymer not having active energy ray curability) and a monomer and / or oligomer having at least one active energy ray-curable group. The active energy ray-curable adhesive may also be a mixture of a polymer having active energy ray curability and a monomer and / or oligomer having at least one active energy ray-curable group.

[0085] The active energy ray-curable polymer is preferably a (meth)acrylic acid ester polymer (hereinafter sometimes referred to as "active energy ray-curable polymer") having an active energy ray-curable functional group (active energy ray-curable group) introduced into its side chain. This active energy ray-curable polymer is preferably one obtained by reacting an acrylic polymer having a functional group-containing monomer unit with an unsaturated group-containing compound having a functional group bonded to the functional group. In this specification, (meth)acrylic acid means both acrylic acid and methacrylic acid. The same applies to other similar terms. Furthermore, the term "polymer" also includes the concept of "copolymer."

[0086] The acrylic polymer having the functional group-containing monomer unit may be obtained by polymerizing other monomers together with the functional group-containing monomer. As such functional group-containing monomers and other monomers, and the unsaturated group-containing compounds, known compounds can be used, for example, those disclosed in WO 2018 / 084021.

[0087] The weight-average molecular weight of the active energy radiation-curable polymer is preferably 10,000 or more, particularly preferably 150,000 or more, and even more preferably 200,000 or more. The weight-average molecular weight is preferably 1,500,000 or less, particularly preferably 1,000,000 or less. The weight-average molecular weight (Mw) in this specification is a value measured by gel permeation chromatography (GPC) in terms of standard polystyrene.

[0088] As the above-mentioned active energy ray non-curable polymer component, for example, the above-mentioned acrylic polymer before being reacted with the unsaturated group-containing compound can be used.

[0089] The weight-average molecular weight of the acrylic polymer as the non-active energy ray-curable polymer component is preferably 10,000 or more, more preferably 150,000 or more, and even more preferably 200,000 or more, and is preferably 1,500,000 or less, and even more preferably 1,000,000 or less.

[0090] Furthermore, as the above-mentioned monomer and / or oligomer having at least one active energy ray-curable group, for example, an ester of a polyhydric alcohol and (meth)acrylic acid can be used.

[0091] When ultraviolet rays are used as the active energy rays for curing the active energy ray-curable adhesive, it is preferable to add a photopolymerization initiator to the adhesive. In addition, the adhesive may also contain an active energy ray-non-curable polymer component or oligomer component, a crosslinking agent, etc.

[0092] In this embodiment, the thickness of the adhesive layer 12 is preferably 1 μm or more, particularly preferably 3 μm or more, and even more preferably 5 μm or more. Furthermore, the thickness of the adhesive layer 12 is preferably 70 μm or less, particularly preferably 30 μm or less, and even more preferably 15 μm or less. By keeping the thickness of the adhesive layer 12 within the above-mentioned range, the workpiece processing sheet 1 according to this embodiment can easily exhibit the desired adhesiveness.

[0093] (3) Release sheet In the workpiece processing sheet 1 of this embodiment, a release sheet may be laminated on the side of the adhesive layer 12 opposite the substrate 11 (hereinafter sometimes referred to as the "adhesive side") in order to protect that side until it is attached to the workpiece.

[0094] The release sheet may have any configuration, and may be, for example, a plastic film that has been subjected to a release treatment using a release agent or the like. Specific examples of such plastic films include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, and polyolefin films such as polypropylene and polyethylene. Silicone-based, fluorine-based, and long-chain alkyl-based release agents can be used, and among these, silicone-based ones are preferred because they are inexpensive and provide stable performance.

[0095] There are no particular limitations on the thickness of the release sheet, and it may be, for example, 16 μm or more and 250 μm or less.

[0096] (4) Other In the workpiece processing sheet 1 according to this embodiment, an adhesive layer may be laminated on the surface of the adhesive layer 12 opposite the substrate 11. In this case, the workpiece processing sheet 1 according to this embodiment can be used as a dicing / die bonding sheet. A workpiece is attached to the surface of the adhesive layer opposite the adhesive layer 12, and the adhesive layer is diced together with the workpiece to obtain a chip on which the individual adhesive layers are laminated. The individual adhesive layers allow the chip to be easily fixed to the object on which it is to be mounted. The material constituting the adhesive layer described above is preferably a material containing a thermoplastic resin and a low-molecular-weight thermosetting adhesive component, or a material containing a B-stage (semi-cured) thermosetting adhesive component.

