JPWO2020100491A1 - Work sheet - Google Patents

Abstract

A work processing sheet including a base material and an adhesive layer, wherein the pressure-sensitive adhesive layer is composed of an active energy ray-curable pressure-sensitive adhesive, and the adhesive force of the work processing sheet to a silicon wafer is F0. For the work processing after heating the laminate formed by laminating the work processing sheet on a silicon wafer at 150 ° C. for 1 hour and then irradiating the pressure-sensitive adhesive layer constituting the laminate with active energy rays. When the adhesive force of the sheet to the silicon wafer is F2, the adhesive force F0 is 600 mN / 25 mm or more and 20000 mN / 25 mm or less, and the ratio of the adhesive force F2 to the adhesive force F0 (F2 / F0) is 0.66 or less. Work sheet for processing. According to such a work processing sheet, it is possible to satisfactorily separate the processed work after the heat treatment while exhibiting sufficient adhesive force to the work when processing the work. ..

Description

The present invention relates to a work processing sheet 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 "work") are manufactured in a large diameter state, and these are small element pieces (hereinafter, "chip"). After being cut and separated (dyed) and individually separated (picked up), the process is moved to the next step, the mounting step. At this time, a 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 step of dicing, cleaning, drying, expanding, picking up, and mounting. Such a work processing sheet is required to have a performance that allows the work to be well held on the sheet during processing, but can be easily separated when the processed work is separated from the sheet.

The chips obtained as described above may be subsequently heat-treated. For example, the chips may be subjected to processing such as vapor deposition, sputtering, and baking for dehumidification. Further, when the chip is expected to be used in a high temperature environment, a heating test may be performed to confirm the reliability in such an environment. Usually, these heat treatments are performed with the obtained chips placed on a heating tray.

In recent years, it has been studied to perform the heat treatment of the chip as described above on the work processing sheet. That is, after dicing the work on the work processing sheet, it has been studied to heat-treat the chips while they are placed on the work processing sheet without transferring the obtained chips to the heating tray. There is. In this case, the process can be simplified.

Patent Documents 1 to 3 disclose an adhesive sheet that is supposed to be heat-treated as described above. In particular, the pressure-sensitive adhesive sheet disclosed in Patent Document 1 has a base material layer and a pressure-sensitive adhesive layer made of a radiation-curable pressure-sensitive adhesive, and the pressure-sensitive adhesive layer has an adhesive strength against SUS304 after bonding of 0.5 N /. The layer is 20 mm or more, and is cured by the stimulus received until the completion of the resin sealing process, so that the peeling force against the package becomes 2.0 N / 20 mm or less. Further, in the pressure-sensitive adhesive sheet disclosed in Patent Document 2, the pressure-sensitive adhesive layer is formed of a pressure-sensitive adhesive composition containing a predetermined pressure-sensitive adhesive component and a predetermined tetrazole compound. Further, in the pressure-sensitive adhesive sheet disclosed in Patent Document 3, a pressure-sensitive adhesive layer containing a predetermined acrylic polymer, an energy ray-polymerizable oligomer, a predetermined polymerization initiator, and a cross-linking agent on a heat-resistant base material. A pressure-sensitive adhesive layer made of a forming material is formed.

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

However, when the heat treatment of the chip as described above is performed on the conventional work processing sheet, the adhesive force of the work processing sheet to the chip is improved by heating, and as a result, the chip is transferred from the sheet after the heat treatment. There was a problem that it could not be picked up well. Such a problem could not be sufficiently solved even by using an adhesive sheet having a predetermined heat resistance as disclosed in Patent Documents 1 to 3.

The present invention has been made in view of such an actual situation, and the work after processing has been subjected to heat treatment while exhibiting sufficient adhesive force to the work when processing the work. It is an object of the present invention to provide a work processing sheet capable of satisfactorily separating the above-mentioned materials.

In order to achieve the above object, first, the present invention is a work processing sheet including a base material and a pressure-sensitive adhesive layer laminated on one side of the base material, and the pressure-sensitive adhesive layer is active. It is composed of an energy ray-curable adhesive, the adhesive strength of the work processing sheet to the silicon wafer is F0, and the laminate formed by laminating the work processing sheet to the silicon wafer is heated at 150 ° C. for 1 hour. After that, when the adhesive force of the work processing sheet to the silicon wafer after irradiating the adhesive layer constituting the laminated body with active energy rays is F2, the adhesive force F0 is determined. Provided is a work processing sheet characterized in that the ratio of the adhesive force F2 to the adhesive force F0 (F2 / F0) is 0.66 or less, which is 600 mN / 25 mm or more and 20000 mN / 25 mm or less (invention). 1).

In the work processing sheet according to the above invention (Invention 1), when the above-mentioned adhesive force F0 is in the above range, sufficient adhesive force can be exerted on the work when the work is processed. On the other hand, the pressure-sensitive adhesive layer is composed of an active energy ray-curable pressure-sensitive adhesive, and the above-mentioned pressure ratio (F2 / F0) is within the above range, so that the processed work is attached. Even when the work sheet is heated in, by irradiating it with active energy rays after that, the adhesive force to the work after processing can be sufficiently reduced, thereby improving the work after processing. Can be separated into.

In the above invention (Invention 1), the Young's modulus of the pressure-sensitive adhesive layer at 23 ° C. after heating the work processing sheet at 150 ° C. for 1 hour is defined as E1, and the work processing sheet is heated at 150 ° C. for 1 hour. When the Young's modulus of the pressure-sensitive adhesive layer at 23 ° C. after heating and further irradiating the pressure-sensitive adhesive layer constituting the work processing sheet with active energy rays is E2, the Young's modulus The ratio (E2 / E1) of the Young's modulus E2 to the rate E1 is preferably 13 or more (Invention 2).

In the above inventions (Inventions 1 and 2), the Young's modulus of the pressure-sensitive adhesive layer in the work processing sheet at 23 ° C. is set to E0, and the pressure-sensitive adhesive after heating the work processing sheet at 150 ° C. for 1 hour. When the Young's modulus of the layer at 23 ° C. 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).

Secondly, the present invention is a work processing sheet including a base material and a pressure-sensitive adhesive layer laminated on one side of the base material, and the pressure-sensitive adhesive layer is composed of an active energy ray-curable pressure-sensitive adhesive. The glass transition temperature of the active energy ray-curable pressure-sensitive adhesive is −50 ° C. or higher and 10 ° C. or lower, and the active energy ray-curable pressure-sensitive adhesive contains a monomer having a polar group as a constituent monomer. Provided is a work processing sheet containing a system copolymer (Invention 4).

