JP7296944B2 - Work processing sheet - Google Patents

Description

TECHNICAL FIELD The present invention relates to a work processing sheet that can be suitably used for processing a work having an uneven surface.

Semiconductor wafers made of silicon, gallium arsenide, etc., and various types of packages are manufactured in a state of large diameter. is transferred to the mounting process, which is the process of . At this time, the object to be cut, such as a semiconductor wafer, is subjected to processing such as back grinding, dicing, cleaning, drying, expanding, picking up, and mounting while being adhered to a work processing sheet having a base material and an adhesive layer. is done.

In recent years, the use of work processing sheets such as those described above to process glass plates has increased. For example, in manufacturing a camera module mounted on a mobile phone or a smart phone, fine glass pieces are required. It can be obtained by dicing. That is, after attaching a glass plate to the work processing sheet, the glass plate is cut with a dicing blade to obtain individualized glass pieces (glass chips).

When dicing a semiconductor wafer or a glass plate using a work processing sheet, it is necessary to ensure that the formed chips are not unintentionally separated or dropped from the work processing sheet (chip flying) during dicing. Desired.

Patent Literature 1 discloses a work processing sheet using a glass plate as a work, one of the problems of which is to suppress chip flying as described above. In the work processing sheet, a substrate having a predetermined thickness and a predetermined tensile elastic modulus is used as the base material, and the pressure-sensitive adhesive layer has a predetermined thickness, so that the chip fly as described above and further , to suppress the occurrence of chipping (chipping) on the cut surface of the chip.

Patent No. 3838637

By the way, a workpiece having an uneven surface may be processed using the above-described workpiece processing sheet. For example, a semiconductor wafer with circuits and electrodes formed on the surface, or a glass plate with a partial print on the surface, is diced on a work processing sheet, and a semiconductor chip with circuits and electrodes on the surface. , a glass chip with partial printing on the surface is produced.

When a workpiece having such unevenness is processed using a work processing sheet, the surface of the workpiece having the unevenness is applied to the surface of the adhesive layer of the work processing sheet opposite to the base material ( Hereinafter, it may be referred to as an “adhesive surface”.) may be attached. In this case, after the processing is completed, in the workpiece separated from the workpiece processing sheet, the adhesive constituting the adhesive layer adheres (adhesive residue) to the surface attached to the adhesive surface, especially near the unevenness of the surface. is likely to occur. Such glue residue can degrade the performance of the resulting chip or the product in which it is incorporated. In particular, since glass chips are often used in applications that require high light transmittance, when manufacturing glass chips using a work processing sheet, the light transmittance may be greatly reduced. It is strongly required that there is no sticky adhesive residue. However, the conventional work processing sheet disclosed in Patent Literature 1 cannot sufficiently suppress the occurrence of adhesive residue.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and provides a work processing sheet capable of suppressing the occurrence of chip flying during dicing and suppressing the occurrence of adhesive residue during peeling. With the goal.

In order to achieve the above object, firstly, the present invention provides a work processing sheet comprising a substrate and an adhesive layer laminated on one side of the substrate, wherein the adhesive layer has a weight It is formed from a pressure-sensitive adhesive composition containing an acrylic copolymer having an average molecular weight of 100,000 or more and 2,500,000 or less and an active energy ray-curable component having a weight average molecular weight of 2,000 or more and 40,000 or less, A work processing sheet is provided, wherein the content of low molecular weight components having a molecular weight of less than 800 in the active energy ray-curable component is 20% by mass or less (Invention 1).

In the work processing sheet according to the above invention (Invention 1), the adhesive layer is formed from an adhesive composition containing the above-described acrylic copolymer and an active energy ray-curable component, and , the weight-average molecular weight of the active energy ray-curable component and the content of the predetermined low molecular weight component in the active energy ray-curable component are within the ranges described above, respectively, so that the work processing sheet is exposed to active energy ray Before irradiation, it exhibits good adhesiveness to the work. As a result, it is possible to satisfactorily suppress chip flying during dicing. Furthermore, in the work processing sheet, the adhesive layer has a high cohesive force after being irradiated with the active energy ray, and even if the work has unevenness on the surface, there is no adhesive residue at the time of peeling. can be suppressed.

In the above invention (invention 1), the active energy ray-curable component preferably contains a polyfunctional acrylate (invention 2).

In the above inventions (inventions 1 and 2), the active energy ray-curable component preferably has a weight average molecular weight of more than 2,500 (invention 3).

In the above inventions (inventions 1 to 3), the acrylic copolymer preferably does not have active energy ray curability (invention 4).

In the above inventions (Inventions 1 to 4), the thickness of the adhesive layer is preferably 10 μm or more and 100 μm or less (Invention 5).

In the above inventions (Inventions 1 to 5), the substrate is preferably a polyethylene terephthalate film (Invention 6).

In the above inventions (inventions 1 to 6), the work of the work processing sheet is a work having an uneven surface, and the surface of the pressure-sensitive adhesive layer opposite to the base material has the unevenness of the work. It is preferably attached to the surface to be covered (Invention 7).

In the above inventions (Inventions 1 to 7), it is preferable to use a glass plate as the work (Invention 8).

In the above inventions (Inventions 1 to 8), it is preferably a dicing sheet (Invention 9).

The work processing sheet according to the present invention can suppress the occurrence of chip flying during dicing and the occurrence of adhesive residue during peeling.

Embodiments of the present invention will be described below.
A work processing sheet according to this embodiment includes a substrate and an adhesive layer laminated on one side of the substrate.

1. Components of Work Processing Sheet (1) Base Material In the work processing sheet according to the present embodiment, the base material is not particularly limited as long as it exhibits the desired functions when the work processing sheet is used. . When using a workpiece that has no or relatively low permeability to active energy rays, such as a semiconductor wafer, the substrate preferably has good permeability to active energy rays. By irradiating the adhesive layer with active energy rays through the base material, the adhesive layer can be cured satisfactorily. In addition, even when a work made of a material having good permeability to active energy rays, such as a glass member, is used, the surface of the glass member has unevenness (for example, unevenness due to printing). is present, and even if there is a possibility that sufficient transparency to the active energy ray cannot be exhibited due to the unevenness, the substrate preferably has good transparency to the active energy ray. .

For example, the substrate is preferably a resin film mainly composed of a resin-based material, and specific examples thereof include polyester-based films such as polyethylene terephthalate film, polybutylene terephthalate film, and polyethylene naphthalate; ethylene-acetic acid; Vinyl copolymer film; Ethylene-based copolymer film such as ethylene-(meth)acrylic acid copolymer film, ethylene-methyl(meth)acrylate copolymer film, and other ethylene-(meth)acrylic acid ester copolymer films Polymerized film; Polyolefin film such as polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, ethylene-norbornene copolymer film, norbornene resin film; Polyvinyl chloride film, vinyl chloride copolymer film, etc. Polyvinyl chloride film; (meth)acrylate copolymer film; polyurethane film; polyimide film; polystyrene film; polycarbonate film; Examples of polyethylene films include low density polyethylene (LDPE) films, linear low density polyethylene (LLDPE) films, high density polyethylene (HDPE) films, and the like. Modified films such as these crosslinked films and ionomer films are also used. Further, the base material may be a laminated film formed by laminating a plurality of films described above. In this laminated film, the materials constituting each layer may be of the same type or of different types. In addition, "(meth)acrylic acid" in this specification means both acrylic acid and methacrylic acid. The same is true for other similar terms.