[0097] Furthermore, in the workpiece processing sheet 1 according to this embodiment, a protective film forming layer may be laminated on the adhesive surface of the adhesive layer 12. In this case, the workpiece processing sheet 1 according to this embodiment can be used as a sheet for both protective film formation and dicing. With such a sheet, a workpiece is attached to the surface of the protective film forming layer opposite the adhesive layer 12, and the protective film forming layer is diced together with the workpiece to obtain a chip on which a singulated protective film forming layer is laminated. The workpiece preferably has a circuit formed on one side. In this case, the protective film forming layer is typically laminated on the side opposite the side on which the circuit is formed. The singulated protective film forming layer can be cured at a predetermined time to form a protective film with sufficient durability on the chip. The protective film forming layer is preferably made of an uncured curable adhesive.

[0098] 2. Manufacturing method of workpiece processing sheet There are no particular limitations on the method for producing the workpiece processing sheet 1 according to this embodiment. For example, it is preferable to obtain the workpiece processing sheet 1 by forming an adhesive layer 12 on a release sheet, and then laminating one side of the substrate 11 on the surface of the adhesive layer 12 opposite to the release sheet.

[0099] The pressure-sensitive adhesive layer 12 can be formed by a known method. For example, a coating liquid containing a pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer 12 and, if desired, a solvent or dispersion medium is prepared. The coating liquid is then applied to the releasable surface of a release sheet (hereinafter sometimes referred to as the "release surface"). The resulting coating film is then dried to form the pressure-sensitive adhesive layer 12.

[0100] The coating liquid can be applied by a known method, such as bar coating, knife coating, roll coating, blade coating, die coating, or gravure coating. The properties of the coating liquid are not particularly limited as long as it allows application, and the liquid may contain components for forming the pressure-sensitive adhesive layer 12 as a solute or as a dispersoid. The release sheet may be peeled off as a processing material, or may protect the pressure-sensitive adhesive layer 12 until it is attached to the adherend.

[0101] When the adhesive composition for forming the adhesive layer 12 contains the above-mentioned crosslinking agent, it is preferable to change the above-mentioned drying conditions (temperature, time, etc.) or to separately perform a heat treatment to promote the crosslinking reaction between the polymer component in the coating film and the crosslinking agent, thereby forming a crosslinked structure with a desired density in the adhesive layer 12. Furthermore, in order to promote the above-mentioned crosslinking reaction sufficiently, after the adhesive layer 12 and the substrate 11 are bonded together, curing may be performed, for example, by leaving the adhesive layer 12 to stand in an environment of 23°C and a relative humidity of 50% for several days.

[0102] 3. How to use the workpiece processing sheet The workpiece processing sheet 1 according to this embodiment can be used for processing workpieces such as semiconductor wafers. That is, after the adhesive surface of the workpiece processing sheet 1 according to this embodiment is attached to the workpiece, the workpiece can be processed on the workpiece processing sheet 1. Depending on the processing, the workpiece processing sheet 1 according to this embodiment can be used as a back-grinding sheet, dicing sheet, expanding sheet, pickup sheet, etc. Examples of workpieces include semiconductor components such as semiconductor wafers and semiconductor packages, and glass components such as glass plates.

[0103] As described above, the workpiece processing sheet 1 according to this embodiment exhibits excellent expandability, and is therefore particularly suitable for use as a dicing sheet, an expanding sheet, or a pickup sheet among the above-mentioned workpiece processing sheets.

[0104] When the workpiece processing sheet 1 according to this embodiment has the adhesive layer described above, the workpiece processing sheet 1 can be used as a dicing / die bonding sheet. Furthermore, when the workpiece processing sheet 1 according to this embodiment has the protective film forming layer described above, the workpiece processing sheet 1 can be used as a protective film forming / dicing sheet.

