Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P72/00—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof
  • H10P72/70—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping
  • H10P72/74—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping using temporarily an auxiliary support
  • H10P72/7402—Wafer tapes, e.g. grinding or dicing support tapes
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J7/00—Adhesives in the form of films or foils
  • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J7/00—Adhesives in the form of films or foils
  • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
  • C09J7/38—Pressure-sensitive adhesives [PSA]
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J7/00—Adhesives in the form of films or foils
  • C09J7/40—Adhesives in the form of films or foils characterised by release liners
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J7/00—Adhesives in the form of films or foils
  • C09J7/50—Adhesives in the form of films or foils characterised by a primer layer between the carrier and the adhesive
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P54/00—Cutting or separating of wafers, substrates or parts of devices
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P72/00—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof
  • H10P72/70—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping
  • H10P72/74—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping using temporarily an auxiliary support
  • H10P72/7412—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping using temporarily an auxiliary support the auxiliary support including means facilitating the separation of a device or wafer from the auxiliary support
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P72/00—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof
  • H10P72/70—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping
  • H10P72/74—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping using temporarily an auxiliary support
  • H10P72/7416—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping using temporarily an auxiliary support used during dicing or grinding
  • H10P72/742—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping using temporarily an auxiliary support used during dicing or grinding involving stretching of the auxiliary support post dicing
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P72/00—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof
  • H10P72/70—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping
  • H10P72/74—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping using temporarily an auxiliary support
  • H10P72/744—Details of chemical or physical process used for separating the auxiliary support from a device or a wafer
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P95/00—Generic processes or apparatus for manufacture or treatments not covered by the other groups of this subclass
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J2203/00—Applications of adhesives in processes or use of adhesives in the form of films or foils
  • C09J2203/326—Applications of adhesives in processes or use of adhesives in the form of films or foils for bonding electronic components such as wafers, chips or semiconductors
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J2301/00—Additional features of adhesives in the form of films or foils
  • C09J2301/20—Additional features of adhesives in the form of films or foils characterized by the structural features of the adhesive itself
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J2301/00—Additional features of adhesives in the form of films or foils
  • C09J2301/30—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier

Definitions

• the present invention relates to an adhesive tape for electronic components. More specifically, the present invention relates to an adhesive tape for electronic components that can be used to fix wafers in the dicing process in which wafers such as semiconductor wafers and glass wafers are divided into chip-shaped elements.
• Electronic components such as chip-type electronic components, including integrated circuits (ICs), resistors, capacitors, coils, and IR cut filters, are generally manufactured by attaching a sticky and elastic adhesive tape for electronic components to a wafer, such as a semiconductor wafer or glass wafer, followed by a dicing process in which the wafer is divided into chips, an expanding process in which the processing tape is expanded, and a pick-up process in which the divided chips are picked up.
• a sticky and elastic adhesive tape for electronic components to a wafer, such as a semiconductor wafer or glass wafer, followed by a dicing process in which the wafer is divided into chips, an expanding process in which the processing tape is expanded, and a pick-up process in which the divided chips are picked up.
• Patent Document 1 discloses a stealth dicing method for a wafer, which includes a process of forming a modified region inside the wafer by multiphoton absorption and designating this modified region as the portion to be cut by irradiating laser light onto the inside of a semiconductor substrate to which an adhesive tape for electronic components is attached, with an adhesive layer (die-bond resin layer) interposed therebetween, and a process of cutting the wafer and adhesive layer along the portion to be cut by expanding the adhesive tape for electronic components.
• the wafer cutting method described in Patent Document 1 mentioned above the wafer is cut without contact by irradiating it with laser light and expanding the adhesive tape for electronic components, so the physical load on the wafer is small and it is possible to cut the wafer without generating cutting chips, as occurs with the currently mainstream blade dicing.
• the adhesive layer is cut by expansion, no cutting chips from the adhesive layer are generated. For this reason, this method is attracting attention as an excellent technology that can replace blade dicing.
