Workpiece processing sheet

Abstract

The present invention relates to a workpiece processing sheet 1 comprising at least a substrate 2 and an adhesive layer 3 laminated on a first surface of the substrate 2. The second surface of the substrate 2 has an arithmetic mean roughness (Ra) of 0.01 μm to 0.4 μm, a maximum height roughness (Rz) of 0.01 μm to 2.5 μm, and a light transmittance of 40% or more at a wavelength of 532 nm. The workpiece processing sheet 1 exhibits excellent laser markability and is resistant to laser light.

Description

Technical Field

[0001] The present invention relates to a workpiece processing sheet, in particular to a workpiece processing sheet suitable for laser marking of a workpiece. Background Art

[0002] In recent years, semiconductor devices have been manufactured using a mounting method known as flip-chip. In this method, when mounting a semiconductor chip with a circuit surface having electrodes such as bumps, the circuit surface of the semiconductor chip is bonded to a chip mounting portion such as a lead frame. As a result, the backside of the semiconductor chip, where no circuitry is formed, is exposed.

[0003] Therefore, to protect semiconductor chips, a hard protective film made of an organic material is often formed on the back side of the semiconductor chip. For example, Patent Document 1 discloses a protective film-forming and dicing sheet in which a protective film-forming layer capable of forming the protective film is formed on a dicing sheet. This protective film-forming and dicing sheet allows a protective film to be formed on a semiconductor wafer and then subsequently diced to obtain semiconductor chips with protective films.

[0004] In addition, the dicing sheet itself comprises a base material and an adhesive layer provided on one side thereof. In order to improve the peelability of the semiconductor chip with the protective film when picking up, an ultraviolet curable adhesive that reduces the adhesive strength by ultraviolet irradiation is sometimes used as the adhesive of the adhesive layer.

[0005] Typically, the protective film is printed to indicate the semiconductor chip's product number, etc. This printing method is typically laser marking, which involves irradiating the protective film with a laser. Laser marking involves irradiating the protective film with laser light through a dicing sheet that also serves as a dicing sheet.

[0006] The protective film is generally made of a black resin composition. When laser marking is performed on the protective film, it is generally possible to print well on the protective film even with a relatively low laser output.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Laid-Open No. 2006-140348 Summary of the Invention

[0010] Technical Problems to be Solved by the Invention

[0011] In recent years, laser marking has been proposed for workpieces such as semiconductor wafers and glass plates. However, when laser marking inorganic materials, problems often arise, such as poor printing quality, rough marking, and low printing accuracy.

[0012] Furthermore, when laser marking inorganic materials using the aforementioned method, the laser output must be high, which can easily cause the base material of the cutting sheet to burn. This reduces the light transmittance of the burned portion, making it difficult to clearly see the printed text on the workpiece. Furthermore, when the cutting sheet's adhesive layer is UV-curable, UV curing reduces the UV transmittance of the burned portion of the base material. Consequently, the adhesive layer in that portion fails to fully cure, leaving adhesive residue on the picked-up chip.

[0013] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a workpiece processing sheet that has excellent laser marking properties and is resistant to laser light.

[0014] Technical means to solve technical problems

[0015] In order to achieve the above-mentioned purpose, first, the present invention provides a sheet for workpiece processing, which comprises at least a substrate and an adhesive layer stacked on the first surface side of the substrate, and the workpiece processing sheet is characterized in that the arithmetic mean roughness (Ra) of the second surface of the substrate is greater than 0.01 μm and less than 0.4 μm, the maximum height roughness (Rz) of the second surface of the substrate is greater than 0.01 μm and less than 2.5 μm, and the transmittance of the substrate at a wavelength of 532 nm is greater than 40% (Invention 1).

[0016] In the above invention (Invention 1), by adjusting the physical properties of the substrate as described above, the laser used for laser marking, particularly laser light with a wavelength of 532 nm, easily transmits through the substrate and the workpiece processing sheet. This allows for excellent laser marking of the workpiece, resulting in highly accurate printing. Furthermore, the substrate does not readily absorb the laser energy, which prevents it from being burned or printed on. Consequently, the substrate's light transmittance is prevented from being lost due to burning, and the printed text formed on the workpiece can be clearly seen through the workpiece processing sheet.

[0017] In the above invention (Invention 1), it is preferred that the light transmittance of the substrate at a wavelength of 400 nm is 40% or more (Invention 2).

[0018] In the above inventions (Inventions 1 and 2), it is preferred that the light transmittance of the substrate at a wavelength of 800 nm is 45% or more (Invention 3).

[0019] The workpiece processing sheet in the above inventions (Inventions 1 to 3) is preferably used for an application including a step of laser marking a workpiece via the workpiece processing sheet (Invention 4).

[0020] The workpiece processing sheet in the above inventions (Inventions 1 to 4) is preferably used for cutting (Invention 5).

[0021] The workpiece processing sheet in the above invention (Invention 5) is preferably used for stealth cutting (Invention 6).

[0022] Effects of the Invention

[0023] The workpiece processing sheet of the present invention not only has excellent laser marking properties but also has resistance to laser light. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a cross-sectional view of a workpiece processing sheet according to one embodiment of the present invention.

[0025] Figure 2 This is a cross-sectional view showing an example of use of a workpiece processing sheet according to one embodiment of the present invention, specifically, a stacked structure. DETAILED DESCRIPTION

[0026] Hereinafter, embodiments of the present invention will be described.