[0105] Furthermore, when the adhesive layer 12 in the workpiece processing sheet 1 according to this embodiment is composed of the aforementioned active energy ray-curable adhesive, it is also preferable to irradiate the adhesive layer 12 with active energy rays during use. That is, when processing of a workpiece on the workpiece processing sheet 1 is completed and the processed workpiece is to be separated from the workpiece processing sheet 1, it is preferable to irradiate the adhesive layer 12 with active energy rays before the separation. This hardens the adhesive layer 12, effectively reducing the adhesive strength of the adhesive sheet to the processed workpiece, and facilitating separation of the processed workpiece.

[0106] The above-described embodiments have been described to facilitate understanding of the present invention, and are not intended to limit the present invention. Therefore, each element disclosed in the above embodiments is intended to include all design modifications and equivalents that fall within the technical scope of the present invention.

[0107] For example, in the workpiece processing sheet 1 according to this embodiment, another layer may be laminated between the base material 11 and the adhesive layer 12, or on the surface of the base material 11 opposite the adhesive layer 12. In addition, another layer may be laminated on the surface of the surface layer 111 opposite the intermediate layer 112, between the surface layer 111 and the intermediate layer 112, between the intermediate layer 112 and the back layer 113, and on the surface of the back layer 113 opposite the intermediate layer 112. [Example]

[0108] The present invention will be explained in more detail below with reference to examples, but the scope of the present invention is not limited to these examples.

[0109] Example 1 (1) Preparation of substrate 45 parts by mass of random polypropylene resin (manufactured by Japan Polypropylene Corporation, product name "Novatec FX3B"), 16 parts by mass of olefin-based thermoplastic elastomer (manufactured by Japan Polypropylene Corporation, product name "Wellnex RFX4V"), 15 parts by mass of acid-modified resin (manufactured by SK Functional Polymers, product name "BONDINE LX4110", ethyl acrylate content: 5% by mass, acid component content: 3% by mass), and 25 parts by mass of antistatic agent (manufactured by Sanyo Chemical Industry Co., Ltd., product name "Pelectron PVH") were each dried and then kneaded in a twin-screw kneader to obtain pellets for the surface layer.

[0110] Furthermore, 28 parts by mass of random polypropylene resin (manufactured by Japan Polypropylene Corporation, product name "Novatec FX3B"), 39 parts by mass of olefin-based thermoplastic elastomer (manufactured by Japan Polypropylene Corporation, product name "Wellnex RFX4V"), and 33 parts by mass of styrene-based thermoplastic elastomer (manufactured by Asahi Kasei Corporation, product name "Tuftec H1041", styrene-ethylene / butylene-styrene copolymer, styrene ratio: 30 wt%) were dried and then kneaded in a twin-screw kneader to obtain pellets for the intermediate layer.

[0111] Furthermore, 70 parts by mass of an olefin-based thermoplastic elastomer (manufactured by Japan Polypropylene Corporation, product name "Wellnex RFX4V") and 30 parts by mass of an antistatic agent (manufactured by Sanyo Chemical Industry Co., Ltd., product name "Pelectron PVH") were each dried and then kneaded in a twin-screw kneader to obtain pellets for the back layer.

[0112] The three types of pellets obtained as described above were co-extruded using a small T-die extruder (manufactured by Toyo Seiki Seisakusho, product name "Labo Plastomill") to obtain a three-layer substrate consisting of a 4 μm thick surface layer, a 64 μm thick middle layer, and a 12 μm thick back layer laminated in that order.

[0113] (2) Preparation of adhesive composition A (meth)acrylic acid ester polymer was obtained by polymerizing 62 parts by weight of n-butyl acrylate, 10 parts by weight of methyl methacrylate, and 28 parts by weight of 2-hydroxyethyl acrylate by solution polymerization. Subsequently, 2-methacryloyloxyethyl isocyanate (MOI) was added in an amount equivalent to 80 mol% of the 2-hydroxyethyl acrylate constituting the (meth)acrylic acid ester polymer, and dibutyltin dilaurate (DBTDL) was added as a tin-containing catalyst in an amount of 0.13 parts by weight per 100 parts by weight of the (meth)acrylic acid ester polymer. The mixture was then allowed to react at 50°C for 24 hours to obtain a (meth)acrylic acid ester polymer having active energy ray-curable groups introduced into its side chains. The weight-average molecular weight of the active energy ray-curable polymer was measured using the method described below and found to be 500,000.