• the division technology described in the above-mentioned document is mainly intended for semiconductor wafers, but it can also be applied to glass wafers by changing the laser engine of the equipment to one for glass.
• the stealth dicing method uses adhesive tape for electronic components that is used in conventional blade dicing processes.
• the stress (expansion force) during expansion is absorbed by the adhesive tape for electronic components, and the expansion force is not sufficiently transmitted to the modified area inside the wafer, making it difficult to chip the wafer with a good yield.
• the adhesive layer when used on wafers with complex, stepped adherend shapes, the adhesive layer needs to be thick so that it can conform to the steps. However, if the adhesive layer is made thick, the stress is relieved when it is expanded, reducing the ability to separate the wafer. This makes it difficult to achieve both the ability of the adhesive tape for electronic components to conform to the steps on the wafer surface and the ability to separate the wafer.
• a stealth dicing adhesive sheet that is made up of a substrate and an adhesive layer formed on one side thereof, in which the adhesive sheet has a Young's modulus of 200 to 600 MPa at 23°C, and the adhesive layer has a storage modulus of 0.10 to 50 MPa at 23°C (see Patent Document 2).
• a dicing tape in which, after radiation exposure or heat treatment, the tensile load at a tape elongation rate of 10% under test conditions of a width of 25 mm, a gauge length and grip length of 100 mm, and a tensile speed of 300 mm/min is 30 N or more, and the surface roughness Ra of the back surface of the base film of the expanding dicing tape is 0.3 ⁇ m or more (see Patent Document 3).
• the present invention aims to provide an adhesive tape for electronic components that can be bonded to thick, hard wafers with uneven surfaces with sufficient conformity, can be expanded to effectively divide the wafer into chips, and does not contaminate the chips with broken pieces of the adhesive layer.
• the adhesive tape for electronic components is an adhesive tape for electronic components having a base film and an adhesive layer, the adhesive layer being a radiation-curable adhesive layer that is cured by exposure to radiation, and an intermediate layer that is not cured by exposure to radiation is provided between the base film and the adhesive layer, and is characterized in that the tape is used for wafer dicing, which includes a singulation process in which the adhesive layer is irradiated with radiation and then expanded to singulate the wafer.
• the adhesive tape for electronic components preferably has a total thickness of 5 to 100 ⁇ m for the adhesive layer and intermediate layer.
• the thickness of the intermediate layer is 30% or more of the total thickness of the adhesive layer and the intermediate layer.
• the adhesive tape for electronic components is preferably 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.
• the adhesive tape for electronic components preferably has a total thickness of 170 ⁇ m or less for the base film, adhesive layer, and intermediate layer.
• the above-mentioned adhesive tape for electronic components is preferably used in an expanded state maintaining process in which the expanded state is maintained by sandwiching the base film, adhesive layer, and intermediate layer between the outer peripheral surface of the inner ring and the inner peripheral surface of the outer ring.
• the above-mentioned adhesive tape for electronic components is preferably used for dicing wafers that have steps on their surfaces.
• the adhesive tape for electronic components preferably has a tack strength of 200 kPa or more when the intermediate layer is laminated on the base film.
• even thick and hard wafers with uneven surfaces can be bonded with sufficient conformity to the adhesive tape for electronic components, and by expanding the adhesive tape for electronic components, the wafer can be effectively divided into chips without contaminating the chips with broken pieces of the adhesive layer.
• 1 is a cross-sectional view illustrating a schematic structure of an adhesive tape for electronic components according to an embodiment of the present invention.
• 1A to 1C are cross-sectional views illustrating a laser processing step in a wafer singulation method using an adhesive tape for electronic components according to an embodiment of the present invention.
• 1A to 1C are cross-sectional views illustrating a tape application step in a wafer singulation method using an adhesive tape for electronic components according to an embodiment of the present invention.