[0027] Figure 1 : is a cross-sectional view of a workpiece processing sheet according to one embodiment of the present invention. Figure 1 As shown, the workpiece processing sheet 1 of this embodiment comprises a base material 2, a first surface side ( Figure 1 The workpiece processing sheet 1 is constructed by a first surface (the upper side) of the substrate 2 and a release sheet 6 laminated on the adhesive layer 3. The release sheet 6 is peeled off when the workpiece processing sheet 1 is used. Before that, the release sheet 6 protects the adhesive layer 3. The release sheet 6 can also be omitted from the workpiece processing sheet 1 of this embodiment. Here, the surface of the substrate 2 on the adhesive layer 3 side is called the "first surface", and the surface on the opposite side ( Figure 1 The lower surface in the figure is called the "second surface".

[0028] As an example, the workpiece processing sheet 1 of the present embodiment can be used to hold a workpiece in a laser marking process and a cutting process for a semiconductor wafer or a glass plate as a workpiece, but the present invention is not limited thereto.

[0029] In addition, in addition to components made of inorganic materials such as semiconductor wafers and glass plates, components made of organic materials such as protective films or adhesive layers stacked thereon, or surface layers of packages can also be targets of laser marking in this embodiment.

[0030] The workpiece processing sheet 1 of the present embodiment is usually formed into a long strip shape and wound into a roll shape, and is used in a roll-to-roll system.

[0031] 1. Constituent components of workpiece processing sheets

[0032] (1) Base material

[0033] (1-1)Physical properties

[0034] The arithmetic mean roughness (Ra) of the second surface of the substrate 2 (hereinafter sometimes referred to as the "back surface of the substrate 2") is greater than or equal to 0.01 μm and less than or equal to 0.4 μm, and the maximum height roughness (Rz) is greater than or equal to 0.01 μm and less than or equal to 2.5 μm. In addition, the transmittance of the substrate 2 at a wavelength of 532 nm is greater than or equal to 40%. The arithmetic mean roughness (Ra) and the maximum height roughness (Rz) in this specification are values ​​measured in accordance with JIS B0601:1999. In addition, the transmittance in this specification is measured by using a spectrophotometer as a measuring instrument and by a direct light receiving method. The details of the measuring method are shown in the test examples described later.

[0035] By making the arithmetic mean roughness (Ra) and the maximum height roughness (Rz) of the second surface of the substrate 2 within the above ranges, and the transmittance of the substrate 2 at a wavelength of 532 nm within the above ranges, the laser used for laser marking, especially the laser with a wavelength of 532 nm, can easily transmit the substrate 2 and the workpiece processing sheet 1. As a result, the workpiece can be well printed based on laser marking, and high-precision printing can be formed. In addition, the substrate 2 is not easy to absorb the energy of the laser, which can prevent the substrate 2 from being burned or printed. Therefore, the decrease in the transmittance of the substrate 2 due to burning does not occur, and the printing formed on the workpiece can be well visually recognized through the workpiece processing sheet 1. Furthermore, when the adhesive layer 3 is composed of an ultraviolet curable adhesive, when the adhesive layer 3 is irradiated with ultraviolet rays through the substrate 2, the ultraviolet rays reach the adhesive layer 3 without any problem, and the adhesive layer 3 is well cured. Therefore, the problem of residual glue of the adhesive adhering to the picked-up chip is not easy to occur. That is, the workpiece processing sheet 1 of the present embodiment has excellent laser marking properties and is resistant to laser light.

[0036] Furthermore, by making the base material 2 satisfy the above-mentioned physical properties, the transmittance of the laser light used in stealth dicing is also improved, and the workability of stealth dicing is excellent.

[0037] Furthermore, by setting the arithmetic mean roughness (Ra) and the maximum height roughness (Rz) of the second surface of the substrate 2 within the above ranges, it is possible to suppress the sticking of the workpiece processing sheet 1. That is, unwinding from the roll of the workpiece processing sheet 1 can be performed smoothly, and unintended peeling at the interface is less likely to occur during unwinding.

[0038] As mentioned above, the upper limit of the arithmetic mean roughness (Ra) of the back surface of the substrate 2 is 0.4 μm or less, preferably 0.2 μm or less, and particularly preferably less than 0.1 μm. If the arithmetic mean roughness (Ra) exceeds 0.4 μm, the unevenness of the back surface of the substrate 2 will hinder the transmission of the laser. On the other hand, from the perspective of preventing sticking, the lower limit of the arithmetic mean roughness (Ra) is 0.01 μm or more, preferably 0.015 μm or more.

[0039] Furthermore, as described above, the maximum height roughness (Rz) of the back surface of the substrate 2 is 2.5 μm or less, preferably 1.5 μm or less, and particularly preferably 0.5 μm or less. If the maximum height roughness (Rz) exceeds 2.5 μm, the unevenness of the back surface of the substrate 2 will hinder the transmission of the laser. On the other hand, from the perspective of preventing sticking, the lower limit of the maximum height roughness (Rz) is 0.01 μm or more, preferably 0.013 μm or more, and particularly preferably 0.1 μm or more.

[0040] Since an adhesive layer 3 is stacked on the first surface of the substrate 2 (hereinafter sometimes referred to as the "front side of the substrate 2"), the concavo-convex on the front side of the substrate 2 is buried by the adhesive layer 3, and therefore the arithmetic mean roughness (Ra) and the maximum height roughness (Rz) of the front side of the substrate 2 are not particularly limited. However, if the values ​​of the arithmetic mean roughness (Ra) and the maximum height roughness (Rz) are too large, it is sometimes possible that the concavo-convex on the front side of the substrate 2 is not buried by the adhesive layer 3, and therefore the upper limit value of the arithmetic mean roughness (Ra) of the front side of the substrate 2 is preferably 2.5 μm or less. The lower limit value of the arithmetic mean roughness (Ra) of the front side of the substrate 2 is not particularly limited, but in the film-making method of the film, it is usually 0.01 μm or more. In addition, based on the above reasons, the maximum height roughness (Rz) of the front side of the substrate 2 is preferably 2.5 μm or less based on the upper limit value. The lower limit value of the maximum height roughness (Rz) of the front surface of the substrate 2 is not particularly limited, but is usually 0.01 μm or more in the film forming method.