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

In the above inventions (Inventions 1 to 5), a dicing sheet is preferable (Invention 6).

The work processing sheet according to the present invention can satisfactorily separate the processed work after the heat treatment while exhibiting sufficient adhesive force to the work when the work is processed. can.

Hereinafter, embodiments of the present invention will be described.
The work processing sheet according to the present embodiment includes a base material and an adhesive layer laminated on one side of the base material. Further, the pressure-sensitive adhesive layer is composed of an active energy ray-curable pressure-sensitive adhesive.

1. 1. Physical characteristics of the work processing sheet (1) Adhesive force 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 600 mN / 25 mm or more. It is preferably 900 mN / 25 mm or more, and more preferably 1200 mN / 25 mm or more. Further, the adhesive force F0 is preferably 20000 mN / 25 mm or less, particularly preferably 5000 mN / 25 mm or less, and further preferably 3000 mN / 25 mm or less. The adhesive force F0 means the initial adhesive force measured for a work sheet that has not been subjected to treatment such as heating or irradiation with active energy rays, which will be described later.

In the work processing sheet according to the present embodiment, when the adhesive force F0 is in the above range, the work can be satisfactorily held on the work processing sheet. Therefore, when machining the work, even if an impact is generated due to the machining, it is possible to satisfactorily suppress the movement or dropping of the work after the machining. In particular, when the adhesive force F0 is 600 mN / 25 mm or more, it becomes easy to hold the work well during processing. On the other hand, when the adhesive force F0 is 20000 mN / 25 mm or less, when the work processing sheet is irradiated with active energy rays described later, the adhesive force to the processed work is likely to be sufficiently reduced. As a result, the work after processing can be easily separated from the work processing sheet.

In the work processing sheet according to the present embodiment, the laminate formed by laminating the work processing sheet on the silicon wafer is heated at 150 ° C. for 1 hour, and then the pressure-sensitive adhesive layer constituting the laminate is further applied. When the adhesive force of the work processing sheet to the silicon wafer after irradiation with the active energy ray is F2, the ratio of the adhesive force F2 to the above-mentioned adhesive force F0 (F2 / F0) is 0.66 or less. Is preferable, and in particular, it is preferably 0.2 or less, and further preferably 0.15 or less. When the ratio (F2 / F0) is 0.66 or less, it becomes easy to satisfactorily balance the retention of the work during processing and the separation of the work after processing after irradiation with active energy rays. In particular, even when the work sheet after processing is attached to the work sheet and the work sheet is exposed to heat treatment, the processed work can be well separated from the work sheet. It will be easy. The lower limit of the ratio (F2 / F0) is not particularly limited, but may be, for example, 0.01 or more.

In the work processing sheet according to the present embodiment, the above-mentioned 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. .. Further, the adhesive strength F2 is preferably 30 mN / 25 mm or more. When the adhesive force F2 is in the above range, the ratio (F2 / F0) can be easily adjusted to the above range.

In the work processing sheet according to the present embodiment, the adhesive strength of the work processing sheet to the silicon wafer after heating the laminate formed by laminating the work processing sheet on the silicon wafer at 150 ° C. for 1 hour is set to F1. In some cases, the adhesive strength F1 is preferably 1000 mN / 25 mm or more, and particularly preferably 2300 mN / 25 mm or more. Further, the adhesive strength F1 is preferably 5000 mN / 25 mm or less. When the adhesive force F1 is in the above range, the ratio (F2 / F0) can be easily adjusted to the above range.

The details of the above-mentioned methods for measuring the adhesive strengths F0, F1 and F2 are as described in the test examples described later.

(2) Young's modulus In the work processing sheet according to the present embodiment, the Young's modulus of the pressure-sensitive adhesive layer at 23 ° C. after heating the work processing sheet at 150 ° C. for 1 hour is set to E1, and the work processing sheet is used. When the Young's modulus of the pressure-sensitive adhesive layer at 23 ° C. after heating at 150 ° C. for 1 hour and then irradiating the pressure-sensitive adhesive layer constituting the work processing sheet with active energy rays is E2. In addition, the ratio (E2 / E1) of the Young's modulus E2 to the Young's modulus E1 is preferably 13 or more, particularly preferably 15 or more, and further preferably 18 or more.

As described above, the pressure-sensitive adhesive layer in the present embodiment is composed of an active energy ray-curable pressure-sensitive adhesive. In general, the components present in the active energy ray-curable pressure-sensitive adhesive for achieving the active energy ray-curability carry out a predetermined reaction by heating, and the curing of the pressure-sensitive adhesive may proceed due to this reaction. be. For example, when the above component is an acryloyl group, the carbon-carbon double bond in the acryloyl group may be cleaved by heating and the polymerization reaction may proceed. As described above, when the reaction of the above components proceeds by heating, further curing of the pressure-sensitive adhesive layer does not proceed satisfactorily even if the active energy rays are subsequently irradiated. However, in the work processing sheet according to the present embodiment, if the ratio (E2 / E1) is within the above range, the adhesive strength is satisfactorily reduced by irradiation with active energy rays even after heat treatment. It becomes easy to make it. As a result, it is possible to effectively suppress unintentional dropping of the work after processing before irradiation with active energy rays.

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

In the work processing sheet according to the present embodiment, when the Young's modulus of the pressure-sensitive 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, particularly preferably 2.3 or more, and further preferably 2.6 or more. The Young's modulus E0 means the initial Young's modulus measured for the pressure-sensitive adhesive layer that has not been subjected to treatment such as heating or irradiation with active energy rays.

In general, the pressure-sensitive adhesive tends to soften when heated, increasing its adhesion to the adherend. However, in the work processing sheet according to the present embodiment, when the ratio (E1 / E0) is in the above range, the adhesive is less likely to be softened by heating, and the adhesiveness due to the heat treatment is excessively improved. It can be effectively suppressed. As a result, after the pressure-sensitive adhesive layer is irradiated with the active energy rays, the processed work can be easily separated satisfactorily.

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

In the work processing sheet 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. .. The Young's modulus E0 is preferably 15 MPa or less, particularly preferably 10 MPa or less, and further preferably 5 MPa or less. When the Young's modulus E0 is in the above range, the ratio (E1 / E0) can be easily adjusted to the above range.

In the work processing sheet 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. .. The Young's modulus E1 is preferably 100 MPa or less, particularly preferably 50 MPa or less, and further preferably 10 MPa or less. When the Young's modulus E1 is in the above range, the ratio (E2 / E1) and the ratio (E1 / E0) can be easily adjusted to the above ranges, respectively.