• 1A to 1C are cross-sectional views illustrating a schematic diagram of a singulation step in a wafer singulation method using an adhesive tape for electronic components according to an embodiment of the present invention.
• FIG. 2 is a perspective view showing a state in which an expander is held by clamping an adhesive tape for electronic components according to an embodiment of the present invention between the outer peripheral surface of an inner ring and the inner peripheral surface of an outer ring.
• This is a cross-sectional view taken along line AA' of Figure 6.
• 4A to 4C are cross-sectional views illustrating a schematic diagram of a singulation step in another wafer singulation method using the adhesive tape for electronic components according to an embodiment of the present invention.
• FIG. 2 is a cross-sectional view that illustrates an expanded state maintaining step for maintaining an expanded state using the pressure-sensitive adhesive tape for electronic components according to an embodiment of the present invention.
• the adhesive tape 1 for electronic components has 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.
• the adhesive tape 1 for electronic components may further include a release film (not shown) on the adhesive layer 3 to protect the adhesive layer 3.
• the adhesive tape 1 for electronic components may be a long laminate of the base film 2, the adhesive layer 3, the intermediate layer 4, and the release film wound in a roll, or cut into sheets at predetermined lengths.
• the adhesive layer 3, the intermediate layer 4, and the release film only the base film 2, the adhesive layer 3, and the intermediate layer 4 may be punched in advance into a predetermined label shape (so-called precut processing) as in conventional dicing tapes.
• precut processing a predetermined label shape
• the material of the base film 2 is not particularly limited as long as it is easy to stretch during the expanding process of the pressure-sensitive adhesive tape 1 for electronic components, does not break, and transmits the stress caused by the expanding process to the adhesive layer 3 sufficiently to adequately divide the wafer 6 (see FIG. 2). It is preferable for the base film 2 to have uniform and isotropic expandability, since this allows the wafer to be cut evenly in all directions during the expanding process. From these viewpoints, it is preferable for the base film 2 to be selected from polyolefins, polyvinyl chloride, and urethane elastomers.
• the polyolefins mentioned above include homopolymers or copolymers of ⁇ -olefins such as polyethylene, polypropylene, ethylene-propylene copolymer, polybutene-1, poly-4-methylpentene-1, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl acrylate copolymer, ethylene-acrylic acid copolymer, ionomers, or mixtures thereof.
• ⁇ -olefins such as polyethylene, polypropylene, ethylene-propylene copolymer, polybutene-1, poly-4-methylpentene-1, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl acrylate copolymer, ethylene-acrylic acid copolymer, ionomers, or mixtures thereof.
• ionomer resins which are synthetic resins that utilize the cohesive force of metal ions to form polymer aggregates
• ionomer resins which are synthetic resins that utilize the cohesive force of metal ions to form polymer aggregates
• ionomer resins in which ethylene-(meth)acrylic acid binary copolymers or ethylene-(meth)acrylic acid-(meth)acrylic acid alkyl ester terpolymers are crosslinked with metal ions.
• metal ions contained in the ionomer resins, but examples include zinc ions and sodium ions. Zinc ions are preferred in terms of low leaching and low pollution.
• crosslinked resins selected from low density polyethylene having a specific gravity of 0.910 or more and less than 0.930, very low density polyethylene having a specific gravity of less than 0.910, and ethylene-vinyl acetate copolymers are also suitable.
• a method of crosslinking a method of irradiating the resin with energy rays such as electron beams can be mentioned.
• Such a thermoplastic crosslinked resin has a certain degree of uniform extensibility because crosslinked and non-crosslinked sites coexist in the resin.
• thermoplastic crosslinked resin contains almost no chlorine atoms in the molecular chain structure, so that even if the tape that is no longer needed after use is incinerated, it does not generate chlorinated aromatic hydrocarbons such as dioxins and their analogues, and the environmental load is small.
• non-crosslinked resin is a mixed resin of polypropylene and a styrene-based copolymer.