Among the films described above, it is preferable to use a polyester-based film as the base material in the present embodiment, and a polyethylene terephthalate film is particularly preferable. Polyethylene terephthalate films tend to achieve relatively high elastic moduli. Therefore, by using polyethylene terephthalate film as a base material, even if impact is applied to the work processing sheet during work processing (for example, dicing), vibration and deformation of the work processing sheet can be prevented. easy to suppress. As a result, it becomes easy to suppress damage, movement, and the like of the work and the work after processing. In particular, when a glass member is used as the work, the member is very fragile compared to a semiconductor wafer or the like, and is likely to break during processing on the work processing sheet. Therefore, when the glass plate is diced on the work processing sheet, chipping is likely to occur on the cut surface of the glass chip obtained by the dicing. However, by using a polyethylene terephthalate film as the substrate, it is possible to satisfactorily suppress the occurrence of chipping as described above.

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

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

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

(2) Adhesive layer The adhesive layer in the present embodiment comprises an acrylic copolymer having a weight average molecular weight of 100000 or more and 2500000 or less and an active energy ray-curable component having a weight average molecular weight of 2000 or more and 40000 or less. It is formed from a pressure-sensitive adhesive composition containing and. The content of the low-molecular weight component having a molecular weight of less than 800 in the active energy ray-curable component is 20% by mass or less.

In the work processing sheet according to the present embodiment, the work processing sheet is separated from the work after processing because the adhesive layer is formed from an adhesive composition containing an active energy ray-curable component. At this time, the adhesive layer can be cured by irradiation with active energy rays, and the adhesive force of the work processing sheet to the work can be reduced. This makes it possible to easily perform the separation described above.

Further, in the work processing sheet according to the present embodiment, the active energy ray-curable component used has a weight average molecular weight of 2000 or more and 40000 or less, and the active energy ray-curable component has a molecular weight of 800. When the content of the low-molecular-weight component is 20% by mass or less, it is possible to satisfactorily achieve both suppression of chip flying during dicing and suppression of adhesive residue during peeling. In particular, the weight average molecular weight of the active energy ray-curable component is moderately small, so that the work processing sheet has good adhesion to the work and the work after processing before irradiation with the active energy ray. It will demonstrate. As a result, the work and the work after processing can be held well on the work processing sheet. It is possible to suppress flight well. In addition, the weight average molecular weight of the active energy ray-curable component is moderately large, and the content of the above-described low molecular weight component is 20% by mass or less, so that after irradiation with an active energy ray, the pressure-sensitive adhesive The layer will have high cohesive strength. As a result, it is possible to satisfactorily suppress the occurrence of adhesive residue on the work separated from the work processing sheet.

When the weight average molecular weight of the active energy ray-curable component exceeds 40,000, it becomes difficult for the work processing sheet to achieve sufficient adhesive strength to the work, and chip flying during dicing cannot be sufficiently suppressed. From this point of view, the weight average molecular weight of the active energy ray-curable component is preferably 20,000 or less, particularly preferably 10,000 or less.

Further, when the weight average molecular weight of the active energy ray-curable component is less than 2000, the cohesive strength of the adhesive layer is not sufficiently improved after irradiation with the active energy ray, resulting in adhesive residue. From this point of view, the weight average molecular weight of the active energy ray-curable component is preferably 2,300 or more, and more than 2,500.

In addition, the weight average molecular weight (Mw) in this specification is the value of standard polystyrene conversion measured by the gel permeation chromatography method (GPC method).

Furthermore, even when the content of the low-molecular weight component having a molecular weight of less than 800 in the active energy ray-curable component exceeds 20% by mass, the cohesive force of the adhesive layer is sufficient after the irradiation with the active energy ray. It does not improve, and adhesive residue occurs. From this point of view, the content of the low-molecular-weight components described above is preferably 18% by mass or less.

Although it is preferable that the low-molecular-weight component described above is not substantially contained in the active-energy-ray-curable component, it is necessary to completely prevent the low-molecular-weight component from remaining or forming during the production of the active-energy-ray-curable component. is usually difficult. Therefore, the lower limit of the content of the low-molecular-weight component in the active-energy-ray-curable component is generally 0% by mass or more, and may be 1% by mass or more.

The details of the method for measuring the content of the low-molecular-weight component having a molecular weight of less than 800 in the active-energy-ray-curable component are as described in the later-described test examples.

(2-1) Acrylic Copolymer The acrylic copolymer in the present embodiment is not particularly limited as long as it has a weight average molecular weight of 100,000 or more and 2,500,000 or less.

The acrylic copolymer in the present embodiment has a weight average molecular weight of 100,000 or more and 2,500,000 or less, and is distinguished from the active energy ray-curable component described above in this respect. The weight-average molecular weight of the acrylic copolymer is preferably 150,000 or more, particularly preferably 300,000 or more, from the viewpoint of facilitating adjustment of the cohesive force of the pressure-sensitive adhesive layer to a desired range. Moreover, the weight average molecular weight of the acrylic copolymer is preferably 2,000,000 or less, particularly preferably 1,800,000 or less, from the viewpoint of easily achieving the desired adhesive strength.

The acrylic copolymer in the present embodiment may or may not have active energy ray curability. In the work processing sheet according to the present embodiment, the acrylic copolymer is used in combination with the active energy ray-curable component described above, and in the case of such a combination, the adhesive force can be easily controlled. From the viewpoint that it is easy to effectively suppress chip flying, it is preferable that the acrylic copolymer does not have active energy ray curability.

The above-mentioned acrylic copolymer not having active energy ray curability is not particularly limited as long as it contains an acrylic monomer as a monomer unit constituting the polymer. It is preferably a copolymer of monomers. The (meth)acrylic acid alkyl ester monomer preferably has an alkyl group with 1 or more carbon atoms, particularly preferably 2 or more carbon atoms. The (meth)acrylic acid alkyl ester monomer preferably has an alkyl group with 18 or less carbon atoms, particularly preferably 8 or less. Specific examples of (meth)acrylic acid alkyl ester monomers include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, and n-(meth)acrylate. -pentyl, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-decyl (meth)acrylate, lauryl (meth)acrylate, myristyl (meth)acrylate , palmityl (meth)acrylate, stearyl (meth)acrylate, and the like. Among these, from the viewpoint that the adhesive force of the work processing sheet according to the present embodiment can be easily adjusted to a desired range, and thereby it is possible to effectively suppress chip flying, n-butyl acrylate is preferably used. The (meth)acrylic acid alkyl ester monomers described above may be used alone, or two or more thereof may be used in combination.

