JP7606911B2 - Workpiece processing sheet, manufacturing method for workpiece processing sheet, and manufacturing method for processed workpiece - Google Patents

Description

The present invention relates to a workpiece processing sheet, a method for manufacturing a workpiece processing sheet, and a method for manufacturing a processed workpiece.

A dicing sheet used as a workpiece processing sheet is constructed with an adhesive layer on a base film, and is attached to a workpiece such as a semiconductor wafer using the adhesive layer, and is used in this state for dicing. After dicing, if necessary, the adhesive strength of the adhesive layer is reduced by curing it through exposure to energy rays such as ultraviolet light, and the processed workpiece such as a semiconductor chip is picked up. Dicing sheets with various configurations have been proposed so far depending on the purpose.

In the dicing process of workpieces such as semiconductor wafers, a dicing die bonding sheet is sometimes used that combines a film adhesive and a dicing sheet to bond semiconductor elements to lead frames or organic substrates. In addition, a composite sheet for forming a back surface protective film that combines a protective film forming film and a dicing sheet is also used to protect the back surface of the workpiece of a semiconductor device that uses a mounting method known as the face down method.

When picking up a workpiece such as a semiconductor chip using a workpiece processing sheet such as a dicing sheet, a dicing die bonding sheet, or a composite sheet for forming a back surface protective film, static electricity called peeling electrification occurs between the workpiece and the workpiece processing sheet. In order to prevent the adverse effects of this static electricity on the adherend (such as a circuit), workpiece processing sheets in which the back side of the base film has been antistatically treated, workpiece processing sheets in which an antistatic agent has been added to and mixed with the base film, workpiece processing sheets in which an antistatic agent has been added to and mixed with the adhesive layer, and workpiece processing sheets in which an antistatic layer has been provided between the base film and the adhesive layer are known (see, for example, Patent Documents 1 and 2).

JP 2008-255345 A JP 2008-280520 A

It is believed that treatment to prevent peel-off static electricity in workpiece processing sheets can be provided between the base film and the adhesive layer, which makes it easier to suppress the adverse effects of the antistatic agent on other surfaces and also makes it easier to obtain the effect of peel-off static electricity.
However, when provided between the base film and the pressure-sensitive adhesive layer, the adhesion between the base film and the pressure-sensitive adhesive layer may be impaired. Even if an attempt is made to select a composition with good adhesion, the pot life of the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer may become short, making it impossible to ensure an appropriate pot life.

The present invention aims to provide a workpiece processing sheet having an antistatic layer between a base film and an adhesive layer, in which the adhesion between the base film and the adhesive layer is good and the adhesive composition for forming the adhesive layer has an appropriate pot life, as well as a method for manufacturing the workpiece processing sheet and a method for manufacturing a processed workpiece.

The present invention has the following aspects.
[1] A workpiece processing sheet comprising a base film, an antistatic layer provided on the base film, and an adhesive layer provided on the antistatic layer,
The antistatic layer contains a conductive polymer,
the pressure-sensitive adhesive layer is formed using an energy ray-curable pressure-sensitive adhesive composition including as blending components an acrylic resin having a hydroxyl group and an energy ray-polymerizable unsaturated group, one or more catalysts selected from the group consisting of an acetylacetone zirconium complex, a metal soap whose metal species is zirconium, and an acetylacetone zinc complex, and a crosslinking agent;
The crosslinking agent is a work processing sheet containing one or more hexamethylene diisocyanate-based polyisocyanates selected from the group consisting of biuret type, isocyanurate type, adduct type, bifunctional prepolymer type, and block type.
[2] The workpiece processing sheet according to [1], wherein the ratio of the blending amount (parts by mass) of the crosslinking agent to the total mass of the structural units having a hydroxyl group that constitute the acrylic resin is 0.35 or more.
[3] The method for producing a workpiece processing sheet according to [1] or [2], wherein the base film, the antistatic layer, and the adhesive layer are laminated in this order,
reacting an acrylic resin having a hydroxyl group with a compound having an isocyanate group and an energy ray-polymerizable unsaturated group in the presence of the catalyst to form a urethane bond between the isocyanate group and a part of the hydroxyl group, thereby preparing an acrylic resin having the hydroxyl group and the energy ray-polymerizable unsaturated group;
preparing the energy ray-curable pressure-sensitive adhesive composition by blending the acrylic resin having a hydroxyl group and an energy ray-polymerizable unsaturated group with the crosslinking agent;
and producing the pressure-sensitive adhesive layer using the energy ray-curable pressure-sensitive adhesive composition.
[4] A method for manufacturing a workpiece using the workpiece processing sheet according to [1] or [2],
A step of attaching the surface of the adhesive layer in the work processing sheet opposite to the base film side to one surface of the work, thereby preparing a laminate of the work processing sheet and the work;
A step of processing the work in the laminate to produce a workpiece composite in which the workpiece is held by the adhesive layer in the workpiece processing sheet;
irradiating the pressure-sensitive adhesive layer with energy rays from the outside of the base film side of the workpiece composite to harden the pressure-sensitive adhesive layer;
and a step of separating and picking up the workpiece from the cured product of the adhesive layer.

According to the present invention, there is provided a work processing sheet having an antistatic layer between a base film and an adhesive layer, in which the adhesion between the base film and the adhesive layer is good and the adhesive composition for forming the adhesive layer has an appropriate pot life, as well as a method for manufacturing the work processing sheet and a method for manufacturing a processed workpiece.

1 is a cross-sectional view showing a schematic diagram of one embodiment of a workpiece processing sheet of the present invention. FIG. 2 is a cross-sectional view showing a schematic diagram of another embodiment of the workpiece processing sheet of the present invention. 1 is a cross-sectional view showing a schematic diagram of one embodiment of a method for manufacturing a workpiece according to the present invention;

<<Work processing sheets>>

The workpiece processing sheet of the present invention will be described with reference to the drawings. Note that the drawings used in the following description may show the main parts enlarged for the sake of convenience in order to make the features of the present invention easier to understand, and the dimensional ratios of each component may not necessarily be the same as in reality.

FIG. 1 is a cross-sectional view showing a schematic diagram of one embodiment of the workpiece processing sheet of the present invention.
The workpiece processing sheet 101 shown here is a dicing sheet comprising a base film 11, an antistatic layer 111 provided on the base film 11, and an adhesive layer 12 provided on the antistatic layer 111.

In the workpiece processing sheet 101, an antistatic layer 111 is laminated on one surface (hereinafter sometimes referred to as the "first surface") 11a of the base film 11, and an adhesive layer 12 is laminated on the surface (hereinafter sometimes referred to as the "first surface") 111a of the antistatic layer 111 opposite the base film 11.

The workpiece processing sheet 101 shown in FIG. 1 is used by attaching the first surface 12a of the adhesive layer 12 opposite the base film 11 to the surface of a workpiece (not shown) such as a semiconductor wafer, opposite the surface on which the circuit is formed.