• a propylene homopolymer or copolymer for example, a block type or random type propylene-ethylene copolymer
• a random type propylene-ethylene copolymer has low rigidity and is preferable. If the content of the ethylene structural unit in the propylene-ethylene copolymer is 0.1 mass% or more, it is preferable in that the rigidity of the base film 2 is low and the compatibility between the resins in the mixed resin is high. If the rigidity of the base film 2 is appropriate, the severability of the wafer 6 (see FIG. 2) is improved, and if the compatibility between the resins is high, the extrusion discharge amount is likely to be stabilized.
• the content of the ethylene structural unit in the propylene-ethylene copolymer is 7 mass% or less, it is preferable in that the polymerization reaction to obtain the propylene-ethylene copolymer can be stably performed. It is more preferable that the content of the ethylene structural unit is 5 mass% or less.
• the styrene copolymer is a copolymer of a conjugated diene compound and an aromatic vinyl compound.
• aromatic vinyl compound include styrene, t-butylstyrene, ⁇ -methylstyrene, p-methylstyrene, divinylbenzene, 1,1-diphenylstyrene, N,N-diethyl-p-aminoethylstyrene, vinyltoluene, and p-tert-butylstyrene.
• the conjugated diene compound include butadiene, isoprene, 1,3-pentadiene, and 2,3-dimethyl-1,3-butadiene.
• the styrene-based polymer may be hydrogenated, and a styrene-hydrogenated isoprene-styrene copolymer is preferred.
• a styrene-hydrogenated isoprene-styrene copolymer is preferred.
• the styrene-based copolymer When the styrene-based copolymer is hydrogenated, it has good compatibility with polypropylene and can prevent embrittlement and discoloration due to oxidative deterioration caused by double bonds in the main chain.
• the content of the styrene structural unit in the styrene copolymer is 5% by mass or more, it is preferable in that the styrene copolymer is easily polymerized stably when prepared. If it is 40% by mass or less, it is flexible and has high extensibility.
• styrene copolymer either a block copolymer or a random copolymer can be used.
• a random copolymer is preferred because the styrene structural units are uniformly dispersed, the rigidity can be prevented from becoming too large, and the extensibility of the base film 2 is improved.
• a polypropylene content of 30% by mass or more in the mixed resin of polypropylene and styrene copolymer is preferable in that thickness unevenness of the base film 2 can be suppressed. If the thickness of the base film 2 is uniform, the expandability is easily isotropic. More preferably, it is 50% by mass or more. Furthermore, if the polypropylene content 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 is too high, the force required to expand the base film 2 becomes large, so the load on the device increases, and it may not be possible to expand sufficiently to separate the wafer 6 (see FIG. 2).
• the lower limit of the content of the styrene copolymer in the mixed resin is preferably 10% by mass or more, and it is easy to adjust the rigidity of the base film 2 to be suitable for the device.
• An upper limit of 70% by mass or less is preferable in that thickness unevenness can be suppressed, and 50% by mass or less is more preferable.
• the base film 2 In order to cure the adhesive layer 3 (described below) by irradiating it with radiation and thereby reduce its adhesive strength, it is preferable that the base film 2 has the above characteristics and is also radiation-transmitting.
• the base film 2 is a single layer, but is not limited to this and may be multiple layers.
• the multiple layers may be multiple layers formed by laminating two or more types of resin layers, or multiple layers formed by laminating layers of one type of resin. If the two or more types of resins are crosslinked resins or non-crosslinked resins, it is preferable from the viewpoint that the properties of each are enhanced and expressed, and if a crosslinked resin and a non-crosslinked resin are combined and laminated, it is preferable from the viewpoint that the shortcomings of each are compensated for.
• the multi-layer base film 2 can be manufactured by a conventional extrusion method, lamination method, or the like. When using a lamination method, an adhesive may be interposed between the layers. A conventional adhesive can be used as the adhesive.