The acrylic copolymer described above preferably contains 50% by mass or more, particularly preferably 60% by mass or more, of a (meth)acrylic acid alkyl ester monomer as a monomer unit constituting the polymer. In addition, the acrylic copolymer preferably contains 98% by mass or less, particularly 95% by mass or less, of a (meth)acrylic acid alkyl ester monomer as a monomer unit constituting the polymer. preferable.

In addition, when the pressure-sensitive adhesive composition contains a cross-linking agent, which will be described later, the above-described acrylic copolymer can easily be cross-linked well, and the adhesive strength can be adjusted to a desired range. From the viewpoint of facilitating the formation of a polymer, it is preferable to contain a functional group-containing monomer as a monomer unit constituting the polymer. Examples of the functional group possessed by the functional group-containing monomer include a hydroxyl group, a carboxy group, an amino group, a substituted amino group, an epoxy group, etc. Among them, a hydroxyl group and a carboxy group are preferred, and a carboxy group is particularly preferred. In addition, different types of functional group-containing monomers may be used in combination.

When a monomer having a carboxy group (carboxy group-containing monomer) is used as the functional group-containing monomer, examples thereof include ethylenically unsaturated carboxylic acids, specific examples of which include acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, citraconic acid and the like. Among these, acrylic acid is preferable from the viewpoint of reactivity of the carboxy group and copolymerizability. These may be used alone or in combination of two or more.

When a monomer having a hydroxyl group (hydroxyl group-containing monomer) is used as the functional group-containing monomer, examples thereof include hydroxyalkyl (meth)acrylates, and specific examples thereof include 2-hydroxyethyl (meth)acrylate. , 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate etc. Among these, 2-hydroxyethyl (meth)acrylate is preferable from the viewpoint of reactivity of hydroxyl group and copolymerizability. These may be used alone or in combination of two or more.

The acrylic copolymer described above preferably contains 0.1% by mass or more, particularly preferably 0.5% by mass or more, of a functional group-containing monomer as a monomer unit constituting the polymer. Furthermore, it is preferable to contain 1 mass % or more. In addition, the acrylic copolymer preferably contains 30% by mass or less, particularly preferably 20% by mass or less, of a functional group-containing monomer as a monomer unit constituting the polymer. It is preferably contained at 15% by mass or less.

The acrylic copolymer may contain monomers other than the (meth)acrylic acid alkyl ester monomer and the functional group-containing monomer described above as monomer units constituting the polymer.

Examples of the other monomers include alkoxyalkyl group-containing (meth)acryls such as methoxymethyl (meth)acrylate, methoxyethyl (meth)acrylate, ethoxymethyl (meth)acrylate, and ethoxyethyl (meth)acrylate. acid esters; (meth)acrylic acid esters having an aliphatic ring such as cyclohexyl (meth)acrylate; (meth)acrylic acid esters having an aromatic ring such as phenyl (meth)acrylate; Crosslinkable acrylamide; (meth)acrylic acid ester having a non-crosslinkable tertiary amino group such as N,N-dimethylaminoethyl (meth)acrylate and N,N-dimethylaminopropyl (meth)acrylate; acetic acid vinyl; styrene; These may be used alone or in combination of two or more.

The polymerization mode of the acrylic copolymer may be a random copolymer or a block copolymer. Moreover, the polymerization method is not particularly limited, and polymerization can be performed by a general polymerization method.

When the acrylic copolymer in the present embodiment is an acrylic copolymer having active energy ray-curable properties, the acrylic copolymer has active energy ray-curable functional groups (active energy A (meth)acrylic acid ester polymer into which a linear curable group) is introduced is preferable. Such a (meth)acrylic acid ester polymer contains the above-described functional group-containing monomer (and, if desired, the above-described (meth)acrylic acid alkyl ester monomer and other monomers) as monomer units constituting the polymer. It is preferably obtained by reacting the contained (meth)acrylic acid ester polymer with an unsaturated group-containing compound containing a functional group capable of bonding to the functional group of the functional group-containing monomer.

The unsaturated group-containing compound described above is not particularly limited as long as it has an unsaturated group and a functional group capable of reacting with the functional group of the functional group-containing monomer unit described above.

The functional group of the unsaturated group-containing compound can be appropriately selected according to the type of functional group of the functional group-containing monomer. For example, when the functional group of the functional group-containing monomer is a hydroxyl group, an amino group or a substituted amino group, the functional group of the unsaturated group-containing compound is preferably an isocyanate group or an epoxy group, and the functional group of the functional group-containing monomer is an epoxy group. In the case of a group, the functional group possessed by the unsaturated group-containing compound is preferably an amino group, a carboxyl group or an aziridinyl group.

The unsaturated group possessed by the unsaturated group-containing compound is preferably an active energy ray-polymerizable carbon-carbon double bond. The number of carbon-carbon double bonds in the unsaturated group-containing compound is preferably one or more. Further, the number of carbon-carbon double bonds in the unsaturated group-containing compound is preferably 6 or less, particularly preferably 4 or less.

Preferred examples of unsaturated group-containing compounds include 2-methacryloyloxyethyl isocyanate, meta-isopropenyl-α,α-dimethylbenzyl isocyanate, methacryloyl isocyanate, allyl isocyanate, 1,1-(bisacryloyloxymethyl)ethyl isocyanate; An acryloyl monoisocyanate compound obtained by reacting a diisocyanate compound or polyisocyanate compound with hydroxyethyl (meth)acrylate; obtained by reacting a diisocyanate compound or polyisocyanate compound, a polyol compound, and hydroxyethyl (meth)acrylate acryloyl monoisocyanate compound; glycidyl (meth)acrylate; (meth)acrylic acid, 2-(1-aziridinyl)ethyl (meth)acrylate, 2-vinyl-2-oxazoline, 2-isopropenyl-2-oxazoline, etc. is mentioned.

When obtaining an acrylic copolymer having active energy ray curability by reacting an unsaturated group-containing compound with a (meth)acrylic acid ester polymer containing a functional group-containing monomer, the above (meth) Depending on the combination of the functional group of the acrylic acid ester polymer and the functional group of the unsaturated group-containing compound, reaction temperature, pressure, solvent, time, presence or absence of catalyst, and type of catalyst can be appropriately selected. . As a result, the functional groups present in the (meth)acrylic acid ester polymer react with the functional groups in the unsaturated group-containing compound, and the unsaturated groups form side chains in the (meth)acrylic acid ester polymer. to obtain an acrylic copolymer having active energy ray curability.

(2-2) Active energy ray-curable component The active energy ray-curable component in the present embodiment is active energy ray-curable, has a weight average molecular weight of 2000 or more and 40000 or less, and is active energy ray-curable. There is no particular limitation as long as the content of low-molecular-weight components having a molecular weight of less than 800 in the components is 20% by mass or less. In particular, from the viewpoint that the weight average molecular weight is easily adjusted to the above range and the content of the low molecular weight component is easily adjusted to the above range, the active energy ray-curable component is a polyfunctional acrylate oligomer or modified product. is preferred.