[0041] As described above, the transmittance of substrate 2 at a wavelength of 532 nm is 40% or greater, preferably 50% or greater, particularly preferably 60% or greater, and even more preferably 75% or greater. If the transmittance at a wavelength of 532 nm is less than 40%, the energy of the laser light primarily used in laser marking (particularly the laser light at a wavelength of 532 nm) is absorbed by substrate 2, causing the substrate 2 to easily burn. The upper limit of the transmittance at a wavelength of 532 nm is not particularly limited and may be 100%.

[0042] Furthermore, the light transmittance of the substrate 2 at a wavelength of 400 nm is preferably 40% or greater, more preferably 45% or greater, particularly preferably 50% or greater, and even more preferably 75% or greater. By setting the light transmittance at a wavelength of 400 nm to 40% or greater, visible light is easily transmitted, thereby allowing for better visual recognition of printed characters formed on the workpiece through the substrate 2 and the workpiece processing sheet 1.

[0043] Furthermore, the light transmittance of the substrate 2 at a wavelength of 800 nm is preferably 45% or greater, more preferably 55% or greater, particularly preferably 65% ​​or greater, and even more preferably 75% or greater. By setting the light transmittance at a wavelength of 800 nm to 45% or greater, visible light is easily transmitted, thereby allowing for better visual recognition of printed characters formed on the workpiece through the substrate 2 and the workpiece processing sheet 1.

[0044] (1-2)Thickness

[0045] The thickness of the substrate 2 is not particularly limited as long as it can function appropriately in each process in which the workpiece processing sheet 1 is used. Specifically, the thickness of the substrate 2 is preferably 20 μm or more, particularly preferably 25 μm or more, and even more preferably 50 μm or more. Furthermore, the thickness of the substrate 2 is preferably 450 μm or less, particularly preferably 400 μm or less, and even more preferably 350 μm or less. By setting the thickness of the substrate 2 within the above range, the workpiece processability and laser transmittance can be well maintained.

[0046] (1-3) Materials

[0047] The substrate 2 is preferably composed of a resin film. Specific examples of the resin film constituting the substrate 2 include polyethylene films such as low-density polyethylene (LDPE) film, linear low-density polyethylene (LLDPE) film, and high-density polyethylene (HDPE) film; polyolefin films such as polypropylene film, ethylene-propylene copolymer film, polybutene film, polybutadiene film, polymethylpentene film, ethylene-norbornene copolymer film, and norbornene resin film; ethylene copolymer films such as ethylene-vinyl acetate copolymer film, ethylene-(meth)acrylic acid copolymer film, and ethylene-(meth)acrylate copolymer film; polyvinyl chloride films such as polyvinyl chloride film and vinyl chloride copolymer film; polyester films such as polyethylene terephthalate film and polybutylene terephthalate film; polyurethane film; polyimide film; polystyrene film; polycarbonate film; and fluororesin film. Furthermore, modified films such as cross-linked films and ionomer films of the above films may also be used. Furthermore, a laminated film may be formed by laminating a plurality of the above films of the same or different types. In addition, the term "(meth)acrylic acid" in this specification refers to acrylic acid and methacrylic acid, and the same applies to other similar terms.

[0048] Among the above, polyolefin films, polyvinyl chloride films, and ethylene copolymer films are preferred. Among polyolefin films, polyethylene films are preferred, and low-density polyethylene (LDPE) films are particularly preferred. Furthermore, among polyvinyl chloride films, polyvinyl chloride films are particularly preferred, and among ethylene copolymer films, ethylene-(meth)acrylic acid copolymer films are particularly preferred. These resin films are likely to satisfy the above-mentioned physical properties. Furthermore, from the perspectives of expandability, workpiece adhesion, and chip peelability, the above-mentioned resin films are also preferred.

[0049] The resin film may be subjected to a surface treatment such as oxidation or embossing, or a primer treatment (primer treatment) on one or both sides as needed to improve adhesion to the adhesive layer 3 laminated thereon. Examples of the oxidation method include corona discharge treatment, plasma discharge treatment, chromium oxidation treatment (wet type), flame treatment, hot air treatment, ozone, and ultraviolet irradiation treatment. Examples of the embossing method include sandblasting and thermal spraying.

[0050] Furthermore, the resin film of the substrate 2 may contain various additives such as a colorant, a flame retardant, a plasticizer, an antistatic agent, a lubricant, and a filler.

[0051] (1-4) Manufacturing Method

[0052] The resin film constituting the substrate 2 can be manufactured by a manufacturing method corresponding to the type of resin film, mainly manufactured by a T-die method of extrusion molding. In order to manufacture a resin film having the above-mentioned arithmetic mean roughness (Ra), maximum height roughness (Rz) and light transmittance, it is necessary not to involve air (bubbles) when the resin film is formed into a film. For example, by performing extrusion molding under reduced pressure, vacuum, etc., it is possible to suppress the involvement of the above-mentioned air and manufacture a resin film without traces of bubbles. In addition, by adjusting the surface roughness of each process roller such as a cooling roller during film formation, a resin film without traces of bubbles can also be manufactured. However, the method for manufacturing a resin film having the above-mentioned arithmetic mean roughness (Ra), maximum height roughness (Rz) and light transmittance is not limited thereto.

[0053] (2)Adhesive layer

[0054] The adhesive layer 3 of the workpiece processing sheet 1 of the present embodiment can be composed of a non-active energy ray curable adhesive or an active energy ray curable adhesive. As the non-active energy ray curable adhesive, it is preferred that it has the required adhesive strength and re-peelability, for example, acrylic adhesives, rubber adhesives, silicone adhesives, urethane adhesives, polyester adhesives, polyvinyl ether adhesives, etc. can be used. Among them, acrylic adhesives are preferred because they can effectively suppress the workpiece or processed object from falling off during the cutting process.

