Adhesive tape for electronic component

Abstract

The present invention provides an adhesive tape for electronic components, which can sufficiently follow and adhere to a thick and hard wafer having a step on the surface, and can favorably break the wafer into a chip shape by expanding the adhesive tape for electronic components, and furthermore, fragments of an adhesive layer do not contaminate the chip. This adhesive tape (1) for electronic components has a base film (2) and an adhesive layer (3), the adhesive layer (3) is a radiation-curable adhesive layer (3) that is cured by irradiation with radiation, and an intermediate layer (4) that is not cured by irradiation with radiation is provided between the base film (2) and the adhesive layer (3). The adhesive tape (1) for electronic components is used for dicing a wafer (6) including a singulation step in which the wafer is singulated by expansion after the adhesive layer (3) is irradiated with radiation.

Description

Technical Field

[0001] The present invention relates to an adhesive tape for electronic components, and more particularly, to an adhesive tape for electronic components that can be used to secure wafers during a dicing process for separating wafers such as semiconductor wafers and glass wafers into chip-shaped components. Background Art

[0002] Chip-type electronic components such as ICs (integrated circuits), resistors, capacitors, coils, IR cut-off filters, etc. are generally manufactured by attaching the adhesive and stretchable electronic components to wafers such as semiconductor wafers and glass wafers with adhesive tape, and then performing a cutting process to separate the wafer into chip units, an expansion process to expand the processing tape, and a picking process to pick up the separated chips.

[0003] In the wafer dicing process, cutting with a blade has been the mainstream method in the past. However, in recent years, due to the miniaturization and thinning of electronic components, debris called shavings has become a problem, thereby causing a problem of reduced yield.

[0004] To address this problem, in recent years, a so-called stealth dicing method has been proposed as a wafer slicing method, which uses a laser processing device to slice wafers contactlessly. For example, Patent Document 1 discloses a wafer slicing method as a stealth dicing method, which comprises the steps of irradiating a semiconductor substrate having an adhesive tape for electronic components attached thereto via an adhesive layer (die-bonding resin layer) with focused light and irradiating the substrate with laser light to form a modified region within the wafer due to multiphoton absorption, using the modified region as a predetermined slicing portion, and then slicing the wafer and adhesive layer along the predetermined slicing portion by expanding the adhesive tape for electronic components.

[0005] The wafer slicing method described in Patent Document 1 utilizes laser irradiation and the expansion of an adhesive tape for electronic components to achieve non-contact slicing of the wafer. This reduces the physical load on the wafer and allows slicing without the wafer chips that are generated by currently mainstream blade dicing. Furthermore, since the adhesive layer is separated by expansion, no adhesive chips are generated. Therefore, this method has attracted considerable attention as an excellent alternative to blade dicing.

[0006] The separation technology described in the above-mentioned document is mainly for semiconductor wafers, but it can also be applied to glass wafers by changing the laser engine of the device to one for glass.

[0007] In addition, in the stealth dicing method, the adhesive tape for electronic components used in the previous dicing process using a blade is used. When producing micro-sized semiconductor chips, the stress (expansion force) during expansion is absorbed by the adhesive tape for electronic components, and the expansion force is not fully transmitted to the modified area inside the wafer, making it difficult to chip the wafer with a good yield.

[0008] In addition, when used for wafers with complex adherend shapes and step differences, the adhesive layer must be thickened so that the adhesive layer can fully follow the step differences. However, if the adhesive layer is thickened, the stress will be relaxed during expansion and the wafer's separability will be reduced. Therefore, it is difficult to strike a balance between the adhesive tape for electronic components' followability to the wafer's surface step differences and the wafer's separability.

[0009] Therefore, as an adhesive sheet for stealth cutting consisting of a substrate and an adhesive layer formed on one side thereof, an adhesive sheet for stealth cutting has been proposed (see Patent Document 2), wherein the Young's modulus of the adhesive sheet at 23°C is 200 to 600 MPa, and the storage elastic modulus of the adhesive layer at 23°C is 0.10 to 50 MPa.

[0010] In addition, a dicing tape has been proposed (see patent document 3), which, after radiation irradiation treatment or heat treatment, has a tensile load of 30 N or more when the tape elongation is 10% under the test conditions of a width of 25 mm, a distance between marking lines and a distance between clamps of 100 mm, and a tensile speed of 300 mm / min, and the surface roughness Ra of the back side of the expanded base film of the dicing tape is 0.3 μm or more.

[0011] Prior art literature

[0012] Patent Literature

[0013] Patent Document 1: Japanese Patent Application Laid-Open No. 2003-338467

[0014] Patent Document 2: Japanese Patent No. 5128575

[0015] Patent Document 3: Japanese Patent No. 4927393 Summary of the Invention

[0016] Problems to be solved by the invention

[0017] For example, when separating and picking up thick and hard wafers, such as glass wafers used to manufacture optical filters, the adhesive layer must be further thickened to allow it to adequately follow the steps created on the wafer. When the adhesive layer is further thickened, even when the adhesive sheet for stealth dicing described in Patent Document 2 is expanded, there is a concern that the expansion force may not be sufficiently transmitted, preventing the wafer from being properly separated along the intended cutting section.

[0018] Here, in order to ensure good splitting properties even with a thick adhesive layer, it is conceivable to expand the adhesive layer after irradiation, as in the dicing tape described in Patent Document 3. However, if a thick adhesive layer is irradiated and cured before expansion, there is a problem that the cured adhesive layer breaks, and fragments thereof fall off the base film and contaminate the chip.

[0019] Therefore, an object of the present invention is to provide an adhesive tape for electronic components that can fully follow and adhere to thick and hard wafers with surface steps, and by expanding the adhesive tape for electronic components, the wafer can be well separated into chips, and fragments of the adhesive layer will not contaminate the chips.

[0020] Means for solving problems

[0021] In order to solve the above-mentioned problems, the adhesive tape for electronic components of the present invention is characterized in that it is an adhesive tape for electronic components comprising a base film and an adhesive layer, the adhesive layer being a radiation-curing adhesive layer that is cured by irradiation with radiation, and an intermediate layer that is not cured by irradiation with radiation being provided between the base film and the adhesive layer. The adhesive tape for electronic components is used for dicing wafers in a singulation process that includes singulating the wafers by expansion after irradiation with radiation.

[0022] In the adhesive tape for electronic components, the total thickness of the adhesive layer and the intermediate layer is preferably 5 to 100 μm.

[0023] In the adhesive tape for electronic components, the thickness of the intermediate layer is preferably 30% or more of the total thickness of the adhesive layer and the intermediate layer.

[0024] In the adhesive tape for electronic components, the thickness of the intermediate layer is preferably less than 30% of the thickness of the adhesive layer, and the intermediate layer contains a polyester-based adhesive composition.

[0025] In the adhesive tape for electronic components, the total thickness of the base film, the adhesive layer, and the intermediate layer is preferably 170 μm or less.

[0026] The adhesive tape for electronic components is preferably used in an expanded state maintaining step of maintaining the expanded state by sandwiching the base film, the adhesive layer, and the intermediate layer between the outer peripheral surface of the inner ring and the inner peripheral surface of the outer ring.

[0027] The adhesive tape for electronic components is preferably used for dicing a wafer having a level difference on the surface.

[0028] The pressure-sensitive adhesive tape for electronic components preferably has an initial tack of 200 kPa or more in a state where the intermediate layer is laminated on the base film.

[0029] Effects of the Invention

[0030] According to the present invention, even if the wafer is thick and hard with a step difference on the surface, the electronic component adhesive tape can fully follow and adhere to it. By expanding the electronic component adhesive tape, the wafer can be well divided into chips, and the chips will not be contaminated by fragments of the adhesive layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a cross-sectional view schematically showing the structure of the adhesive tape for electronic components according to the embodiment of the present invention.

[0032] Figure 2 This is a cross-sectional view schematically showing a laser processing step in a method of singulating a wafer using the adhesive tape for electronic components according to an embodiment of the present invention.

[0033] Figure 3 This is a cross-sectional view schematically showing a tape attaching step in a method of singulating a wafer using the adhesive tape for electronic components according to an embodiment of the present invention.

[0034] Figure 4 It is a cross-sectional view schematically showing a singulation step in a method of singulating a wafer using the adhesive tape for electronic components according to an embodiment of the present invention.

[0035] Figure 5 This is a cross-sectional view schematically showing a chip pickup process using the adhesive tape for electronic components according to an embodiment of the present invention.

