KR20240110981A - Workpiece processing sheet - Google Patents

Abstract

A work processing sheet including a base material and an adhesive layer, wherein the adhesive layer is composed of an active energy ray-curable adhesive, the adhesive force of the work processing sheet to a silicon wafer is set to F0, and the work processing sheet is attached to a silicon wafer. After the laminate formed by combining the laminate is heated at 150° C. for 1 hour and the adhesive layer constituting the laminate is irradiated with active energy rays, when the adhesive force of the work processing sheet to the silicon wafer is set to F2, the adhesive force F0 is A sheet for work processing that is between 600 mN/25 mm and 20000 mN/25 mm, and the ratio of adhesive force F2 to adhesive force F0 (F2/F0) is 0.66 or lower. According to this sheet for work processing, sufficient adhesive force to the work is exhibited during processing of the work, and after heat treatment, the processed work can be separated satisfactorily.

Description

Sheet for work processing {WORKPIECE PROCESSING SHEET}

The present invention relates to a sheet for work processing that can be suitably used for dicing.

Semiconductor wafers such as silicon and gallium arsenide and various packages (hereinafter, these may be collectively referred to as “works”) are manufactured in a large-diameter state, and these are device small pieces (hereinafter referred to as “chips”). After being cut and separated (diced) and individually separated (picked up), they are transferred to the next process, the mount process. At this time, the work such as a semiconductor wafer is attached to a work processing sheet provided with a base material and an adhesive layer and is subjected to each process of dicing, cleaning, drying, expansion, pickup, and mounting. Such a sheet for work processing is required to have the ability to maintain the work well on the sheet during processing and to easily separate the processed work from the sheet.

The chip obtained as described above may be subsequently subjected to heat treatment. For example, there are cases where chips are subjected to processes such as vapor deposition, sputtering, and baking for dehumidification. Additionally, if the chip is expected to be used in a high-temperature environment, a heating test may be performed to confirm reliability in such an environment. Usually, this heat treatment is performed with the obtained chip placed on a heating tray.

Recently, conducting the heat treatment of chips as described above on a sheet for work processing has been studied. That is, after dicing a workpiece on a workpiece processing sheet, heat treatment is being conducted on the chips while they are placed on the workpiece processing sheet, rather than transferring the obtained chips to a heating tray. In this case, the process can be simplified.

Patent Documents 1 to 3 disclose adhesive sheets that are assumed to be subjected to the heat treatment described above. In particular, the adhesive sheet disclosed in Patent Document 1 has a base material layer and an adhesive layer made of a radiation-curing adhesive, and the adhesive layer has an adhesive force to SUS304 after bonding of 0.5 N/20 mm or more, and the resin It hardens due to stimulation received until the completion of the encapsulation process, forming a layer whose peeling force from the package is 2.0 N/20 mm or less. In addition, in the adhesive sheet disclosed in Patent Document 2, the adhesive layer is formed from an adhesive composition containing a predetermined adhesive component and a predetermined tetrazole compound. In addition, in the pressure-sensitive adhesive sheet disclosed in Patent Document 3, a pressure-sensitive adhesive layer made of a pressure-sensitive adhesive layer-forming material containing a predetermined acrylic polymer, an energy ray-polymerizable oligomer, a predetermined polymerization initiator, and a crosslinking agent is formed on a heat-resistant substrate. there is.

Japanese Patent No. 5144634 Japanese Patent No. 5555578 Japanese Patent No. 5565173

However, when the heat treatment of chips as described above is performed on a conventional workpiece processing sheet, the adhesion of the workpiece processing sheet to the chip is improved by heating, and as a result, chips cannot be picked up favorably from the sheet after the heat treatment. There was a problem where it couldn't be done. This problem could not be sufficiently solved even if an adhesive sheet having a predetermined heat resistance disclosed in Patent Documents 1 to 3 was used.

The present invention is made in view of this actual situation, and aims to provide a workpiece processing sheet that exhibits sufficient adhesive force to the workpiece during processing of the workpiece and is capable of separating the processed workpiece well after heat treatment. The purpose.

In order to achieve the above object, the first invention is a sheet for work processing comprising a base material and an adhesive layer laminated on one side of the base material, wherein the adhesive layer is composed of an active energy ray-curable adhesive, , the adhesive force of the work processing sheet to the silicon wafer is set to F0, and the laminate formed by bonding the work processing sheet to the silicon wafer is heated at 150° C. for 1 hour, and then the adhesive layer constituting the laminate is heated. After further irradiation of active energy rays, when the adhesive force of the work processing sheet to the silicon wafer is set to F2, the adhesive force F0 is 600 mN/25 mm or more and 20000 mN/25 mm or less, and the adhesive force with respect to the adhesive force F0 A sheet for work processing is provided, wherein the ratio of F2 (F2/F0) is 0.66 or less (invention 1).

In the sheet for work processing according to the invention (invention 1), the adhesive force F0 described above is within the above range, and sufficient adhesive force can be exhibited to the work when processing the work. On the other hand, since the adhesive layer is composed of an active energy ray-curable adhesive and the above-mentioned adhesive force ratio (F2/F0) is within the above range, the sheet for work processing is heated while the workpiece after processing is attached. Even in this case, by subsequently irradiating active energy rays, the adhesive force to the processed work can be sufficiently reduced, and as a result, the processed work can be separated satisfactorily.

In the above invention (invention 1), after heating the workpiece processing sheet at 150°C for 1 hour, the Young's modulus of the adhesive layer at 23°C is set to E1, and after heating the workpiece processing sheet at 150°C for 1 hour, After further irradiating active energy rays to the adhesive layer constituting the work processing sheet, when the Young's modulus of the adhesive layer at 23°C is E2, the ratio of the Young's modulus E2 to the Young's modulus E1 (E2/E1 ) is preferably 13 or more (invention 2).

In the above inventions (inventions 1 and 2), the Young's modulus at 23°C of the adhesive layer in the work processing sheet is set to E0, and after heating the work processing sheet at 150°C for 1 hour, the pressure-sensitive adhesive layer is heated at 23°C. When the Young's modulus is E1, the ratio (E1/E0) of the Young's modulus E1 to the Young's modulus E0 is preferably 2.0 or more (Invention 3).

The second invention is a sheet for work processing comprising a base material and an adhesive layer laminated on one side of the base material, wherein the adhesive layer is composed of an active energy ray-curable adhesive, and the active energy ray-curable adhesive is The glass transition temperature is -50°C or higher and 10°C or lower, and the active energy ray-curable adhesive includes an acrylic copolymer containing a monomer having a polar group as a constituent monomer. Provided is a sheet for work processing, characterized in that ( Invention 4).

In the above invention (invention 4), the acrylic copolymer preferably has a functional group having active energy ray curability introduced into the side chain (invention 5).

In the above inventions (inventions 1 to 5), it is preferable that it is a dicing sheet (invention 6).

The workpiece processing sheet according to the present invention exhibits sufficient adhesive force to the workpiece when processing the workpiece, and can also satisfactorily separate the processed workpiece after heat treatment.

Hereinafter, embodiments of the present invention will be described.

The sheet for work processing according to the present embodiment includes a base material and an adhesive layer laminated on one side of the base material. Additionally, the adhesive layer is composed of an active energy ray-curable adhesive.