Here, the term "workpiece" refers to a wafer or a semiconductor device panel.
Examples of the "wafer" include semiconductor wafers made of elemental semiconductors such as silicon, germanium, and selenium, and compound semiconductors such as GaAs, GaP, InP, CdTe, ZnSe, and SiC; and insulator wafers made of insulators such as sapphire and glass.
The term "semiconductor device panel" refers to an assembly of two or more semiconductor devices, each having one or more electronic components sealed with a sealing resin layer, arranged side by side in a plane.
A circuit is formed on one surface of each of these workpieces, and in this specification, the surface of the workpiece on which the circuit is formed is referred to as the "circuit surface," and the surface of the workpiece opposite to the circuit surface is referred to as the "rear surface."
The work is divided by means of dicing or the like to become workpieces. In this specification, as in the case of the work, the surface of the workpiece on which a circuit is formed is referred to as the "circuit side," and the surface of the workpiece opposite to the circuit side is referred to as the "rear side."
Both the circuit surface of the workpiece and the circuit surface of the workpiece are provided with protruding electrodes such as bumps, pillars, etc. The protruding electrodes are preferably made of solder.

In the workpiece processing sheet 101, the antistatic layer contains a conductive polymer,
the pressure-sensitive adhesive layer is formed using an energy ray-curable pressure-sensitive adhesive composition including as blending components an acrylic resin having a hydroxyl group and an energy ray-polymerizable unsaturated group, one or more catalysts selected from the group consisting of an acetylacetone zirconium complex, a metal soap whose metal species is zirconium, and an acetylacetone zinc complex, and a crosslinking agent;
The crosslinking agent contains one or more hexamethylene diisocyanate-based polyisocyanates selected from the group consisting of biuret types, isocyanurate types, adduct types, bifunctional prepolymer types, and block types.

In the workpiece processing sheet 101, the antistatic layer contains a conductive polymer, so when the workpiece processing sheet is used to pick up a workpiece such as a semiconductor chip, the generation of static electricity between the workpiece and the workpiece processing sheet can be prevented.
In the workpiece processing sheet 101, since the crosslinking agent contains the hexamethylene diisocyanate-based polyisocyanate, good adhesion can be maintained between the base film and the adhesive layer.

The catalyst accelerates the reaction rate when a hydroxyl group of a hydroxyl group-containing compound reacts with an isocyanate group of an isocyanate group-containing compound to form a urethane bond.
Therefore, the catalyst accelerates the reaction rate when a urethane bond is formed by reacting a hydroxyl group of a hydroxyl group-containing copolymer with an isocyanate group of a compound having an isocyanate group and an energy ray-polymerizable unsaturated group, and the catalyst accelerates the reaction rate when a urethane bond is formed by reacting an isocyanate group of the hexamethylene diisocyanate-based polyisocyanate with a hydroxyl group of an acrylic resin having a hydroxyl group and an energy ray-polymerizable unsaturated group in an energy ray-curable pressure-sensitive adhesive composition.

However, the catalyst only has a moderate effect of promoting the reaction rate at room temperature. Therefore, when forming the adhesive layer using the energy ray-curable adhesive composition, the reaction between the hydroxyl groups of the acrylic resin and the crosslinking agent can be allowed to proceed slowly by selecting the catalyst, and the pot life of the energy ray-curable adhesive composition can be improved.

In the workpiece processing sheet 101, the adhesive layer is formed using an energy ray curable adhesive composition containing the catalyst and the crosslinking agent as blending components, so even though an antistatic layer containing a conductive polymer is provided, the adhesion between the base film and the adhesive layer is good. The reason for this is unclear, but it is presumed that when the adhesive layer is laminated on the antistatic layer containing a conductive polymer, the crosslinking agent contained in the adhesive layer acts on the contact surface with the antistatic layer, resulting in excellent adhesion between the adhesive layer and the antistatic layer, and as a result, excellent adhesion between the base film and the adhesive layer.

When the workpiece processing sheet 101 is viewed in plan from above the adhesive layer 12 side, the adhesive layer 12 has a shape such as a circle.

The workpiece processing sheet of the present invention is not limited to the workpiece processing sheet 101 shown in FIG. 1, and some of the configuration shown in FIG. 1 may be changed, deleted, or added within the scope that does not impair the effects of the present invention.

For example, FIG. 2 is a cross-sectional view showing a schematic diagram of another embodiment of the workpiece processing sheet of the present invention. The workpiece processing sheet 101' shown here is a dicing sheet including an antistatic layer 112, a base film 11 provided on the antistatic layer 112, an antistatic layer 111 provided on the base film 11, and an adhesive layer 12 provided on the antistatic layer 111. In FIG. 2 and subsequent figures, components that are the same as those shown in the figures already described are given the same reference numerals as in the figures already described, and detailed descriptions thereof are omitted.

In the workpiece processing sheet 101', the base film 11 is laminated on one surface 112a of the antistatic layer 112, the antistatic layer 111 is laminated on the first surface 11a of the base film 11 opposite the antistatic layer 112, and the adhesive layer 12 is laminated on the first surface 111a of the antistatic layer 111 opposite the base film 11.

The workpiece processing sheet 101' shown in FIG. 2 is used by attaching the first surface 12a of the adhesive layer 12 opposite the base film 11 to the back surface of a workpiece (not shown) such as a semiconductor wafer, opposite the circuit surface.

Below, we will explain each layer that makes up the dicing sheet as the workpiece processing sheet of the present invention.

[Base film]
The constituent material of the base film is preferably various resins, and specifically, for example, polyethylene (sometimes abbreviated as low density polyethylene (LDPE), linear low density polyethylene (LLDPE), high density polyethylene (HDPE, etc.)), polypropylene, polybutene, polybutadiene, polymethylpentene, styrene-ethylenebutylene-styrene block copolymer, polyvinyl chloride, vinyl chloride copolymer, polyethylene terephthalate (sometimes abbreviated as PET), polybutylene terephthalate, polyurethane, polyurethane acrylate, polyimide, ethylene vinyl acetate copolymer, ionomer resin, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic acid ester copolymer, polystyrene, polycarbonate, fluororesin, water additive, modified product, crosslinked product or copolymer of any of these resins, etc. are mentioned. From the viewpoint of cutting chip suppression and expandability, low density polyethylene (LDPE) film, ethylene-methacrylic acid (EMAA) copolymer film, ethylene-(meth)acrylate (EMMA) copolymer film are preferable.

In this specification, "(meth)acrylic acid" is a concept that includes both "acrylic acid" and "methacrylic acid." The same applies to terms similar to (meth)acrylic acid. For example, "(meth)acrylate" is a concept that includes both "acrylate" and "methacrylate," and "(meth)acryloyl group" is a concept that includes both "acryloyl group" and "methacryloyl group."