[0055] On the other hand, since active energy ray-curable adhesives can reduce their adhesive strength upon exposure to active energy rays, they can be easily separated from the workpiece or workpiece processing sheet 1 upon exposure to active energy rays. In this embodiment, the active energy ray-curable adhesive is preferably an ultraviolet-curable adhesive. This exhibits and exerts the aforementioned adhesive residue suppression effect.

[0056] The active energy ray-curable adhesive constituting the adhesive layer 3 may contain an active energy ray-curable polymer as its main component, or a mixture of a non-active energy ray-curable polymer and an active energy ray-curable multifunctional monomer and / or oligomer as its main component.

[0057] Hereinafter, the case where the active energy ray-curable adhesive contains a polymer having active energy ray curability as a main component will be described.

[0058] The preferred active energy ray-curable polymer is a (meth)acrylate (co)polymer (A) having an active energy ray-curable functional group (active energy ray-curable group) introduced into a side chain (hereinafter sometimes referred to as "active energy ray-curable polymer (A)"). The active energy ray-curable polymer (A) is preferably obtained by reacting a (meth)acrylic copolymer (a1) having a monomer unit containing a functional group with an unsaturated group-containing compound (a2) having a substituent bonded to the functional group.

[0059] The acrylic copolymer (a1) is composed of a structural unit derived from a functional group-containing monomer and a structural unit derived from a (meth)acrylic acid ester monomer or a derivative thereof.

[0060] As the functional group-containing monomer of the structural unit of the acrylic copolymer (a1), a monomer having a polymerizable double bond and a functional group such as a hydroxyl group, an amino group, a substituted amino group, or an epoxy group in the molecule is preferred.

[0061] More specific examples of the functional group-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. These functional group-containing monomers can be used alone or in combination of two or more.

[0062] As the (meth)acrylate monomer constituting the acrylic copolymer (a1), alkyl (meth)acrylates having an alkyl group with 1 to 20 carbon atoms, cycloalkyl (meth)acrylates, and benzyl (meth)acrylates can be used. Among them, alkyl (meth)acrylates having an alkyl group with 1 to 18 carbon atoms, such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate, are particularly preferably used.

[0063] The acrylic copolymer (a1) contains structural units derived from the above-mentioned functional group-containing monomers usually at a ratio of 3 to 100% by mass, preferably 5 to 40% by mass, and structural units derived from (meth)acrylate monomers or derivatives thereof usually at a ratio of 0 to 97% by mass, preferably 60 to 95% by mass.

[0064] The acrylic copolymer (a1) can be obtained by copolymerizing the above-mentioned functional group-containing monomers, (meth)acrylate monomers or derivatives thereof by a conventional method. In addition to the above-mentioned monomers, dimethylacrylamide, vinyl formate, vinyl acetate, styrene and the like may also be copolymerized.

[0065] The active energy ray-curable polymer (A) can be obtained by reacting the acrylic copolymer (a1) having the functional group-containing monomer unit with the unsaturated group-containing compound (a2) having a substituent bonded to the functional group.

[0066] The substituent of the unsaturated group-containing compound (a2) can be appropriately selected depending on the type of functional group of the functional group-containing monomer unit of the acrylic copolymer (a1). For example, when the functional group is a hydroxyl group, an amino group, or a substituted amino group, the substituent is preferably an isocyanate group or an epoxy group. When the functional group is an epoxy group, the substituent is preferably an amino group, a carboxyl group, or an aziridine group.

[0067] The unsaturated group-containing compound (a2) contains 1 to 5, preferably 1 to 2, active energy ray-polymerizable carbon-carbon double bonds in one molecule. Specific examples of such unsaturated group-containing compounds (a2) include 2-methacryloyloxyethyl isocyanate, m-isopropenyl-α,α-dimethylbenzyl isocyanate, methacryloyl isocyanate, allyl isocyanate, 1,1-(bisacryloyloxymethyl)ethyl isocyanate; acryloyl monoisocyanate compounds obtained by reacting a diisocyanate compound or a polyisocyanate compound with hydroxyethyl (meth)acrylate; acryloyl monoisocyanate compounds obtained by reacting a diisocyanate compound or a polyisocyanate compound with a polyol compound and hydroxyethyl (meth)acrylate; glycidyl (meth)acrylate; (meth)acrylic acid, 2-(1-aziridinyl)ethyl (meth)acrylate, 2-vinyl-2-oxazoline, and 2-isopropenyl-2-oxazoline.

[0068] The unsaturated group-containing compound (a2) is usually used in a ratio of 10 to 100 mol%, preferably 20 to 95 mol%, based on the functional group-containing monomer of the acrylic copolymer (a1).

[0069] In the reaction between the acrylic copolymer (a1) and the unsaturated group-containing compound (a2), the reaction temperature, pressure, solvent, reaction time, presence or absence of a catalyst, and catalyst type can be appropriately selected depending on the combination of functional groups and substituents. Thus, the functional groups present in the acrylic copolymer (a1) react with the substituents in the unsaturated group-containing compound (a2), introducing unsaturated groups into the side chains of the acrylic copolymer (a1), thereby obtaining the active energy ray-curable polymer (A).

[0070] The weight average molecular weight of the active energy ray-curable polymer (A) obtained in this manner is preferably 10,000 or more, particularly preferably 150,000 to 1,500,000, and even more preferably 200,000 to 1,000,000. The weight average molecular weight (Mw) herein is a value measured by gel permeation chromatography (GPC) in terms of polystyrene.