• the thickness of the base film 2 is preferably 60 to 150 ⁇ m. If the thickness of the base film 2 is too thin, the base film 2 may break, or the tensile strength may be insufficient and the expand-and-cut may not be possible. If the thickness of the base film 2 is too thick, the amount of deformation relative to the amount of stretching during the expand-and-cut may be insufficient, and the distance between the elements of the wafer 6 (see FIG. 2) may become too short, making it impossible to apply the subsequent pick-up process. Furthermore, the base film 2 may be difficult to deform during pick-up, which may deteriorate the pick-up properties and cause pick-up failure or chip breakage. The thickness of the base film 2 is more preferably 80 to 120 ⁇ m.
• the adhesive layer 3 is not particularly limited as long as it has the properties of not peeling off from the wafer during the dicing process, of having retention properties to the extent that defects such as chip flying do not occur, of transmitting stress due to expansion to the wafer, and of being capable of being peeled off from the wafer when picked up.
• the main polymer component that makes up the adhesive can be appropriately selected from various types of polymers such as (meth)acrylic resin, epoxy resin, natural rubber resin, and synthetic rubber resin, but among these, (meth)acrylic resin is preferable.
• (Meth)acrylic resin allows easy control of adhesive strength.
• the base polymer constituting the adhesive layer 3 preferably has a glass transition temperature of -65°C to -30°C.
• the glass transition temperature refers to the glass transition temperature measured by DSC (differential scanning calorimeter) at a heating rate of 0.1°C/min. If the glass transition temperature exceeds -30°C, the adhesion to the adherend tends to improve, and there is a risk of adhesive residue remaining on the electronic component when the electronic component is peeled off. If the glass transition temperature is less than -65°C, the adhesive becomes very sticky, which has a negative effect on handling during work, and is therefore undesirable.
• the base polymer constituting the adhesive preferably has a weight-average molecular weight Mw of 700,000 or more. If the weight-average molecular weight Mw of the base polymer is less than 700,000, low molecular weight components will bleed out onto the surface of the adhesive layer 3, contaminating the adherend. In addition, when the electronic component is peeled off, there is a risk of adhesive residue remaining on the electronic component.
• the adhesive layer 3 is a radiation-curable type that is cured by exposure to radiation.
• the adhesive composition constituting the radiation-curable adhesive layer 3 can be a combination of a polymer constituting the adhesive and a radiation-polymerizable compound, or a polymer constituting the adhesive that incorporates a functional group (preferably an ethylenically unsaturated group) that polymerizes with radiation.
• the adhesive contains a photopolymerization initiator to promote polymerization by radiation.
• the adhesive contains a crosslinking agent.
• the resin used in the adhesive layer 3 is not particularly limited, and known adhesive resins such as chlorinated polypropylene resin, acrylic resin, polyester resin, polyurethane resin, and epoxy resin can be used, but an acrylic adhesive with an acrylic polymer as the base polymer is preferred.
• acrylic polymers include acrylic polymers using one or more of (meth)acrylic acid alkyl esters (e.g., methyl ester, ethyl ester, propyl ester, isopropyl ester, butyl ester, isobutyl ester, s-butyl ester, t-butyl ester, pentyl ester, isopentyl ester, hexyl ester, heptyl ester, octyl ester, 2-ethylhexyl ester, isooctyl ester, nonyl ester, decyl ester, isodecyl ester, undecyl ester, dodecyl ester, tridecyl ester, tetradecyl ester, hexadecyl ester, octadecyl ester, eicosyl ester, and other linear or branched alkyl esters having an alkyl
• the acrylic polymer may contain units corresponding to other monomer components copolymerizable with the (meth)acrylic acid alkyl ester or cycloalkyl ester, if necessary, for the purpose of modifying the cohesive strength, heat resistance, etc.
• 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; 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, and 10-hydroxydecyl (meth)acrylate.
• hydroxyl group-containing monomers such as 12-hydroxylauryl (meth)acrylate, (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, (meth)acryloyloxynaphthalenesulfonic acid; phosphoric acid group-containing monomers such as 2-hydroxyethylacryloylphosphate; acrylamide, acrylonitrile, etc.