In the work processing sheet 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. The Young's modulus E2 is preferably 300 MPa or less, particularly preferably 250 MPa or less, and further preferably 200 MPa or less. When the Young's modulus E2 is in the above range, the ratio (E2 / E1) can be easily adjusted to the above range.

The details of each of the above-mentioned Young's modulus E0, E1 and E2 measuring methods are as described in the test examples described later.

2. Components of Work Processing Sheet (1) Base Material In the work processing sheet according to the present embodiment, the base material exhibits a desired function in the process of using the work processing sheet, and preferably the adhesive layer is cured. It is not particularly limited as long as it exhibits good permeability to the active energy rays irradiated for the purpose and has a predetermined heat resistance.

For example, the base material is preferably a resin film whose main material is a resin-based material, and specific examples thereof include an ethylene-vinyl acetate copolymer film; an ethylene- (meth) acrylic acid copolymer film, and the like. Ethylene-based copolymer films such as ethylene- (meth) methyl acrylate copolymer film and other ethylene- (meth) acrylic acid ester copolymer films; polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene Polyethylene-based films such as films, ethylene-norbornene copolymer films, norbornene resin films, cycloolefin resin films; polyvinyl chloride-based films such as polyvinyl chloride films and vinyl chloride copolymer films; polyethylene terephthalate films, polybutylene terephthalates Films, polyester films such as polycyclohexylene methylene terephthalate, polyethylene naphthalate; (meth) acrylic acid ester copolymer films; polyurethane films; polyimide films; polystyrene films; polycarbonate films; fluororesin films; polyphenylene sulfide films, etc. Can be mentioned. Examples of the polyethylene film include a low density polyethylene (LDPE) film, a linear low density polyethylene (LLDPE) film, a high density polyethylene (HDPE) film and the like. Further, modified films such as these crosslinked films and ionomer films are also used. Further, the base material may be a laminated film in which a plurality of the above-mentioned films are laminated. In this laminated film, the materials constituting each layer may be the same type or different types. Among the above films, the base material is an annealed polyester film, a heat resistant polyester film, a polycarbonate film, a polyphenylene sulfide film, or a cycloolefin from the viewpoint of excellent permeability of active energy rays and heat resistance. It is preferable to use a resin film. In addition, "(meth) acrylic acid" in this specification means both acrylic acid and methacrylic acid. The same applies to other similar terms.

The substrate may contain various additives such as flame retardants, plasticizers, antistatic agents, lubricants, antioxidants, colorants, infrared absorbers, ultraviolet absorbers, ion scavengers and the like. The content of these additives is not particularly limited, but is preferably in the range in which the base material exhibits a desired function.

The surface on which the pressure-sensitive adhesive layer of the base material is laminated may be subjected to surface treatment such as primer treatment, corona treatment, and plasma treatment in order to improve the adhesion to the pressure-sensitive adhesive layer.

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

(2) Adhesive Layer In the work processing sheet according to the present embodiment, the adhesive layer is composed of an active energy ray-curable adhesive. Since the pressure-sensitive adhesive layer is composed of an active energy ray-curable pressure-sensitive adhesive, the pressure-sensitive adhesive layer can be cured by irradiation with active energy rays to reduce the adhesive force of the work processing sheet to the adherend. .. This makes it possible to easily separate the machined work from the work processing sheet.

Further, it is preferable that the pressure-sensitive adhesive layer in the present embodiment can achieve the above-mentioned adhesive strength. From this point of view, the pressure-sensitive adhesive layer in the present embodiment has an active energy ray-curable pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer having a glass transition temperature of −50 ° C. or higher and 10 ° C. or lower and active energy ray-curable. The pressure-sensitive adhesive preferably contains an acrylic copolymer containing a monomer having a polar group as a constituent monomer. By providing the pressure-sensitive adhesive layer composed of such an active energy ray-curable pressure-sensitive adhesive, the work processing sheet can easily achieve the above-mentioned adhesive strength.

From the viewpoint that the work processing sheet can more easily achieve the above-mentioned adhesive force, the glass transition temperature is particularly preferably −20 ° C. or higher, and further preferably −15 ° C. or higher. From the same viewpoint, the glass transition temperature is particularly preferably 5.0 ° C. or lower, and further preferably 3.0 ° C. or lower. The details of the method for measuring the glass transition temperature are as described in Test Examples described later.

The active energy ray-curable pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer may be mainly composed of a polymer having active energy ray-curable property, or an active energy ray-curable polymer (active energy ray-curable polymer). It may be mainly composed of a mixture of a polymer having no polymer) and a monomer and / or an oligomer having at least one or more active energy ray-curable groups.

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

The active energy ray-curable polymer is a (meth) acrylic acid ester (co) polymer (A) in which a functional group (active energy ray-curable group) having active energy ray curability is introduced into a side chain (hereinafter referred to as “A”). It may be referred to as "active energy ray-curable polymer (A)"). This active energy ray-curable polymer (A) is composed of an acrylic copolymer (a1) having a functional group-containing monomer unit and an unsaturated group-containing compound (a2) having a functional group bonded to the functional group. It is preferably obtained by reaction.

As the functional group-containing monomer described above, a monomer having a polymerizable double bond and a functional group such as a hydroxy group, a carboxy group, an amino group, an amide group, a benzyl group and a glycidyl group in the molecule is preferable. Above all, it is preferable to use a monomer containing a hydroxy group as a functional group (hydroxy group-containing monomer).

Examples of the hydroxy group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 2-hydroxybutyl (meth) acrylate. Examples thereof include 3-hydroxybutyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate, and among these, 2-hydroxyethyl acrylate is preferably used. These may be used alone or in combination of two or more.

Examples of the carboxy 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 alone or in combination of two or more.

Examples of the amino group-containing monomer or the amide group-containing monomer include aminoethyl (meth) acrylate and n-butylaminoethyl (meth) acrylate. These may be used alone or in combination of two or more.

The acrylic copolymer (a1) preferably contains the structural unit derived from the functional group-containing monomer in an amount of 1% by mass or more, particularly preferably 5% by mass or more, and further contains 10% by mass or more. It is preferable to do so. Further, the acrylic copolymer (a1) preferably contains the structural unit derived from the functional group-containing monomer in an amount of 35% by mass or less, and particularly preferably in an amount of 30% by mass or less. When the acrylic copolymer (a1) contains the functional group-containing monomer in the above range, the desired active energy ray-curable polymer (A) can be easily formed.

As described above, the acrylic copolymer (a1) preferably contains a monomer having a polar group (monomer containing a polar group) as a monomer unit constituting the polymer. As a result, the polarity of the obtained active energy ray-curable pressure-sensitive adhesive is improved, and the above-mentioned adhesive strength can be easily achieved.