The number of functional groups of the active energy ray-curable component is preferably 2 or more, particularly preferably 5 or more. Also, the number of functional groups is preferably 20 or less, particularly preferably 10 or less. When the number of functional groups of the active energy ray-curable component is within the above range, the pressure-sensitive adhesive layer can be easily cured to a desired extent by irradiation with an active energy ray. is easier to separate, and it is possible to effectively suppress adhesive residue on the work.

Preferred examples of the polyfunctional acrylate include trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, pentaerythritol triacrylate, dipentaerythritol monohydroxypentaacrylate, dipentaerythritol hexaacrylate, 1,4-butylene glycol diacrylate, Polyfunctional acrylates such as 1,6-hexanediol diacrylate can be mentioned.

Moreover, examples of the above modified products include urethane modified products, epoxy modified products, ester modified products, and the like. Among these, the modified product is preferably a urethane modified product from the viewpoint that the weight average molecular weight can be easily adjusted to the range described above and the content of the low molecular weight component can be easily adjusted to the range described above.

The urethane-modified product is preferably obtained by reacting the polyfunctional acrylate described above with a polyisocyanate compound. Examples of the polyisocyanate compound include alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate; aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate and xylylene diisocyanate; and aliphatic polyisocyanates such as hexamethylene diisocyanate. etc. Among these, alicyclic polyisocyanates are preferred, and isophorone diisocyanate is particularly preferred.

As the active energy ray-curable component in the present embodiment, a polyfunctional urethane acrylate obtained by reacting pentaerythritol triacrylate and alicyclic polyisocyanate is preferable, and in particular, pentaerythritol triacrylate and isophorone diisocyanate are reacted. Difunctional to 20-functional polyfunctional urethane acrylates obtained by

In the active energy ray-curable component in the present embodiment, the content of low molecular weight components having a molecular weight of less than 1200 in the active energy ray-curable component is preferably 50% by mass or less, particularly 45% by mass. It is preferably 42% by mass or less, more preferably 42% by mass or less. When the content of the low molecular weight component having a molecular weight of less than 1200 is 50% by mass or less, it becomes easy to adjust the content of the low molecular weight component having a molecular weight of less than 800 within the range described above. The lower limit of the content of low-molecular-weight components having a molecular weight of less than 1,200 is not particularly limited, and is usually 0% by mass or more, and may be 1% by mass. The details of the method for measuring the content of the low-molecular-weight component having a molecular weight of less than 1,200 are as described in the later-described test examples.

The content of the active energy ray-curable component in the adhesive composition in the present embodiment is preferably 10 parts by mass or more, particularly 20 parts by mass or more, with respect to 100 parts by mass of the acrylic copolymer described above. and more preferably 30 parts by mass or more. Also, the content is preferably 300 parts by mass or less, particularly preferably 200 parts by mass or less, and further preferably 150 parts by mass or less. When the content of the active energy ray-curable component is within the above range, the pressure-sensitive adhesive layer after irradiation with an active energy ray has an appropriate cohesive force, and the processed work separated from the work processing sheet It is possible to effectively suppress the occurrence of adhesive residue. In addition, since the content of the active energy ray-curable component is 10 parts by mass or more, the adhesive layer can be easily cured by irradiation with the active energy ray, and the work after processing can be removed from the work processing sheet. When separating, it becomes possible to separate more easily. On the other hand, since the content of the active energy ray-curable component is 300 parts by mass or less, the work processing sheet according to the present embodiment exhibits good adhesion to the work before being irradiated with the active energy ray. It becomes easy to use, and chip flying can be effectively suppressed. Moreover, since the content of the active energy ray-curable component is 300 parts by mass or less, it is possible to prevent the elastic modulus of the pressure-sensitive adhesive layer from becoming excessively low before the irradiation with the active energy ray. As a result, vibration and deformation of the workpiece machining sheet during machining of the workpiece are suppressed, and high-precision machining is possible. In particular, when dicing is performed using a work processing sheet, it is possible to effectively suppress the occurrence of chipping.

(2-3) Crosslinking agent The pressure-sensitive adhesive composition in the present embodiment preferably contains a crosslinking agent. By including a cross-linking agent in the pressure-sensitive adhesive composition, it becomes possible to cross-link the acrylic copolymer in the pressure-sensitive adhesive layer and form a favorable three-dimensional network structure. As a result, the cohesive force of the resulting pressure-sensitive adhesive is further improved, and it is possible to effectively suppress the occurrence of adhesive residue on the workpiece separated from the workpiece processing sheet after irradiation with the active energy ray. When the pressure-sensitive adhesive composition contains a cross-linking agent, the acrylic copolymer preferably contains the functional group-containing monomer described above as a monomer unit constituting the polymer. It is preferable to contain a functional group-containing monomer having a highly reactive functional group with the agent.

Examples of the above-mentioned cross-linking agents include isocyanate-based cross-linking agents, epoxy-based cross-linking agents, amine-based cross-linking agents, melamine-based cross-linking agents, aziridine-based cross-linking agents, hydrazine-based cross-linking agents, aldehyde-based cross-linking agents, oxazoline-based cross-linking agents, and metal alkoxides. cross-linking agents, metal chelate-based cross-linking agents, metal salt-based cross-linking agents, ammonium salt-based cross-linking agents, and the like. These cross-linking agents can be selected according to the functional group derived from the functional group-containing monomer that the acrylic copolymer has. In addition, these crosslinking agents can be used individually by 1 type or in combination of 2 or more types.

The isocyanate-based cross-linking agent contains at least a polyisocyanate compound. Examples of polyisocyanate compounds include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate; and alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate. , and their biuret, isocyanurate, and adducts which are reaction products with low-molecular-weight active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil. Among these, trimethylolpropane-modified aromatic polyisocyanate, particularly trimethylolpropane-modified tolylene diisocyanate is preferable.

When the pressure-sensitive adhesive composition in the present embodiment contains a cross-linking agent, the content of the cross-linking agent in the pressure-sensitive adhesive composition is 1 part by mass or more with respect to 100 parts by mass of the acrylic copolymer described above. is preferred, and 5 parts by mass or more is particularly preferred. Moreover, the content is preferably 20 parts by mass or less, and particularly preferably 15 parts by mass or less. When the content of the cross-linking agent is 1 part by mass or more, it becomes easier to improve the cohesive force of the pressure-sensitive adhesive layer after irradiation with active energy rays, thereby effectively suppressing adhesive residue. . In addition, when the content of the cross-linking agent is 20 parts by mass or less, the degree of cross-linking becomes appropriate, and the pressure-sensitive adhesive layer easily exhibits the desired adhesive strength, thereby effectively suppressing chip flying. It becomes possible to

(2-4) Photopolymerization Initiator The adhesive composition in the present embodiment preferably contains a photopolymerization initiator. By including a photopolymerization initiator in the pressure-sensitive adhesive composition, it is possible to reduce the polymerization curing time and the amount of light irradiation when the pressure-sensitive adhesive layer is cured by irradiation with active energy rays.