[0114] 100 parts by mass (solid content equivalent, same below) of the (meth)acrylic acid ester polymer obtained above, having active energy ray-curable groups introduced into the side chains, 2 parts by mass of 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one (manufactured by BASF, product name "Omnirad 127") as a photopolymerization initiator, and 1 part by mass of trimethylolpropane-modified tolylene diisocyanate (manufactured by Tosoh Corporation, product name "Coronate L") as a crosslinking agent were mixed in a solvent to obtain a coating liquid of an adhesive composition.

[0115] (3) Formation of adhesive layer The adhesive composition coating solution obtained in step (2) above was applied to the release surface of a release sheet (manufactured by Lintec Corporation, product name "SP-PET381031"), which was made of a 38 μm thick polyethylene terephthalate film with a silicone-based release agent layer formed on one side, and the resulting mixture was dried by heating to obtain a laminate in which a 5 μm thick adhesive layer was formed on the release sheet.

[0116] (4) Preparation of adhesive sheet After corona treatment was applied to the surface layer side of the substrate obtained in the above step (1), the corona-treated surface was bonded to the adhesive layer side of the laminate obtained in the above step (3) to obtain a work processing sheet.

[0117] Here, the weight average molecular weight (Mw) is a weight average molecular weight measured using gel permeation chromatography (GPC) under the following conditions (GPC measurement) and converted into standard polystyrene. <Measurement conditions> Measurement equipment: Tosoh HLC-8320 GPC columns (passed in the following order): Tosoh Corporation TSK gel superH-H TSK gel super HM-H TSK gel superH2000 Measurement solvent: tetrahydrofuran ·Measurement temperature: 40℃

[0118] Example 2 Low-density polyethylene (Ube Industries, Ltd., product name "F244N", melt flow rate: 2 g / 10 min) for the surface layer and back layer, and low-density polyethylene (Ube Industries, Ltd., product name "F522A", low-density polyethylene, melt flow rate: 5 g / 10 min) for the middle layer were co-extruded using a small T-die extruder (Toyo Seiki Seisakusho, product name "Labo Plastomill") to obtain a three-layer substrate consisting of a 21 μm thick surface layer, a 28 μm thick middle layer, and a 21 μm thick back layer laminated in that order. A workpiece processing sheet was obtained in the same manner as in Example 1, except that this substrate was used.

[0119] Example 3 28 parts by mass of random polypropylene resin (manufactured by Japan Polypropylene Corporation, product name "Novatec FX3B"), 45 parts by mass of olefin-based thermoplastic elastomer (manufactured by Japan Polypropylene Corporation, product name "Wellnex RFX4V"), and 30 parts by mass of antistatic agent (manufactured by Sanyo Chemical Industry Co., Ltd., product name "Pelectron PVH") were dried and then kneaded in a twin-screw kneader to obtain pellets for the surface layer.

[0120] In addition, 38 parts by mass of random polypropylene resin (manufactured by Japan Polypropylene Corporation, product name "Novatec FX3B") and 62 parts by mass of olefin-based thermoplastic elastomer (manufactured by Japan Polypropylene Corporation, product name "Wellnex RFX4V") were each dried and then kneaded in a twin-screw kneader to obtain pellets for the intermediate layer.

[0121] Furthermore, 65 parts by mass of an olefin-based thermoplastic elastomer (manufactured by Japan Polypropylene Corporation, product name "Wellnex RFX4V") and 35 parts by mass of an antistatic agent (manufactured by Sanyo Chemical Industry Co., Ltd., product name "Pelectron PVH") were each dried and then kneaded in a twin-screw kneader to obtain pellets for the back layer.

[0122] The three pellets obtained as described above were co-extruded using a small T-die extruder (manufactured by Toyo Seiki Seisakusho, product name "Labo Plastomill") to obtain a three-layer substrate consisting of a 4 μm thick surface layer, a 68 μm thick middle layer, and an 8 μm thick back layer laminated in that order. A workpiece processing sheet was obtained in the same manner as in Example 1, except that this substrate was used.