Examples of the polar group-containing monomer include acryloyl morpholine, isobornyl acrylate, methyl methacrylate, vinyl acetate, benzyl acrylate, glycidyl methacrylate and the like, and among these, acryloyl morpholine or isobornyl acrylate is particularly used. It is preferable to do so.

The acrylic copolymer (a1) preferably contains a structural unit derived from the polar group-containing monomer in an amount of 3.0% by mass or more, particularly preferably 5.0% by mass or more, and further, 8 It is preferably contained in an amount of 0.0% by mass or more. Further, the acrylic copolymer (a1) preferably contains a structural unit derived from the polar group-containing monomer in an amount of 12.0% by mass or less. When the acrylic copolymer (a1) contains the polar group-containing monomer in the above range, the polarity of the obtained active energy ray-curable pressure-sensitive adhesive can be effectively improved, whereby the above-mentioned adhesive strength can be effectively improved. Will be easy to achieve.

Further, the acrylic copolymer (a1) contains a monomer (Tg adjusting monomer) for adjusting the glass transition temperature (Tg) of the active energy ray-curable pressure-sensitive adhesive as a monomer unit constituting the polymer. Is also preferable. As a result, the obtained active energy ray-curable pressure-sensitive adhesive tends to have the above-mentioned glass transition temperature (Tg). Examples of preferable monomers that also serve as Tg-adjusting monomers include those described above as examples of polar group-containing monomers, and among them, acryloylmorpholin or isobornyl acrylate is particularly preferable.

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

The dissolution parameter (SP value) of the Tg adjusting monomer described above 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 adjusting monomer is 9.8 or more, it becomes easy to adjust the adhesive force of the work processing sheet to the above-mentioned range, and in particular, the initial adhesive force F0 can be easily adjusted to the above-mentioned range. It becomes. As a result, the work can be easily held on the work processing sheet during processing. 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 the structural unit derived from the Tg-adjusting monomer in an amount of 3.0% by mass or more, particularly preferably 5.0% by mass or more, and further 8. It is preferably contained in an amount of 0% by mass or more. Further, the acrylic copolymer (a1) preferably contains a structural unit derived from the Tg-adjusting monomer in an amount of 12.0% by mass or less. When the acrylic copolymer (a1) contains the Tg adjusting monomer in the above range, the glass transition temperature of the obtained active energy ray-curable pressure-sensitive adhesive can be easily adjusted in the above range.

As the acrylic copolymer (a1), it is also preferable to use a (meth) acrylic acid alkyl ester monomer having an alkyl group having 1 to 20 carbon atoms as the monomer unit constituting the polymer. As such a (meth) acrylic acid alkyl ester monomer, a (meth) acrylic acid alkyl ester monomer having an alkyl group having 1 to 18 carbon atoms is particularly preferable. Further, from the viewpoint of easily obtaining a pressure-sensitive adhesive having excellent heat resistance, a (meth) acrylic acid alkyl ester monomer having an alkyl group having 8 or more carbon atoms is preferable. Preferred examples of the (meth) acrylic acid alkyl ester monomer having an alkyl group having 1 to 20 carbon atoms are methyl methacrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and n- (meth) acrylic acid. Examples thereof include butyl and 2-ethylhexyl (meth) acrylate. These may be used individually by 1 type, and may be used in combination of 2 or more type.

The acrylic copolymer (a1) preferably contains 50% by mass or more of the above-mentioned structural unit derived from the (meth) acrylic acid alkyl ester monomer having 1 to 20 carbon atoms in the alkyl group. It is preferably contained in an amount of 60% by mass or more, and more preferably 70% by mass or more. Further, the acrylic copolymer (a1) may contain the above-mentioned structural unit derived from the (meth) acrylic acid alkyl ester monomer having 1 to 20 carbon atoms in the alkyl group in an amount of 99% by mass or less. It is preferably contained in an amount of 95% by mass or less, and more preferably 90% by mass or less.

The acrylic copolymer (a1) can be preferably obtained by copolymerizing the above-described monomers or derivatives thereof by a conventional method, but in addition to these monomers, an alicyclic structure is formed in the molecule. The monomer (monomer containing an alicyclic structure), dimethylacrylamide, vinyl formate, styrene and the like may be copolymerized.

Examples of the alicyclic structure-containing monomer include cyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, adamantyl (meth) acrylate, isobornyl (meth) acrylate, and dicyclo (meth) acrylate. Examples thereof include pentenyl and dicyclopentenyloxyethyl (meth) acrylate. These may be used individually by 1 type, and may be used in combination of 2 or more type.

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

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, an amino group or an amide group, the functional group of the unsaturated group-containing compound (a2) is preferably an isocyanate group or an epoxy group, and is acrylic. When the functional group of the copolymer (a1) is a glycidyl group, the functional group of the unsaturated group-containing compound (a2) is preferably an amino group, a carboxy group or an aziridinyl group.

The unsaturated group-containing compound (a2) contains at least one, preferably 1 to 6, and more preferably 1 to 4 active energy ray-polymerizable carbon-carbon double bonds in one molecule. It has been. Specific examples of such an unsaturated group-containing compound (a2) include 2-methacryloyloxyethyl isocyanate, meta-isopropenyl-α, α-dimethylbenzyl isocyanate, methacryloyl isocyanate, allyl isocyanate, 1,1-( Bisacryloyloxymethyl) ethyl isocyanate; Acryloyl monoisocyanate compound obtained by reacting a diisocyanate compound or polyisocyanate compound with hydroxyethyl (meth) acrylate; a diisocyanate compound or polyisocyanate compound, a polyol compound, and (meth) acrylic. Acryloyl monoisocyanate compound obtained by reaction with hydroxyethyl acid acid; glycidyl (meth) acrylate; (meth) acrylic acid, 2- (1-aziridinyl) ethyl (meth) acrylate, 2-vinyl-2-oxazoline, 2 -Isocyanate-2-oxazoline and the like can be mentioned.

The unsaturated group-containing compound (a2) is preferably 50 mol% or more, particularly preferably 60 mol% or more, still more preferably 60 mol% or more, based on the number of moles of the functional group-containing monomer of the acrylic copolymer (a1). It is used in a proportion of 70 mol% or more. The unsaturated group-containing compound (a2) is preferably 95 mol% or less, particularly preferably 93 mol% or less, and further, with respect to the number of moles of the functional group-containing monomer of the acrylic copolymer (a1). It is preferably used in a proportion of 90 mol% or less.