1. Physical properties of sheet for work processing

(1) Adhesion

In the work processing sheet according to the present embodiment, when the adhesive force of the work processing sheet to the silicon wafer is F0, the adhesive force F0 is preferably 600 mN/25 mm or more, and particularly preferably 900 mN/25 mm or more. And, it is also preferably 1200 mN/25 mm or more. Additionally, the adhesive force F0 is preferably 20000 mN/25 mm or less, especially 5000 mN/25 mm or less, and further preferably 3000 mN/25 mm or less. In addition, the adhesive force F0 refers to the initial adhesive force measured on a workpiece processing sheet that has not been subjected to treatment such as heating or active energy ray irradiation, which will be described later.

In the workpiece processing sheet according to the present embodiment, the adhesive force F0 is within the above range, so that the workpiece can be well maintained on the workpiece processing sheet. For this reason, when machining a workpiece, for example, even if an impact occurs during machining, movement or dropping of the workpiece after machining can be well suppressed. In particular, when the adhesive force F0 is 600 mN/25 mm or more, it becomes easy to maintain the workpiece well during processing. On the other hand, when the adhesive force F0 is 20000 mN/25 mm or less, when the sheet for work processing is irradiated with active energy rays, which will be described later, it becomes easy to sufficiently reduce the adhesive force to the processed work, and as a result, the adhesive force to the processed work is easily reduced. It becomes easier to separate from the processing sheet.

In the sheet for work processing according to the present embodiment, a laminate formed by bonding the sheet for work processing to a silicon wafer is heated at 150° C. for 1 hour, and then the adhesive layer constituting the laminate is further irradiated with active energy rays. When the adhesion of the sheet for work processing to the silicon wafer is F2, the ratio (F2/F0) of the adhesive force F2 to the adhesive force F0 described above is preferably 0.66 or less, particularly preferably 0.2 or less, and further preferably 0.15 or less. desirable. When the ratio (F2/F0) is 0.66 or less, it becomes easy to achieve both good maintenance of the workpiece during processing and separation of the workpiece after processing after irradiation with active energy rays. In particular, even when the work processing sheet is exposed to heat treatment while the processed work is stuck on the work processing sheet, it becomes easy to separate the processed work from the work processing sheet with good results. Additionally, the lower limit of the ratio (F2/F0) is not particularly limited, but may be, for example, 0.01 or more.

In the sheet for work processing according to the present embodiment, the above-described adhesive force F2 is preferably 1000 mN/25 mm or less, particularly preferably 500 mN/25 mm or less, and further preferably 150 mN/25 mm or less. Additionally, the adhesive force F2 is preferably 30 mN/25 mm or more. When the adhesive force F2 is in the above range, it becomes easy to adjust the ratio (F2/F0) to the above range.

In the work processing sheet related to the present embodiment, when the adhesive force of the work processing sheet to the silicon wafer is set to F1 after a laminate formed by bonding the work processing sheet to a silicon wafer is heated at 150° C. for 1 hour, the adhesive force F1 It is preferably 1000 mN/25 mm or more, and especially 2300 mN/25 mm or more. Additionally, the adhesive force F1 is preferably 5000 mN/25 mm or less. When the adhesive force F1 is within the above range, it becomes easy to adjust the ratio (F2/F0) to the above range.

In addition, the details of each measurement method for the above-mentioned adhesive forces F0, F1, and F2 are as described in the test examples described later.

(2) Young’s modulus

In the workpiece processing sheet according to the present embodiment, after heating the workpiece processing sheet at 150°C for 1 hour, the Young's modulus of the adhesive layer at 23°C is set to E1, and after heating the workpiece processing sheet at 150°C for 1 hour, After further irradiating active energy rays to the adhesive layer constituting the work processing sheet, when the Young's modulus of the adhesive layer at 23°C is E2, the ratio of the Young's modulus E2 to the Young's modulus E1 (E2/E1) It is preferably 13 or more, especially 15 or more, and further preferably 18 or more.

As described above, the adhesive layer in this embodiment is comprised of an active energy ray-curable adhesive. In general, the component for achieving active energy ray curability present in an active energy ray curable adhesive may undergo a predetermined reaction when heated, and as a result, curing of the adhesive may progress. For example, when the above component is an acryloyl group, the carbon-carbon double bond in the acryloyl group may be split by heating, and a polymerization reaction may proceed. In this way, when the reaction of the above components proceeds by heating, further curing of the adhesive layer does not proceed satisfactorily even if active energy rays are applied afterwards. However, in the sheet for work processing according to the present embodiment, if the ratio (E2/E1) is in the above range, the adhesive strength is easily reduced to a good degree by irradiation of active energy rays even after heat treatment. For this reason, unintentional dropping of the workpiece after processing can be effectively suppressed before irradiation with active energy rays.

Additionally, the upper limit of the ratio (E2/E1) is not particularly limited, and may be, for example, 25 or less.

In the work processing sheet according to the present embodiment, when the Young's modulus of the adhesive layer in the work processing sheet at 23°C is E0, the ratio (E1/E0) of the Young's modulus E1 to the Young's modulus E0 is 2.0 or more. It is preferable, and it is especially preferable that it is 2.3 or more, and it is further preferable that it is 2.6 or more. In addition, the Young's modulus E0 refers to the initial Young's modulus measured on the adhesive layer that has not been subjected to treatment such as heating or active energy ray irradiation.

Generally, when an adhesive is heated, it softens and tends to increase adhesion to the adherend. However, in the workpiece processing sheet according to the present embodiment, if the ratio (E1/E0) is within the above range, softening of the adhesive due to heating is unlikely to occur, and excessive improvement in adhesion due to heat treatment can be effectively suppressed. do. As a result, it becomes easy to separate the processed workpiece satisfactorily after irradiating the adhesive layer with active energy rays.

Additionally, the upper limit of the ratio (E1/E0) is not particularly limited, and may be, for example, 3.5 or less.

In the sheet for work processing according to the present embodiment, the Young's modulus E0 described above is preferably 2.0 MPa or more, particularly preferably 2.3 MPa or more, and further preferably 2.5 MPa or more. Additionally, the Young's modulus E0 is preferably 15 MPa or less, particularly preferably 10 MPa or less, and further preferably 5 MPa or less. Since the Young's modulus E0 is in the above range, it becomes easy to adjust the ratio (E1/E0) to the above range.

In the sheet for work processing according to the present embodiment, the Young's modulus E1 described above is preferably 5.0 MPa or more, particularly preferably 6.0 MPa or more, and further preferably 7.0 MPa or more. Additionally, the Young's modulus E1 is preferably 100 MPa or less, particularly preferably 50 MPa or less, and further preferably 10 MPa or less. Since the Young's modulus E1 is in the above range, it becomes easy to adjust the ratio (E2/E1) and the ratio (E1/E0) to the above-mentioned ranges, respectively.

In the sheet for work processing according to the present embodiment, the Young's modulus E2 described above is preferably 100 MPa or more, particularly preferably 130 MPa or more, and further preferably 140 MPa or more. Additionally, the Young's modulus E2 is preferably 300 MPa or less, particularly preferably 250 MPa or less, and further preferably 200 MPa or less. Since the Young's modulus E2 is in the above range, it becomes easy to adjust the ratio (E2/E1) to the above range.

In addition, the details of each measurement method for the Young's modulus E0, E1, and E2 described above are as described in the test examples described later.

2. Components of sheet for work processing

(1) Description

In the work processing sheet according to the present embodiment, the base material exhibits a desired function in the use process of the work processing sheet, and preferably exhibits good permeability to active energy rays irradiated for curing of the adhesive layer. At the same time, there is no particular limitation as long as it has a predetermined heat resistance.