[0123] Comparative Example 1 Ethylene-methacrylic acid copolymer (EMAA) (manufactured by DuPont-Mitsui Polychemicals, product name "Nucrel N0903HC") was extruded using a small T-die extruder (manufactured by Toyo Seiki Seisakusho, product name "Labo Plastomill") to obtain an 80 μm-thick EMAA film. A workpiece processing sheet was obtained in the same manner as in Example 1, except that the EMAA film was used as the substrate.

[0124] Comparative Example 2 One side of an EMAA film prepared in the same manner as in Comparative Example 1 was irradiated with an electron beam under the following conditions. A workpiece processing sheet was obtained in the same manner as in Example 1, except that the EMAA film after electron beam irradiation was used as a substrate and an adhesive layer was laminated on the surface of the substrate that had been irradiated with the electron beam. Electron beam irradiation conditions Irradiation amount: 110kGy Number of irradiations: 1 Total irradiation dose: 110kGy

[0125] [Test Example 1] (Measurement of breaking elongation) The substrates prepared in the examples and comparative examples were cut into 15 mm × 150 mm test pieces. At this time, the 150 mm side was parallel to the MD direction (flow direction during the production of the substrate) of the substrate, and the 15 mm side was parallel to the CD direction (direction perpendicular to the MD direction) of the substrate (hereinafter, the test pieces may be referred to as "MD test pieces"). Then, the breaking elongation of the MD test pieces was measured in accordance with JIS K7127:1999.

[0126] Specifically, the MD test piece was placed in a tensile tester (Shimadzu Corporation, product name "Autograph AG-Xplus 100N") with a chuck distance of 100 mm, and then subjected to a tensile test in which the test piece was pulled in the long side direction (MD) of the substrate at a speed of 200 mm / min in an environment of 23°C, and the breaking elongation (%) was measured. The results are shown in Table 2 as breaking elongation in the MD direction.

[0127] In addition, the substrate was cut in the same manner as above, except that the MD and CD directions were reversed, to obtain test pieces (hereinafter, these test pieces may be referred to as "CD test pieces"). The breaking elongation (%) of the CD test pieces was also measured in the same manner as above. The results are shown in Table 2 as breaking elongation in the CD direction.

[0128] [Test Example 2] (Measurement of tensile stress and its ratio) For MD test pieces prepared in the same manner as in Test Example 1, a tensile test was performed in accordance with JIS K7127:1999 using a tensile testing machine (Shimadzu Corporation, product name "Autograph AG-Xplus 100N"), with a chuck distance of 100 mm, at 23°C and a rate of 200 mm / min. The MD test pieces were pulled in the longitudinal direction (MD direction) at a tensile elongation rate (%) of 0% to 150% and the change in tensile stress (MPa) was measured. The tensile stress (MPa) was recorded at 10%, 25%, and 50% elongation. These tensile stresses are shown in Table 2 as MD tensile stresses.

[0129] Furthermore, a tensile test was conducted in the same manner as in Test Example 1, in which the CD test piece was pulled in the long side direction (CD direction) as described above. The change in tensile stress (MPa) was measured as the tensile elongation (%) increased from 0% to 150%. The tensile stress (MPa) was recorded at elongations of 10%, 25%, and 50%. These tensile stresses are shown in Table 2 as the tensile stress in the CD direction.

[0130] The ratio of the tensile stress in the MD direction at 10% elongation to the tensile stress in the CD direction at 10% elongation (R 10% ) was calculated. Similarly, the tensile stress ratio (R 25% ), and the ratio of tensile stress at 50% elongation (R 50% ) were calculated. These results are also shown in Table 2.

[0131] [Test Example 3] (Evaluation of expandability) One side of a 6-inch silicon wafer was ground to a thickness of 350 μm using a grinder (manufactured by Disco Corporation, product name "DFG8540"), and the exposed surface of the adhesive layer exposed by peeling the release sheet from the workpiece processing sheet produced in the Examples and Comparative Examples was attached to the ground surface using a laminator.