In the reaction between the acrylic copolymer (a1) and the unsaturated group-containing compound (a2), the functional group of the acrylic copolymer (a1) and the functional group of the unsaturated group-containing compound (a2) are used. Depending on the combination, the reaction temperature, pressure, solvent, time, presence / absence of catalyst, and type of polymer 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), and the unsaturated group is contained in the acrylic copolymer (a1). It is introduced into the side chain to obtain an active energy ray-curable polymer (A).

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 200,000 or more. It is preferable to have it. The weight average molecular weight (Mw) is preferably 1.5 million or less, and particularly preferably 1 million or less. The weight average molecular weight (Mw) in the present specification is a standard polystyrene-equivalent value measured by a gel permeation chromatography method (GPC method).

Even when the active energy ray-curable pressure-sensitive adhesive contains a polymer having active energy ray-curable property such as the active energy ray-curable polymer (A) as a main component, the active energy ray-curable pressure-sensitive adhesive has active energy. It may further contain a linear curable monomer and / or oligomer (B).

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

Examples of the active energy ray-curable monomer and / or oligomer (B) include monofunctional acrylic acid esters such as cyclohexyl (meth) acrylate and isobornyl (meth) acrylate, trimethyl propantri (meth) acrylate, and the like. Pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, polyethylene Examples thereof include polyfunctional acrylic acid esters such as glycol di (meth) acrylate and dimethylol tricyclodecandi (meth) acrylate, polyester oligo (meth) acrylate, and polyurethane oligo (meth) acrylate.

When the active energy ray-curable monomer and / or the oligomer (B) is blended with the active energy ray-curable polymer (A), the active energy ray-curable monomer and / or the active energy ray-curable monomer in the active energy ray-curable pressure-sensitive adhesive. Alternatively, the content of the oligomer (B) is preferably more than 0 parts by mass, particularly preferably 60 parts by mass or more, with respect to 100 parts by mass of the active energy ray-curable polymer (A). The content is preferably 250 parts by mass or less, and particularly preferably 200 parts by mass or less, with respect to 100 parts by mass of the active energy ray-curable polymer (A).

Here, when ultraviolet rays are used as the active energy rays for curing the active energy ray-curable pressure-sensitive adhesive, it is preferable to add a photopolymerization initiator (C), and the photopolymerization initiator (C) is used. Therefore, the polymerization curing time and the amount of light irradiation can be reduced.

The photopolymerization initiator (C) in the present 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 the photopolymerization initiator (C) showing a 5% weight loss temperature of 200 ° C. or higher, it becomes easy to adjust the adhesive strength of the work processing sheet within the above-mentioned range, and in particular, heating and irradiation with active energy are performed. After that, the adhesive force F2 can be easily adjusted to the above-mentioned range. As a result, even when the heat treatment is performed, the work after processing can be easily separated from the work processing sheet. The upper limit of the 5% weight loss temperature is not particularly limited, and may be, for example, 300 ° C. or lower, particularly 280 ° C. or lower, or 250 ° C. or lower. The details of the method for measuring the 5% weight loss temperature are as described in 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, methyl benzoin benzoate, benzoin dimethyl ketal, 2, 4-diethylthioxanthone, 1-hydroxycyclohexylphenylketone, benzyldiphenylsulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, benzyl, dibenzyl, diacetyl, β-chloranthraquinone, (2,4,6- Trimethylbenzyldiphenyl) phosphine oxide, 2-benzothiazole-N, N-diethyldithiocarbamate, oligo {2-hydroxy-2-methyl-1- [4- (1-propenyl) phenyl] propanone}, 2,2- Dimethoxy-1,2-diphenylethane-1-one, 2-hydroxy-1-{4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2-methyl-propane-1- For example, on. Among these, it is preferable to use 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2-methyl-propane-1-one. These may be used alone or in combination of two or more.

When the photopolymerization initiator (C) contains the active energy ray-curable polymer (A) (active energy ray-curable monomer and / or oligomer (B), the active energy ray-curable polymer (A) ) And the total amount of the active energy ray-curable monomer and / or oligomer (B) 100 parts by mass) 0.1 parts by mass or more, particularly 0.5 parts by mass or more with respect to 100 parts by mass. preferable. When the photopolymerization initiator (C) contains the active energy ray-curable polymer (A) (active energy ray-curable monomer and / or oligomer (B), the photopolymerization initiator (C) is an active energy ray-curable polymer. (A) and the total amount of the active energy ray-curable monomer and / or oligomer (B) 100 parts by mass) It is preferable to use the amount of 10 parts by mass or less, particularly 6 parts by mass or less with respect to 100 parts by mass.

In the active energy ray-curable pressure-sensitive adhesive, other components may be appropriately added in addition to the above components. Examples of other components include an active energy ray non-curable polymer component or an oligomer component (D), a cross-linking agent (E), and the like.

Examples of the active energy ray non-curable polymer component or oligomer component (D) include polyacrylic acid esters, polyesters, polyurethanes, polycarbonates, polyolefins, etc., and polymers having a weight average molecular weight (Mw) of 3000 to 2.5 million or Oligomers are preferred. By blending the component (D) with an active energy ray-curable pressure-sensitive adhesive, the tackiness and peelability before curing, the strength after curing, the adhesiveness with other layers, the storage stability and the like can be improved. The blending 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 cross-linking agent (E), a polyfunctional compound having reactivity with a functional group of the active energy ray-curable polymer (A) or the like can be used. Examples of such polyfunctional 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, etc. Reactive phenolic resins and the like can be mentioned.

The blending amount of the cross-linking agent (E) is preferably 0.01 part by mass or more, and particularly preferably 1 part by mass or more, with respect to 100 parts by mass of the active energy ray-curable polymer (A). The amount of the cross-linking agent (E) to be blended is preferably 20 parts by mass or less, and particularly preferably 17 parts by mass or less, based on 100 parts by mass of the active energy ray-curable polymer (A).

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

As the active energy ray non-curable polymer component, for example, the same component as the above-mentioned acrylic copolymer (a1) can be used.

As the monomer and / or oligomer having at least one or more active energy ray-curable groups, the same one as the above-mentioned component (B) can be selected. The blending ratio of the active energy ray non-curable polymer component to the monomer and / or oligomer having at least one active energy ray curable group is at least 1 with respect to 100 parts by mass of the active energy ray non-curable polymer component. It is preferably 1 part by mass or more of the monomer and / or oligomer having two or more active energy ray-curable groups, and particularly preferably 60 parts by mass or more. Further, the compounding ratio is preferably 200 parts by mass or less of a monomer and / or an oligomer having at least one active energy ray-curable group with respect to 100 parts by mass of the active energy ray non-curable polymer component. In particular, it is preferably 160 parts by mass or less.