[0036] Figure 6 This is a perspective view schematically showing a state in which the electronic component according to an embodiment of the present invention is held expanded by being sandwiched between the outer peripheral surface of the inner ring and the inner peripheral surface of the outer ring by an adhesive tape.

[0037] Figure 7 yes Figure 6 A-A' cross-section diagram.

[0038] Figure 8 This is a cross-sectional view schematically showing a singulation step in another wafer singulation method using the adhesive tape for electronic components according to an embodiment of the present invention.

[0039] Figure 9 This is a cross-sectional view schematically showing an expanded state maintaining step of maintaining the expanded state using the adhesive tape for electronic components according to an embodiment of the present invention. DETAILED DESCRIPTION

[0040] Hereinafter, embodiments of the present invention will be described in detail.

[0041] like Figure 1As shown, the adhesive tape 1 for electronic components according to the embodiment of the present invention comprises a base film 2 and an adhesive layer 3, and an intermediate layer 4 is provided between the base film 2 and the adhesive layer 3. In addition, the adhesive tape 1 for electronic components may also have a release film (not shown) on the adhesive layer 3 for protecting the adhesive layer 3. The adhesive tape 1 for electronic components may also roll the long laminate of the base film 2, the adhesive layer 3, the intermediate layer 4 and the release film into a roll shape, or may cut it into sheets at specific length intervals. In addition, in the long laminate of the base film 2, the adhesive layer 3, the intermediate layer 4 and the release film, it is also possible to pre-punch the base film 2, the adhesive layer 3 and the intermediate layer 4 into a specific label shape (so-called pre-cutting process) as in the case of conventional cutting tapes. Below, each component of the adhesive tape 1 for electronic components according to the present embodiment is described in detail.

[0042] (Base film 2)

[0043] The material of the base film 2 is preferably selected from the following materials: Figure 2 ) The substrate film 2 is preferably a film having uniform and isotropic expansion, as long as the stress generated by expansion is sufficiently transmitted to the adhesive layer 3. This is preferable because the wafer can be cut uniformly in all directions during the expansion process. Based on these considerations, it is preferably selected from polyolefins, polyvinyl chloride, and urethane elastomers.

[0044] Examples of the polyolefins include homopolymers or copolymers of α-olefins such as polyethylene, polypropylene, ethylene-propylene copolymers, polybutene-1, poly-4-methylpentene-1, ethylene-vinyl acetate copolymers, ethylene-ethyl acrylate copolymers, ethylene-methyl acrylate copolymers, ethylene-acrylic acid copolymers, and ionomers, and mixtures thereof.

[0045] Particularly preferred are ionomer resins, synthetic resins obtained by forming polymers into aggregates using the cohesive force of metal ions. Examples include ionomer resins obtained by crosslinking ethylene-(meth)acrylic acid dipolymers or ethylene-(meth)acrylic acid-alkyl (meth)acrylate terpolymers with metal ions. These are suitable for the expansion process due to their uniform expandability. The metal ions contained in the ionomer resins are not particularly limited, and examples include zinc ions and sodium ions. Zinc ions are preferred due to their low solubility and low contamination properties.

[0046] In addition to the above-mentioned ionomer resins, ionomer resins obtained by crosslinking a resin selected from low-density polyethylene having a specific gravity of 0.910 or more and less than 0.930, ultra-low-density polyethylene having a specific gravity less than 0.910, and ethylene-vinyl acetate copolymer are also preferred.

[0047] As a crosslinking method, one can irradiate the above-mentioned resin with energy rays such as electron beams. Such thermoplastic crosslinked resins have a certain uniform expandability because crosslinked sites and non-crosslinked sites coexist in the resin. In addition, since such thermoplastic crosslinked resins contain almost no chlorine atoms in their molecular chain structure, even if the tape is no longer needed after use and is incinerated, chlorinated aromatic hydrocarbons such as dioxins and their analogs are not generated, and the environmental impact is also small. By appropriately adjusting the amount of energy rays irradiated on the above-mentioned polyethylene and ethylene-vinyl acetate copolymer, a resin with sufficiently uniform expandability can be obtained.

[0048] In addition, as the non-crosslinked resin, for example, a mixed resin of polypropylene and a styrene-based copolymer can be exemplified.

[0049] As polypropylene, for example, a homopolymer or copolymer of propylene, such as a block type or random type propylene-ethylene copolymer, can be used. Random type propylene-ethylene copolymer is preferred because of its low rigidity. If the content of ethylene structural units in the propylene-ethylene copolymer is 0.1% by mass or more, it is preferred in terms of low rigidity of the base film 2 and high compatibility of the resins in the mixed resin. If the rigidity of the base film 2 is appropriate, the wafer 6 (see Figure 2 ) is improved, and when the compatibility of the resins is high, it is easy to stabilize the extrusion discharge. More preferably, it is 1% by mass or more. In addition, if the content of ethylene structural units in the propylene-ethylene copolymer is 7% by mass or less, it is preferred in order to ensure stable polymerization reaction to obtain the propylene-ethylene copolymer. More preferably, it is 5% by mass or less.

[0050] Styrene-based copolymers are copolymers of conjugated diene compounds and aromatic vinyl compounds. Examples of aromatic vinyl compounds include styrene, tert-butylstyrene, α-methylstyrene, p-methylstyrene, divinylbenzene, 1,1-diphenylstyrene, N,N-diethyl-p-aminoethylstyrene, vinyltoluene, and p-tert-butylstyrene. Examples of conjugated diene compounds include butadiene, isoprene, 1,3-pentadiene, and 2,3-dimethyl-1,3-butadiene.

[0051] As the styrene-based polymer, hydrogenated ones can also be used, preferably styrene-hydrogenated isoprene-styrene copolymer. If hydrogenated, the styrene-based copolymer has good compatibility with polypropylene and can prevent embrittlement and discoloration caused by oxidative degradation of double bonds in the main chain.

[0052] In addition, a content of styrene structural units in the styrene copolymer of 5% by mass or more is preferred for easy and stable polymerization during the preparation of the styrene copolymer. Furthermore, a content of 40% by mass or less provides flexibility and high expandability. A content of 25% by mass or less is more preferred, and a content of 15% by mass or less is even more preferred.

[0053] As the styrene-based copolymer, either a block copolymer or a random copolymer can be used. Random copolymers are preferred because they have uniformly dispersed styrene structural units, which can suppress excessive rigidity and improve the expandability of the base film 2.

[0054] If the content of polypropylene in the mixed resin of polypropylene and styrene copolymer is 30% by mass or more, it is preferable in terms of suppressing uneven thickness of the base film 2. If the thickness of the base film 2 is uniform, the expandability is easily isotropic. More preferably, it is 50% by mass or more. In addition, if the content of polypropylene is 90% by mass or less, the rigidity of the base film 2 can be appropriately set. If the rigidity of the base film 2 becomes too large, the force required to expand the base film 2 becomes large, and thus the load on the device becomes large, and the wafer 6 (reference Figure 2 ) may not be able to expand sufficiently. The lower limit of the content of the styrene-based copolymer in the mixed resin is preferably 10% by mass or more, as this allows for easy adjustment to a rigidity suitable for the substrate film 2 of the device. An upper limit of 70% by mass or less is preferred for suppressing thickness unevenness, and more preferably 50% by mass or less.

[0055] In order to cure the adhesive layer 3 described later by radiation irradiation and reduce the adhesive strength, the base film 2 preferably has the above-mentioned properties and is also radio-transmissive.

[0056] It should be noted that Figure 1 In the example shown, the base film 2 is a single layer, but is not limited thereto and may also be a multilayer. The multilayer may be a laminate of two or more layers made of resins, or a laminate of layers made of a single resin. It is preferable for the two or more resins to be cross-linked or non-cross-linked, in order to further enhance and develop their respective properties. Combining a cross-linked resin with a non-cross-linked resin and laminating them is also preferable in order to compensate for the shortcomings of each.

[0057] As a method for producing the multilayer base film 2, a conventional extrusion method, a lamination method, etc. can be used. When the lamination method is used, an adhesive can be interposed between the layers. As the adhesive, a conventional adhesive can be used.

[0058] The thickness of the base film 2 is preferably 60 to 150 μm. If the thickness of the base film 2 is too thin, the base film 2 may break, and the expansion and separation may not be possible due to insufficient tensile strength. If the thickness of the base film 2 is too thick, the amount of deformation is insufficient for the stretching amount during expansion and separation, which may cause the wafer 6 (see Figure 2 ) shortens the distance between components, potentially making it unsuitable for subsequent pickup processes. Furthermore, the base film 2 becomes difficult to deform during pickup, which can deteriorate pickup performance and lead to pickup failures and chip damage. The thickness of the base film 2 is more preferably 80 to 120 μm.