The resin constituting the base film may be one type or two or more types, and if there are two or more types, the combination and ratio of these can be selected arbitrarily.

The base film may be one layer (i.e., a single layer) or two or more layers. When the base film is made of multiple layers, these layers may be the same or different from each other. That is, all layers may be the same, all layers may be different, or only some layers may be the same. When the layers are different from each other, the combination of these layers is not particularly limited as long as it does not impair the effect of the present invention. Here, the layers being different from each other means that at least one of the material and thickness of each layer is different from each other.
In this specification, not only in the case of a base film, "multiple layers may be the same or different" means "all layers may be the same, all layers may be different, or only some layers may be the same", and further, "multiple layers are different" means "at least one of the constituent materials and thicknesses of each layer is different from each other".

The thickness of the substrate film can be appropriately selected depending on the purpose, but is preferably from 20 μm to 200 μm, more preferably from 25 μm to 150 μm, and particularly preferably from 30 μm to 100 μm.
Here, the "thickness of the base film" means the thickness of the entire base film, and for example, the thickness of a base film consisting of multiple layers means the total thickness of all layers constituting the base film. Note that, as a method for measuring the thickness of the base film, for example, a method of measuring the thickness at any five points using a contact thickness meter and calculating the average of the measured values can be mentioned.

In order to improve adhesion to other layers, such as a pressure-sensitive adhesive layer, provided thereon, the substrate film may be subjected to a surface treatment such as sandblasting, solvent treatment, embossing, or an oxidation treatment such as corona discharge treatment, electron beam irradiation treatment, plasma treatment, ozone/ultraviolet radiation treatment, flame treatment, chromic acid treatment, or hot air treatment.
The surface of the base film may be treated with a primer.
The base film may also have an antistatic coating layer, a layer that prevents the base film from adhering to other sheets or to an adsorption table when the film-like adhesive composite sheet is stacked and stored, and the like.
Of these, it is preferable for the substrate film to have its surface subjected to electron beam irradiation treatment in order to prevent the generation of fragments of the substrate film due to friction of the blade when dicing the workpiece, whereas it is preferable for the substrate film not to have been subjected to electron beam irradiation treatment in order to facilitate pick-up.

[Antistatic Layer]
Examples of the conductive polymer used in the antistatic layer include polypyrrole-based conductive polymers, polythiophene-based conductive polymers, polyaniline-based conductive polymers, and polyacetylene-based conductive polymers, and polypyrrole-based conductive polymers and polythiophene-based conductive polymers are preferred.
The polypyrrole-based conductive polymer can be used as a water-dispersible conductive polymer obtained by emulsion polymerization of pyrrole (monomer).
Polythiophene-based conductive polymers can also be used as the water-dispersible conductive polymer.

By using a water-dispersible conductive polymer, the coating liquid (polymer composition) used to form the antistatic layer can be prepared as a water dispersion, eliminating the need to use an organic solvent in the coating liquid. This makes it possible to suppress alteration or deterioration of the base film substrate caused by organic solvents. The coating liquid is prepared by adding a binder resin to the water-dispersible conductive polymer as necessary, and the coating liquid is applied, heated, and dried to form the antistatic layer.

The thickness of the antistatic layer can be appropriately selected depending on the purpose, but is preferably 20 to 200 nm, more preferably 25 to 150 nm, and particularly preferably 30 to 100 nm.

[Adhesive layer]
The pressure-sensitive adhesive layer is formed using an energy ray-curable pressure-sensitive adhesive composition containing as blending components an acrylic resin having a hydroxyl group and an energy ray-polymerizable unsaturated group, one or more catalysts selected from the group consisting of an acetylacetone zirconium complex, a metal soap whose metal species is zirconium, and an acetylacetone zinc complex, and a crosslinking agent, wherein the crosslinking agent contains one or more hexamethylene diisocyanate-based polyisocyanates selected from the group consisting of a biuret type, an isocyanurate type, an adduct type, a bifunctional prepolymer type, and a block type.

The adhesive layer may be one layer (i.e., a single layer) or two or more layers. When the adhesive layer is a multi-layer structure, the multi-layer structure may be the same or different. For example, an antistatic layer 111 is laminated on one surface 11a of a substrate film 11, and an adhesive layer 12 is laminated on the surface 111a of the antistatic layer 111 opposite the substrate film 11, the adhesive layer 12 being composed of a first adhesive layer 121 on the opposite side of the antistatic layer 111 and a second adhesive layer 122 on the antistatic layer 111 side, and the first adhesive layer 121 may be formed using the energy ray curable adhesive composition.

The thickness of the pressure-sensitive adhesive layer can be appropriately selected depending on the purpose, but is preferably 1 to 100 μm, more preferably 1 to 60 μm, and particularly preferably 1 to 30 μm.
Here, the "thickness of the adhesive layer" means the thickness of the entire adhesive layer, and for example, the thickness of an adhesive layer consisting of multiple layers means the total thickness of all layers constituting the adhesive layer. The thickness of the adhesive layer can be measured, for example, by measuring the thickness at any five points using a contact thickness meter and calculating the average of the measured values.

The adhesive layer can be formed using an adhesive composition containing various components for constituting the adhesive layer. The ratio of the contents of the components in the adhesive composition that do not vaporize at room temperature is usually the same as the ratio of the contents of the components in the adhesive layer. In this specification, "room temperature" means a temperature that is not particularly cooled or heated, that is, an ordinary temperature, and examples of such temperatures include temperatures of 15 to 30°C.

The adhesive layer contains an acrylic resin having an energy ray-polymerizable unsaturated group, so that the adhesive layer can be irradiated with energy rays to reduce its adhesiveness, making it easier to pick up the workpiece. The process of irradiating the adhesive layer with energy rays to reduce its adhesiveness may be performed after the workpiece processing sheet is attached to the adherend, or may be performed in advance before attaching the workpiece processing sheet to the adherend.

In the present invention, the term "energy ray" refers to electromagnetic waves or charged particle beams that have an energy quantum, and examples of such beams include ultraviolet rays and electron beams.
The ultraviolet light can be irradiated by using, for example, a UV-LED, a high-pressure mercury lamp, a fusion H lamp, a xenon lamp, etc. as an ultraviolet light source. The electron beam can be generated by an electron beam accelerator or the like.
In the present invention, "energy ray curable" means a property of being cured by irradiation with energy rays, and "non-energy ray curable" means a property of not being cured even when irradiated with energy rays.

[Adhesive composition]
The energy ray-curable adhesive composition is a raw material for producing the adhesive layer, and contains an acrylic resin having a hydroxyl group and an energy ray-polymerizable unsaturated group, one or more catalysts selected from the group consisting of an acetylacetone zirconium complex, a metal soap whose metal species is zirconium, and an acetylacetone zinc complex, and a crosslinking agent.
The acrylic resin in the pressure-sensitive adhesive composition is an acrylic resin having a hydroxyl group and an energy ray-polymerizable unsaturated group.
In this specification, the energy ray-curable pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer may be simply referred to as an "adhesive composition." The term "acrylic resin" in the pressure-sensitive adhesive composition means "acrylic resin having a hydroxyl group and an energy ray-polymerizable unsaturated group," unless otherwise specified.