In this case as well, the photopolymerization initiator (C) and the cross-linking agent (E) can be appropriately blended in the same manner as described above.

The thickness of the pressure-sensitive adhesive layer is preferably 1 μm or more, and more preferably 5 μm or more. The thickness is preferably 50 μm or less, and more preferably 40 μm or less. When the thickness of the pressure-sensitive adhesive layer is within the above range, the above-mentioned adhesive strength can be easily achieved.

(3) Release Sheet In the work processing sheet according to the present embodiment, the surface of the pressure-sensitive adhesive layer opposite to the base material (hereinafter, may be referred to as “adhesive surface”) is attached to the work until it is attached to the work. A release sheet may be laminated on the surface for the purpose of protecting the surface. The structure of the release sheet is arbitrary, and examples thereof include a plastic film peeled with a release agent or the like. Specific examples of the plastic film include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, and polyolefin films such as polypropylene and polyethylene. As the release agent, silicone type, fluorine type, long chain alkyl type and the like can be used, and among these, the silicone type which can obtain stable performance at low cost is preferable. The thickness of the release sheet is not particularly limited, but is usually 20 μm or more and 250 μm or less.

(4) Other Members In the work processing sheet according to the present embodiment, the adhesive layer may be laminated on the adhesive surface of the adhesive layer. In this case, the work processing sheet according to the present embodiment can be used as a dicing / die bonding sheet by providing the adhesive layer as described above. In such a work processing sheet, the work is attached to the surface of the adhesive layer opposite to the adhesive layer, and the adhesive layer is diced together with the work, so that the individualized adhesive layers are laminated. You can get the chips that have been made. The individualized adhesive layer allows the chip to be easily fixed to the object on which the chip is mounted. As the material constituting the adhesive layer described above, a material containing a thermoplastic resin and a low molecular weight thermosetting adhesive component, a material containing a B stage (semi-curable) thermosetting adhesive component, and the like are used. It is preferable to use it.

Further, in the work processing sheet 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 work processing sheet according to the present embodiment can be used as a protective film forming and dicing sheet. In such a work processing sheet, the work is attached to the surface of the protective film forming layer opposite to the adhesive layer, and the protective film forming layer is diced together with the work to form an individualized protective film. Chips with laminated layers can be obtained. As the work, it is preferable to use a work having a circuit formed on one surface, and in this case, a protective film forming layer is usually laminated on a surface opposite to the surface on which the circuit is formed. The individualized protective film forming layer is cured at a predetermined timing to form a protective film having sufficient durability on the chip. The protective film forming layer is preferably made of an uncured curable adhesive.

The work processing sheet according to the present embodiment preferably satisfies the above-mentioned conditions regarding the adhesive strength, but when the above-mentioned adhesive layer or protective film forming layer is laminated on the adhesive layer. It is sufficient that the pressure-sensitive adhesive layer before these layers are laminated satisfies the above-mentioned adhesive strength.

3. 3. Manufacturing Method of Work Processing Sheet The manufacturing method of the work processing sheet according to the present embodiment is not particularly limited, and preferably, the work processing sheet according to the present embodiment has an adhesive layer laminated on one side of the base material. Manufactured by

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

When the coating liquid for forming the pressure-sensitive adhesive layer contains a cross-linking agent, the above-mentioned drying conditions (temperature, time, etc.) may be changed, or a heat treatment may be separately provided in the coating film. The cross-linking reaction between the active energy ray-curable polymer (A) or the active energy ray non-curable polymer and the cross-linking agent may be allowed to proceed to form a cross-linked structure in the pressure-sensitive adhesive layer at a desired abundance density. In order to allow this cross-linking reaction to proceed sufficiently, after laminating an adhesive layer on the base material by the above method or the like, the obtained work processing sheet is placed in an environment of, for example, 23 ° C. and a relative humidity of 50% for several days. Curing such as standing still may be performed.

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

4. How to use the work processing sheet The work processing sheet according to the present embodiment can be used for processing the work. That is, after the adhesive surface of the work processing sheet according to the present embodiment is attached to the work, the work can be processed on the work processing sheet. Depending on the processing, the work processing sheet according to the present embodiment can be used as a back grind sheet, a dicing sheet, an expanding sheet, a pickup sheet, or the like. Here, examples of the work include semiconductor members such as semiconductor wafers and semiconductor packages, and glass members such as glass plates.

Further, when the work processing sheet according to the present embodiment includes the adhesive layer described above, the work processing sheet can be used as a dicing / die bonding sheet. Further, when the work processing sheet according to the present embodiment includes the above-mentioned protective film forming layer, the work processing sheet can be used as a protective film forming and dicing sheet.

When the 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, the pressure-sensitive adhesive layer on the work processing sheet is applied before the separation. It is preferable to irradiate with active energy rays. As a result, the adhesive layer is cured, the adhesive force of the work processing sheet to the processed work is satisfactorily reduced, and the processed work can be easily separated.

As the above-mentioned active energy ray, for example, an electromagnetic wave or a charged particle beam having an energy quantum can be used, and specifically, an ultraviolet ray, an electron beam, or the like can be used. In particular, ultraviolet rays that are easy to handle are preferable. Irradiation of ultraviolet rays, a high-pressure mercury lamp, can be performed by a xenon lamp, LED, etc., the dose of ultraviolet ray is illuminance 50 mW / cm ² or more, and preferably 1000 mW / cm ² or less. Further, the light amount is preferably at 50 mJ / cm ² or more, particularly preferably at 80 mJ / cm ² or more, and further preferably not 200 mJ / cm ² or more. Further, the light amount is preferably at 10000 mJ / cm ² or less, particularly preferably at 5000 mJ / cm ² or less, and further preferably not 2000 mJ / cm ² or less. On the other hand, the irradiation of the electron beam can be performed by an electron beam accelerator or the like, and the irradiation amount of the electron beam is preferably 10 grad or more and 1000 grad or less.

In the work processing sheet according to the present embodiment, since the adhesive force F0 is within the above-mentioned range, sufficient adhesive force is exhibited to the work when the work is processed, and the work or the work after processing can be subjected to sufficient adhesive force. Problems such as movement and dropping can be suppressed satisfactorily. Further, the pressure-sensitive adhesive layer is composed of an active energy ray-curable pressure-sensitive adhesive, and the pressure ratio of F2 / F0 is within the above-mentioned range. Even when the work is heated, the adhesive force to the work after processing can be sufficiently reduced by irradiating the work with active energy rays after that, so that the work after processing can be picked up satisfactorily. can. Therefore, the work processing sheet according to the present embodiment is suitable for applications in which the work processing sheet is exposed to a high temperature environment with the work or the processed work attached on the work processing sheet. Can be used. In particular, in the work processing sheet according to the present embodiment, 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. It is suitable to be used for various purposes.