• These copolymerizable monomer components can 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.
• polyfunctional monomers and the like can also be included as copolymerization monomer components as necessary.
• polyfunctional monomers include 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, and urethane (meth)acrylate.
• the amount of polyfunctional monomer used is preferably 30% by weight or less of the total monomer components in terms of adhesive properties, etc.
• Acrylic polymers can be prepared, for example, by applying a suitable method such as solution polymerization, emulsion polymerization, bulk polymerization, or suspension polymerization to a mixture of one or more component monomers.
• various methods can be adopted, such as a method of crosslinking using an appropriate 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, or a method of mixing a low molecular weight compound having two or more carbon-carbon double bonds and crosslinking by irradiating with radiation.
• an external crosslinking agent is used, the amount used is determined appropriately depending on the balance with the base polymer to be crosslinked and further depending on the use as an adhesive.
• An example of a radiation-curable adhesive is an additive-type radiation-curable adhesive in which a radiation-curable monomer component or a radiation-curable oligomer component is added to the adhesive described above.
• radiation-curable monomer components to be added include urethane (meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,4-butanediol di(meth)acrylate, etc.
• These monomer components can be used alone or in combination of two or more.
• the radiation-curable oligomer component may be a variety of oligomers, such as urethane-based, polyether-based, polyester-based, polycarbonate-based, and polybutadiene-based oligomers, and those with a molecular weight in the range of about 100 to 30,000 are suitable.
• the amount of radiation-curable monomer component or oligomer component to be blended can be appropriately determined according to the type of adhesive layer 3, so as to reduce the adhesive strength of the adhesive layer 3. In general, the amount is, for example, 5 to 500 parts by weight, and preferably 70 to 150 parts by weight, per 100 parts by weight of the base polymer, such as an acrylic polymer, that constitutes the adhesive.
• examples of radiation curable adhesives include endogenous type radiation curable adhesives that use a base polymer in which radiation curable groups have been introduced into the polymer side chain, main chain, or main chain end.
• Endogenous type radiation curable adhesives do not need to contain low molecular weight components such as oligomer components, or do not contain large amounts of them, so they are preferred because they can form adhesive layer 3 with a stable layer structure without the oligomer components moving within the adhesive over time.
• the base polymer into which the radiation-curable group has been introduced can be any polymer that has a carbon-carbon double bond and is adhesive, without any particular restrictions.
• a base polymer one that has an acrylic polymer as the basic skeleton is preferable.
• the basic skeleton of an acrylic polymer include the acrylic polymers listed above.
• one method is to first copolymerize a monomer having a functional group into the acrylic polymer, and then to carry out a condensation or addition reaction with a compound having a functional group and a carbon-carbon double bond that can react with this functional group while maintaining the radiation curability of the carbon-carbon double bond.
• combinations of these functional groups include a carboxylic acid group and an epoxy group, a carboxylic acid group and an aziridyl group, and a hydroxyl group and an isocyanate group.
• a combination of a hydroxyl group and an isocyanate group is preferred because of the ease of tracking the reaction.
• the functional group may be on either the acrylic polymer or the compound, but the preferred combination is that the acrylic polymer has a hydroxyl group and the compound has an isocyanate group.
• examples of isocyanate compounds having a carbon-carbon double bond include methacryloyl isocyanate, 2-methacryloyloxyethyl isocyanate, and m-isopropenyl- ⁇ , ⁇ -dimethylbenzyl isocyanate.
• the acrylic polymer may be a copolymer of the hydroxyl group-containing monomers listed above, or ether compounds such as 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, and diethylene glycol monovinyl ether.
• Intrinsic radiation-curable adhesives can use the base polymer (particularly acrylic polymer) having the carbon-carbon double bond alone, but can also contain photopolymerizable compounds such as the radiation-curable monomer components and oligomer components to the extent that the properties are not adversely affected.