(Acrylic resin)
The acrylic resin having a hydroxyl group and an energy ray polymerizable unsaturated group can be, for example, a resin obtained by copolymerizing a (meth)acrylic acid ester not containing a hydroxyl group, a hydroxyl group-containing monomer, and, if necessary, a non-(meth)acrylic acid ester other than these, and reacting the hydroxyl group of the obtained hydroxyl group-containing copolymer (hereinafter sometimes referred to as a "precopolymer") with the isocyanate group of a compound having an isocyanate group and an energy ray polymerizable unsaturated group to form a urethane bond. By making the molar amount of the isocyanate group in the compound having an isocyanate group and an energy ray polymerizable unsaturated group less than the molar amount of the hydroxyl group in the hydroxyl group-containing monomer, an acrylic resin having a hydroxyl group and an energy ray polymerizable unsaturated group can be obtained.
The acrylic resin has an energy ray polymerizable unsaturated group in the side chain, which improves the releasability from the adherend due to the reduced adhesiveness of the adhesive layer after the polymerization reaction (hardening), thereby improving the pick-up ability of the workpiece.

The (meth)acrylic acid esters include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-octyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate (lauryl (meth)acrylate), tridecyl (meth)acrylate, tetradecyl (meth)acrylate (myristyl (meth)acrylate), pentadecyl (meth)acrylate, hexadecyl (meth)acrylate (palmityl (meth)acrylate), heptadecyl (meth)acrylate, oct ... Examples include alkyl (meth)acrylates in which the alkyl group constituting the alkyl ester has a chain structure containing 1 to 18 carbon atoms, such as tadecyl (meth)acrylate (stearyl (meth)acrylate) and isooctadecyl (meth)acrylate (isostearyl (meth)acrylate); cycloalkyl (meth)acrylates such as isobornyl (meth)acrylate and dicyclopentanyl (meth)acrylate; aralkyl (meth)acrylates such as benzyl (meth)acrylate; cycloalkenyl (meth)acrylates such as dicyclopentenyl (meth)acrylate; cycloalkenyloxyalkyl (meth)acrylates such as dicyclopentenyloxyethyl (meth)acrylate; imide (meth)acrylates; and glycidyl group-containing (meth)acrylates such as glycidyl (meth)acrylate.

Examples of the hydroxyl group-containing monomer include hydroxyl group-containing (meth)acrylates such as hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate.

Preferred examples of the non-(meth)acrylic acid ester include (meth)acrylic acid, itaconic acid, vinyl acetate, acrylonitrile, styrene, and N-methylolacrylamide.

The (meth)acrylic acid ester, the hydroxyl group-containing monomer, the non-(meth)acrylic acid ester, and other monomers constituting the acrylic resin may each be of one type or two or more types.

Examples of the compound having an isocyanate group and an energy ray-polymerizable unsaturated group include isocyanate group-containing (meth)acrylic acid esters such as 2-methacryloyloxyethyl isocyanate.
The compound having an isocyanate group and an energy ray-polymerizable unsaturated group constituting the acrylic resin may be of one type or two or more types.

The adhesive composition may contain only one type of acrylic resin, or two or more types.

The content of the acrylic resin in the adhesive composition is preferably 80% by mass or more, more preferably 90% by mass or more, based on the total amount of all components contained in the adhesive composition other than the solvent. The content of the acrylic resin in the adhesive composition is preferably 99% by mass or less, more preferably 97% by mass or less, based on the total amount of all components contained in the adhesive composition other than the solvent.

(catalyst)
The catalyst is selected from the group consisting of acetylacetone zirconium complexes, metal soaps in which the metal species is zirconium, and acetylacetone zinc complexes.

Acetylacetone Zirconium Complex As the acetylacetone zirconium complex, a commercially available product such as zirconium (IV) acetylacetone can be used.

Metal Soap The metal soap contained in the pressure-sensitive adhesive composition is not limited as long as the metal species is zirconium. Examples of the metal soap include zirconium myristate, zirconium palmitate, zirconium stearate, zirconium oleate, zirconium laurate, zirconium ricinoleate, zirconium octylate, zirconium 2-ethylhexanoate, and fatty acid zirconium salts bonded to fatty acids such as zirconium oxide (2-ethylhexanoate).

The above metal soap may be one or more types. Commercially available metal soaps may be used.

The number of carbon atoms in the fatty acid of the fatty acid zirconium salt is preferably 5 to 20, more preferably 6 to 18, and particularly preferably 7 to 16.

Zinc Acetylacetone Complex As the zinc acetylacetone complex, commercially available zinc acetylacetonate (II) monohydrate can be used.

The content (blending amount) of the catalyst in the pressure-sensitive adhesive composition may be appropriately adjusted depending on the activity of the catalyst, but is preferably 0.001 to 1.5 parts by mass, more preferably 0.005 to 1.0 part by mass, and particularly preferably 0.01 to 0.5 parts by mass, relative to 100 parts by mass of the acrylic resin.
The catalyst content (blended amount) of the pressure-sensitive adhesive composition is preferably 0.001 to 1.5 parts by mass, more preferably 0.005 to 1.0 part by mass, and particularly preferably 0.01 to 0.5 parts by mass, relative to 100 parts by mass of the precopolymer.

(Crosslinking Agent)
The crosslinking agent contains one or more hexamethylene diisocyanate-based polyisocyanates (hereinafter referred to as "HMDI-based crosslinking agents") selected from the group consisting of biuret types, isocyanurate types, adduct types, bifunctional prepolymer types, and block types.

Since polyisocyanate is used as a crosslinking agent, a crosslinked structure can be easily introduced into the adhesive layer by the reaction between these isocyanate groups and the hydroxyl groups of the acrylic resin. Since an HMDI-based crosslinking agent is used, good adhesion between the substrate film and the adhesive layer can be maintained.

Biuret-type HMDI crosslinking agents include biurets, which are trimers, tetramers, or pentamers of hexamethylene diisocyanate.

Isocyanurate-type HMDI crosslinking agents include isocyanurates that are trimers, pentamers, or heptamers of hexamethylene diisocyanate.

Examples of the adduct-type HMDI crosslinking agent include polyisocyanates in which hexamethylene diisocyanate is added to all or some of the hydroxyl groups of a polyol, or to all or some of the amino groups of a polyamine.
As the adduct type HMDI crosslinking agent, those adducted with polyols such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, etc. are more preferable, and among these, those adducted with propanetriol are even more preferable.

Examples of bifunctional prepolymer type HMDI crosslinking agents include diisocyanates in which hexamethylene diisocyanate is added to the hydroxyl groups at both ends of a bifunctional polyol such as a polyol or polyester polyol.