When the work processing sheet according to the present embodiment is used as a dicing sheet, and after dicing, the tip is attached to the work processing sheet for occasional heat treatment, the heating conditions include, for example, heating. The temperature is preferably 40 ° C. or higher, particularly preferably 80 ° C. or higher, and further preferably 100 ° C. or higher. Further, the heating temperature is preferably 150 ° C. or lower, particularly preferably 130 ° C. or lower, and further preferably 120 ° C. or lower. Further, the heating time is preferably, for example, 3 minutes or more, particularly preferably 10 minutes or more, and further preferably 30 minutes or more. Further, the heating time is preferably 60 minutes or less, particularly preferably 50 minutes or less, and further preferably 40 minutes or less. The work processing sheet according to the present embodiment can satisfactorily separate chips even when heated under the above-mentioned conditions.

The embodiments described above are described for facilitating the understanding of the present invention, and are not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

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

Hereinafter, the present invention will be described in more detail with reference to Examples and the like, but the scope of the present invention is not limited to these Examples and the like.

[Example 1]
(1) Preparation of Adhesive Composition Acrylic copolymer obtained by copolymerizing 70 parts by mass of 2-ethylhexyl acrylate, 10 parts by mass of acryloylmorpholine, and 20 parts by mass of 2-hydroxyethyl acrylate. And 90 mol% of methacryloyloxyethyl isocyanate (MOI) was reacted with respect to the number of moles of 2-hydroxyethyl acrylate of the acrylic copolymer to obtain an active energy ray-curable polymer. The weight average molecular weight (Mw) of this active energy ray-curable polymer was measured by the method described later and found to be 830,000.

An aliphatic isocyanate having 100 parts by mass of the obtained active energy ray-curable polymer (solid content equivalent, the same applies hereinafter) and hexamethylene diisocyanate as a cross-linking agent (manufactured by Nippon Polyurethane Industry Co., Ltd., product name "Coronate HX"). 1.2 parts by mass and 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2-methyl-propane-1- as a photopolymerization initiator On (manufactured by BASF, product name "Omnirad 127", 5% weight loss temperature: 220 ° C.) was mixed with 1.2 parts by mass in a solvent to obtain a pressure-sensitive adhesive composition. The 5% weight reduction temperature of the photopolymerization initiator is set to a temperature rise rate of 5 ° C. from room temperature to 300 ° C. using a differential thermal / thermogravimetric simultaneous measuring device (manufactured by SHIMADZU, product name “DTG-60”). It was measured by heating in minutes.

(2) Formation of Adhesive Layer Against the peeling surface of a release sheet (manufactured by Lintec Corporation, product name "SP-PET381031") in which a silicone-based release agent layer is formed on one side of a 38 μm-thick polyethylene terephthalate film. The pressure-sensitive adhesive composition was applied, dried by heating, and then cured under the conditions of 23 ° C. and 50% RH for 7 days to form a pressure-sensitive adhesive layer having a thickness of 5 μm on the release sheet.

(3) Preparation of Work Sheet Processing Polyester film (manufactured by Kurabo Industries Ltd.) having a heat-resistant surface with a thickness of 75 μm as a base material and the surface opposite to the release sheet of the adhesive layer formed in the above step (2). , Product name "Torsena") was attached to one side to obtain a work sheet.

Here, the above-mentioned weight average molecular weight (Mw) is a standard polystyrene-equivalent weight average molecular weight measured by gel permeation chromatography (GPC) (GPC measurement).

[Examples 2 to 8 and Comparative Examples 1 to 4]
Work sheet for work processing in the same manner as in Example 1, except that the composition and weight average molecular weight of the acrylic copolymer are changed as shown in Table 1 and the composition of the pressure-sensitive adhesive composition is changed as shown in Table 2. Manufactured.

[Test Example 1] (Measurement of glass transition temperature of adhesive)
By laminating a plurality of pressure-sensitive adhesive layers of the work processing sheets produced in Examples and Comparative Examples, a laminated body of pressure-sensitive adhesive layers having a thickness of 800 μm was produced. Subsequently, the laminate of the pressure-sensitive adhesive layer was punched into a circle having a diameter of 10 mm to obtain a sample for measurement. Using a dynamic viscoelasticity measuring device (manufactured by TA Instruments, product name "ARES"), the measurement sample has a frequency of 1 Hz, a measurement temperature range of -50 to 150 ° C, and a temperature rise rate of 3 ° C. Tan δ was measured under the condition of / min, and the temperature at the peak top was defined as Tg. The results are shown in Table 3.

[Test Example 2] (Measurement of adhesive strength)
The workpiece processing sheets produced in Examples and Comparative Examples were cut into strips having a width of 25 mm. The release sheet is peeled off from the obtained strip-shaped work processing sheet, and the adhesive surface of the exposed adhesive layer is mirror-processed with respect to the mirror surface of the silicon wafer at a temperature of 23 ° C. and a relative humidity of 50%. Under the environment, they were bonded together using a 2 kg rubber roller and allowed to stand for 20 minutes to prepare a sample for measurement.

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

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

Further, the measurement sample obtained in the same manner as above was heated at 150 ° C. for 1 hour using an oven. Further, the pressure-sensitive adhesive layer was irradiated with ultraviolet rays under the following conditions via the base material. For this measurement sample, the adhesive strength (mN / 25 mm) with respect to the silicon wafer was measured in the same manner as described above. The adhesive strength obtained by this is shown in Table 3 as the adhesive strength F2.
<Ultraviolet irradiation conditions>
・ Uses high-pressure mercury lamp ・ Illuminance 230mW / cm ² , light intensity 190mJ / cm ²
・ UV illuminance / photometer uses "UVPF-A1" manufactured by iGraphics.

Further, 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 from the three types of adhesive forces obtained as described above. These results are shown in Table 3.

[Test Example 3] (Measurement of Young's modulus of adhesive)
A plurality of laminates of the pressure-sensitive adhesive layer and the release sheet produced in the same manner as in the above step (2) of Example 1 were prepared for each of Examples and Comparative Examples. Then, by laminating a predetermined number of pressure-sensitive adhesive layers in the laminated body, a pressure-sensitive adhesive layer sample for measurement composed of a pressure-sensitive adhesive layer having a thickness of 200 μm was prepared.