[0071] Even when the active energy ray-curable adhesive contains an active energy ray-curable polymer as a main component, the active energy ray-curable adhesive may further contain an active energy ray-curable monomer and / or oligomer (B).

[0072] As the active energy ray-curable monomer and / or oligomer (B), for example, esters of polyols and (meth)acrylic acid can be used.

[0073] Examples of the active energy ray-curable monomer and / or oligomer (B) include monofunctional acrylates such as cyclohexyl (meth)acrylate and isobornyl (meth)acrylate; polyfunctional acrylates such as trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, and dihydroxymethyltricyclodecane di(meth)acrylate; polyester oligo(meth)acrylates, polyurethane oligo(meth)acrylates, and the like.

[0074] When the active energy ray-curable monomer and / or oligomer (B) is incorporated, the content of the active energy ray-curable monomer and / or oligomer (B) in the active energy ray-curable adhesive is preferably 5 to 80% by mass, particularly preferably 20 to 60% by mass.

[0075] Here, when ultraviolet rays are used as active energy rays for curing the active energy ray-curable resin composition, it is preferable to add a photopolymerization initiator (C). By using the photopolymerization initiator (C), the polymerization curing time and the light irradiation dose can be reduced.

[0076] Specific examples of the photopolymerization initiator (C) include benzophenone, acetophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin benzoic acid, benzoin methyl benzoate, benzoin dimethyl ketal, 2,4-diethylthioxanthone, 1-hydroxycyclohexyl phenyl ketone, benzyldiphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, benzyl, dibenzyl, diacetyl, β-chloroanthraquinone, (2,4,6-trimethylbenzyldiphenyl)phosphine oxide, 2-benzothiazolyl N,N-diethyldithiocarbamate, oligo{2-hydroxy-2-methyl-1-[4-(1-propenyl)phenyl]propanone}, and 2,2-dimethoxy-1,2-diphenylethane-1-one. These photopolymerization initiators may be used alone or in combination of two or more.

[0077] The photopolymerization initiator (C) is preferably used in an amount within the range of 0.1 to 10 parts by mass, particularly preferably 0.5 to 6 parts by mass, relative to 100 parts by mass of the active energy ray-curable polymer (A) (when the active energy ray-curable monomer and / or oligomer (B) is blended, the total amount of the active energy ray-curable polymer (A) and the active energy ray-curable monomer and / or oligomer (B) is 100 parts by mass).

[0078] In addition to the above components, the active energy ray-curable adhesive may also contain other components as appropriate. Examples of the other components include polymer components or oligomer components (D) that do not have active energy ray curability, and crosslinking agents (E).

[0079] Examples of the non-active energy ray-curable polymer component or oligomer component (D) include polyacrylates, polyesters, polyurethanes, polycarbonates, and polyolefins, and polymers or oligomers having a weight average molecular weight (Mw) of 3,000 to 2,500,000 are preferred.

[0080] As the crosslinking agent (E), a polyfunctional compound reactive with the functional groups possessed by the active energy ray-curable polymer (A) etc. can be used. Examples of such polyfunctional compounds include isocyanate compounds, epoxy compounds, amine compounds, melamine compounds, aziridine compounds, hydrazine compounds, aldehyde compounds, oxazoline compounds, metal alkoxide compounds, metal chelate compounds, metal salts, ammonium salts, and reactive phenolic resins.

[0081] By incorporating the above-mentioned other components (D) and (E) into the active energy ray-curable adhesive, it is possible to improve the tackiness and releasability before curing, the strength after curing, the adhesion to other layers, the storage stability, etc. The amount of these other components incorporated is not particularly limited and can be appropriately determined within the range of 0 to 40 parts by mass relative to 100 parts by mass of the active energy ray-curable polymer (A).

[0082] Next, the case where the active energy ray-curable adhesive contains, as a main component, a mixture of a polymer component not having active energy ray curability and an active energy ray-curable multifunctional monomer and / or oligomer will be described below.

[0083] As the polymer component not having active energy ray curability, for example, the same components as those described above for the acrylic copolymer (a1) can be used. The content of the polymer component not having active energy ray curability in the active energy ray curable resin composition is preferably 20 to 99.9% by mass, particularly preferably 30 to 80% by mass.

[0084] The active energy ray-curable polyfunctional monomer and / or oligomer may be the same as that for component (B). The blend ratio of the non-active energy ray-curable polymer component to the active energy ray-curable polyfunctional monomer and / or oligomer is preferably 10 to 150 parts by mass, particularly preferably 25 to 100 parts by mass, of the polyfunctional monomer and / or oligomer per 100 parts by mass of the polymer component.

[0085] In this case, a photopolymerization initiator (C), a crosslinking agent (E), and the like may be appropriately blended in the same manner as described above.

[0086] The thickness of the adhesive layer 3 is not particularly limited as long as it can appropriately function in each step using the workpiece processing sheet 1. Specifically, it is preferably 1 to 50 μm, particularly preferably 2 to 30 μm, and further preferably 3 to 20 μm.

[0087] (3) Peel sheet

[0088] The release sheet 6 in this embodiment protects the adhesive layer 3 until the workpiece processing sheet 1 is used. The release sheet 6 in this embodiment is directly laminated on the adhesive layer 3, but the present invention is not limited to this. Alternatively, another layer (such as a die-bonding film) may be laminated on the adhesive layer 3, and the release sheet 6 may be laminated on the other layer.

[0089] The release sheet 6 can be constructed in any manner; for example, a release sheet made from a plastic film treated with a release agent or the like can be used. 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. Silicones, fluorine-based release agents, and long-chain alkyl release agents can be used, with silicones being preferred due to their low cost and stable performance. The thickness of the release sheet is not particularly limited, but is typically approximately 20 to 250 μm.