Examples of blocked HMDI crosslinking agents include polyisocyanates in which all or some of the isocyanate groups of biuret, isocyanurate, adduct, or bifunctional prepolymer HMDI crosslinking agents are masked with a blocking agent such as alcohol, phenol, oxime, or lactam.

The adhesive composition may contain only one type of HMDI-based crosslinking agent, or two or more types.

The number of moles of isocyanate groups of the HMDI crosslinking agent in the adhesive composition is preferably 0.2 times or more the number of moles of hydroxyl groups of the acrylic resin in the adhesive composition. In this way, the adhesive layer after curing has a reduced adhesiveness, which improves the peelability from the adherend, and improves the pick-up property of the workpiece.
In addition, the number of moles of isocyanate groups in the HMDI crosslinking agent in the pressure-sensitive adhesive composition is preferably 3 times or less the number of moles of hydroxyl groups in the acrylic resin in the pressure-sensitive adhesive composition, which can further suppress the generation of by-products between the HMDI crosslinking agents.

The content of the HMDI-based crosslinking agent in the adhesive composition may be adjusted as appropriate so that the number of moles of isocyanate groups falls within the range described above, but while satisfying these conditions, it is preferably 0.01 to 20 parts by mass, more preferably 0.1 to 15 parts by mass, and particularly preferably 0.3 to 10 parts by mass, per 100 parts by mass of the acrylic resin.

The ratio of the amount (parts by mass) of the crosslinking agent to the total mass of the hydroxyl group-containing structural units constituting the acrylic resin is preferably 0.35 or more. The hydroxyl group-containing structural units constituting the acrylic resin can be determined, for example, by subtracting the structural units reacted with the compound having an isocyanate group and an energy ray-polymerizable unsaturated group from the hydroxyl group-containing structural units constituting the precopolymer.
The ratio of the amount of the crosslinking agent (parts by mass) is preferably 0.35 or more, more preferably 0.36 or more, and even more preferably 0.37 or more. The ratio of the amount of the crosslinking agent (parts by mass) is preferably 1.0 or less, more preferably 0.9 or less, and even more preferably 0.8 or less.

(Photopolymerization initiator)
The pressure-sensitive adhesive composition preferably contains a photopolymerization initiator in addition to the acrylic resin, the catalyst, and the crosslinking agent.
The photopolymerization initiator may be a known one, and specifically, examples of the photopolymerization initiator include α-ketol compounds such as 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone, α-hydroxy-α,α'-dimethylacetophenone, 2-methyl-2-hydroxypropiophenone, and 1-hydroxycyclohexyl phenyl ketone; acetophenone compounds such as methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, and 2-methyl-1-[4-(methylthio)-phenyl]-2-morpholinopropane-1; benzoin ether compounds such as benzoin ethyl ether, benzoin isopropyl ether, and anisoin methyl ether; and ketal compounds such as benzyl dimethyl ketal. aromatic sulfonyl chloride compounds such as 2-naphthalenesulfonyl chloride; photoactive oxime compounds such as 1-phenone-1,1-propanedione-2-(o-ethoxycarbonyl)oxime; benzophenone compounds such as benzophenone, benzoylbenzoic acid, and 3,3'-dimethyl-4-methoxybenzophenone; thioxanthone compounds such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, and 2,4-diisopropylthioxanthone; camphorquinone; halogenated ketones; acylphosphinoxides; and acylphosphonates.

The pressure-sensitive adhesive composition may contain only one type of photopolymerization initiator, or two or more types.

When a photopolymerization initiator is used, the content of the photopolymerization initiator in the adhesive composition is preferably 0.05 to 20 parts by mass, more preferably 0.1 to 10 parts by mass, and even more preferably 1 to 5 parts by mass, relative to 100 parts by mass of the acrylic resin. When the content of the photopolymerization initiator is equal to or greater than the lower limit, the effect of using the photopolymerization initiator can be sufficiently obtained. Furthermore, when the content of the photopolymerization initiator is equal to or less than the upper limit, the generation of by-products from excess photopolymerization initiator is suppressed, and the curing of the adhesive layer proceeds more smoothly.

(solvent)
The pressure-sensitive adhesive composition preferably further contains a solvent in addition to the acrylic resin, the catalyst, and the crosslinking agent.
The solvent is not particularly limited, but preferred examples include hydrocarbons such as toluene and xylene; alcohols such as methanol, ethanol, 2-propanol, isobutyl alcohol (2-methylpropan-1-ol), and 1-butanol; esters such as ethyl acetate; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran; and amides (compounds having an amide bond) such as dimethylformamide and N-methylpyrrolidone.
The pressure-sensitive adhesive composition may contain only one type of solvent, or two or more types of solvents.

When the adhesive composition contains a solvent, the solvent content is preferably 40 to 90% by mass, and more preferably 50 to 80% by mass.

(Other ingredients)
The pressure-sensitive adhesive composition may contain, in addition to the acrylic resin and HMDI-based crosslinking agent, other components that do not fall under the category of a photopolymerization initiator, a crosslinking agent, and a solvent, within the range that does not impair the effects of the present invention.
The other components may be known ones and may be arbitrarily selected depending on the purpose, and are not particularly limited. Preferred examples of the other components include various additives such as dyes, pigments, antidegradants, antistatic agents, flame retardants, silicone compounds, and chain transfer agents.
The pressure-sensitive adhesive composition may contain only one type of other component, or two or more types of such other components.

The pressure-sensitive adhesive composition is obtained by blending an acrylic resin with a component other than the acrylic resin.
The order of addition of the components is not particularly limited, and two or more components may be added simultaneously.
For example, the energy ray-curable pressure-sensitive adhesive composition can be obtained by preparing a reaction product containing an acrylic resin having a hydroxyl group and an energy ray-polymerizable unsaturated group, and blending the reaction product with the crosslinking agent.
The method for mixing the components during blending is not particularly limited, and may be appropriately selected from known methods such as a method of mixing by rotating a stirrer or stirring blade, a method of mixing using a mixer, a method of mixing by applying ultrasound, etc.
The temperature and time during addition and mixing of each component are not particularly limited as long as the components do not deteriorate, and may be adjusted appropriately. The temperature is preferably 15 to 30°C.

The adhesive layer may be formed by adjusting, for example, the number of energy ray polymerizable unsaturated groups such as (meth)acryloyl groups contained in each component such as the acrylic resin blended into the adhesive composition, the type and amount of crosslinking agent, the type of monomer constituting the acrylic resin, the type and amount of catalyst, etc., so that the elastic modulus after curing by energy ray irradiation falls within a predetermined range.