[0059] (Adhesive layer 3)

[0060] The adhesive layer 3 is not particularly limited as long as it does not peel off from the wafer during the dicing process, has sufficient retention to prevent defects such as wafer jump, transmits the expanded stress to the wafer, and can be peeled off from the wafer during pickup.

[0061] The polymer constituting the main component of the adhesive (also referred to as a binder polymer or matrix polymer) can be appropriately selected from a variety of polymers such as (meth)acrylic resins, epoxy resins, natural rubber resins, and synthetic rubber resins. Among these, (meth)acrylic resins are preferred. (Meth)acrylic resins are easy to control in terms of adhesive strength.

[0062] The base polymer constituting the adhesive layer 3 preferably has a glass transition temperature of -65°C to -30°C. Here, the glass transition temperature refers to the glass transition temperature measured by DSC (differential scanning calorimetry) at a heating rate of 0.1°C / min. When the glass transition temperature exceeds -30°C, the adhesion to the adherend is easily improved, so there is a concern that the adhesive may leave residue on the electronic component when the electronic component is peeled off. If the glass transition temperature is less than -65°C, the adhesive becomes too viscous, which may adversely affect the handling during operation and is therefore not preferred.

[0063] The matrix polymer constituting the adhesive preferably has a weight-average molecular weight of 700,000 or greater. If the matrix polymer has a weight-average molecular weight (Mw) of less than 700,000, low-molecular-weight components may ooze out onto the surface of the adhesive layer 3 and contaminate the adherend. Furthermore, there is a concern that adhesive residue may remain on the electronic component when the electronic component is peeled off.

[0064] The adhesive layer 3 is a radiation-curing type that solidifies by irradiating radiation. As the adhesive composition constituting the radiation-curing adhesive layer 3, a polymer constituting the adhesive and a radiation-polymerizable compound can be used in combination, or a polymer constituting the adhesive can be used that incorporates a functional group (preferably an ethylenically unsaturated group) that is polymerized by radiation. In order to promote polymerization by radiation, it is preferred to include a photopolymerization initiator. In addition, it is also preferred to include a cross-linking agent. By incorporating a monomer having a functional group that can react with a cross-linking agent into the polymer constituting the adhesive, film hardness and gel fraction can be adjusted. In addition, as needed, additives and additives other than those mentioned above can also be included. The following will be described in more detail.

[0065] The resin used in the adhesive layer 3 is not particularly limited, and known adhesives such as chlorinated polypropylene resin, acrylic resin, polyester resin, polyurethane resin, and epoxy resin can be used. However, an acrylic adhesive having an acrylic polymer as a base polymer is preferred.

[0066] Examples of acrylic polymers include those using one or more of (meth)acrylates (e.g., methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, amyl, isoamyl, hexyl, heptyl, octyl, 2-ethylhexyl, isooctyl, nonyl, decyl, isodecyl, undecyl, dodecyl, tridecyl, tetradecyl, hexadecyl, octadecyl, eicosyl, etc., with an alkyl group having 1 to 30 carbon atoms, particularly linear or branched alkyl esters having 4 to 18 carbon atoms, and cycloalkyl (meth)acrylates (e.g., cyclopentyl, cyclohexyl, etc.) as monomer components. The term "(meth)acrylate" refers to acrylate and / or methacrylate, and "(meth)" in the present invention has the same meaning.

[0067] The acrylic polymer may contain units corresponding to other monomer components copolymerizable with the (meth)acrylate or cycloalkyl ester, if necessary, for the purpose of improving cohesive strength, heat resistance, and the like. Examples of such monomer components include carboxyl group-containing monomers such as acrylic acid, methacrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid; acid anhydride monomers such as maleic anhydride and itaconic anhydride; hydroxyl group-containing monomers such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)methyl (meth)acrylate; sulfonic acid group-containing monomers such as styrenesulfonic acid, allylsulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid; phosphate group-containing monomers such as 2-hydroxyethylacryloyl phosphate; acrylamide, acrylonitrile, and the like. These copolymerizable monomer components may be used alone or in combination. The amount of these copolymerizable monomers used is preferably 40% by weight or less of the total monomer components.

[0068] In addition, acrylic polymers are crosslinkable, so they can also include multifunctional monomers etc. as comonomer components as needed. As these multifunctional monomers, for example hexanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, epoxy (meth)acrylate, polyester (meth)acrylate, carbamate (meth)acrylate etc. can be enumerated. These multifunctional monomers can use one or more than two kinds. The usage amount of multifunctional monomers, based on adhesion characteristics etc., is preferably below 30 weight % of all monomer components.

[0069] The acrylic polymer can be prepared by applying an appropriate method such as solution polymerization, emulsion polymerization, bulk polymerization, or suspension polymerization to a mixture of one or more component monomers.

[0070] In addition, in order to control the crosslinking density of the adhesive layer 3 and improve the pickup properties, suitable methods such as: using a suitable external crosslinking agent such as a polyfunctional isocyanate compound, a polyfunctional epoxy compound, a melamine compound, a metal salt compound, a metal chelate compound, an amino resin compound or a peroxide for crosslinking treatment; mixing a low molecular weight compound having two or more carbon-carbon double bonds and crosslinking it by irradiation with radiation, etc. can be used. When using an external crosslinking agent, its amount is determined appropriately based on the balance with the base polymer to be crosslinked, and further based on the use purpose of the adhesive. Generally speaking, it is preferably less than about 20 parts by weight relative to 100 parts by weight of the aforementioned base polymer, and more preferably 0.1 to 20 parts by weight. It should be noted that, based on the viewpoint of preventing deterioration, in addition to the aforementioned components, various adhesive imparting agents, anti-aging agents and other additives can also be used as needed in the adhesive.

[0071] Examples of the radiation-curable adhesive include addition-type radiation-curable adhesives obtained by blending a radiation-curable monomer component and a radiation-curable oligomer component into the above-mentioned adhesive.

[0072] Examples of the radiation-curable monomer components to be incorporated include urethane (meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentanediol tetra(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and 1,4-butanediol di(meth)acrylate. These monomer components may be used alone or in combination of two or more.

[0073] Examples of radiation-curable oligomers include urethane, polyether, polyester, polycarbonate, and polybutadiene oligomers, with molecular weights ranging from approximately 100 to 30,000 being suitable. The amount of radiation-curable monomeric and oligomeric components incorporated can be appropriately determined based on the type of adhesive layer 3 to reduce the adhesive strength of the adhesive layer 3. Generally, the amount is, for example, 5 to 500 parts by weight, and preferably approximately 70 to 150 parts by weight, relative to 100 parts by weight of the base polymer, such as an acrylic polymer, constituting the adhesive.

[0074] In addition to the aforementioned additive-type radiation-curing adhesives, radiation-curing adhesives using a matrix polymer containing radiation-curing groups incorporated into the polymer side chains, main chain, or main chain terminals are also examples of radiation-curing adhesives. Intrinsic radiation-curing adhesives are preferred because they do not require or contain excessive amounts of low-molecular-weight oligomers, which prevents oligomers from migrating within the adhesive over time, resulting in a stable layered adhesive layer 3.

[0075] The matrix polymer into which the radiation-curable group is introduced can be used without particular limitation, and any matrix polymer having carbon-carbon double bonds and exhibiting adhesive properties can be used. Such matrix polymers are preferably those having an acrylic polymer as a basic skeleton. Examples of the basic skeleton of the acrylic polymer include the acrylic polymers exemplified above.

[0076] The method for introducing a radiation-curable group into an acrylic polymer is not particularly limited, and various methods can be used. However, introducing a radiation-curable group into a polymer side chain is relatively easy in terms of molecular design. For example, a method can be used in which a monomer having a functional group is pre-copolymerized with an acrylic polymer, and then a compound having a functional group reactive with the functional group and a carbon-carbon double bond is subjected to a condensation or addition reaction while maintaining the radiation-curability of the carbon-carbon double bond.