[0132] Twenty minutes after attachment, the silicon wafer was diced into individual chips using a dicing device (manufactured by Disco Corporation, product name "DFD6362") under the following dicing conditions. Dicing Conditions Chip size: 5mm x 5mm Cutting Height Z1: 0.135 mm Z2: 0.060mm Blades: Z1 and Z2 (both manufactured by Disco) Z1: Product name "ZH05-SD3000-50DD" Z2: Product name “NBC-SD3000-50BB” Blade rotation speed Z1: 30,000 rpm Z2: 45,000 rpm Cutting speed: 20mm / sec Cutting water amount: 1.0L / min Cutting water temperature: 20℃

[0133] Thereafter, an ultraviolet irradiation device (manufactured by Lintec Corporation, product name "RAD-2000") was used to irradiate the adhesive layer of the workpiece processing sheet with ultraviolet light through the substrate in a nitrogen atmosphere (light intensity 160 mJ / cm2).2 ), and the adhesive layer was cured.

[0134] The workpiece processing sheet with the diced chips and ring frame attached was then placed in an expanding device (Hugle Electronics, product name "HS-1840"), and the ring frame was pulled down at a speed of 1 mm / sec until the workpiece processing sheet broke. The amount of pull-down (mm) at break was then recorded. If the sheet did not break even after reaching the device's pull-down limit (80 mm), it was recorded as ">80 mm." Furthermore, the expandability was evaluated based on the following criteria. The amount of pull-down at break and the evaluation results are shown in Table 2. ◯: The amount of pull-down at the time of breakage was 20 mm or more. ×: The amount of pull-down at break was less than 20 mm.

[0135] [Table 1]

[0136] [Table 2]

[0137] As is clear from Table 2, the workpiece processing sheets produced in the examples exhibited excellent expandability. [Industrial Applicability]

[0138] The workpiece processing sheet of the present invention can be suitably used for processing workpieces such as semiconductor wafers. [Explanation of symbols]

[0139] 1...Work processing sheet 11...Base material 111…Surface layer 112...Middle class 113...Back layer 12...Adhesive layer

Claims

1. A workpiece processing sheet comprising a substrate and an adhesive layer laminated on one side of the substrate, the substrate comprises a surface layer located proximal to the pressure-sensitive adhesive layer, a back layer located distal to the pressure-sensitive adhesive layer, and an intermediate layer located between the surface layer and the back layer; each of the surface layer, the intermediate layer, and the back layer contains a polyolefin resin and a thermoplastic elastomer; each of the front surface layer and the back surface layer contains an antistatic agent; The substrate is cut into a strip having a short side of 15 mm, and a tensile test is carried out on the resulting test piece at a chuck distance of 100 mm and a tensile speed of 200 mm / min in an environment of 23°C. The breaking elongation measured when the test piece is pulled in the MD direction and the CD direction is 600% or more, The ratio of the tensile stress at 25% elongation measured when a tensile test is performed in which the substrate is pulled in the MD direction to the tensile stress at 25% elongation measured when a tensile test is performed in which the substrate is pulled in the CD direction (R ２５％ ) is 1.3 or less, The ratio of the tensile stress at 50% elongation measured when a tensile test is performed in which the substrate is pulled in the MD direction to the tensile stress at 50% elongation measured when a tensile test is performed in which the substrate is pulled in the CD direction (R ５０％ ) is 1.3 or less A workpiece processing sheet characterized by:

2. The intermediate layer does not contain the antistatic agent, or The intermediate layer contains the antistatic agent in a content (unit: mass %) that is smaller than that of each of the front surface layer and the back surface layer.

2. The workpiece processing sheet according to claim 1.

3. each of the surface layer, the intermediate layer, and the back layer contains polyethylene; The polyethylene contained in the intermediate layer has a melt flow rate (MFR) measured in accordance with JIS K7210-1 different from that of the polyethylene contained in the surface layer and the back layer.

2. The workpiece processing sheet according to claim 1.

4. A work processing sheet as described in Claim 3, characterized in that the melt flow rate of the polyethylene contained in the intermediate layer is greater than the melt flow rate of each of the polyethylenes contained in the surface layer and the back layer.

5. 5. The workpiece processing sheet according to claim 1, which is a dicing sheet.

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