The pressure-sensitive adhesive layer can be formed by applying a pressure-sensitive adhesive composition to the surface of the base film and drying it.
At this time, if necessary, the applied pressure-sensitive adhesive composition may be heated to crosslink it. The heating conditions can be, for example, but are not limited to, 100 to 130° C. for 1 to 5 minutes.
Alternatively, the adhesive layer can be formed on the base film by applying the adhesive composition to the release-treated surface of a release film, drying the adhesive composition to form an adhesive layer, bonding the resulting adhesive layer to the surface of the base film, and removing the release film as necessary.

The adhesive composition may be applied to the surface of the substrate film or the release layer surface of the release material by a known method, such as a method using various coaters, such as an air knife coater, blade coater, bar coater, gravure coater, roll coater, roll knife coater, curtain coater, die coater, knife coater, screen coater, Mayer bar coater, or kiss coater.

<Release film>
The release film is not particularly limited, and commercially available release films can be used, such as polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene naphthalate film, polybutylene terephthalate film, polyurethane film, ethylene vinyl acetate copolymer film, ionomer resin film, ethylene-(meth)acrylic acid copolymer film, ethylene-(meth)acrylic acid ester copolymer film, polystyrene film, polycarbonate film, polyimide film, fluororesin film, etc. Crosslinked films of these films can also be used. Furthermore, laminated films of these films can also be used.

The surface tension of the release film on the surface in contact with the adhesive layer is preferably 40 mN/m or less, more preferably 37 mN/m or less, and particularly preferably 35 mN/m or less. The lower limit is usually about 25 mN/m. A release film with such a relatively low surface tension can be obtained by appropriately selecting the material, or by applying a release agent to the surface of the release film and carrying out a release treatment.

The release agents used in the peeling process include alkyd-based, silicone-based, fluorine-based, unsaturated polyester-based, polyolefin-based, wax-based, and rubber-based agents, but alkyd-based, silicone-based, and fluorine-based release agents are particularly preferred because they are heat resistant.

To use the above release agents to perform a release treatment on the surface of a film or other substrate for the release film, the release agent can be applied directly without solvent, or diluted with a solvent or made into an emulsion, using a gravure coater, Mayer bar coater, air knife coater, roll coater, or the like, and the release film to which the release agent has been applied can be left at room temperature or under heat, or cured with an electron beam to form a release agent layer.

The surface roughness (Ra) of the release film is preferably 10 to 100 nm, more preferably 15 to 60 nm, and even more preferably 20 to 50 nm.

<<Method of manufacturing workpiece processing sheet>>
The method for producing a workpiece processing sheet of the present invention is a method for producing a workpiece processing sheet, comprising laminating the base film, the antistatic layer, and the adhesive layer in this order,
reacting an acrylic resin having a hydroxyl group with a compound having an isocyanate group and an energy ray-polymerizable unsaturated group in the presence of the catalyst to form a urethane bond between the isocyanate group and a part of the hydroxyl group, thereby preparing an acrylic resin having the hydroxyl group and the energy ray-polymerizable unsaturated group;
preparing the energy ray-curable pressure-sensitive adhesive composition by blending the acrylic resin having a hydroxyl group and an energy ray-polymerizable unsaturated group with the crosslinking agent;
and forming the pressure-sensitive adhesive layer using the energy ray-curable pressure-sensitive adhesive composition.

For example, a coating liquid containing the conductive polymer described above is applied onto a base film, and dried as necessary to form an antistatic layer on the base film. Separately, the adhesive composition described above is applied onto a release film, and dried as necessary to form an adhesive layer on the release film. By attaching the adhesive layer and the antistatic layer on the base film, a workpiece processing sheet can be obtained in which the base film, antistatic layer, adhesive layer, and release film are laminated in this order. The release film can be removed as necessary when using the workpiece processing sheet.

<<Method of manufacturing workpiece>>
The method for manufacturing a workpiece according to the present invention is a method for manufacturing the workpiece, comprising the steps of:
A step of attaching the surface of the adhesive layer in the work processing sheet opposite to the base film side to one surface of the work, thereby preparing a laminate of the work processing sheet and the work;
A step of processing the work in the laminate to produce a workpiece composite in which the workpiece is held by the adhesive layer in the workpiece processing sheet;
irradiating the pressure-sensitive adhesive layer with energy rays from the outside of the base film side of the workpiece composite to harden the pressure-sensitive adhesive layer;
and a step of picking up the workpiece by separating it from the cured product of the adhesive layer.

For example, Figure 3 is a cross-sectional view showing a schematic embodiment of the method for manufacturing a workpiece of the present invention. In the method for manufacturing a workpiece of this embodiment, a workpiece processing sheet 101 includes a base film 11, an antistatic layer 111 provided on the base film 11, and an adhesive layer 12 provided on the antistatic layer 111. The method for manufacturing the workpiece of this embodiment includes the steps of: (a) attaching the surface 12a of the adhesive layer 12 in the workpiece processing sheet 101 opposite the base film 11 side to one surface 9b of the workpiece to produce a laminate of the workpiece processing sheet 101 and the workpiece 9; (b) processing the workpiece 9 in the laminate to produce a workpiece composite in which the workpiece 9' is held by the adhesive layer 12 in the workpiece processing sheet 101; (c) irradiating the adhesive layer 12 with energy rays from the outside of the base film 11 side of the workpiece composite to harden the adhesive layer 12; and (d) using a pull-off means 7 to pull off and pick up the workpiece 9' from the hardened adhesive layer 12, as shown in FIG. 3(c).

The workpiece processing sheet of the present invention can also be used as a dicing die bonding sheet combined with a film-like adhesive for bonding a semiconductor element to a lead frame, an organic substrate, etc. It can also be used as a composite sheet for forming a back surface protective film combined with a protective film forming film for protecting the back surface of a workpiece of a semiconductor device.

The present invention will be explained in more detail below using examples of dicing sheets as workpiece processing sheets. However, the present invention is not limited to the examples shown below.

[Example 1]
(Production of acrylic resin)
In a nitrogen atmosphere, a reaction apparatus equipped with a stirrer, a condenser, a thermometer, and a nitrogen inlet tube was used to prepare an ethyl acetate solution (250 parts by mass, solids concentration 40% by mass) of a precopolymer obtained by copolymerizing 62 parts by mass of butyl acrylate (BA), 10 parts by mass of methyl methacrylate (MMA), and 28 parts by mass of 2-hydroxyethyl acrylate (HEA). 0.012 parts by mass of Zr(C ₅ H ₇ O ₂ ) ₄ (product name: Nursem (registered trademark) zirconium compound, manufactured by Nippon Chemical Industry Co., Ltd.) and methyl ethyl ketone were added to the precopolymer, which was obtained by copolymerizing 62 parts by mass of butyl acrylate (BA), 10 parts by mass of methyl methacrylate (MMA), and 28 parts by mass of 2-hydroxyethyl acrylate (HEA). The mixture was stirred at 50° C. for 1 hour to prepare a solution with a solids concentration of 35% by mass. Thereafter, 30 parts by mass (an amount such that isocyanate groups account for 80 mol % relative to 100 mol % of hydroxyl groups in the HEA) of 2-methacryloyloxyethyl isocyanate (2-isocyanatoethyl methacrylate, hereinafter sometimes abbreviated as "MOI") was added and reacted at 50°C for 48 hours (MOI addition reaction) to obtain a reaction product containing an acrylic resin having hydroxyl groups and energy ray-polymerizable unsaturated groups. The molecular weight of the obtained acrylic resin was measured, and it was found to have a weight average molecular weight of 500,000.