[0077] Examples of combinations of these functional groups include carboxylic acid groups and epoxy groups, carboxylic acid groups and aziridine groups, and hydroxyl groups and isocyanate groups. Among these functional group combinations, the combination of hydroxyl groups and isocyanate groups is preferred due to the ease of reaction tracking. Furthermore, if a combination such as the aforementioned acrylic polymer having a carbon-carbon double bond is generated through the combination of these functional groups, the functional groups can be located on either side of the acrylic polymer or the aforementioned compound. With regard to the aforementioned preferred combination, the acrylic polymer having a hydroxyl group and the aforementioned compound having an isocyanate group are preferred. In this case, examples of isocyanate compounds having a carbon-carbon double bond include methacryloyl isocyanate, 2-methacryloyloxyethyl isocyanate, and m-isopropenyl-α,α-dimethylbenzyl isocyanate. Furthermore, as acrylic polymers, copolymers of the aforementioned hydroxyl-containing monomers, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, and ether compounds such as diethylene glycol monovinyl ether can be used.

[0078] Intrinsic radiation-curing adhesives can use the aforementioned matrix polymer (particularly an acrylic polymer) having carbon-carbon double bonds alone, but may also contain a photopolymerizable compound such as the aforementioned radiation-curable monomeric component or oligomer component, to the extent that the properties are not deteriorated. The amount of the photopolymerizable compound added is generally within the range of 30 parts by weight or less, preferably 0 to 10 parts by weight, per 100 parts by weight of the matrix polymer.

[0079] When the radiation-curable adhesive is cured by ultraviolet rays or the like, it preferably contains a photopolymerization initiator.

[0080] Among the above acrylic polymers, (meth)acrylate copolymers composed of an acrylic acid ester represented by CH2=CHCOOR (wherein R is an alkyl group having 4 to 18 carbon atoms), a hydroxyl group-containing monomer, and an isocyanate compound having a radically reactive carbon-carbon double bond in the molecule are particularly preferred.

[0081] The carbon-carbon double bond content of the adhesive layer 3 is preferably 0.5 meq / g or more and 1.8 meq / g or less. If the carbon-carbon double bond content is less than 0.5 meq / g, adhesive residue from the adhesive tape 1 may adhere to the surface of the electronic component when the chip-shaped electronic component is peeled from the adhesive tape 1, potentially causing a so-called "sticky residue." The carbon-carbon double bond content in approximately 10 g of heat-dried adhesive can be quantitatively determined by the weight gain method using a bromine addition reaction in a vacuum and dark environment.

[0082] The (meth)acrylate copolymer may contain units corresponding to other monomer components as needed.

[0083] Examples of the double bond-containing isocyanate compound include methacryloyl isocyanate, acryloyl isocyanate, 2-methacryloyloxyethyl isocyanate, 2-acryloyloxyethyl isocyanate, and m-isopropenyl-α,α-dimethylbenzyl isocyanate. The double bond-containing isocyanate compound may be used alone or in combination of two or more.

[0084] In addition, in radiation-curing adhesives, in order to adjust the adhesive force before radiation irradiation and the adhesive force after radiation irradiation, external crosslinking agents can also be appropriately used. As specific means of external crosslinking methods, methods of adding so-called crosslinking agents such as polyisocyanate compounds, epoxy compounds, aziridine compounds, and melamine-based crosslinking agents and reacting can be cited. When using an external crosslinking agent, its usage amount can be appropriately determined based on the balance with the crosslinked base polymer and then based on the use purpose as an adhesive. The usage amount of the external crosslinking agent is generally less than 20 parts by weight (preferably 0.1 to 10 parts by weight) relative to 100 parts by weight of the aforementioned base polymer. In addition, in radiation-curing adhesives, in addition to the aforementioned components, various previously known adhesive imparting agents, anti-aging agents, foaming agents and other additives can also be used as needed.

[0085] The adhesive layer 3 can be formed by applying the above-mentioned adhesive composition on a release film (not shown) and drying the coating.

[0086] It should be noted that the adhesive layer 3 may also be a structure formed by laminating multiple layers. When there are multiple layers, the layer for bonding the electronic components is preferably a radiation-curing adhesive as described above, but heat-foaming adhesives may also be used for other layers. Radiation-curing adhesives are adhesives that are cured by ultraviolet rays, electron beams, etc. and are easy to peel off when peeled off. Heat-foaming adhesives are adhesives that are easy to peel off by using a foaming agent or expansion agent.

[0087] Furthermore, if necessary, a release film, typically used as a separator, may be attached to the side of the adhesive layer 3 to protect the adhesive layer 3 until it is put into practical use. Examples of materials constituting the release film include synthetic resin films such as polyethylene, polypropylene, and polyethylene terephthalate, and paper. To improve releasability from the adhesive layer 3, the surface of the synthetic resin film may be subjected to a release treatment such as silicone treatment, long-chain alkyl treatment, or fluorine treatment, as needed. The thickness of the release film is typically 10 to 100 μm, preferably approximately 25 to 50 μm.

[0088] (Middle layer 4)

[0089] The intermediate layer 4 is not cured by irradiation with radiation. As a resin used for the radiation-uncurable intermediate layer 4 that is not cured by irradiation with radiation, a copolymer containing a structural unit derived from an alkyl (meth)acrylate monomer and a structural unit derived from 2-hydroxypropyl acrylate, 2-hydroxyethyl (meth)acrylate, and / or 2-hydroxybutyl acrylate, wherein the copolymer containing the structural unit derived from the alkyl (meth)acrylate monomer is cross-linked with an isocyanate compound, can be used.

[0090] The intermediate layer 4 comprises an acrylic copolymer having a hydroxyl value of 45 to 100 and composed of 70 to 95% by mass of a (meth)acrylate monomer having an alkyl group with 4 or more carbon atoms and 5 to 30% by mass of 2-hydroxypropyl acrylate, and polyoxypropylene having a number average molecular weight of 3,000 to 10,000, preferably cross-linked with an isocyanate cross-linking agent.

[0091] Here, examples of the (meth)acrylate alkyl ester monomers having an alkyl group with 4 or more carbon atoms include butyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, 2-methylpropyl (meth)acrylate, 2-methylbutyl (meth)acrylate, 2-ethylbutyl (meth)acrylate, 2-methylhexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 1,2-dimethylbutyl (meth)acrylate, and lauryl acrylate. Among these, those having an alkyl group with 8 or more carbon atoms are particularly preferred.

[0092] The copolymer constituting the intermediate layer 4 preferably contains 65 to 90% by mass of structural units derived from an alkyl (meth)acrylate monomer having an alkyl group with 4 or more carbon atoms. If the content of structural units derived from an alkyl (meth)acrylate monomer is too high, the adhesive has too few crosslinking points and insufficient properties can be achieved. If the content is too low, the pot life from mixing the intermediate layer composition until application to the substrate film 2 is shortened, hindering the production of the adhesive tape 1 for electronic components of the present invention.

[0093] In addition, as monomers containing crosslinkable functional groups, 2-hydroxypropyl acrylate and 4-hydroxybutyl acrylate are preferably used, and as structural units, they contain 10 to 30% by mass. When using functional group-containing monomers such as 2-hydroxyethyl acrylate, which has a shorter chain length than 2-hydroxypropyl acrylate, the crosslinking reaction is fast and the pot life is shortened, which hinders the manufacture of the semiconductor processing tape 1 of the present invention. When using monomers with longer chain lengths, the crosslinking reaction proceeds slowly, resulting in a problem of extremely long completion time of the crosslinking reaction. In addition, if the functional group-containing monomer is less than 10% by mass, the polarity is low, the adhesion to the adhesive layer 3 is reduced, and when the adhesive layer 3 is expanded after being cured by radiation irradiation, there is a concern that fragments of the adhesive layer 3 will fall off.

[0094] Furthermore, it is preferred that the acrylic copolymer, wherein the structural units derived from an alkyl (meth)acrylate monomer having an alkyl group with 4 or more carbon atoms account for 70 to 90% by mass and the functional group-containing monomer is 2-hydroxyethyl acrylate and / or 2-hydroxypropyl acrylate, have a hydroxyl value of 25 to 100 mgKOH / g. A hydroxyl value of less than 25 mgKOH / g results in low polarity, reduced adhesion to the adhesive layer 3, and the adhesive layer 3 may fragment and fall off when expanded after curing by radiation.

[0095] The polyoxypropylene having a number average molecular weight of 3,000 to 10,000 is not particularly limited as long as it is 3,000 to 10,000, and can be appropriately selected from known polyoxypropylenes. A number average molecular weight of less than 3,000 causes low-molecular-weight components to migrate to the adherend surface, increasing contamination. A number average molecular weight exceeding 10,000 deteriorates compatibility with the acrylic copolymer, causing incompatible components to migrate to the adherend surface, increasing contamination. Therefore, the number average molecular weight is preferably within the range of 3,000 to 10,000.