Examples of photoinitiators include benzophenone, acetophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin benzoic acid, benzoin methyl benzoate, benzoin dimethyl ketal, 2,4-diethylthio xanthone, 1-hydroxycyclohexylphenyl ketone, 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-diphenylethan-1-one and the like. Among these, it is preferable to use 1-hydroxycyclohexylphenyl ketone. The photopolymerization initiators described above may be used alone, or two or more of them may be used in combination.

When the adhesive composition in the present embodiment contains a photopolymerization initiator, the content of the photopolymerization initiator in the adhesive composition is 0.1 with respect to 100 parts by mass of the acrylic copolymer described above. It is preferably at least 1 part by mass, particularly preferably at least 1 part by mass. Also, the content is preferably 10 parts by mass or less, particularly preferably 5 parts by mass or less. When the content of the photopolymerization initiator is within the above range, the adhesive layer can be efficiently cured by irradiation with active energy rays, thereby increasing the adhesive strength of the work processing sheet to the work after processing. It becomes easier to reduce the adhesiveness well, and it becomes possible to effectively suppress the occurrence of adhesive residue on the work.

(2-5) Other components The pressure-sensitive adhesive composition in the present embodiment contains desired additives, such as silane coupling agents and antistatic agents, as long as they do not impair the above-described effects of the work processing sheet according to the present embodiment. , tackifiers, antioxidants, light stabilizers, softeners, fillers, refractive index modifiers and the like can be added. A polymerization solvent and a dilution solvent, which will be described later, are not included in the additives constituting the pressure-sensitive adhesive composition.

(2-6) Preparation method of adhesive composition The adhesive composition in the present embodiment is produced by producing an acrylic polymer, the obtained acrylic polymer, an active energy ray-curable component, and, if desired, It can be produced by mixing a cross-linking agent, a photopolymerization initiator, and an additive.

When the acrylic polymer does not have an active energy ray, the acrylic polymer can be produced by polymerizing a mixture of monomers constituting the polymer by a conventional radical polymerization method. The polymerization is preferably carried out by a solution polymerization method using a polymerization initiator as desired. Examples of the polymerization solvent include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, and methyl ethyl ketone, and two or more of them may be used in combination.

Examples of polymerization initiators include azo compounds and organic peroxides, and two or more of them may be used in combination. Examples of azo compounds include 2,2′-azobisisobutyronitrile, 2,2′-azobis(2-methylbutyronitrile), 1,1′-azobis(cyclohexane 1-carbonitrile), 2 ,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile), dimethyl 2,2'-azobis(2-methylpropionate) , 4,4′-azobis(4-cyanovaleric acid), 2,2′-azobis(2-hydroxymethylpropionitrile), 2,2′-azobis[2-(2-imidazolin-2-yl) propane] and the like.

Examples of organic peroxides include benzoyl peroxide, t-butylperbenzoate, cumene hydroperoxide, diisopropylperoxydicarbonate, di-n-propylperoxydicarbonate, di(2-ethoxyethyl)peroxy dicarbonate, t-butylperoxyneodecanoate, t-butylperoxybivalate, (3,5,5-trimethylhexanoyl)peroxide, dipropionylperoxide, diacetylperoxide and the like.

The weight average molecular weight of the resulting polymer can be adjusted by adding a chain transfer agent such as 2-mercaptoethanol in the polymerization step.

When the acrylic polymer has an active energy ray, the acrylic polymer contains the functional group-containing monomer described above, optionally the (meth)acrylic acid alkyl ester monomer described above, and the other monomers described above. After obtaining a (meth)acrylic acid ester polymer by polymerizing, an unsaturated group-containing compound capable of bonding to the functional group of the functional group-containing monomer is added to the (meth)acrylic acid ester polymer. It can be obtained by reacting by a conventionally known method.

After the acrylic polymer is obtained, an active energy ray-curable component, optionally a cross-linking agent, a photopolymerization initiator, other additives, and a diluent solvent are added to the solution of the acrylic polymer and mixed thoroughly. By doing so, a coating liquid of the pressure-sensitive adhesive composition can be obtained. In any of the above components, if a solid one is used, or if precipitation occurs when mixed with other components in an undiluted state, the component is added alone in advance to a dilution solvent. It may be dissolved or diluted prior to mixing with other ingredients.

Examples of the diluting solvent include aliphatic hydrocarbons such as hexane, heptane and cyclohexane; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as methylene chloride and ethylene chloride; Alcohols such as 1-methoxy-2-propanol, ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone and cyclohexanone, esters such as ethyl acetate and butyl acetate, and cellosolve solvents such as ethyl cellosolve are used.

The concentration/viscosity of the coating liquid thus prepared is not particularly limited as long as it is within a range that allows coating, and can be appropriately selected according to the situation. For example, the pressure-sensitive adhesive composition is diluted to a concentration of 10% by mass or more and 60% by mass or less. When obtaining the coating liquid, the addition of a diluent solvent or the like is not a necessary condition, and the diluent solvent may not be added as long as the pressure-sensitive adhesive composition has a viscosity that allows coating. In this case, the pressure-sensitive adhesive composition becomes a coating liquid in which the polymerization solvent for the acrylic polymer is used as the diluting solvent.

(2-7) Thickness of Adhesive Layer The thickness of the adhesive layer in the present embodiment is preferably 10 μm or more, particularly preferably 20 μm or more. Also, the thickness is preferably 100 μm or less, particularly preferably 50 μm or less. When the thickness of the adhesive layer is 10 μm or more, the work processing sheet can easily exhibit good adhesive strength, and it is possible to effectively suppress the work processing sheet floating during dicing and chip flying. becomes. In addition, since the thickness of the adhesive layer is 10 μm or more, chip flying can be effectively suppressed when the work is separated from the work processing sheet, and good unevenness embedding can be easily obtained. becomes. On the other hand, when the thickness of the adhesive layer is 100 μm or less, the adhesive force to the processed work after irradiation with the active energy ray is moderately reduced, and the work can be more easily separated from the work processing sheet. easier. In general, when the thickness of the adhesive layer is increased, chip fly is suppressed and unevenness is improved, but adhesive residue is likely to occur. However, according to the work processing sheet according to the present embodiment, it is possible to satisfactorily suppress the occurrence of adhesive residue. Therefore, in the work processing sheet according to the present embodiment, when the thickness of the pressure-sensitive adhesive layer is relatively thick, it is possible to satisfactorily achieve both the effects of suppressing chip flying and good embedding of irregularities and the suppression of adhesive residue. can do.

(3) Release Sheet In the work processing sheet according to the present embodiment, a release sheet is laminated on the adhesive surface of the adhesive layer for the purpose of protecting the adhesive surface until the adhesive surface is attached to the workpiece. may The configuration of the release sheet is arbitrary, and an example thereof is a plastic film subjected to release treatment with 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, a silicone-based, fluorine-based, or long-chain alkyl-based release agent can be used, and among these, a silicone-based release agent is preferred because it is inexpensive and provides stable performance. Although the thickness of the release sheet is not particularly limited, it is usually 20 μm or more and 250 μm or less.