(Production of Pressure-Sensitive Adhesive Composition)
For 100 parts by mass (solid content) of the obtained energy ray curable acrylic resin, 3 parts by mass of "OMNILAD 127 (solid content 100 mass%)" manufactured by BASF as a photopolymerization initiator and 2.9 parts by mass (2.175 parts by mass in dry equivalent) of hexamethylene diisocyanate (HMDI) polyisocyanate crosslinking agent "Tosoh Corporation, product name: CORONATE (registered trademark) HL (solid content 75 mass%)" were dissolved, and the solid content concentration was adjusted to 30 mass%, to prepare an energy ray curable adhesive composition. In the adhesive composition of Example 1, the ratio of the blending amount (parts by mass) of the crosslinking agent to the total mass of the structural units having a hydroxyl group constituting the acrylic resin was 0.388.

(Manufacturing of dicing sheets)
A release film (SP-PET3801, manufactured by Lintec), one side of which had been treated with a light release type silicone resin for release, was used as a polyethylene terephthalate (PET) film (thickness: 38 μm). The pressure-sensitive adhesive composition was applied to the release-treated surface using a comma coater, and the film was dried at 90° C. for 1 minute to form a pressure-sensitive adhesive layer having a thickness of 5 μm.

A butylated melamine resin (2 parts by mass, manufactured by DIC Corporation, product name "Super Beckamine (registered trademark) J820-60") serving as a binder resin was added to an emulsion containing a polypyrrole-based conductive polymer (100 parts by mass (solid content)) obtained by emulsion polymerization of pyrrole (monomer), and the mixture was thoroughly mixed to obtain a coating liquid for forming an antistatic layer.
After one side of an ethylene-methacrylic acid (EMAA) copolymer film having a thickness of 80 μm was subjected to corona irradiation, the above-mentioned coating liquid for forming an antistatic layer was applied to the same side and dried by heating to form an antistatic layer having a thickness of 50 nm. This resulted in a laminate of a substrate film and an antistatic layer.

The exposed surface of the antistatic layer of the laminate was bonded to the exposed surface of the adhesive layer, and the laminate was stored for two weeks in an environment of 23°C and 50% RH to obtain a dicing sheet of Example 1, which is constructed by laminating the base film, antistatic layer, adhesive layer, and release film in this order in the thickness direction.

[Example 2]
A dicing sheet of Example 2 was obtained in the same manner as in Example 1, except _that 0.012 parts by mass of Zr(C ₅ H ₇ O ₂ ) ₄ (product name: Nursem (registered trademark) zirconium compound, manufactured by Nippon Chemical Industry Co., Ltd.) used in the adhesive composition in Example 1 was changed to 0.12 parts by mass of ZrO(C 8 H ₁₅ O ₂ ) ₂ (2-ethylhexanoic acid) zirconium oxide (IV), manufactured by Fujifilm Wako Pure Chemical Industries Co., Ltd.), and the acrylic resin solution was prepared at 45° C. for 48 hours instead of 50° C. The molecular weight of the acrylic resin in Example 2 was measured, and the weight average molecular weight was 500,000.

[Example 3]
In Example 1, _0.012 parts by mass of Zr( _C5H7O2 ) ₄ ( _trade name: Nacem (registered trademark) zirconium compound, manufactured by Nippon Chemical Industry Co., Ltd.) used in the adhesive composition was changed to 0.10 parts by mass of _Zn ( _{C5H7O2 ) 2.H2O} (trade name: zinc acetylacetonate (II) _monohydrate , manufactured by Fujifilm Wako Pure Chemical Industries Co., Ltd.), and the acrylic resin solution was prepared at 50°C for 48 hours instead of 60°C for 48 hours. The dicing sheet of Example 3 was obtained in the same manner as in Example 1. The molecular weight of the acrylic resin in Example 3 was measured and found to be a weight average molecular weight of 500,000.

[Example 4]
A dicing sheet of Example 4 was obtained in the same manner as in Example 1, except that the amount of the HMDI-based crosslinking agent "Tosoh Corporation, product name: Coronate (registered trademark) HL (solid content 75% by mass)" used in the adhesive composition in Example 3 was changed from 2.9 parts by mass (2.175 parts by mass in dry equivalent) to 4.3 parts by mass (3.225 parts by mass in dry equivalent). When the molecular weight of the acrylic resin in Example 4 was measured, the weight average molecular weight was 500,000.

[Comparative Example 1]
In Example 1, 0.012 parts by mass of Zr(C ₅ H ₇ O ₂ ) ₄ (trade name: NASEM (registered trademark) zirconium compound, manufactured by Nippon Chemical Industry Co., Ltd.) used in the adhesive composition was changed to 0.14 parts by mass of (C ₁₁ H ₂₃ COO) ₂ Sn(C ₄ H ₉ ) ₂ (di-n-butyltin dilaurate, manufactured by Fujifilm Wako Pure Chemical Industries Co., Ltd.), and the time was changed from 48 hours at 50°C to 48 hours at 60°C to prepare an acrylic resin solution, and 2.9 parts by mass (2.175 parts by mass in dry equivalent) of HMDI-based crosslinking agent "manufactured by Tosoh Corporation, product name: Coronate (registered trademark) HL (solid content 75% by mass)" was changed to 2.29 parts by mass (1.7175 parts by mass in dry equivalent) to obtain a dicing sheet of Comparative Example 1 in the same manner as in Example 1. The molecular weight of the acrylic resin in Comparative Example 1 was measured and found to be a weight average molecular weight of 500,000.

[Comparative Example 2]
A dicing sheet of Comparative Example 2 was obtained in the same manner as in Comparative Example 1, except that the amount of the HMDI-based crosslinking agent "Tosoh Corporation, product name: Coronate (registered trademark) HL (solid content 75% by mass)" used in the adhesive composition in Comparative Example 1 was changed from 2.29 parts by mass (1.7175 parts by mass in dry equivalent) to 4.3 parts by mass (3.225 parts by mass in dry equivalent). When the molecular weight of the acrylic resin in Comparative Example 2 was measured, the weight average molecular weight was 500,000.