[0090] (4) Other components

[0091] In the workpiece processing sheet 1 of the present embodiment, an adhesive layer can also be stacked on the surface of the adhesive layer 3 opposite to the substrate 2 (hereinafter sometimes referred to as the "adhesive surface"). In this case, by providing the workpiece processing sheet 1 of the present embodiment with the above-mentioned adhesive layer, it can be used as a cutting-solidification chip. A workpiece is attached to the surface of the adhesive layer of such a cutting-solidification chip opposite to the adhesive layer, and the workpiece and the adhesive layer are cut at the same time, thereby obtaining a chip stacked with a singulated adhesive layer. The chip can be easily fixed to an object on which the chip is mounted by the singulated adhesive layer. As the material constituting the above-mentioned adhesive layer, it is preferred to use a material containing a thermoplastic resin and a low molecular weight thermosetting adhesive component, or a material containing a B-stage (semi-cured) thermosetting adhesive component.

[0092] In addition, in the workpiece processing sheet 1 of the present embodiment, a protective film forming layer can also be stacked on the adhesive surface in the adhesive layer 3. In this case, the workpiece processing sheet 1 of the present embodiment can be used as a protective film forming and cutting sheet. The workpiece is attached to the surface of the protective film forming layer of this protective film forming and cutting sheet on the opposite side to the adhesive layer, and the workpiece and the protective film forming layer are cut at the same time, thereby obtaining a chip stacked with a singulated protective film forming layer. As the object to be cut, it is preferred to use a workpiece with a circuit formed on one side. In this case, a protective film forming layer is usually stacked on the surface opposite to the surface on which the circuit is formed. By curing the singulated protective film forming layer at a specified time point (preferably before the cutting process), a protective film with sufficient durability can be formed on the workpiece or chip. Preferably, the protective film forming layer is composed of an uncured curable adhesive.

[0093] In these cases, the target of laser marking is not the workpiece itself, but the adhesive layer or protective film. However, even in these cases, the above-mentioned excellent laser markability and laser resistance can be achieved.

[0094] 2. Method for manufacturing workpiece processing sheet

[0095] To produce the workpiece processing sheet 1, as an example, a coating agent for the adhesive layer containing an adhesive constituting the adhesive layer 3 and, if necessary, a solvent is applied to the release surface of a release sheet 6 and dried to form the adhesive layer 3. The substrate 2 is then pressure-bonded to the exposed surface of the adhesive layer 3 to obtain the workpiece processing sheet 1 consisting of the substrate 2, the adhesive layer 3, and the release sheet 6.

[0096] The adhesive layer 3 of this embodiment is preferably attached to a fixture such as a lead frame. In this case, when the adhesive layer 3 is composed of an active energy ray-curable adhesive, it is preferably not cured. This maintains a high adhesive strength to the fixture such as a lead frame.

[0097] The laminate of the substrate 2 and the adhesive layer 3 may be half-cut as needed to form a desired shape, such as a circular shape corresponding to the workpiece (semiconductor wafer).

[0098] 3. How to use the workpiece processing sheet

[0099] The workpiece processing sheet 1 of this embodiment is preferably used for cutting. Examples of cutting methods include blade cutting, stealth cutting, plasma cutting, laser cutting, and water jet cutting, with blade cutting and stealth cutting being preferred. Examples of workpieces include, but are not limited to, semiconductor wafers and glass plates made of inorganic materials, as well as various packages.

[0100] Hereinafter, as an example, a method of manufacturing chips from a semiconductor wafer as a workpiece by blade dicing or stealth dicing using the workpiece processing sheet 1 of the present embodiment will be described.

[0101] First, the workpiece processing sheet 1 that has been wound into a roll is unwound while peeling off the peeling sheet 6. Figure 2 As shown, a semiconductor wafer 7 and a lead frame 8 are attached to the adhesive layer 3 of the workpiece processing sheet 1. This results in a laminated structure (hereinafter sometimes referred to as "laminated structure L") having a structure in which the semiconductor wafer 7 and the lead frame 8 are laminated on the surface of the workpiece processing sheet 1 facing the adhesive layer 3.

[0102] Next, a laser marking process is performed on the stacked structure L. Specifically, a laser irradiation device for laser marking is used to irradiate the semiconductor wafer 7 with laser light through the workpiece processing sheet 1 to perform desired printing on the semiconductor wafer 7. Laser light with a wavelength of 532 nm is mainly used as the laser.

[0103] In the workpiece processing sheet 1 of this embodiment, by setting the physical properties of the substrate 2 as described above, laser light easily transmits through the sheet, enabling excellent laser marking of the workpiece, resulting in highly accurate marking. Furthermore, since the substrate 2 does not readily absorb the laser energy, scorching of the substrate 2 is prevented. Consequently, the decrease in light transmittance of the substrate 2 due to scorching is avoided, and the marking formed on the workpiece can be clearly seen through the sheet 1.

[0104] Next, the stacked structure L is subjected to a dicing step. In the case of blade dicing, a dicing blade is used to cut the semiconductor wafer 7 and separate it, thereby obtaining chips. Then, an expansion step is performed by stretching the workpiece processing sheet 1 to increase the spacing between the chips, making them easier to pick up in the subsequent pickup step.

[0105] On the other hand, during stealth cutting, a laser irradiation device (laser cutter) for splitting processing is used to irradiate the semiconductor wafer 7 with laser light through the workpiece processing sheet 1 to form a modified layer in the semiconductor wafer 7. In addition, by setting the physical properties of the substrate 2 to the above, the transmittance of the laser of the laser cutter is also excellent. Then, by implementing an expansion step of stretching the workpiece processing sheet 1, a force (tensile force in the main surface direction) is applied to the semiconductor wafer 7. As a result, the semiconductor wafer 7 attached to the workpiece processing sheet 1 is split to obtain chips.