[0096] The amount of polyoxypropylene incorporated is not particularly limited and can be appropriately adjusted within a range that achieves the desired adhesive strength. It can be appropriately selected within the range of 0.5 to 5 parts by mass relative to 100 parts by mass of the acrylic copolymer. If the amount of polyoxypropylene incorporated is less than 0.5 parts, there is a concern that fragments of the adhesive layer 3 may fall off when the adhesive layer 3 is expanded after being cured by radiation.

[0097] The copolymer constituting the middle layer is cross-linked by an isocyanate compound. There is no particular limitation on the isocyanate compound, and examples thereof include aromatic isocyanates such as 4,4'-diphenylmethane diisocyanate, toluene diisocyanate, xylene diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4'-[2,2-bis(4-phenoxyphenyl)propane] diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 2,4'-dicyclohexylmethane diisocyanate, lysine diisocyanate, lysine triisocyanate, etc. Specifically, as a commercially available product, CORONATE L (trade name, manufactured by Japan Polyurethane Co., Ltd.) etc. can be used.

[0098] The content of the isocyanate compound in the intermediate layer 4 is preferably 1 to 12 parts by mass relative to 100 parts by mass of the copolymer. This is because if the isocyanate compound exceeds 12 parts by mass, the pot life from mixing the intermediate layer composition until coating on the base film 2 becomes short, causing problems during the production of the adhesive tape 1 for electronic components.

[0099] In addition, the intermediate layer 4 may also use a polyester polymer as the base polymer. The polyester resin may use a curing agent curing type resin or a thermosetting resin, etc., and a curing agent curing type resin is preferably used. When using a curing agent curing type resin, a crosslinking agent is added to the resin, and the resin is cured by curing after coating / drying. When using a thermosetting resin, the resin is cured by heating after coating. The curing agent curing type polyester resin composition is a composition containing a polyester resin having a functional group that can react with a curing agent, and a polyester polyol having a hydroxyl group can be preferably used. In addition, the curing agent is a compound that reacts with the functional group of the curing agent curing type polyester resin composition and is used to adjust the adhesive force and cohesive force. The aforementioned isocyanate compound having two or more isocyanate groups in the molecule can be preferably used.

[0100] The adhesive composition used to form the intermediate layer 4 may contain known additives such as an adhesion promoter, an anti-aging agent, a filler, a colorant, a flame retardant, an antistatic agent, a softener, an antioxidant, a plasticizer, and a surfactant, as needed.

[0101] The initial adhesion of the intermediate layer 4 when laminated on the substrate film 2 is preferably 200 kPa or more. The initial adhesion of the intermediate layer 4 is the peak value in the probe initial adhesion test. The measurement of the probe initial adhesion can be carried out, for example, using the initial adhesion tester TAC-II of Leska Co., Ltd. The measurement mode is a "continuous load" in which the probe is pushed to a set pressure value and the pressure value is maintained until a set time has passed. The laminate of the intermediate layer 4 and the substrate film 2 is arranged with the intermediate layer 4 on top. The cylindrical probe contacts the intermediate layer 4 from above and then pulls it upward to measure the force required for the pull-off.

[0102] If the initial tack of the intermediate layer 4 is less than 200 kPa, the ability to retain the adhesive layer 3 is reduced, and when the adhesive layer 3 is expanded after being cured by radiation irradiation, fragments of the adhesive layer 3 may fall off.

[0103] The initial adhesion to the intermediate layer 4 can be adjusted by appropriately combining the carbon number of the alkyl group, the mixing ratio of the (meth)acrylate alkyl ester monomer and 2-hydroxypropyl acrylate, the hydroxyl value, the number average molecular weight of polyoxypropylene, the mixing ratio of polyoxypropylene, and the like.

[0104] It should be noted that the intermediate layer 4 may have a single layer or a laminated layer. A primer layer or the like may be provided between the substrate film 2 and the intermediate layer 4 as needed. In this case, the initial tack of the layer in contact with the adhesive layer 3 is preferably 200 kPa or greater when the substrate film 2 is laminated with other layers.

[0105] The thickness of the intermediate layer 4 is preferably 30% or more of the combined thickness of the adhesive layer 3 and the intermediate layer 4, preferably 5 to 60 μm, preferably less than 50 μm, and more preferably less than 20 μm. By setting the thickness of the intermediate layer 4 to 30% or more of the combined thickness of the adhesive layer 3 and the intermediate layer 4, if the thickness and composition of the adhesive layer 3, the composition of the intermediate layer, and the thickness and composition of the base film meet specific requirements, the distance between the chips in the MD (machine direction) of the adhesive tape 1 for electronic components (kerf width) can be well ensured when the wafer 6 is divided into chips 9. It should be noted that the so-called MD direction refers to the direction of travel during the manufacture of the base film 2, the direction in which the base film 2 is unwound, and the longitudinal direction when it is made into a roll. It should be noted that when the intermediate layer 4 is composed of a polyester adhesive, even if the thickness of the intermediate layer 4 is less than 30% of the combined thickness of the adhesive layer 3 and the intermediate layer 4, the kerf width in the MD direction can be well ensured. If the thickness of the intermediate layer 4 is less than 5 μm, the adhesion to the adhesive layer 3 is weak, and there is a concern that fragments of the adhesive layer 3 may fall off when the adhesive layer 3 is expanded after being cured by radiation. If the thickness of the intermediate layer 4 is thicker than 60 μm, the stress (expansion force) generated when the adhesive tape 1 for electronic components is expanded is absorbed by the adhesive tape 1 for electronic components and cannot be fully transmitted to the wafer 6. As a result, there is a concern that the wafer 6 cannot be chipped with a good yield.

[0106] In addition, the total thickness of the adhesive layer 3 and the intermediate layer is preferably 5 to 100 μm, more preferably 20 μm or more, further preferably 30 μm or more, further preferably 40 μm or more, and further preferably more than 50 μm. In addition, it is preferably 70 μm or less. A thickness of 4 μm or less is difficult to manufacture. When the thickness of the adhesive layer 3 is thin, when the shape of the adherend is complex and there is a step difference on the surface of the adherend, the adhesive layer 3 cannot follow the step difference of the wafer and will trap air near the step difference. On the contrary, when the thickness of the adhesive layer 3 is too thick, the responsiveness of the pin that lifts up when picking up the chip is poor, and there is a concern that the pickup property is reduced. In addition, since there is a concern that the tape will fall off the fixture if the thickness is too thick, the total thickness of the base film 2, the adhesive layer 3 and the intermediate layer 4 is preferably 170 μm or less.

[0107] The intermediate layer 4 can be formed by applying and drying the intermediate layer composition described above on the base film 2. Subsequently, the adhesive layer 3 is bonded to the intermediate layer 4 and the release film is peeled off to produce the adhesive tape 1 for electronic components.

[0108] As described above, the radiation-uncurable interlayer 4 that is not cured by irradiation has been described. However, in this specification, the term "not cured by irradiation" includes the case where the interlayer 4 is substantially not cured by irradiation. The term "substantially not cured by irradiation" means that the initial tack of the interlayer 4 after irradiation, when laminated on the base film 2, is 200 kPa or greater.

[0109] Therefore, if the initial tack of the intermediate layer 4 after radiation irradiation in the state laminated on the base film 2 is 200 kPa or more, the intermediate layer 4 can be composed of the same composition as the adhesive layer 3. In order to achieve an initial tack of 200 kPa or more in the intermediate layer 4 after radiation irradiation in the same composition as the adhesive layer 3, the amount of carbon-carbon double bonds in the adhesive using a base polymer into which a radiation-curable group is introduced can be set to less than 0.1 meq / g, or the amount of curing agent added can be reduced.

[0110] <Purpose>

[0111] The adhesive tape 1 for electronic components of the present invention is used in a method for manufacturing electronic components, which comprises irradiating an adhesive layer 3 with radiation and then expanding the adhesive layer 3 to form a wafer 6 (see FIG. Figure 2 ) formed within the modified region 7 (see Figure 2 ) as a starting point along the dividing lines. Therefore, there are no particular restrictions on the other steps or the order of the steps. For example, it can be preferably used in the following electronic component manufacturing methods (A) and (B).