[Comparative Example 3]
In Example 2, the HMDI-based crosslinking agent "manufactured by Tosoh Corporation, product name: Coronate (registered trademark) HL (solid content 75% by mass)" 2.9 parts by mass (2.175 parts by mass in dry equivalent) used in the adhesive composition was changed to a xylene diisocyanate-based (XDI-based) polyisocyanate crosslinking agent "manufactured by Mitsui Polyurethane Co., Ltd., product name: D-110N (solid content 75% by mass)" 2.9 parts by mass (2.175 parts by mass in dry equivalent). A dicing sheet of Comparative Example 3 was obtained in the same manner as in Example 2. When the molecular weight of the acrylic resin in Comparative Example 3 was measured, the weight average molecular weight was 500,000.

[Comparative Example 4]
In Example 2, the HMDI-based crosslinking agent "manufactured by Tosoh Corporation, product name: Coronate (registered trademark) HL (solid content 75% by mass)" 2.9 parts by mass (2.175 parts by mass in dry equivalent) used in the adhesive composition was changed to a tolylene diisocyanate-based (TDI-based) polyisocyanate crosslinking agent "manufactured by Tosoh Corporation, product name: Coronate (registered trademark) L (solid content 75% by mass)" 2.9 parts by mass (2.175 parts by mass in dry equivalent), and the dicing sheet of Comparative Example 3 was obtained in the same manner as in Example 2. When the molecular weight of the acrylic resin in Comparative Example 3 was measured, the weight average molecular weight was 500,000.

[Pot life evaluation]
The viscosity of the adhesive composition immediately after preparation when producing the dicing sheets of Examples 1 to 4 and Comparative Examples 1 to 4 was measured using a B-type viscometer. Thereafter, the adhesive composition was stored in an environment of 23° C., and the viscosity of the adhesive composition was measured every hour up to 12 hours using the B-type viscometer.
The time required for the viscosity to increase to 1.5 times the viscosity immediately after preparation was defined as the pot life of the pressure-sensitive adhesive composition. The evaluation results are shown in Tables 1 and 2.

[Adhesion evaluation]
The dicing sheets of Examples 1 to 4 and Comparative Examples 1 to 4 were irradiated with ultraviolet light (illuminance: 230 mW/ ^cm2, light quantity: 190 mJ/ ^cm2 ) from the side of the base film using RAD2000. Thereafter, the release film was peeled off, and 100 cross-cuts of 10 x 10 were made on the surface of the adhesive layer in a grid pattern at intervals of 5 mm, and an adhesive tape (Nichiban Co., Ltd., Cellotape (registered trademark)) was applied to the surface of the adhesive layer cross-cut in the grid pattern, and a peel test was performed in accordance with the grid tape method of JIS K 5600-5-6:1999 (cross-cut method). The number n of squares that had completely smooth edges and were not peeled off among the 100 grid patterns was expressed in the form of "n/100". The evaluation results are shown in Tables 1 to 2.

As shown in Tables 1 and 2, the dicing sheet as a workpiece processing sheet of the present invention comprises a base film, an antistatic layer provided on the base film, and an adhesive layer provided on the antistatic layer, and therefore can prevent the generation of static electricity between the workpiece and the workpiece processing sheet.
In the dicing sheets of Examples 1 to 4, the adhesive layer is formed using an energy ray-curable adhesive composition containing as blending components an acrylic resin having a hydroxyl group and an energy ray-polymerizable unsaturated group, one or more catalysts selected from the group consisting of acetylacetone zirconium complexes, metal soaps whose metal species is zirconium, and acetylacetone zinc complexes, and an HMDI-based crosslinking agent. Therefore, the adhesive layer has excellent adhesion between the base film and the adhesive layer, and the adhesive composition for forming the adhesive layer has an appropriate pot life.

In the dicing sheet of Comparative Example 1, which used a tin-based catalyst, the pot life of the adhesive composition for forming the adhesive layer was short, and the adhesion between the base film and the adhesive layer was also poor. In the dicing sheet of Comparative Example 2, which used a tin-based catalyst, the adhesion between the base film and the adhesive layer was improved by increasing the amount of HMDI-based crosslinking agent, but the pot life of the adhesive composition for forming the adhesive layer became even shorter.

In the dicing sheets of Comparative Examples 3 and 4, which used an XDI-based crosslinking agent or a TDI-based crosslinking agent, the adhesion between the base film and the adhesive layer was poor.

The workpiece processing sheet of the present invention can be used to process workpieces such as semiconductor wafers.

11: Base film, 11a: First surface of base film, 111: Antistatic layer, 111a: First surface of antistatic layer, 12: Adhesive layer, 12a: First surface of adhesive layer, 7: Peeling means, 9: Work, 9a: Circuit surface of work, 9b: Back surface of work, 9': Workpiece, 9a': Circuit surface of workpiece, 101: Workpiece processing sheet

Claims (4)

A workpiece processing sheet comprising a base film, an antistatic layer provided on the base film, and an adhesive layer provided on the antistatic layer,
The antistatic layer contains a conductive polymer,
the pressure-sensitive adhesive layer is formed using an energy ray-curable pressure-sensitive adhesive composition including as blending components an acrylic resin having a hydroxyl group and an energy ray-polymerizable unsaturated group, one or more catalysts selected from the group consisting of an acetylacetone zirconium complex, a metal soap whose metal species is zirconium, and an acetylacetone zinc complex, and a crosslinking agent;
The crosslinking agent is a work processing sheet containing one or more hexamethylene diisocyanate-based polyisocyanates selected from the group consisting of biuret type, isocyanurate type, adduct type, bifunctional prepolymer type, and block type. The workpiece processing sheet according to claim 1, wherein the ratio of the amount (parts by mass) of the crosslinking agent to the total mass of the structural units having a hydroxyl group that constitute the acrylic resin is 0.35 or more. The method for producing a workpiece processing sheet according to claim 1 or 2, wherein the base film, the antistatic layer, and the adhesive layer are laminated in this order,
reacting an acrylic resin having a hydroxyl group with a compound having an isocyanate group and an energy ray-polymerizable unsaturated group in the presence of the catalyst to form a urethane bond between the isocyanate group and a part of the hydroxyl group, thereby preparing an acrylic resin having the hydroxyl group and the energy ray-polymerizable unsaturated group;
preparing the energy ray-curable pressure-sensitive adhesive composition by blending the acrylic resin having a hydroxyl group and an energy ray-polymerizable unsaturated group with the crosslinking agent;
and producing the pressure-sensitive adhesive layer using the energy ray-curable pressure-sensitive adhesive composition. A method for manufacturing a workpiece using the workpiece processing sheet according to claim 1 or 2,
A step of attaching the surface of the adhesive layer in the work processing sheet opposite to the base film side to one surface of the work, thereby preparing a laminate of the work processing sheet and the work;
A step of processing the work in the laminate to produce a workpiece composite in which the workpiece is held by the adhesive layer in the workpiece processing sheet;
irradiating the pressure-sensitive adhesive layer with energy rays from the outside of the base film side of the workpiece composite to harden the pressure-sensitive adhesive layer;
and a step of separating and picking up the workpiece from the cured product of the adhesive layer.

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