For example, the base material is preferably a resin film mainly made of a resin-based material, and specific examples include ethylene-vinyl acetate copolymer film; Ethylene-based copolymer films such as ethylene-(meth)acrylic acid copolymer film, ethylene-methyl (meth)acrylate copolymer film, and other ethylene-(meth)acrylic acid ester copolymer films; Polyolefin-based films such as polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, ethylene norbornene copolymer film, norbornene resin film, and cycloolefin resin film; Polyvinyl chloride-based films such as polyvinyl chloride film and vinyl chloride copolymer film; Polyester-based films such as polyethylene terephthalate film, polybutylene terephthalate film, polycyclohexylene dimethylene terephthalate, and polyethylene naphthalate; (meth)acrylic acid ester copolymer film; polyurethane film; polyimide film; polystyrene film; polycarbonate film; fluororesin film; Polyphenylene sulfide film, etc. can be mentioned. Examples of polyethylene films include low-density polyethylene (LDPE) films, linear low-density polyethylene (LLDPE) films, and high-density polyethylene (HDPE) films. Additionally, modified films such as crosslinked films and ionomer films are also used. In addition, the base material may be a laminated film formed by laminating multiple films described above. In this laminated film, the materials constituting each layer may be of the same type or may be of different types. As a base material, among the above films, an annealed polyester film, a heat-resistant polyester film, a polycarbonate film, a polyphenylene sulfide film, and a cycloolefin resin film are selected from the viewpoint of excellent permeability of active energy rays and heat resistance. It is desirable to use . In addition, “(meth)acrylic acid” in this specification means both acrylic acid and methacrylic acid. The same goes for other similar terms.

The base material may contain various additives such as a flame retardant, a plasticizer, an antistatic agent, a lubricant, an antioxidant, a colorant, an infrared absorber, an ultraviolet ray absorber, and an ion trap. The content of these additives is not particularly limited, but is preferably within a range that allows the base material to exhibit the desired function.

The surface of the substrate on which the adhesive layer is laminated may be subjected to surface treatment such as primer treatment, corona treatment, or plasma treatment in order to increase adhesion to the adhesive layer.

The thickness of the base material can be appropriately set depending on the method in which the sheet for work processing is used, but is usually preferably 20 μm or more, and particularly preferably 25 μm or more. In addition, the thickness is usually preferably 450 μm or less, and particularly preferably 300 μm or less.

(2) Adhesive layer

In the sheet for work processing according to the present embodiment, the adhesive layer is composed of an active energy ray-curable adhesive. Since the adhesive layer is composed of an active energy ray-curable adhesive, the adhesive layer can be cured by irradiation of active energy rays, thereby reducing the adhesive force of the sheet for work processing to the adherend. This makes it possible to easily separate the processed work from the work processing sheet.

Moreover, it is preferable that the adhesive layer in this embodiment can achieve the above-mentioned adhesive force. From this point of view, the adhesive layer in the present embodiment has a glass transition temperature of the active energy ray-curable adhesive constituting the adhesive layer is -50°C or more and 10°C or less, and the active energy ray-curable adhesive is a monomer having a polar group. It is preferable to include an acrylic copolymer containing as a constituent monomer. By providing an adhesive layer composed of such an active energy ray-curable adhesive, the sheet for work processing can easily achieve the above-mentioned adhesive strength.

From the viewpoint of making it easier for the sheet for work processing to achieve the above-mentioned adhesive strength, the glass transition temperature is particularly preferably -20°C or higher, and further preferably -15°C or higher. Moreover, from the same viewpoint, the glass transition temperature is particularly preferably 5.0°C or lower, and is further preferably 3.0°C or lower. In addition, the details of the method for measuring the glass transition temperature are as described in the test examples described later.

The active energy ray curable adhesive constituting the adhesive layer may be composed mainly of a polymer with active energy ray curable properties, and may contain an active energy ray non-curable polymer (polymer that does not have active energy ray curable properties) and at least one active energy ray curable adhesive. It may be composed as a main component of a mixture of monomers and/or oligomers having a pre-curable group.

First, the case where the active energy ray-curable adhesive contains a polymer having active energy ray curability as the main component will be described below.

The polymer having active energy ray curing property is a (meth)acrylic acid ester (co)polymer (A) (hereinafter referred to as “active energy ray curing polymer (A)” into which a functional group (active energy ray curing group) having active energy ray curing property is introduced into the side chain. )”, it is preferable. This active energy ray-curable polymer (A) is preferably obtained by reacting an acrylic copolymer (a1) having a functional group-containing monomer unit with an unsaturated group-containing compound (a2) having a functional group bonded to the functional group.

As the above-mentioned functional group-containing monomer, monomers having a polymerizable double bond and functional groups such as a hydroxy group, carboxyl group, amino group, amide group, benzyl group, and glycidyl group in the molecule are preferable. Among these, monomers containing a hydroxy group as a functional group are preferable. (Hydroxy group-containing monomer) is preferably used.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth)acrylic acid, 2-hydroxypropyl (meth)acrylic acid, 3-hydroxypropyl (meth)acrylic acid, and 2-hydroxybutyl (meth)acrylic acid. , 3-hydroxybutyl (meth)acrylic acid, 4-hydroxybutyl (meth)acrylic acid, etc. Among these, it is preferable to use 2-hydroxyethyl acrylate. Additionally, these are used individually or in combination of two or more types.

Examples of the carboxyl group-containing monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. These may be used individually, or two or more types may be used in combination.

Examples of the amino group-containing monomer or amide group-containing monomer include aminoethyl (meth)acrylate, n-butyl aminoethyl (meth)acrylate, and the like. These may be used individually, or two or more types may be used in combination.

The acrylic copolymer (a1) preferably contains 1 mass% or more of structural units derived from the functional group-containing monomer, particularly preferably 5 mass% or more, and further preferably contains 10 mass% or more. . Furthermore, the acrylic copolymer (a1) preferably contains 35% by mass or less of structural units derived from the functional group-containing monomer, and especially preferably contains 30% by mass or less. When the acrylic copolymer (a1) contains the functional group-containing monomer in the above range, it becomes easy to form the desired active energy ray-curable polymer (A).

As described above, the acrylic copolymer (a1) preferably contains a monomer having a polar group (polar group-containing monomer) as a monomer unit constituting the polymer. As a result, the polarity of the resulting active energy ray-curable adhesive improves, making it easier to achieve the above-mentioned adhesive strength.

Examples of polar group-containing monomers include acryloyl morpholine, isobornyl acrylate, methyl methacrylate, vinyl acetate, benzyl acrylate, and glycidyl methacrylate. Among these, acryloyl morpholine or It is preferred to use isobornyl acrylate.

The acrylic copolymer (a1) preferably contains 3.0% by mass or more of structural units derived from the polar group-containing monomer, particularly preferably 5.0% by mass or more, and further preferably contains 8.0% by mass or more. . In addition, the acrylic copolymer (a1) preferably contains 12.0% by mass or less of structural units derived from the polar group-containing monomer. When the acrylic copolymer (a1) contains the polar group-containing monomer in the above range, the polarity of the resulting active energy ray-curable adhesive can be effectively improved, thereby making it easier to achieve the above-mentioned adhesive strength.