[0112] A method (A) for manufacturing an electronic component, comprising the following steps:

[0113] (a) a laser processing step of irradiating a portion of the wafer to be divided with laser light 5 to form a modified region 7 based on multiphoton absorption inside the wafer 6;

[0114] (b) a tape attaching step of attaching the adhesive layer 3 of the adhesive tape 1 for electronic components to the back surface of the wafer 6,

[0115] (c) a radiation irradiation step of irradiating the adhesive layer 3 with radiation,

[0116] (d) a singulation step of expanding the electronic component adhesive tape 1 to separate the wafer 6 along the dividing lines to obtain a plurality of chips 9,

[0117] (e) A picking-up step of picking up the chip 9 from the adhesive layer 3 of the adhesive tape 1 for electronic components.

[0118] A method (B) for manufacturing an electronic component, comprising the following steps:

[0119] (a) a tape attaching step of attaching the adhesive layer 3 of the adhesive tape 1 for electronic components to the back surface of the wafer,

[0120] (b) irradiating the portion of the wafer to be divided with laser light 5 to form a modified region 7 based on multiphoton absorption inside the wafer 6,

[0121] (c) a radiation irradiation step of irradiating the adhesive layer 3 with radiation,

[0122] (d) a singulation step of expanding the electronic component adhesive tape 1 to separate the wafer 6 along the dividing lines to obtain a plurality of chips 9,

[0123] (e) A picking-up step of picking up the chip 9 from the adhesive layer 3 of the adhesive tape 1 for electronic components.

[0124] <How to use>

[0125] Regarding the method of using the adhesive tape 1 for electronic components of the present invention when it is applied to the above-mentioned method for producing electronic components (A), while referring to Figures 2 to 5 While explaining.

[0126] like Figure 2 As shown, the portion of the wafer 6 to be divided is irradiated with the laser beam 5 , and a reformed region 7 based on multiphoton absorption is formed inside the wafer 6 .

[0127] Next, if Figure 3 As shown, the adhesive layer 3 of the adhesive tape 1 for electronic components is bonded to the back surface of the wafer 6, and a fixing jig 8 is attached to the outer periphery of the adhesive layer 3. Subsequently, the adhesive layer 3 is irradiated with radiation from the base film 2 side of the adhesive tape 1 for electronic components to cure the adhesive layer 3.

[0128] Next, the adhesive tape 1 for electronic components, to which the wafer 6 having the modified region 7 is attached and attached, is mounted on the fixing jig 8 , with the base film 2 side facing downward, on the stage 10 of the expansion device.

[0129] Next, if Figure 4 As shown, with the fixing jig 8 secured to the expansion device, the expansion device's stage 10 is raised to expand the electronic component adhesive tape 1. The expansion conditions include, for example, an expansion speed of 0.1 to 20 mm / sec and an expansion amount (lift) of 1 to 70 mm. By stretching the electronic component adhesive tape 1 radially along the wafer 6, the wafer 6 is separated into individual chips 9 starting from the aforementioned modified region 7.

[0130] At this time, since the adhesive layer 3 is cured, if the amount of expansion is large, it may break due to the expansion force. However, even if it breaks, the fragments are held by the intermediate layer 4 and do not contaminate the chip 9.

[0131] Then, if Figure 5 As shown, the chip 9 is lifted up from the base film 2 side by the lift pins 11 and picked up by the suction chuck 12 .

[0132] In addition, if Figure 6 、 7 As shown, the adhesive tape 1 for electronic components can be preferably used in the following process: for example, using a clamp ring manufactured by Technovision Co., Ltd. as a fixing fixture 8, between the singulation process and the pickup process, the adhesive tape 1 for electronic components (base film 2, adhesive layer 3 and intermediate layer 4) is clamped between the outer peripheral surface of the inner ring 82 and the inner peripheral surface of the outer ring 81 to maintain the expanded state.

[0133] In this case, the singulation process is performed as follows. Figure 8 As shown, wafer 6 with modified region 7 is bonded, and adhesive tape 1 for electronic components, mounted on ring frame 13, is placed on an expansion device and secured. In this state, pressing portion 14 is lowered, pressing adhesive tape 1 for electronic components downward from the substrate film 2. This stretches adhesive tape 1 in the radial direction of wafer 6, separating wafer 6 into individual chips 9 starting from modified region 7.

[0134] In the above-mentioned singulation process, after the adhesive tape 1 for electronic components is in the expanded state, the expanded state maintaining process is continuously performed. Figure 9 First, the pushing portion 15 is raised to press the adhesive tape 1 for electronic components, and the outer ring 81 is raised to fit into the inner ring 82 held by the pressing portion 14. As a result, the adhesive tape 1 for electronic components (base film 2, adhesive layer 3 and intermediate layer 4) is clamped between the outer circumference of the inner ring 82 and the inner circumference of the outer ring 81, and is kept in an expanded state. In this state, the adhesive tape 1 for electronic components near the inner ring 82 and the outer ring 81 is cut by a blade (not shown). Figure 6 、 7 While maintaining the expanded state as shown, it can be stored or transported until the picking-up process is carried out.

[0135] The adhesive tape for electronic components of the present invention includes the following aspects.

[0136] [1] An adhesive tape for electronic components, characterized in that it is an adhesive tape for electronic components comprising a base film and an adhesive layer, wherein the adhesive layer is a radiation-curing adhesive layer that is cured by irradiation with radiation, and an intermediate layer that is not cured by irradiation with radiation is provided between the base film and the adhesive layer, and the adhesive tape for electronic components is used for dicing wafers in a singulation process including singulation of the wafers by expansion after irradiation with radiation.

[0137] [2] The adhesive tape for electronic components according to [1], wherein the total thickness of the adhesive layer and the intermediate layer is 5 to 100 μm.

[0138] [3] The adhesive tape for electronic components according to [1] or [2], wherein the thickness of the intermediate layer is at least 30% of the total thickness of the adhesive layer and the intermediate layer.

[0139] [4] The adhesive tape for electronic components according to [1] or [2], wherein the thickness of the intermediate layer is less than 30% of the thickness of the adhesive layer, and the intermediate layer contains a polyester-based adhesive composition.

[0140] [5] The adhesive tape for electronic components according to any one of [1] to [4], wherein the total thickness of the base film, the adhesive layer, and the intermediate layer is 170 μm or less.

[0141] [6] The adhesive tape for electronic components as described in any one of [1] to [5], which is used in an expanded state maintaining step of maintaining the expanded state by clamping the base film, the adhesive layer and the intermediate layer between the outer peripheral surface of the inner ring and the inner peripheral surface of the outer ring.

[0142] [7] The adhesive tape for electronic components according to any one of [1] to [6], which is used for dicing a wafer having a step difference on its surface.

[0143] [8] The adhesive tape for electronic components according to any one of [1] to [7], wherein the initial tack of the intermediate layer in a state where the intermediate layer is laminated on the base film is 200 kPa or more.

[0144] Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited to these Examples.

[0145] (Production of Base Film)

[0146] Substrate film A: 10 μm of NUCREL AN4214C (trade name, MitsuiDow PolyChemical Co., Ltd.) of ethylene-methacrylic acid copolymer, 80 μm of ethylene-methacrylic acid-(2-methylpropyl acrylate) ternary copolymer-Zn ++Ionomer resin HIMILAN 1855 (trade name, manufactured by Mitsui Dow Polychemical Co., Ltd.) and 10 μm thick NUCREL AN4214C were laminated and extrusion-molded to produce a film having a total thickness of 100 μm. This was used as a base film.

[0147] Substrate film B: 15 μm of NUCREL AN4214C (trade name, MitsuiDow PolyChemical Co., Ltd.) of ethylene-methacrylic acid copolymer, 120 μm of ethylene-methacrylic acid-(2-methylpropyl acrylate) ternary copolymer-Zn ++ Ionomer resin HIMILAN 1855 (trade name, manufactured by Mitsui Dow Polychemical Co., Ltd.) and 15 μm thick NUCREL AN4214C were laminated and extrusion-molded to produce a film having a total thickness of 150 μm. This was used as a base film.

[0148] Substrate film C: 10 μm of NUCREL AN4214C (trade name, MitsuiDow PolyChemical Co., Ltd.) of ethylene-methacrylic acid copolymer, 60 μm of ethylene-methacrylic acid-(2-methylpropyl acrylate) ternary copolymer-Zn ++ Ionomer resin HIMILAN 1855 (trade name, manufactured by Mitsui Dow Polychemical Co., Ltd.) and 10 μm thick NUCREL AN4214C were laminated and extrusion-molded to produce a film having a total thickness of 80 μm. This was used as a base film.