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

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

Further, the pressure-sensitive adhesive layer sample for measurement obtained in the same manner as described above was heated at 150 ° C. for 1 hour using an oven. Further, the pressure-sensitive adhesive layer sample for measurement after heating was irradiated with ultraviolet rays under the following conditions. The Young's modulus (MPa) was determined for this measurement pressure-sensitive adhesive layer sample in the same manner as described above. The results obtained as a result are shown in Table 3 as Young's modulus E2.
<Ultraviolet irradiation conditions>
・ Uses high-pressure mercury lamp ・ Illuminance 230mW / cm ² , light intensity 580mJ / cm ²
・ UV illuminance / photometer uses "UVPF-A1" manufactured by iGraphics.

Further, from the three types of Young's modulus 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 off from the work processing sheet manufactured in Examples and Comparative Examples, and a tape mounter (manufactured by Lintec Corporation, product name "Adwill RAD2500 m / 12") was used on the exposed surface of the exposed adhesive layer. A polished surface of a 2000-polished 6-inch silicon wafer (thickness: 350 μm) was attached. Subsequently, using a dicing apparatus (manufactured by Disco Corporation, product name "DFD-6362"), dicing was performed by cutting from the 6-inch silicon wafer side while supplying running water to the cutting portion under the following dicing conditions.

<Dicing conditions>
・ Dicing device: DFD-6362 manufactured by Disco Corporation
-Blade: NBC-2H 2050 27HECC manufactured by Disco Corporation
-Blade width: 0.025 to 0.030 mm
・ Amount of cutting edge: 0.640 to 0.760 mm
・ Blade rotation speed: 50,000 rpm
・ Cutting speed: 20 mm / sec
-Cut depth: 20 μm from the surface of the work processing sheet on the adhesive layer side to the base material
・ Running water supply: 1.0 L / min
・ Running water temperature: Room temperature ・ Cut size: 2mm x 2mm

After that, the work processing sheet to which the chips obtained in the dicing process are attached is visually observed, the number of chips that have fallen off from the work processing sheet during the dicing process is counted, and the number is divided into the number in the dicing process. The chip scattering rate (unit:%) was calculated by dividing by. Based on this calculation result, the initial adhesiveness was evaluated based on the following criteria. The evaluation results are shown in Table 3.
◯: The chip scattering rate is less than 10%.
X: The chip scattering rate is 10% or more.

[Test Example 5] (Evaluation of pickup suitability)
Using the workpiece processing sheets produced 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 × 10 mm.

After the completion of dicing, the work processing sheet on which the chips were placed was placed in an oven and heated at 150 ° C. for 1 hour. Subsequently, the pressure-sensitive adhesive layer in the work processing sheet was irradiated with ultraviolet rays under the following conditions via the base material.
<Ultraviolet irradiation conditions>
・ Uses high-pressure mercury lamp ・ Illuminance 230mW / cm ² , light intensity 190mJ / cm ²
・ UV illuminance / photometer uses "UVPF-A1" manufactured by iGraphics.

100 chips were picked up from the work processing sheet after ultraviolet irradiation, and the pick-up suitability was evaluated based on the following criteria. The results are shown in Table 3.
⊚: Of the 100 chips, the number of chips that could be picked up satisfactorily was 95 or more.
◯: Of the 100 chips, the number of chips that could be picked up satisfactorily was less than 95 and 80 or more.
X: Out of 100 chips, the number of chips that could be picked up satisfactorily was less than 80.

Details of the abbreviations and the like shown in Tables 1 and 2 are as follows.
[Composition of active energy ray-curable polymer]
2EHA: 2-ethylhexyl acrylate BA: butyl acrylate ACMO: acryloylmorpholin (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 acrylate MOI: Methacryloyloxyethyl isocyanate [photopolymerization 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 ° C.)
Omnirad TPO: 2,4,6-trimethylbenzoyldiphenylphosphine oxide (manufactured by BASF, product name "Omnirad TPO", 5% weight loss temperature: 225 ° C)

As can be seen from Table 3, the work processing sheet obtained in the examples was excellent in initial adhesiveness and was able to hold the work well on the sheet during processing of the work. Further, it was suggested that the work processing sheet obtained in the examples was excellent in pick-up suitability, that is, the adhesive force to the work after processing was satisfactorily reduced at the time of pick-up.

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

Claims (6)

A work processing sheet including a base material and an adhesive layer laminated on one side of the base material.
The pressure-sensitive adhesive layer is composed of an active energy ray-curable pressure-sensitive adhesive.
The adhesive strength of the work processing sheet to the silicon wafer is set to F0.
The laminate obtained by laminating the work processing sheet on a silicon wafer is heated at 150 ° C. for 1 hour, and then the pressure-sensitive adhesive layer constituting the laminate is irradiated with active energy rays. When the adhesive strength of the work processing sheet to the silicon wafer is F2,
The adhesive strength F0 is 600 mN / 25 mm or more and 20000 mN / 25 mm or less.
A work processing sheet characterized in that the ratio (F2 / F0) of the adhesive force F2 to the adhesive force F0 is 0.66 or less. The Young's modulus of the pressure-sensitive adhesive layer at 23 ° C. after heating the work processing sheet at 150 ° C. for 1 hour was defined as E1.
After heating the work processing sheet at 150 ° C. for 1 hour and then irradiating the pressure-sensitive adhesive layer constituting the work processing sheet with active energy rays, the pressure-sensitive adhesive layer at 23 ° C. When Young's modulus is E2,
The work processing sheet according to claim 1, wherein the ratio (E2 / E1) of the Young's modulus E2 to the Young's modulus E1 is 13 or more. The Young's modulus of the pressure-sensitive adhesive layer in the work processing sheet at 23 ° C. was set to E0.
When the Young's modulus of the pressure-sensitive adhesive layer at 23 ° C. after heating the work processing sheet at 150 ° C. for 1 hour is E1.
The work processing sheet according to claim 1 or 2, wherein the ratio (E1 / E0) of the Young's modulus E1 to the Young's modulus E0 is 2.0 or more. A work processing sheet including a base material and an adhesive layer laminated on one side of the base material.
The pressure-sensitive adhesive layer is composed of an active energy ray-curable pressure-sensitive adhesive.
The glass transition temperature of the active energy ray-curable pressure-sensitive adhesive is −50 ° C. or higher and 10 ° C. or lower.
A work processing sheet, wherein the active energy ray-curable pressure-sensitive adhesive contains an acrylic copolymer containing a monomer having a polar group as a constituent monomer. The work processing sheet according to claim 4, wherein the acrylic copolymer is one in which a functional group having active energy ray curability is introduced into a side chain. The work processing sheet according to any one of claims 1 to 5, wherein the dicing sheet is used.