In addition, the acrylic copolymer (a1) preferably contains a monomer (Tg adjustment monomer) for adjusting the glass transition temperature (Tg) of the active energy ray-curable adhesive as a monomer unit constituting the polymer. For this reason, the obtained active energy ray-curable adhesive tends to have the glass transition temperature (Tg) described above. Preferred examples of monomers that also serve as Tg adjusting monomers include those described above as examples of polar group-containing monomers, and among these, acryloyl morpholine or isobornyl acrylate is particularly preferable.

The glass transition temperature of the above-mentioned Tg adjustment monomer is preferably 30°C or higher, particularly preferably 50°C or higher, and further preferably 90°C or higher. Moreover, the glass transition temperature of the Tg adjustment monomer is preferably 200°C or lower, particularly preferably 180°C or lower, and further preferably 150°C or lower. By using a Tg adjustment monomer having a glass transition temperature in this range, it becomes easy to adjust the glass transition temperature of the active energy ray-curable adhesive to the above-mentioned range. In addition, in this specification, the glass transition temperature for a monomer refers to the glass transition temperature measured for a homopolymer composed only of the monomer.

In addition, the dissolution parameter (SP value) of the above-mentioned Tg adjustment monomer is preferably 9.8 or more, particularly preferably 9.9 or more, and further preferably 10.0 or more. When the SP value of the Tg adjustment monomer is 9.8 or more, it becomes easy to adjust the adhesive force of the sheet for work processing to the above-described range, and in particular, it becomes easy to adjust the initial adhesive force F0 to the above-mentioned range. This makes it easy to hold the workpiece on the workpiece processing sheet during processing. Additionally, the upper limit of the dissolution parameter (SP value) is not particularly limited, and may be, for example, 11 or less.

The acrylic copolymer (a1) preferably contains 3.0% by mass or more of structural units derived from the Tg adjustment monomer, particularly preferably 5.0% by mass or more, and further preferably contains 8.0% by mass or more. . Additionally, the acrylic copolymer (a1) preferably contains 12.0% by mass or less of structural units derived from the Tg-adjusting monomer. When the acrylic copolymer (a1) contains the Tg adjustment monomer in the above range, it becomes easy to adjust the glass transition temperature of the resulting active energy ray-curable adhesive to the above-described range.

For the acrylic copolymer (a1), it is also preferable to use a (meth)acrylic acid alkyl ester monomer whose alkyl group has 1 to 20 carbon atoms as the monomer unit constituting the polymer. As such (meth)acrylic acid alkyl ester monomer, (meth)acrylic acid alkyl ester monomer whose alkyl group has 1 to 18 carbon atoms is particularly preferable. Additionally, from the viewpoint of making it easy to obtain an adhesive with excellent heat resistance, a (meth)acrylic acid alkyl ester monomer whose alkyl group has 8 or more carbon atoms is preferable. Preferred examples of (meth)acrylic acid alkyl ester monomers in which the alkyl group has 1 to 20 carbon atoms include methyl methacrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, and (meth)acrylic acid 2. -Ethylhexyl, etc. can be mentioned. These may be used individually or in combination of two or more types.

The acrylic copolymer (a1) preferably contains 50% by mass or more of structural units derived from the above-mentioned (meth)acrylic acid alkyl ester monomer having 1 to 20 carbon atoms in the alkyl group, and especially contains 60% by mass or more. It is preferable that it contains 70% by mass or more. In addition, the acrylic copolymer (a1) preferably contains 99% by mass or less of structural units derived from the above-mentioned (meth)acrylic acid alkyl ester monomer whose alkyl group has 1 to 20 carbon atoms, especially 95% by mass. It is preferable to contain it at 90% by mass or less.

The acrylic copolymer (a1) can preferably be obtained by copolymerizing the above-described monomers or their derivatives by a conventional method. In addition to these monomers, a monomer having an alicyclic structure in the molecule (alicyclic structure-containing monomer), dimethyl acrylamide , vinyl formate, styrene, etc. may be copolymerized.

Examples of the above-mentioned alicyclic structure-containing monomers include cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, adamantyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, ( Meth) dicyclopentenyl oxyethyl acrylate, etc. are mentioned. These may be used individually or in combination of two or more types.

An active energy ray-curable polymer (A) is obtained by reacting the acrylic copolymer (a1) having the above functional group-containing monomer unit with an unsaturated group-containing compound (a2) having a functional group bonded to the functional group.

The functional group of the unsaturated group-containing compound (a2) can be appropriately selected depending on the type of functional group of the functional group-containing monomer unit of the acrylic copolymer (a1). For example, when the functional group of the acrylic copolymer (a1) is a hydroxy group, amino group, or amide group, the functional group of the unsaturated group-containing compound (a2) is preferably an isocyanate group or an epoxy group, and the acrylic copolymer (a1) When the functional group possessed is a glycidyl group, the functional group possessed by the unsaturated group-containing compound (a2) is preferably an amino group, a carboxyl group, or an aziridinyl group.

In addition, the unsaturated group-containing compound (a2) contains at least one, preferably 1 to 6, more preferably 1 to 4 active energy ray polymerizable carbon-carbon double bonds per molecule. Specific examples of such unsaturated group-containing compound (a2) include, for example, 2-methacryloyloxyethyl isocyanate, metaisopropenyl α,α-dimethyl benzyl isocyanate, methacryloyl isocyanate, allyl isocyanate, 1 , 1-(bisacryloyloxy methyl)ethyl isocyanate; Acryloyl monoisocyanate compounds obtained by reaction of diisocyanate compounds or polyisocyanate compounds with hydroxyethyl (meth)acrylate; an acryloyl monoisocyanate compound obtained by reacting a diisocyanate compound or polyisocyanate compound with a polyol compound and hydroxyethyl (meth)acrylate; (meth)glycidyl acrylate; (meth)acrylic acid, 2-(1-aziridinyl)ethyl (meth)acrylic acid, 2-vinyl-2-oxazoline, 2-isopropenyl-2-oxazoline, etc.

The unsaturated group-containing compound (a2) is preferably 50 mol% or more, particularly preferably 60 mol% or more, more preferably 70 mol% or more, relative to the mole number of the functional group-containing monomer of the acrylic copolymer (a1). It is used as a ratio. In addition, the unsaturated group-containing compound (a2) is preferably 95 mol% or less, particularly preferably 93 mol% or less, and more preferably 90 mol% relative to the mole number of the functional group-containing monomer of the acrylic copolymer (a1). It is used in ratios of less than mole percent.

In the reaction between the acrylic copolymer (a1) and the unsaturated group-containing compound (a2), the temperature, pressure, and solvent of the reaction depend on the combination of the functional group of the acrylic copolymer (a1) and the functional group of the unsaturated group-containing compound (a2). , time, presence or absence of catalyst, and type of catalyst can be appropriately selected. As a result, the functional group present in the acrylic copolymer (a1) reacts with the functional group in the unsaturated group-containing compound (a2), the unsaturated group is introduced into the side chain in the acrylic copolymer (a1), and the active energy ray-curable polymer (A) is obtained. Lose.

The weight average molecular weight (Mw) of the active energy ray-curable polymer (A) thus obtained is preferably 10,000 or more, particularly preferably 150,000 or more, and further preferably 200,000 or more. Moreover, the weight average molecular weight (Mw) is preferably 1.5 million or less, and especially 1 million or less. In addition, the weight average molecular weight (Mw) in this specification is a standard polystyrene conversion value measured by gel permeation chromatography (GPC method).

Even when the active energy ray curable adhesive is mainly composed of a polymer having active energy ray curable properties such as the active energy ray curable polymer (A), the active energy ray curable adhesive contains an active energy ray curable monomer and/or oligomer (B ) may contain more.