[0149] (Raw material for adhesive layer)

[0150] <Polymer>

[0151] Polymer A: An acrylic copolymer (glass transition temperature: -70°C) containing 60% by weight of 2-ethylhexyl acrylate, 29% by weight of butyl acrylate, 10% by weight of 4-hydroxybutyl acrylate, and 1% by weight of methacrylic acid as structural units was synthesized.

[0152] Polymer B: 2-methacryloyloxyethyl isocyanate was added to an acrylic copolymer (glass transition temperature: -64°C) having 78% by weight of 2-ethylhexyl acrylate, 21% by weight of 2-hydroxyethyl acrylate, and 1% by weight of methacrylic acid as structural units so as to have a double bond content of 0.59 (meq / g).

[0153] Polymer C: An acrylic copolymer (glass transition temperature: -64°C) having 78% by weight of 2-ethylhexyl acrylate, 21% by weight of 2-hydroxyethyl acrylate, and 1% by weight of methacrylic acid as structural units, to which 2-methacryloyloxyethyl isocyanate was added so as to have a double bond content of 0.30 (meq / g).

[0154] Polymer D: Polyester resin composition (weight average molecular weight: 15,000, glass transition temperature: -50°C)

[0155] <Photopolymerization Initiator>

[0156] Irgacure 184 (trade name, manufactured by Ciba-Geigy Co., Ltd., Japan)

[0157] <Curing Agent>

[0158] CORONATE L (isocyanate curing agent, trade name, manufactured by TOSOH Corporation)

[0159] (Adhesive composition)

[0160] Adhesive composition a: 5 wt% of a photopolymerization initiator (Irgacure 184 (trade name), manufactured by Ciba-Geigy Co., Ltd., Japan) and 1 wt% of an isocyanate curing agent (CORONATE L (trade name), manufactured by TOSOH Corporation) were added to the weight of polymer A to obtain adhesive composition a.

[0161] Adhesive composition b: 5 wt% of a photopolymerization initiator (Irgacure 184 (trade name), manufactured by Ciba-Geigy Co., Ltd., Japan) and 8 wt% of an isocyanate curing agent (CORONATE L (trade name), manufactured by TOSOH Corporation) were added to the weight of polymer A to obtain adhesive composition b.

[0162] Adhesive composition c: 5 wt% of a photopolymerization initiator (Irgacure 184 (trade name), manufactured by Ciba-Geigy Co., Ltd., Japan) and 2 wt% of an isocyanate curing agent (CORONATE L (trade name), manufactured by TOSOH Corporation) were added to the weight of polymer B to obtain adhesive composition c.

[0163] Adhesive composition d: 5 wt% of a photopolymerization initiator (Irgacure 184 (trade name), manufactured by Ciba-Geigy Co., Ltd., Japan) and 2 wt% of an isocyanate curing agent (CORONATE L (trade name), manufactured by TOSOH Corporation) were added to the weight of polymer C to obtain adhesive composition d.

[0164] Adhesive composition e: An isocyanate curing agent (CORONATEL (trade name), manufactured by TOSOH Corporation) was blended in an amount of 2% by weight based on the weight of the polymer D to obtain an adhesive composition e.

[0165] (Example 1)

[0166] The adhesive composition a was applied to the surface of the substrate film A to a thickness of 10 μm after drying and dried to form an intermediate layer. A release sheet was then attached to the intermediate layer. Subsequently, while peeling the release sheet, the adhesive composition c was applied to the intermediate layer to a thickness of 30 μm after drying and dried to form an adhesive layer, thereby producing the adhesive tape for electronic components of Example 1.

[0167] (Example 2)

[0168] The adhesive composition a was applied to the surface of substrate film A to a thickness of 20 μm after drying and dried to form an intermediate layer. A release sheet was then attached to the intermediate layer. Subsequently, while peeling the release sheet, the adhesive composition c was applied to the intermediate layer to a thickness of 30 μm after drying and dried to form an adhesive layer, thereby producing the adhesive tape for electronic components of Example 2.

[0169] (Example 3)

[0170] The adhesive composition a was applied to the surface of substrate film A to a thickness of 50 μm after drying and dried to form an intermediate layer. A release sheet was then attached to the intermediate layer. Subsequently, while peeling the release sheet, the adhesive composition c was applied to the intermediate layer to a thickness of 60 μm after drying and dried to form an adhesive layer, thereby producing the adhesive tape for electronic components of Example 3.

[0171] (Example 4)

[0172] The adhesive composition a was applied to the surface of the substrate film B to a thickness of 20 μm after drying and dried to form an intermediate layer. A release sheet was then attached to the intermediate layer. Subsequently, while peeling the release sheet, the adhesive composition c was applied to the intermediate layer to a thickness of 30 μm after drying and dried to form an adhesive layer, thereby producing the adhesive tape for electronic components of Example 4.

[0173] (Example 5)

[0174] The adhesive composition b was applied to the surface of the substrate film A to a thickness of 20 μm after drying and dried to form an intermediate layer. A release sheet was then attached to the intermediate layer. Subsequently, while peeling the release sheet, the adhesive composition c was applied to the intermediate layer to a thickness of 30 μm after drying and dried to form an adhesive layer, thereby producing the adhesive tape for electronic components of Example 5.

[0175] (Example 6)

[0176] The adhesive composition e was applied to the surface of the substrate film A to a thickness of 5 μm after drying and dried to form an intermediate layer. A release sheet was then attached to the intermediate layer. Subsequently, while peeling the release sheet, the adhesive composition b was applied to the intermediate layer to a thickness of 40 μm after drying and dried to form an adhesive layer, thereby producing the adhesive tape for electronic components of Example 6.

[0177] (Example 7)

[0178] The adhesive composition e was applied to the surface of the substrate film A to a thickness of 5 μm after drying and dried to form an intermediate layer. A release sheet was then attached to the intermediate layer. Subsequently, while peeling the release sheet, the adhesive composition c was applied to the intermediate layer to a thickness of 40 μm after drying and dried to form an adhesive layer, thereby producing the adhesive tape for electronic components of Example 7.

[0179] (Comparative Example 1)

[0180] The adhesive composition c was applied to the surface of the substrate film A to a thickness of 20 μm after drying and dried to form an intermediate layer. A release sheet was then attached to the intermediate layer. Subsequently, while peeling off the release sheet, the adhesive composition c was applied to the intermediate layer to a thickness of 20 μm after drying and dried to form an adhesive layer, thereby producing the adhesive tape for electronic components of Comparative Example 1.

[0181] (Comparative Example 2)

[0182] The adhesive composition c was applied to the surface of substrate film A to a thickness of 30 μm after drying and dried to form an intermediate layer. A release sheet was then attached to the intermediate layer. Subsequently, while peeling the release sheet, the adhesive composition c was applied to the intermediate layer to a thickness of 30 μm after drying and dried to form an adhesive layer, thereby producing the adhesive tape for electronic components of Comparative Example 2.

[0183] (Comparative Example 3)

[0184] The adhesive composition c was applied to the surface of substrate film A to a thickness of 40 μm after drying and dried to form an intermediate layer. A release sheet was then attached to the intermediate layer. Subsequently, while peeling the release sheet, the adhesive composition c was applied to the intermediate layer to a thickness of 40 μm after drying and dried to form an adhesive layer, thereby producing the adhesive tape for electronic components of Comparative Example 3.

[0185] (Comparative Example 4)

[0186] The adhesive composition d was applied to the surface of the substrate film A to a thickness of 30 μm after drying and dried to form an intermediate layer. A release sheet was then attached to the intermediate layer. Subsequently, while peeling the release sheet, the adhesive composition c was applied to the intermediate layer to a thickness of 30 μm after drying and dried to form an adhesive layer, thereby producing the adhesive tape for electronic components of Comparative Example 4.

[0187] (Comparative Example 5)

[0188] The adhesive composition d was applied to the surface of the substrate film A to a thickness of 40 μm after drying and dried to form an intermediate layer. A release sheet was then attached to the intermediate layer. Subsequently, while peeling the release sheet, the adhesive composition c was applied to the intermediate layer to a thickness of 40 μm after drying and dried to form an adhesive layer, thereby producing the adhesive tape for electronic components of Comparative Example 5.

[0189] (Comparative Example 6)

[0190] The adhesive composition d was applied to the surface of the substrate film A to a thickness of 30 μm after drying and dried to form an intermediate layer. A release sheet was then attached to the intermediate layer. Subsequently, while peeling the release sheet, the adhesive composition c was applied to the intermediate layer to a thickness of 30 μm after drying and dried to form an adhesive layer, thereby producing the adhesive tape for electronic components of Comparative Example 6.