(4) Other members In the work processing sheet according to the present embodiment, an 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 an adhesive layer as described above. In such a work processing sheet, a work is attached to the surface of the adhesive layer opposite to the pressure-sensitive adhesive layer, and the adhesive layer is diced together with the work, thereby laminating the individualized adhesive layers. you can get the chips The chip can be easily fixed to a target on which the chip is mounted by means of the individualized adhesive layer. Examples of the material constituting the adhesive layer include those containing a thermoplastic resin and a low-molecular-weight thermosetting adhesive component, those containing a B-stage (semi-cured) thermosetting adhesive component, and the like. It is preferable to use

In addition, 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 this embodiment can be used as a protective film-forming and dicing sheet. In such a work processing sheet, a 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 individualized protective films. A chip with stacked layers can be obtained. As the object to be cut, one having a circuit formed on one side is preferably used. 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 individualized protective film-forming layer at a predetermined timing, a protective film having sufficient durability can be formed on the chip. The protective film-forming layer is preferably made of an uncured curable adhesive.

2. Physical properties of the work processing sheet According to the present embodiment, the work processing sheet has an adhesive force of 1500 mN/25 mm or more to a silicon wafer (mirror surface of a mirror-finished silicon wafer, the same shall apply hereinafter) before irradiation with an active energy ray. It is preferably 2000 mN/25 mm or more, more preferably 2500 mN/25 mm or more. In the work processing sheet according to the present embodiment, the pressure-sensitive adhesive layer is formed from a pressure-sensitive adhesive composition containing an active energy ray-curable component, so that the above-described adhesive strength is achieved before the active energy ray irradiation. becomes easier. And, since the adhesive force to the silicon wafer before irradiation with the active energy ray is 1500 mN / 25 mm or more, the work or the work after processing can be easily fixed on the work processing sheet. , it is possible to effectively suppress chip flying. Although the upper limit of the adhesive strength is not particularly limited, it is preferably 20000 mN/25 mm or less, and particularly preferably 10000 mN/25 mm or less. Further, the details of the method for measuring the adhesive strength are as described in the test examples described later.

In addition, in the work processing sheet according to the present embodiment, the adhesive force to the silicon wafer after irradiation with active energy rays is preferably 300 mN/25 mm or less, particularly preferably 100 mN/25 mm or less. In the work processing sheet according to the present embodiment, the pressure-sensitive adhesive layer is formed from the pressure-sensitive adhesive composition containing an active energy ray-curable component, so that the above-described adhesive force is achieved after irradiation with an active energy ray. becomes easier. In addition, since the adhesive force to the silicon wafer after irradiation with the active energy ray is 300 mN/25 mm or less, the work after processing can be easily peeled off from the work processing sheet, and the occurrence of adhesive residue can be effectively suppressed. can be done. Moreover, the adhesive force to a silicon wafer after irradiation with active energy rays is preferably 10 mN/25 mm or more. As a result, it becomes easy to suppress separation/dropping of the processed workpiece at an unintended stage after irradiation with the active energy ray. In addition, the details of the method for measuring the adhesive strength are as described in the test examples described later.

3. Method for Manufacturing Work Processing Sheet The method for manufacturing the work processing sheet according to the present embodiment is not particularly limited, and is preferably manufactured by laminating an adhesive layer on one side of a substrate.

Lamination of the pressure-sensitive adhesive layer on one side of the substrate can be performed 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 substrate. In this case, the pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive layer and, if desired, a coating solution containing a solvent or a dispersion medium is prepared, and the release-treated surface of the release sheet (hereinafter sometimes referred to as "release surface") ) on the adhesive layer by applying the coating liquid with a die coater, curtain coater, spray coater, slit coater, knife coater, applicator or the like to form a coating film and drying the coating film. can be formed. The properties of the coating liquid are not particularly limited as long as the coating liquid can be applied. 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 work processing sheet is attached to the work.

When the coating liquid for forming the pressure-sensitive adhesive layer contains a cross-linking agent, by changing the above drying conditions (temperature, time, etc.) or by separately providing heat treatment, the inside of the coating film A crosslinking reaction between the acrylic copolymer and the crosslinking agent is allowed to proceed to form a crosslinked structure with a desired existence density in the pressure-sensitive adhesive layer. In order to allow the cross-linking reaction to proceed sufficiently, after laminating the pressure-sensitive adhesive layer on the base material by the method described above, 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 leaving still may be performed.

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

4. How to use the work processing sheet The work processing sheet according to the present embodiment can be used for processing a 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.

Processing performed using the work processing sheet according to the present embodiment includes back grinding, dicing, expanding, picking up, and the like. These processes may be performed in order on the same work processing sheet.

Further, when separating the processed work from the work processing sheet after the above-described processing is completed, it is preferable to irradiate the adhesive layer with an active energy ray before the separation. As a result, it is possible to reduce the adhesive force to the workpiece after processing, and the separation can be easily performed. As the active energy rays, ultraviolet rays, electron beams, and the like are usually used, and ultraviolet rays, which are easy to handle, are particularly preferable.

The ultraviolet irradiation can be performed by a high-pressure mercury lamp, a fusion lamp, a xenon lamp, or the like, and the irradiation amount of ultraviolet rays is preferably 50 mW/cm ² or more and 1000 mW/cm ² or less. The amount of ultraviolet light is preferably 50 mJ/cm ² or more, particularly preferably 80 mJ/cm ² or more, and more preferably 100 mJ/cm ² or more. The amount of ultraviolet light is preferably 2000 mJ/cm ² or less, particularly preferably 1000 mJ/cm ² or less, and more preferably 500 mJ/cm ² or less.

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

A work to be processed using the work processing sheet according to the present embodiment is not particularly limited. Examples of the work include semiconductor members such as semiconductor wafers and semiconductor packages, and glass members such as glass plates. According to the work processing sheet according to the present embodiment, it is possible to suppress the adhesive residue on the processed work, so it is preferable to select the work that is required not to cause such adhesive residue. Therefore, it is preferable to use a glass plate as the work of the work processing sheet according to the present embodiment. Processed objects such as glass chips obtained by processing a glass plate are often used for applications that require high light transmittance. By manufacturing a chip, it becomes easy to satisfy the above-mentioned requirement of high light transmittance.

A work suitable for the work processing sheet according to the present embodiment is a work having an uneven surface. A work to which the adhesive surface of the sheet is attached is also included.

In general, when a work processing sheet is attached to a work having unevenness as described above, it is difficult for the adhesive layer of the work processing sheet to sufficiently follow the unevenness. Voids that are not in contact with the pressure-sensitive adhesive layer are likely to occur. When the work processing sheet is irradiated with active energy rays in a state where the voids are generated, the oxygen contained in the voids inhibits the curing of the adhesive layer, and as a result, the adhesive is insufficiently cured in the vicinity of the unevenness. A portion of the layer will be generated. As a result, in the processed work separated from the work processing sheet after being irradiated with the active energy ray, adhesive residue is likely to occur in the vicinity of the irregularities.