As the active energy ray-curable monomer and/or oligomer (B), for example, ester of a polyhydric alcohol and (meth)acrylic acid can be used.

Such active energy ray-curable monomers and/or oligomers (B) include, for example, monofunctional acrylic acid esters such as cyclohexyl (meth)acrylate and isobornyl (meth)acrylate, and trimethylolpropane tri(meth)acrylate. ) Acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1, 4-butanediol di(meth)acrylate, 1, 6-hexanediol Multifunctional acrylic acid esters such as di(meth)acrylate, polyethylene glycol di(meth)acrylate, dimethylol tricyclodecane di(meth)acrylate, polyester oligo(meth)acrylate, polyurethane oligo(meth)acrylate Acrylates, etc. can be mentioned.

When mixing an active energy ray curable monomer and/or oligomer (B) with the active energy ray curable polymer (A), the active energy ray curable monomer and/or oligomer (B) in the active energy ray curable adhesive The content is preferably more than 0 parts by mass, and especially preferably 60 parts by mass or more, with respect to 100 parts by mass of the active energy ray-curable polymer (A). Moreover, the content is preferably 250 parts by mass or less, and especially preferably 200 parts by mass or less, based on 100 parts by mass of the active energy ray-curable polymer (A).

Here, when using ultraviolet rays as an active energy ray for curing the active energy ray-curable adhesive, it is preferable to add a photopolymerization initiator (C), and the use of this photopolymerization initiator (C) determines the polymerization curing time and the amount of light irradiation. can be reduced.

The photopolymerization initiator (C) in this embodiment preferably has a 5% weight loss temperature of 200°C or higher, particularly preferably 210°C or higher, and further preferably 220°C or higher. By using a photopolymerization initiator (C) exhibiting a 5% weight loss temperature of 200°C or higher, it becomes easy to adjust the adhesion of the sheet for work processing to the above-mentioned range, and in particular, after heating and irradiation with active energy, the adhesion F2 is adjusted to the above-mentioned range. It becomes easier to adjust. For this reason, even when heat treatment is performed, it becomes easy to separate the processed work from the work processing sheet. Additionally, the upper limit of the 5% weight loss temperature is not particularly limited. For example, it may be 300°C or lower, especially 280°C or lower, and may be 250°C or lower. In addition, the details of the method for measuring the 5% weight loss temperature are as described in the Examples described later.

Specific examples of the photopolymerization initiator (C) include benzophenone, acetophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin benzoic acid, and benzoin methyl benzoate. , benzoin dimethyl ketal, 2, 4-diethylthioxanthone, 1-hydroxy cyclohexylphenyl ketone, benzyl diphenyl sulfide, tetramethyl thiuram monosulfide, azobis isobutyronitrile, benzyl, dibenzyl, di Acetyl, β-chloroanthraquinone, (2, 4, 6-trimethyl benzyl diphenyl) phosphine oxide, 2-benzothiazole-N, N-diethyldithiocarbamate, oligo{2-hydroxy －2-methyl-1-［4-(1-propenyl) phenyl］propanone｝, 2,2-dimethoxy－1,2-diphenyl ethane-1-one, 2-hydroxy-1-｛4 -[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one, etc. are mentioned. Among these, it is preferable to use 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one. . These may be used individually, or two or more types may be used together.

The photopolymerization initiator (C) is an active energy ray-curable polymer (A) (when blending an active energy ray-curable monomer and/or oligomer (B), the active energy ray-curable polymer (A) and the active energy ray-curable monomer (B). And/or it is preferably used in an amount of 0.1 part by mass or more, especially 0.5 part by mass or more, based on 100 parts by mass of the total amount of oligomer (B) (100 parts by mass). In addition, the photopolymerization initiator (C) is an active energy ray-curable polymer (A) (when blending an active energy ray-curable monomer and/or oligomer (B), the active energy ray-curable polymer (A) and the active energy ray-curable polymer (A) It is preferably used in an amount of 10 parts by mass or less, especially 6 parts by mass or less, relative to 100 parts by mass of the total amount of monomer and/or oligomer (B) (100 parts by mass).

In an active energy ray-curable adhesive, in addition to the above components, other components may be blended as appropriate. Other components include, for example, an active energy ray non-curable polymer component or oligomer component (D), a crosslinking agent (E), etc.

Examples of the active energy ray non-curable polymer component or oligomer component (D) include polyacrylic acid ester, polyester, polyurethane, polycarbonate, polyolefin, etc., and have a weight average molecular weight (Mw) of 3000 to 250. Only polymers or oligomers are preferred. By mixing the component (D) into an active energy ray-curable adhesive, the adhesiveness and peelability before curing, the strength after curing, adhesion to other layers, storage stability, etc. can be improved. The compounding amount of the component (D) is not particularly limited and is appropriately determined in the range of more than 0 parts by mass and 50 parts by mass or less with respect to 100 parts by mass of the active energy ray-curable polymer (A).

As the crosslinking agent (E), a polyfunctional compound that has reactivity with the functional group of the active energy ray-curable polymer (A) or the like can be used. Examples of such multifunctional compounds include isocyanate compounds, epoxy compounds, amine compounds, melamine compounds, aziridine compounds, hydrazine compounds, aldehyde compounds, oxazoline compounds, metal alkoxide compounds, metal chelate compounds, metal salts, ammonium salts, and reactive phenol resins. etc. can be mentioned.

The compounding amount of the crosslinking agent (E) is preferably 0.01 part by mass or more, and especially preferably 1 part by mass or more, with respect to 100 parts by mass of the active energy ray-curable polymer (A). Moreover, the compounding amount of the crosslinking agent (E) is preferably 20 parts by mass or less, and especially preferably 17 parts by mass or less, with respect to 100 parts by mass of the active energy ray-curable polymer (A).

Next, the case where the active energy ray-curable adhesive mainly contains a mixture of an active energy ray non-curable polymer component and a monomer and/or oligomer having at least one active energy ray curable group will be described below.

As the active energy ray non-curable polymer component, for example, a component similar to the acrylic copolymer (a1) described above can be used.

As the monomer and/or oligomer having at least one active energy ray-curable group, the same ones as the above-mentioned component (B) can be selected. The mixing ratio of the active energy ray non-curable polymer component and the monomer and/or oligomer having at least one active energy ray curable group is the ratio of the active energy ray non-curable polymer component to 100 parts by mass of the active energy ray non-curable polymer component and the monomer and/or oligomer having at least one active energy ray curable group. It is preferable that the monomer and/or oligomer is 1 part by mass or more, and it is especially preferable that it is 60 parts by mass or more. In addition, the mixing ratio is preferably 200 parts by mass or less of the monomer and/or oligomer having at least one active energy ray-curable group, and particularly preferably 160 parts by mass or less, per 100 parts by mass of the active energy ray non-curable polymer component. .

In this case as well, the photopolymerization initiator (C) and the crosslinking agent (E) can be appropriately mixed as described above.

The thickness of the adhesive layer is preferably 1 μm or more, and more preferably 5 μm or more. In addition, the thickness is preferably 50 μm or less, and more preferably 40 μm or less. When the adhesive layer thickness is within the above range, it becomes easy to achieve the above-mentioned adhesive strength.