[0191] (Comparative Example 7)

[0192] The adhesive composition c was applied to the surface of the substrate film A to a thickness of 5 μm after drying and dried to form an intermediate layer. A release sheet was then attached to the intermediate layer. Subsequently, while peeling the release sheet, the adhesive composition b was applied to the intermediate layer to a thickness of 40 μm after drying and dried to form an adhesive layer. This produced the adhesive tape for electronic components of Comparative Example 7.

[0193] (Comparative Example 8)

[0194] The adhesive composition c was applied to the surface of base film A to a thickness of 5 μm after drying and dried to form an intermediate layer. A release sheet was then attached to the intermediate layer. Subsequently, while peeling the release sheet, the adhesive composition c was applied to the intermediate layer to a thickness of 40 μm after drying and dried to form an adhesive layer, thereby producing the adhesive tape for electronic components of Comparative Example 8.

[0195] The adhesive tapes for electronic components of the above-described Examples and Comparative Examples were subjected to an expansion and breaking test as follows to evaluate their performance. The evaluation results are shown in Table 1.

[0196] Carry out the following steps:

[0197] (a) a step of laminating the adhesive layer of the adhesive tape for electronic components to the glass wafer,

[0198] (b) irradiating the portion of the glass wafer to be divided with laser light to form a modified region based on multiphoton absorption within the glass wafer;

[0199] (c) a radiation irradiation step of irradiating the adhesive layer with radiation,

[0200] (d) A singulation step of obtaining a plurality of chips by expanding the adhesive tape for electronic components and dividing the wafer along dividing lines.

[0201] In step (a), a LINTEC DR3000II (trade name, manufactured by Nitto Seiki Co., Ltd.) was used as a laminating machine to bond the electronic component adhesive tapes of Examples and Comparative Examples to the glass wafer at a bonding pressure of 0.3 MPa and a speed of 5 mm / sec. The glass wafer was bonded to a 10 μm high optical filter with a shield (manufactured by Tanaka Giken Co., Ltd.). The glass wafer was bonded to the electronic component adhesive tape so that the dividing line of the glass wafer was aligned with the MD and TD directions of the substrate film.

[0202] In step (d), the outer periphery of the adhesive tape for electronic components is clamped by a clamp ring consisting of an inner ring and an outer ring, and the carrier of the wafer expansion device (EX-300: manufacturer model) manufactured by Technovision is raised to stretch the adhesive tape for electronic components, thereby implementing expansion. As a condition of step (d), the expansion amount is adjusted so that the expansion speed is 1mm / sec and the expansion height is 20mm. Here, the expansion amount refers to the change in the relative position of the clamp ring and the carrier before and after the carrier is raised. The chip size is 4×4mm square.

[0203] (Convex and concave tracking)

[0204] After step (b), followability was evaluated using the following method. With the adhesive tape for electronic components attached, the diameter of trapped air was observed using a laser microscope from the surface opposite the adhesive surface of the tape. Products with no trapped air were rated as good and scored as "○." Products with an air diameter of less than 100 μm were rated as acceptable and scored as "△." Products with an air diameter of 100 μm or greater were rated as defective and scored as "×."

[0205] (Wafer separation)

[0206] After the above step (d), the glass wafer was checked for chip formation. All glass wafers that were cut along the planned cutting lines were evaluated as good and marked with a ◯. Partially or completely uncut glass wafers were evaluated as defective and marked with a ×.

[0207] (Incision width)

[0208] After step (d), the distance between the chips in the MD direction of the tape was observed using a Mitutoyo measuring microscope. Chips with an average distance of 201 μm or greater, obtained by averaging the distance between five randomly selected chips, were rated as excellent and evaluated as ◎. Chips with a distance between 101 and 200 μm were rated as good and evaluated as ○. Chips with a distance of 100 μm or less were rated as acceptable and evaluated as △.

[0209] (Evaluation of peeling of adhesive layer fragments)

[0210] After step (d), the clamp ring was removed from the tape and the adhesive tape for electronic components was visually inspected for any loose adhesive layer fragments in the area where the clamp ring had been fitted. Products with nine or fewer fragments outside the area of ​​contact with the clamp ring were rated as good and scored as positive. Products with ten or more fragments were rated as defective and scored as negative.

[0211] (Clamp ring falls off)

[0212] During step (d), visually inspect whether the adhesive tape for electronic components has fallen off the jig ring. If the adhesive tape for electronic components has not fallen off the jig ring, it is considered a good product and evaluated as "○". If one or less of five pieces of adhesive tape have fallen off, it is considered an acceptable product and evaluated as "△". If two or more pieces of adhesive tape have fallen off, it is considered a defective product and evaluated as "×".

[0213] [Table 1]

[0214]

[0215] In the adhesive tapes for electronic components of Examples 1 to 7, the adhesive layer is cured by irradiation with radiation, while the intermediate layer is not cured by irradiation. Therefore, the followability, breaking properties, and adhesive layer fragmentation were evaluated as good. In the adhesive tape for electronic components of Example 2, the thickness of the intermediate layer was at least 30% of the combined thickness of the adhesive layer and intermediate layer. Therefore, the incision width was evaluated as excellent compared to Example 1, which had the same structure as Example 2 except that the thickness of the intermediate layer was less than 30% of the combined thickness of the adhesive layer and intermediate layer. In Example 3, the adhesive layer cured by irradiation was thick, so the incision width was worse than that of Examples 1 and 2, but within the acceptable range. In Example 4, the base film was thick, so the incision width was worse than that of Examples 1 and 2, but within the acceptable range. In Example 5, the intermediate layer was hard, so the incision width was worse than that of Examples 1 and 2, but within the acceptable range. In the adhesive tapes for electronic components of Examples 1, 2, and 5, the total thickness of the base film, adhesive layer, and intermediate layer was 170 μm or less, and therefore the results of the evaluation of the clamp ring detachment were superior to those of Examples 3 and 4.

[0216] On the other hand, in the adhesive tapes for electronic components of Comparative Examples 1 to 8, since the intermediate layer was cured by irradiation with radiation, the evaluation of the falling of adhesive layer fragments was poor.

[0217] Description of Reference Numerals

[0218] 1: Adhesive tape for electronic components; 2: Base film; 3: Adhesive layer; 4: Intermediate layer; 5: Laser; 6: Wafer; 7: Modified area; 8: Fixing fixture; 81: Outer ring; 82: Inner ring; 9: Chip; 10: Carrier; 11: Lifting pin; 12: Adsorption chuck; 13: Ring frame; 14: Pressing portion; 15: Pushing portion.

Claims

1. An adhesive tape for electronic components, characterized in that It is an adhesive tape for electronic components having a base film and an adhesive layer. The adhesive layer is a radiation-curing adhesive layer that is cured by irradiation with radiation. An intermediate layer that is not cured by irradiation with radiation is provided between the base film and the adhesive layer. The adhesive tape for electronic components is used for dicing a wafer, and the dicing of the wafer includes a singulation step of irradiating the adhesive layer with radiation and then expanding the adhesive layer to separate the wafer into pieces.

2. The adhesive tape for electronic components according to claim 1, wherein The total thickness of the adhesive layer and the intermediate layer is 5 μm to 100 μm.

3. The adhesive tape for electronic components according to claim 1 or 2, characterized in that The thickness of the intermediate layer is 30% or more of the total thickness of the adhesive layer and the intermediate layer.

4. The adhesive tape for electronic components according to claim 1 or 2, characterized in that The thickness of the intermediate layer is less than 30% of the thickness of the adhesive layer, and the intermediate layer contains a polyester-based adhesive composition.

5. The adhesive tape for electronic components according to claim 1 or 2, characterized in that The total thickness of the base film, the adhesive layer, and the intermediate layer is 170 μm or less.

6. The adhesive tape for electronic components according to claim 1 or 2, characterized in that The expanded state maintaining step is used for maintaining the expanded state by sandwiching the base film, the adhesive layer, and the intermediate layer between the outer peripheral surface of the inner ring and the inner peripheral surface of the outer ring.

7. The adhesive tape for electronic components according to claim 1 or 2, characterized in that The wafer has a step difference on the surface.

8. The adhesive tape for electronic components according to claim 1 or 2, wherein In a state where the intermediate layer is laminated on the base film, the initial tack of the intermediate layer is 200 kPa or more.

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