[0106] Next, a pickup device is used to pick up the chip from the workpiece processing sheet 1. When the adhesive layer 3 of the workpiece processing sheet 1 is composed of an active energy ray-curable adhesive, it is preferred that the adhesive layer 3 be irradiated with active energy rays through the substrate 2 before picking up the chip. This reduces the adhesive strength of the adhesive layer 3, making it easier to pick up the chip. The active energy rays typically used include ultraviolet rays, electron beams, and the like, with ultraviolet rays being particularly preferred due to their ease of handling.

[0107] The ultraviolet irradiation can be performed using a high-pressure mercury lamp, a fusion lamp, a xenon lamp, an LED, etc. The ultraviolet irradiation dose is preferably 50 mW / cm 2 Above, 1000mW / cm 2 The amount of ultraviolet light is preferably 50 mJ / cm 2 Above, particularly preferably 80 mJ / cm 2 More than 100 mJ / cm 2 In addition, the amount of ultraviolet light is preferably 2000mJ / cm 2 Below, particularly preferably 1000 mJ / cm 2 Below, more preferably 500mJ / cm 2 the following.

[0108] As described above, since the burning of the substrate 2 caused by laser marking is suppressed, the adhesive layer 3 can be cured well even if ultraviolet light is irradiated to the adhesive layer 3 through the substrate 2 in the above manner. Therefore, the problem of adhesive residue adhering to the picked-up chip is unlikely to occur.

[0109] The embodiments described above are provided to facilitate understanding of the present invention and are not intended to limit the present invention. Therefore, the elements disclosed in the embodiments described above also encompass all design modifications or equivalents within the technical scope of the present invention.

[0110] For example, another layer may be provided between the base material 2 and the adhesive layer 3 in the workpiece processing sheet 1 , or on the surface of the base material 2 opposite to the adhesive layer 3 .

[0111] Example

[0112] Hereinafter, the present invention will be described in more detail with reference to Examples and the like, but the scope of the present invention is not limited to these Examples and the like.

[0113] [Example 1]

[0114] (1) Preparation of substrate

[0115] A low-density polyethylene resin composition was extruded using a small T-die extruder (manufactured by TOYO SEIKI Co., Ltd., product name "LABOPLASTOMILL") to produce a substrate composed of a resin film having a thickness of 80 μm. The surface roughness (arithmetic mean roughness (Ra) and maximum height roughness (Rz)) of the back side of the resulting substrate was measured using the method described below. The results are shown in Table 1.

[0116] (2) Preparation of adhesive layer coating agent

[0117] 72 parts by mass of butyl acrylate and 28 parts by mass of 2-hydroxyethyl acrylate (HEA) were copolymerized, and the resulting copolymer was reacted with 80 mol % of methacryloyloxyethyl isocyanate (MOI) relative to the HEA of the copolymer to obtain an active energy ray-curable acrylic polymer (weight-average molecular weight of 500,000) having active energy ray-polymerizable groups in its side chains.

[0118] 3.0 parts by mass of a photopolymerization initiator (product name: "Irgacure 184" manufactured by BASF) and 1.0 part by mass of an isocyanate compound (product name: "Coronate L" manufactured by TOSOH CORPORATION) were mixed with 100 parts by mass (solid content concentration; the same shall apply hereinafter) of the above-mentioned active energy ray-curable acrylic polymer, and the mixture was diluted with a solvent to obtain a coating agent for an adhesive layer.

[0119] (3) Manufacturing of workpiece processing sheets

[0120] A release sheet (manufactured by LINTEC CORPORATION, product name "SP-PET 381031") was prepared, with a silicone release layer formed on one side of a 38 μm thick polyethylene terephthalate film. The adhesive layer coating agent described above was applied to the release surface of the release sheet using a knife coater and dried to form a 10 μm thick adhesive layer. The front side of the substrate prepared above was superimposed on the adhesive layer, and the two were bonded together to form a laminate consisting of substrate (80 μm) / adhesive layer (10 μm) / release sheet.

[0121] The obtained laminate was cut in half from the substrate side so as to cut the laminate of the substrate and the adhesive layer, thereby forming a circular workpiece processing sheet having a diameter of 370 mm.

[0122] [Example 2]

[0123] A polyvinyl chloride resin composition was extruded using a small T-die extruder (manufactured by TOYO SEIKI Co., Ltd., product name "LABOPLASTOMILL") to produce a substrate comprising an 80 μm thick resin film. The surface roughness (arithmetic mean roughness (Ra) and maximum height roughness (Rz)) of the back side of the resulting substrate was measured using the methods described below. The results are shown in Table 1.

[0124] A workpiece processing sheet was produced in the same manner as in Example 1 except that the above-mentioned base material was used.

[0125] [Example 3]

[0126] An ethylene-(meth)acrylic acid copolymer resin composition was extruded using a small T-die extruder (manufactured by TOYO SEIKI Co., Ltd., product name "LABOPLASTOMILL") to produce a substrate comprising an 80 μm thick resin film. The surface roughness (arithmetic mean roughness (Ra) and maximum height roughness (Rz)) of the back side of the resulting substrate was measured using the methods described below. The results are shown in Table 1.

[0127] A workpiece processing sheet was produced in the same manner as in Example 1 except that the above-mentioned base material was used.

[0128] [Comparative Example 1]

[0129] An ethylene-(meth)acrylic acid copolymer resin composition was extruded using a small T-die extruder (manufactured by TOYO SEIKI Co., Ltd., product name "LABOPLASTOMILL") to produce a substrate comprising an 80 μm thick resin film. The surface roughness (arithmetic mean roughness (Ra) and maximum height roughness (Rz)) of the back side of the resulting substrate was measured using the methods described below. The results are shown in Table 1.