However, according to the work processing sheet according to the present embodiment, since the adhesive layer is formed from the adhesive composition containing the active energy ray-curable component described above, the voids described above are generated. Even in the case of the adhesive layer, the adhesive layer can be satisfactorily cured by irradiation with active energy rays, thereby favorably improving the cohesive force of the adhesive constituting the adhesive layer. As a result, even if the work has irregularities on its surface, it is possible to satisfactorily suppress adhesive residue.

Examples of workpieces having uneven surfaces as described above include semiconductor wafers and semiconductor packages having circuits and electrodes formed on their surfaces, and glass plates having partially printed surfaces. Another example is a semiconductor wafer, a glass plate, or the like whose surface is processed to form an uneven shape.

In the work processing sheet according to the present embodiment, the pressure-sensitive adhesive layer is formed from the pressure-sensitive adhesive composition containing the active energy ray-curable component described above. Alternatively, it has good adhesive strength to the work after processing, and can satisfactorily suppress chip flying during dicing. Furthermore, in the work processing sheet according to the present embodiment, the adhesive layer is formed from the adhesive composition containing the active energy ray-curable component described above, so that after irradiation with an active energy ray, Thus, the cohesive force of the adhesive constituting the adhesive layer can be improved, and adhesive residue can be suppressed satisfactorily when the work is peeled off.

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 meant 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 substrate and the adhesive layer, or on the surface of the substrate opposite to the adhesive layer.

EXAMPLES 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 An acrylic copolymer was obtained by copolymerizing 91 parts by mass of butyl acrylate and 9 parts by mass of acrylic acid by a solution polymerization method. The weight-average molecular weight (Mw) of the acrylic copolymer was measured by the method described later and found to be 700,000.

Also, an active energy ray-curable component containing a hexafunctional urethane acrylate (urethane acrylate A) was prepared by reacting a urethane oligomer obtained from a polyester-based polyol and isophorone diisocyanate with pentaerythritol triacrylate.

100 parts by mass of the acrylic copolymer obtained as described above (in terms of solid content, hereinafter the same), 47.6 parts by mass of the active energy ray-curable component obtained as described above, and trimethylolpropane as a cross-linking agent Modified tolylene diisocyanate (manufactured by Tosoh Corporation, product name "Coronate L") 11.2 parts by mass, and 1-hydroxycyclohexylphenyl ketone (manufactured by BASF, product name "OMNIRAD 184") as a photopolymerization initiator 3.0 were mixed in methyl ethyl ketone to obtain a coating liquid of an adhesive composition having a solid content concentration of 30% by mass.

(2) Preparation of work processing sheet For the release surface of a release sheet (manufactured by Lintec, product name "SP-PET381031") formed by forming a silicone-based release agent layer on one side of a polyethylene terephthalate film with a thickness of 38 μm Then, the coating liquid of the pressure-sensitive adhesive composition was applied while adjusting the gap using an applicator. The coating film thus obtained was dried at 100° C. for 2 minutes to form an adhesive layer having a thickness of 25 μm, thereby obtaining a laminate of the adhesive layer and the release sheet.

The pressure-sensitive adhesive layer side surface of the laminate obtained as described above and a polyethylene terephthalate film (manufactured by Mitsubishi Chemical Corporation, product name “Diafoil”, thickness: 100 μm) that has been subjected to an easy-adhesion treatment as a base material. A workpiece processing sheet having a configuration of release sheet/adhesive layer (25 μm)/substrate was obtained by laminating the easy-adhesion-treated surface of .

Here, the weight average molecular weight (Mw) described above is a polystyrene-equivalent weight average molecular weight measured using gel permeation chromatography (GPC) under the following conditions (GPC measurement).
<Measurement conditions>
・ GPC measurement device: HLC-8020 manufactured by Tosoh Corporation
・ GPC column (passed in the following order): TSK guard column HXL-H manufactured by Tosoh Corporation
TSK gel GMHXL (x2)
TSK gel G2000HXL
・Measurement solvent: tetrahydrofuran ・Measurement temperature: 40°C

[Example 2]
An active energy ray-curable component containing a hexafunctional urethane acrylate (urethane acrylate B) was prepared by reacting a urethane oligomer obtained from a polyester-based polyol and isophorone diisocyanate with pentaerythritol triacrylate. A work processing sheet was produced in the same manner as in Example 1, except that the active energy ray-curable component was used.

[Example 3]
A work processing sheet was produced in the same manner as in Example 2, except that the content of the active energy ray-curable component was changed as shown in Table 1.

[Comparative Example 1]
An active energy ray-curable component containing a trifunctional urethane acrylate (urethane acrylate C) was produced by reacting a urethane oligomer obtained from a polyester-based polyol and a diisocyanate with pentaerythritol triacrylate. A work processing sheet was produced in the same manner as in Example 1, except that the active energy ray-curable component was used.

[Comparative Example 2]
An active energy ray-curable component containing a hexafunctional urethane acrylate (urethane acrylate D) was produced by reacting a urethane oligomer obtained from a polyester-based polyol and isophorone diisocyanate with pentaerythritol triacrylate. A work processing sheet was produced in the same manner as in Example 1, except that the active energy ray-curable component was used.

[Comparative Example 3]
An active energy ray-curable component containing a 15-functional urethane acrylate (urethane acrylate E) was prepared by reacting a urethane oligomer obtained from a polyester-based polyol and a diisocyanate with dipentaerythritol hexaacrylate. A work processing sheet was produced in the same manner as in Example 1, except that the active energy ray-curable component was used.

[Comparative Examples 4-5]
A work processing sheet was produced in the same manner as in Example 1, except that a pressure-sensitive adhesive composition further containing pentaerythritol triacrylate was added so that the content shown in Table 1 was obtained.

[Test Example 1] (Measurement of molecular weight of active energy ray-curable component)
A molecular weight measurement sample obtained by diluting the active energy ray-curable component used in Examples and Comparative Examples with tetrahydrofuran to 1% by mass was measured for molecular weight under the following conditions. Standard polystyrene was used as a standard in the measurements. From the obtained measurement results, the weight average molecular weight of the active energy ray-curable component was calculated. Table 1 shows the results.
<Measurement conditions>
・ GPC measurement device: HLC-8220 manufactured by Tosoh Corporation
・ GPC column (passed in the following order): TSK gel G1000H manufactured by Tosoh Corporation
TSK gel G2000H
・Measurement solvent: tetrahydrofuran ・Measurement temperature: 40°C

Further, for Examples 1 to 3 and Comparative Examples 1 to 3, from the measurement results obtained as described above, the content of components with a molecular weight of less than 1200 and the content of components with a molecular weight of less than 800 in the active energy ray-curable component. Each content was calculated. Then, for each of these three components, the ratio (% by mass) to the total active energy ray-curable component was calculated. Table 1 shows the results.