(3) Release sheet

In the sheet for work processing according to the present embodiment, the adhesive layer has the purpose of protecting the side opposite to the base material (hereinafter sometimes referred to as “adhesive side”) until it is attached to the work, A release sheet may be laminated on the above surface. The configuration of the release sheet is arbitrary, and an example is one in which a plastic film has been subjected to a release treatment using a release agent or the like. Specific examples of plastic films include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, and polyolefin films such as polypropylene and polyethylene. As the release agent, silicone-based, fluorine-based, long-chain alkyl-based, etc. can be used, and among these, silicone-based because it is inexpensive and provides stable performance is preferable. There is no particular limitation on the thickness of the release sheet, but it is usually 20 μm or more and 250 μm or less.

(4) Other absences

In the sheet for work processing according to the present embodiment, an adhesive layer may be laminated on the adhesive surface of the adhesive layer. In this case, the sheet for work processing according to the present embodiment can be used as a dicing/die bonding sheet by providing an adhesive layer as described above. In such a sheet for work processing, a chip in which the separated adhesive layers are laminated can be obtained by attaching the work to the side of the adhesive layer opposite to the adhesive layer and dicing the adhesive layer together with the work. The chip can be easily fixed to the object on which the chip is mounted by this separate adhesive layer. As the material constituting the above-mentioned adhesive layer, it is preferable to use a material containing a thermoplastic resin and a low molecular weight thermosetting adhesive component, or a material containing a B stage (semi-cured burn) thermosetting adhesive component.

In addition, in the sheet for work processing according to the present embodiment, a protective film forming layer may be laminated on the adhesive surface of the adhesive layer. In this case, the workpiece processing sheet according to this embodiment can be used as a protective film forming and dicing sheet. In such a sheet for work processing, a chip with the separate protective film forming layers laminated can be obtained by attaching the work to the side of the protective film forming layer opposite to the adhesive layer and dicing the protective film forming layer together with the work. It is preferable to use a workpiece with a circuit formed on one side, and in this case, a protective film forming layer is usually laminated on the surface opposite to the surface on which the circuit is formed. By curing the separated protective film forming layer at a predetermined timing, a protective film with sufficient durability can be formed on the chip. The protective film forming layer is preferably made of an uncured curable adhesive.

In addition, the sheet for work processing according to the present embodiment preferably satisfies the above-mentioned conditions regarding adhesive strength, but when the adhesive layer or protective film forming layer described above with respect to the adhesive layer is laminated, the adhesive layer before such layer is laminated. In relation to this, it is sufficient as long as it satisfies the above-mentioned adhesive strength.

3. Manufacturing method of sheet for work processing

The manufacturing method of the sheet for work processing according to this embodiment is not particularly limited, and preferably, the sheet for work processing according to this embodiment is manufactured by laminating an adhesive layer on one side of a base material.

Lamination of the adhesive layer on one side of the substrate can be performed according to a known method. For example, it is preferable to transfer the adhesive layer formed on the release sheet to one side of the substrate. In this case, a coating solution containing the pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive layer and, if desired, further containing a solvent or dispersion medium is prepared, and applied on the peel-treated side (hereinafter sometimes referred to as “release surface”) of the release sheet. , the coating liquid is applied by a die coater, curtain coater, spray coater, slit coater, knife coater, etc. to form a coating film, and the coating film is dried to form an adhesive layer. The properties of the coating liquid are not particularly limited as long as it can be applied, and it may contain a component for forming an adhesive layer as a solute or as a dispersoid. The release sheet in this laminate may be peeled off as a process material, or may be used to protect the adhesive surface of the adhesive layer until the sheet for work processing is attached to the work.

When the coating solution for forming the adhesive layer contains a crosslinking agent, the drying conditions (temperature, time, etc.) described above are changed, or heat treatment is provided separately, and the active energy ray-curable polymer (A) in the coating film is changed. Alternatively, a crosslinking reaction between the active energy ray non-curable polymer and the crosslinking agent may proceed to form a crosslinked structure at a desired density in the adhesive layer. In order to sufficiently advance this crosslinking reaction, after lamination of an adhesive layer on a base material by the method described above, etc., curing is performed such as leaving the obtained sheet for work processing in an environment of, for example, 23°C and 50% relative humidity for several days. It is okay to implement it.

Instead of transferring the adhesive layer formed on the release sheet as described above to one side of the substrate, the adhesive layer may be formed directly on the substrate. In this case, the coating liquid for forming the adhesive layer described above is applied to one side of the substrate to form a coating film, and the coating film is dried to form the adhesive layer.

4. How to use the sheet for work processing

The workpiece processing sheet according to this embodiment can be used for processing workpieces. That is, after attaching the adhesive surface of the workpiece processing sheet according to the present embodiment to the workpiece, the workpiece can be processed on the workpiece processing sheet. According to the above processing, the sheet for work processing according to this embodiment can be used as a back grind sheet, dicing sheet, expansion sheet, pickup sheet, etc. Here, examples of the work include semiconductor members such as semiconductor wafers and semiconductor packages, and glass members such as glass plates.

Additionally, when the sheet for work processing according to the present embodiment is provided with the adhesive layer described above, the sheet for processing the work can be used as a dicing/die bonding sheet. Additionally, when the workpiece processing sheet according to the present embodiment is provided with the protective film forming layer described above, the workpiece processing sheet can be used as a protective film forming and dicing sheet.

When processing of the work is completed on the work processing sheet according to the present embodiment and the processed work is separated from the work processing sheet, it is preferable to irradiate the adhesive layer of the work processing sheet with an active energy ray before the separation. . As a result, the adhesive layer hardens, significantly lowers the adhesive force of the workpiece processing sheet to the processed workpiece, and becomes easier to separate the processed workpiece.

As the above-mentioned active energy ray, for example, those having energy quantum among electromagnetic waves or charged particle beams can be used, and specifically, ultraviolet rays, electron beams, etc. can be used. In particular, ultraviolet rays that are easy to handle are preferable. Irradiation of ultraviolet rays can be performed by a high-pressure mercury lamp, xenon lamp, LED, etc., and the irradiation amount of ultraviolet rays is preferably 50 mW/cm2 or more and 1000 mW/cm2 or less. Additionally, the amount of light is preferably 50 mJ/cm2 or more, especially 80 mJ/cm2 or more, and further preferably 200 mJ/cm2 or more. Additionally, the amount of light is preferably 10000 mJ/cm2 or less, particularly preferably 5000 mJ/cm2 or less, and further preferably 2000 mJ/cm2 or less. On the other hand, irradiation of electron beams can be performed by an electron beam accelerator or the like, and the amount of electron beam irradiation is preferably 10 krad or more and 1000 krad or less.

In the sheet for work processing according to the present embodiment, the adhesive force F0 is within the above-mentioned range, so that sufficient adhesive force is exhibited to the workpiece during processing of the workpiece, and defects such as movement or fall-off of the workpiece or the workpiece after processing are suppressed. It can be suppressed. In addition, since the adhesive layer is composed of an active energy ray-curable adhesive and the adhesive force ratio F2/F0 is within the above-mentioned range, even when the sheet for work processing is heated while the workpiece after processing is attached, the active energy ray By irradiating, the adhesive force to the workpiece after processing can be sufficiently reduced, and thus the workpiece after processing can be picked up satisfactorily. For this reason, the workpiece processing sheet according to the present embodiment can be suitably used for applications in which the workpiece processing sheet is exposed to a high temperature environment with the workpiece or the workpiece after processing attached to the workpiece processing sheet. In particular, the work processing sheet according to the present embodiment is suitable for use in applications where dicing of a silicon wafer or the like is performed on the work processing sheet, and the obtained chips are heat treated on the work processing sheet.