[0130] A workpiece processing sheet was produced in the same manner as in Example 1 except that the above-mentioned base material was used.

[0131] [Comparative Example 2]

[0132] A polyethylene resin composition was extruded using a small T-die extruder (manufactured by TOYO SEIKI Co., Ltd., product name "LABOPLASTOMILL") to produce a substrate comprising a resin film having a thickness of 110 μm. The surface roughness (arithmetic mean roughness (Ra) and maximum height roughness (Rz)) of the back side of the resulting substrate was measured using the method described below. The results are shown in Table 1.

[0133] A workpiece processing sheet was produced in the same manner as in Example 1 except that the above-mentioned base material was used.

[0134] [Comparative Example 3]

[0135] A low-density polyethylene resin composition was extruded using a small T-die extruder (manufactured by TOYO SEIKI Co., Ltd., product name "LABOPLASTOMILL") to produce a substrate composed of a resin film having a thickness of 80 μm. The surface roughness (arithmetic mean roughness (Ra) and maximum height roughness (Rz)) of the back side of the resulting substrate was measured using the method described below. The results are shown in Table 1.

[0136] A workpiece processing sheet was produced in the same manner as in Example 1 except that the above-mentioned base material was used.

[0137] [Test Example 1] <Measurement of Surface Roughness of Substrate>

[0138] The arithmetic mean roughness (Ra; in μm) and maximum height roughness (Rz; in μm) of the back surfaces of the substrates prepared in Examples and Comparative Examples were measured using a contact surface roughness meter (manufactured by Mitutoyo Corporation, product name "SV3000S4") under the following measurement conditions in accordance with JIS B0601:1999. The results are shown in Table 1.

[0139] [Measurement conditions]

[0140] Evaluation length: 10mm

[0141] Reference length: 2.5mm

[0142] Scanning speed: 1.0 mm / sec

[0143] Cut-off value: 0.25mm

[0144] [Test Example 2] <Measurement of Light Transmittance>

[0145] The substrates prepared in the Examples and Comparative Examples were measured for light transmittance using a UV-visible-near-infrared spectrophotometer (manufactured by Shimadzu Corporation, product name "UV-3600") using the direct light method. The light transmittance at wavelengths of 400 nm, 532 nm, and 800 nm was calculated. The results are shown in Table 1.

[0146] [Test Example 3] <Evaluation of Laser Marking Properties>

[0147] Using a tape laminating device (LINTEC CORPORATION, product name "RAD-2700F / 12"), the release sheet was peeled from the workpiece processing sheet used in the Examples and Comparative Examples. The exposed adhesive layer was then attached to the polished surface of a #2000 polished silicon wafer (12-inch diameter, 350μm thickness). Simultaneously, the exposed adhesive layer was attached to a lead frame.

[0148] A laser marker (manufactured by EO Technics Co., Ltd., product name "CSM300M") was used to irradiate the silicon wafer with a laser beam having a wavelength of 532 nm through a workpiece processing sheet. Laser marking was performed on the silicon wafer (character size: 0.2 mm × 0.3 mm, character pitch: 0.3 mm, number of characters: 20 characters).

[0149] The workpiece processing sheet was then peeled from the silicon wafer, and the printed text formed on the silicon wafer was examined using a digital microscope (Keyence Corporation, product name: "Digital Microscope VHX-1000, magnification: 100x"). The results were evaluated as follows: A ◎ rating indicated that the printed text was not rough and had high accuracy; a ○ rating indicated that the printed text was slightly rough but had a relatively high accuracy; and a × rating indicated that the printed text was rough and had low accuracy. The results are shown in Table 1.

[0150] [Test Example 4] <Evaluation of Laser Resistance>

[0151] In the same manner as in Experimental Example 3, a silicon wafer was irradiated with a laser beam having a wavelength of 532 nm through a workpiece processing sheet to print on the silicon wafer. The workpiece processing sheet was then peeled from the silicon wafer, and the substrate of the workpiece processing sheet was visually inspected for burns (printing) caused by the laser beam. Results were evaluated as positive if the substrate was not burnt (printed); negative if the substrate was burnt (printed). The results are shown in Table 1.

[0152] [Table 1]

[0153]

[0154] As can be seen from Table 1, the workpiece processing sheets obtained in Examples have excellent laser marking properties and are also resistant to laser light.

[0155] Industrial Applicability

[0156] The workpiece processing sheet of the present invention is suitable for use in applications including a step of laser marking a workpiece such as a semiconductor wafer or a glass plate via the workpiece processing sheet.

[0157] Description of Reference Numerals

[0158] 1: Workpiece processing sheet; 2: Base material; 3: Adhesive layer; 6: Release sheet; 7: Semiconductor wafer; 8: Lead frame.

Claims

1. A workpiece processing sheet comprising at least a base material and an adhesive layer laminated on a first surface side of the base material, wherein: The arithmetic mean roughness (Ra) of the second surface of the substrate is greater than or equal to 0.01 μm and less than 0.1 μm, The maximum height roughness (Rz) of the second surface of the substrate is greater than or equal to 0.01 μm and less than or equal to 2.5 μm, The light transmittance of the substrate at a wavelength of 532 nm is greater than 40%. The workpiece processing sheet is used for applications including a step of laser marking a workpiece via the workpiece processing sheet.

2. The workpiece processing sheet according to claim 1, wherein: The light transmittance of the substrate at a wavelength of 400 nm is greater than 40%.

3. The workpiece processing sheet according to claim 1, wherein: The light transmittance of the substrate at a wavelength of 800 nm is greater than 45%.

4. The workpiece processing sheet according to claim 1, wherein: It is used for cutting.

5. The workpiece processing sheet according to claim 4, wherein: It is used for invisible cutting.

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