On the other hand, for Comparative Examples 4 and 5, first, a mixture of the active energy ray-curable component used in these examples and pentaerythritol triacrylate was prepared. The content ratio of the active energy ray-curable component and pentaerythritol triacrylate in the mixture was the same as the content ratio of these components in the pressure-sensitive adhesive composition used in Comparative Examples 4 and 5. A molecular weight measurement sample obtained by diluting the above mixture with tetrahydrofuran to 1% by mass was measured for molecular weight in the same manner as described above. From the obtained measurement results, the content of the component having a molecular weight of less than 1200 and the content of the component having a molecular weight of less than 800 in the active energy ray-curable component were calculated. The ratio (% by mass) to the total curable component was calculated. Table 1 shows the results.

[Test Example 2] (Measurement of adhesive strength)
The release sheet was peeled off from the work processing sheets produced in Examples and Comparative Examples, and the exposed surface of the adhesive layer was superimposed on the mirror surface of the mirror-finished silicon wafer in an environment of 23°C temperature and 50% humidity. A roller of 2 kg was reciprocated once to apply a load, and the laminate was left for 20 minutes. Thus, a sample for adhesion measurement was obtained.

The obtained sample for adhesive strength measurement was peeled from the silicon wafer at a peel speed of 300 mm/min and at a peel angle of 180° using a universal tensile tester (manufactured by Shimadzu Corporation, product name "Autograph AG-IS"). The work processing sheet was peeled off with a hand, and the adhesive strength (mN/25 mm) to the silicon wafer was measured by a 180° peeling method according to JIS Z0237:2009. The measurement results are shown in Table 1 as adhesive strength before ultraviolet irradiation (before UV).

Further, with respect to the adhesive strength measurement sample obtained in the same manner as described above, the adhesive layer of the work processing sheet was irradiated with ultraviolet rays through the base material under the following conditions. Thereafter, the work processing sheet was peeled off from the silicon wafer in the same manner as described above, and the adhesive force (mN/25 mm) to the silicon wafer was measured. The measurement results are shown in Table 1 as adhesive strength after ultraviolet irradiation (after UV).
<Ultraviolet irradiation conditions>
・Using a high-pressure mercury lamp ・Illuminance 230mW/cm ² , Light intensity 190mJ/cm ²
・Using “UVPF-A1” manufactured by Eye Graphics Co., Ltd. for UV illuminance and photometer

[Test Example 3] (Evaluation of adhesive residue)
The release sheet was peeled off from the work processing sheets produced in Examples and Comparative Examples, and the exposed adhesive surface of the adhesive layer was attached to the uneven surface of an alkali-free glass plate having uneven surfaces. The irregularities were printed irregularities having a length of 5 mm, a width of 1 mm, and a height of 20 μm provided on the surface of the glass plate.

Twenty minutes after the attachment, the pressure-sensitive adhesive layer of the work processing sheet was irradiated with ultraviolet rays through the substrate under the following conditions. Subsequently, using a universal tensile tester (manufactured by Orientec, product name “Tensilon RTA-T-2M”), the work processing sheet was peeled from the glass plate at a peeling speed of 300 mm / min and a peeling angle of 180 °. bottom.
<Ultraviolet irradiation conditions>
・Using a high-pressure mercury lamp ・Illuminance 230mW/cm ² , Light intensity 190mJ/cm ²
・Using “UVPF-A1” manufactured by Eye Graphics Co., Ltd. for UV illuminance and photometer

On the glass plate from which the work processing sheet has been peeled off, the uneven surface is irradiated with visible light in a direction parallel to the surface using a metal halide lamp, and a digital microscope (manufactured by Keyence Corporation, product name "VHX-5000 , magnification: 1000 times), the presence or absence of residual adhesive (adhesive residue) derived from the adhesive layer was confirmed. Then, adhesive residue was evaluated based on the following criteria. Table 1 shows the results.
A: No adhesive residue was observed.
B: Adhesive residue occurred due to cohesive failure of the adhesive layer.
C: Adhesive residue occurred due to transfer of the adhesive layer.

[Test Example 4] (Evaluation of Chip Flying)
The release sheet was peeled off from the work processing sheet manufactured in Examples and Comparative Examples and left in an environment of temperature 23 ° C. and humidity 50% for 1 week, and a tape mounter (manufactured by Lintec, product name “Adwill RAD 2500 m / 12 ”), a 100 mm square glass plate with a thickness of 200 μm and a ring frame for dicing were attached to the exposed surface of the adhesive layer. Subsequently, the work processing sheet was cut according to the outer diameter of the ring frame. Furthermore, using a dicing machine (manufactured by Disco, product name “DFD-6362”), dicing was performed by cutting from the glass plate side under the following dicing conditions to obtain glass chips of 1 mm square.

<Dicing conditions>
・Dicing device: DFD-6362 manufactured by Disco
・Blade: Disco NBC-2H 2050 27HECC
・Blade width: 0.025 to 0.030 mm
・Blade length: 0.640 to 0.760mm
・Blade speed: 30000rpm
・Cutting speed: 80mm/sec
・ Base material cutting depth: 20 μm
・Cutting water volume: 1.0 L/min
・Cutting water temperature: 20℃
・Dicing size: 1 mm square (plane area is 1 mm ² )

After completion of dicing, the work processing sheet to which the glass chips were attached was visually observed to confirm whether or not the glass chips fell off from the work processing sheet. Table 1 shows the results.

Details of abbreviations and the like in Table 1 are as follows.
PETA: pentaerythritol triacrylate DPHA: dipentaerythritol hexaacrylate IPDI: isophorone diisocyanate DI: diisocyanate

As can be seen from Table 1, in the work processing sheets obtained in the examples, it was possible to satisfactorily suppress adhesive residue and chip flying.

The work processing sheet of the present invention can be suitably used for processing a work having an uneven surface.

Claims (7)

A work processing sheet comprising a substrate and an adhesive layer laminated on one side of the substrate,
From a pressure-sensitive adhesive composition containing an acrylic copolymer in which the pressure-sensitive adhesive layer has a weight average molecular weight of 100,000 or more and 2,500,000 or less, and an active energy ray-curable component whose weight average molecular weight is more than 2,500 and 40,000 or less formed,
The content of the low molecular weight component having a molecular weight of less than 800 in the active energy ray-curable component is 20% by mass or less,
Using a glass plate as a work
A work processing sheet characterized by: 2. The work processing sheet according to claim 1, wherein the active energy ray-curable component contains a polyfunctional acrylate. 3. The work processing sheet according to claim 1 , wherein the acrylic copolymer does not have active energy ray curability. 4. The work processing sheet according to any one of claims 1 to 3, wherein the adhesive layer has a thickness of 10 µm or more and 100 µm or less. The work processing sheet according to any one of claims 1 to 4 , wherein the base material is a polyethylene terephthalate film. The work of the work processing sheet is a work having an uneven surface,
The work processing sheet according to any one of claims 1 to 5 , wherein the surface of the pressure-sensitive adhesive layer opposite to the base material is attached to a surface of the work having unevenness. . The work processing sheet according to any one of claims 1 to 6 , which is a dicing sheet.