When using the workpiece processing sheet according to the present embodiment as a dicing sheet and, after dicing, heat treatment by attaching chips to the workpiece processing sheet, the heating conditions include, for example: , the heating temperature is preferably 40°C or higher, especially 80°C or higher, and further preferably 100°C or higher. Additionally, the heating temperature is preferably 150°C or lower, especially 130°C or lower, and further preferably 120°C or lower. Additionally, the heating time is preferably, for example, 3 minutes or more, especially 10 minutes or more, and further preferably 30 minutes or more. In addition, the heating time is preferably 60 minutes or less, especially 50 minutes or less, and further preferably 40 minutes or less. The sheet for work processing according to the present embodiment can separate chips well even when heated under the conditions described above.

The embodiments described above are described to facilitate understanding of the present invention, and are not described to limit the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents that fall within the technical scope of the present invention.

For example, another layer may be provided between the base material and the adhesive layer, or on the surface of the base material opposite to the adhesive layer.

Example

Hereinafter, the present invention will be described in more detail through examples, etc., but the scope of the present invention is not limited to these examples.

[Example 1]

(1) Preparation of adhesive composition

An acrylic copolymer obtained by copolymerizing 70 parts by mass of 2-ethylhexyl acrylate, 10 parts by mass of acryloyl morpholine, and 20 parts by mass of 2-hydroxyethyl acrylate, and the number of moles of 2-hydroxyethyl acrylate in the acrylic copolymer is 90. An active energy ray-curable polymer was obtained by reacting mol% methacryloyloxyethyl isocyanate (MOI). The weight average molecular weight (Mw) of this active energy ray-curable polymer was measured by the method described later, and was found to be 830,000.

Photopolymerization with 100 parts by mass of the obtained active energy ray-curable polymer (in terms of solid content, the same below) and 1.2 parts by mass of an aliphatic isocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., product name “Coronate HX”) containing hexamethylene diisocyanate as a crosslinking agent. As an initiator, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one (manufactured by BASF, product name: 1.2 parts by mass of "Omnirad 127", 5% weight loss temperature: 220°C) was mixed in a solvent to obtain an adhesive composition. In addition, the 5% weight loss temperature of the photopolymerization initiator was measured by heating from room temperature to 300°C at a temperature increase rate of 5°C/min using a differential heat and thermogravimetric simultaneous measurement device (manufactured by SHIMADZU, product name "DTG-60"). It was done.

(2) Formation of adhesive layer

The pressure-sensitive adhesive composition was applied to the release surface of a release sheet (manufactured by LINTEC Corporation, product name “SP-PET381031”) in which a silicone-based release agent layer was formed on one side of a polyethylene terephthalate film with a thickness of 38 μm, and then heated. After drying, it was cured for 7 days under conditions of 23°C and 50%RH to form an adhesive layer with a thickness of 5 μm on the release sheet.

(3) Production of sheets for work processing

By bonding the side opposite to the release sheet of the adhesive layer formed in the above step (2) with one side of a heat-resistant polyester film (manufactured by KURABO, product name "Torcena") with a thickness of 75 μm as a base material, A sheet for work processing was obtained.

Here, the above-mentioned weight average molecular weight (Mw) is the weight average molecular weight measured using gel permeation chromatography (GPC) (GPC measurement) and converted to standard polystyrene.

[Examples 2 to 8 and Comparative Examples 1 to 4]

A sheet for work processing was manufactured in the same manner as in Example 1, except that the composition and weight average molecular weight of the acrylic copolymer were changed as shown in Table 1 and the composition of the adhesive composition was changed as shown in Table 2.

[Test Example 1] (Measurement of glass transition temperature of adhesive)

A laminate of adhesive layers with a thickness of 800 μm was produced by laminating multiple adhesive layers of the sheets for work processing manufactured in the examples and comparative examples. Subsequently, a sample for measurement was obtained by drilling a circular hole with a diameter of 10 mm through this laminate of the adhesive layer. For the sample for measurement, tanδ was measured using a dynamic viscoelasticity measuring device (manufactured by TA Instruments, product name “ARES”) under the conditions of a frequency of 1 Hz, a measurement temperature range of -50 to 150°C, and a temperature increase rate of 3°C/min. And the temperature of the peak top was set to Tg. The results are shown in Table 3.

[Test Example 2] (Measurement of adhesive force)

The sheet for work processing manufactured in Examples and Comparative Examples was cut into strips with a width of 25 mm. The peeling sheet is peeled from the obtained strip-shaped work processing sheet, and the exposed adhesive surface of the adhesive layer is mirror-finished. For the mirror surface of the silicon wafer, 2 kg of rubber was applied under an environment of a temperature of 23°C and a relative humidity of 50%. They were bonded together using a roller, left to stand for 20 minutes, and used as samples for measurement.

For the obtained measurement sample, a workpiece was separated from a silicon wafer using a universal tensile tester (manufactured by ORIENTEC Co., Ltd., product name "Tensiron UTM-4-100") at a peeling speed of 300 mm/min and a peeling angle of 180°. The sheet for processing was peeled off, and the adhesive force (mN/25 mm) to the silicon wafer was measured according to the 180° peeling method in accordance with JIS Z0237:2009. The adhesive force thus obtained is shown in Table 3 as adhesive force F0.

Additionally, the sample for measurement obtained in the same manner as above was heated at 150°C for 1 hour using an oven. For the sample for measurement after heating, the adhesive force (mN/25 mm) to the silicon wafer was measured in the same manner as above. The adhesive strength thus obtained is shown in Table 3 as adhesive strength F1.

Additionally, the sample for measurement obtained in the same manner as above was heated at 150°C for 1 hour using an oven. Additionally, the adhesive layer was irradiated with ultraviolet rays through the substrate under the following conditions. For this measurement sample, the adhesive force (mN/25 mm) to the silicon wafer was measured in the same manner as above. The adhesive strength thus obtained is shown in Table 3 as adhesive strength F2.

＜Ultraviolet irradiation conditions＞

·Use of high pressure mercury lamp

·Illuminance 230 mW/㎠, light quantity 190 mJ/㎠

・UV illuminance/photometer uses “UVPF-A1” manufactured by iGrafx.

In addition, from the three types of adhesive forces obtained as described above, the ratio of the adhesive force F2 to the adhesive force F0 (F2/F0) and the ratio of the adhesive force F0 to the adhesive force F1 (F0/F1) were calculated, respectively. These results are shown in Table 3.

[Test Example 3] (Measurement of Young’s modulus of adhesive)

A plurality of laminates of an adhesive layer and a release sheet produced in the same manner as in the above step (2) of Example 1 were prepared for each of the Examples and Comparative Examples. Then, a pressure-sensitive adhesive layer sample for measurement consisting of a pressure-sensitive adhesive layer with a thickness of 200 μm was produced by laminating a predetermined number of pressure-sensitive adhesive layers in the above laminate.

The obtained adhesive layer sample for measurement was pulled using a universal tensile tester (manufactured by Shimadzu Corporation, product name "Autograph AG-IS") at a speed of 200 mm/min at a distance between chucks of 30 mm in an environment of 23°C, and the resulting stress was - Young's modulus (MPa) was obtained from the strain curve. The results obtained as a result are shown in Table 3 as Young's modulus E0.

Additionally, the adhesive layer sample for measurement obtained in the same manner as above was heated at 150°C for 1 hour using an oven. For the pressure-sensitive adhesive layer sample for measurement after the heating, Young's modulus (MPa) was determined in the same manner as above. The results obtained as a result are shown in Table 3 as Young's modulus E1.

Additionally, the adhesive layer sample for measurement obtained in the same manner as above was heated at 150°C for 1 hour using an oven. Additionally, the pressure-sensitive adhesive layer sample for measurement after the heating was irradiated with ultraviolet rays under the following conditions. For this sample of the adhesive layer for measurement, Young's modulus (MPa) was determined in the same manner as above. The results obtained as a result are shown in Table 3 as Young's modulus E2.

＜Ultraviolet irradiation conditions＞

·Use of high pressure mercury lamp

·Illuminance 230 mW/㎠, light quantity 580 mJ/㎠

・UV illuminance/photometer uses “UVPF-A1” manufactured by iGrafx.

Additionally, from the three types of Young's moduli obtained as described above, the ratio of Young's modulus E1 to Young's modulus E0 (E1/E0) and the ratio of Young's modulus E2 to Young's modulus E1 (E2/E1) were calculated, respectively. These results are shown in Table 3.

[Test Example 4] (Evaluation of initial adhesiveness)

The release sheet was peeled from the sheet for work processing manufactured in the examples and comparative examples, and the exposed surface of the exposed adhesive layer was polished to #2000 using a tape mounter (manufactured by LINTEC Corporation, product name “Adwill RAD2500m/12”). The polished surface of a 6-inch silicon wafer (thickness: 350 μm) was attached. Subsequently, using a dicing device (manufactured by DISCO Corporation, product name "DFD-6362"), dicing was performed to cut from the 6-inch silicon wafer side while supplying flowing water to the cut section under the following dicing conditions.

＜Dicing conditions＞

· Dicing device: DFD-6362 manufactured by DISCO Corporation

· Blade: NBC-2H 2050 27HECC made by DISCO Corporation

·Blade width: 0.025 ~ 0.030mm

·Knife tip protrusion: 0.640 ~ 0.760mm

·Blade rotation speed: 50000rpm

·Cutting speed　　　：20mm/sec

· Notch depth: 20㎛ from the surface of the adhesive layer side of the work processing sheet to the base material.

· Flowing water supply: 1.0L/min

·Flowing water temperature　　　：room temperature

·Cut size: 2mm×2mm

After that, the work processing sheet to which the chips obtained through the dicing process are attached is visually observed, the number of chips that fall off from the work processing sheet during the dicing process is counted, and the number is calculated as the number of divisions in the dicing process. Divide to obtain the chip scattering rate (unit: %). Based on this calculation result, initial adhesion was evaluated based on the following standards. The evaluation results are shown in Table 3.

○: Chip scattering rate is less than 10%.

×: Chip scattering rate is 10% or more.

[Test Example 5] (Evaluation of pickup aptitude)

Using the sheet for work processing manufactured in Examples and Comparative Examples, dicing was performed in the same manner as in Test Example 4, except that the cut size was changed to 10 mm x 10 mm.

After completion of dicing, the sheet for work processing with the chips placed on it was placed in an oven and heated at 150°C for 1 hour. Subsequently, ultraviolet ray irradiation was performed on the adhesive layer in the sheet for work processing under the following conditions through the substrate.

＜Ultraviolet irradiation conditions＞

·Use of high pressure mercury lamp

·Illuminance 230 mW/㎠, light quantity 190 mJ/㎠

・UV illuminance/photometer uses “UVPF-A1” manufactured by iGrafx.

100 chips were picked up from the sheet for work processing after irradiation with ultraviolet rays, and their pick-up aptitude was evaluated based on the following criteria. The results are shown in Table 3.

◎: Out of 100, the number of chips that could be picked up satisfactorily was 95 or more.

○: Out of 100, the number of chips that could be picked up satisfactorily was less than 95 and more than 80.

×: Out of 100, the number of chips that could be picked up satisfactorily was less than 80.

In addition, details such as abbreviations shown in Table 1 and Table 2 are as follows.

[Composition of active energy ray curable polymer]

2EHA: 2-ethylhexyl acrylic acid

BA: Butyl acrylate

ACMO: Acryloyl morpholine (SP value: 10.1, glass transition temperature: 145°C)

MMA: Methyl methacrylate (SP value: 9.5, glass transition temperature: 105°C)

IBXA: Isobornyl acrylate (SP value: 10.2, glass transition temperature: 94°C)

HEA: 2-hydroxyethyl acrylic acid

MOI: Methacryloyloxyethyl isocyanate

[Light polymerization initiator]

Omnirad 127: 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one (manufactured by BASF, product name) 「Omnirad 127」, 5% weight loss temperature: 220℃)

Omnirad TPO: 2, 4, 6-trimethyl benzoyl diphenyl phosphine oxide (manufactured by BASF, product name “Omnirad TPO”, 5% weight loss temperature: 225°C)

As can be seen from Table 3, the sheet for work processing obtained in the Examples had excellent initial adhesion and could well hold the work on the sheet during processing. In addition, it was suggested that the sheet for work processing obtained in the examples had excellent pick-up aptitude, that is, the adhesive force to the workpiece after processing was significantly reduced during pickup.

The sheet for work processing of the present invention can be suitably used for dicing.

Claims (6)

A sheet for work processing comprising a base material and an adhesive layer laminated on one side of the base material,
The adhesive layer is composed of an active energy ray-curable adhesive,
The adhesion of the work processing sheet to the silicon wafer is F0,
After heating the laminate formed by bonding the sheet for work processing to a silicon wafer for 1 hour at 150°C, ultraviolet rays are applied to the adhesive layer constituting the laminate under the conditions of an illuminance of 230 mW/cm2 and a light amount of 190 mJ/cm2. After further investigation, when the adhesion of the work processing sheet to the silicon wafer was set to F2,
The adhesive force F0 is 600 mN/25 mm or more and 20000 mN/25 mm or less,
A sheet for work processing, characterized in that the ratio (F2/F0) of the adhesive force F2 to the adhesive force F0 is 0.01 or more and 0.66 or less. According to paragraph 1,
After heating the work processing sheet at 150°C for 1 hour, the Young's modulus of the adhesive layer at 23°C is set to E1,
After heating the work processing sheet at 150° C. for 1 hour, ultraviolet rays are further irradiated to the adhesive layer constituting the work processing sheet under the conditions of an illuminance of 230 mW/cm2 and a light amount of 190 mJ/cm2, and then the adhesive layer is When the Young's modulus at 23°C is E2,
A sheet for work processing, characterized in that the ratio (E2/E1) of the Young's modulus E2 to the Young's modulus E1 is 13 or more and 25 or less. According to paragraph 1,
In the work processing sheet, the Young's modulus at 23°C of the adhesive layer is E0,
After heating the work processing sheet at 150°C for 1 hour, when the Young's modulus of the adhesive layer at 23°C is E1,
A sheet for work processing, characterized in that the ratio (E1/E0) of the Young's modulus E1 to the Young's modulus E0 is 2.0 or more and 3.5 or less. According to paragraph 1,
A sheet for work processing, characterized as being a dicing sheet. According to paragraph 1,
A work processing sheet, characterized in that it is used for heat treatment of a work on the work processing sheet. According to paragraph 1,
A sheet for work processing, characterized in that it is used for dicing a work on the work processing sheet and then heat treating the resulting chips by attaching them to the work processing sheet.