• the amount of the photopolymerizable compound is usually within the range of 30 parts by weight or less per 100 parts by weight of the base polymer, and preferably within the range of 0 to 10 parts by weight.
• the radiation-curable adhesive is to be cured by ultraviolet light, etc., it is preferable that it contains a photopolymerization initiator.
• a (meth)acrylic acid ester copolymer comprising an acrylic acid ester represented by CH 2 ⁇ 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 is particularly preferred.
• the amount of carbon-carbon double bonds in the adhesive layer 3 is preferably 0.5 meq/g or more and 1.8 meq/g or less. If the amount of carbon-carbon double bonds is less than 0.5 meq/g, when a chip-shaped electronic component is peeled off from the adhesive tape for electronic components 1, there is a risk that a residue of the adhesive from the adhesive tape for electronic components 1 will adhere to the surface of the electronic component, resulting in so-called adhesive residue.
• the amount of double bonds can be quantitatively measured by the weight increase method using a bromine addition reaction in a dark place in a vacuum to determine the amount of carbon-carbon double bonds contained in approximately 10 g of the adhesive that has been heated and dried.
• the (meth)acrylic acid ester copolymer may contain units corresponding to other monomer components as necessary.
• double bond-containing isocyanate compounds examples include methacryloyl isocyanate, acryloyl isocyanate, 2-methacryloyloxyethyl isocyanate, 2-acryloyloxyethyl isocyanate, m-isopropenyl- ⁇ , ⁇ -dimethylbenzyl isocyanate, etc. Double bond-containing isocyanate compounds can be used alone or in combination of two or more.
• an external crosslinking agent can be used appropriately in the radiation curing adhesive to adjust the adhesive strength before and after radiation exposure.
• Specific means for the external crosslinking method include a method of adding and reacting a so-called crosslinking agent such as a polyisocyanate compound, an epoxy compound, an aziridine compound, or a melamine-based crosslinking agent.
• a so-called crosslinking agent such as a polyisocyanate compound, an epoxy compound, an aziridine compound, or a melamine-based crosslinking agent.
• the amount used is determined appropriately depending on the balance with the base polymer to be crosslinked, and further depending on the intended use as an adhesive.
• the amount of the external crosslinking agent used is generally 20 parts by weight or less (preferably 0.1 to 10 parts by weight) per 100 parts by weight of the base polymer.
• the radiation curing adhesive may contain various additives such as tackifiers, antiaging agents, and foaming agents that are conventionally known.
• the adhesive layer 3 can be formed by applying the adhesive composition as described above onto a release film (not shown) and drying it.
• the adhesive layer 3 may be configured with multiple layers laminated together. When multiple layers are used, it is preferable to use the above-mentioned radiation-curable adhesive for the layer to which the electronic components are attached, but heat-foaming adhesives can also be used for the other layers. Radiation-curable adhesives are cured by ultraviolet light or electron beams, etc., and are easy to peel off, while heat-foaming adhesives are made easy to peel by the use of a foaming agent or expansion agent.
• a release film which is usually used as a separator, may be attached to the adhesive layer 3 to protect the adhesive layer 3 until it is put into practical use.
• materials that can be used for the release film include synthetic resin films such as polyethylene, polypropylene, and polyethylene terephthalate, and paper.
• 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, if necessary, to improve releasability from the adhesive layer 3.
• the thickness of the release film is usually 10 to 100 ⁇ m, and preferably about 25 to 50 ⁇ m.
• the intermediate layer 4 is not cured by irradiation with radiation.
• the resin used for the non-radiation-curable intermediate layer 4, which is not cured by irradiation with radiation may be a copolymer that contains a structural unit derived from a (meth)acrylic acid alkyl ester monomer and a structural unit derived from 2-hydroxypropyl acrylate, 2-hydroxyethyl (meth)acrylate, and/or 2-hydroxybutyl acrylate, and that contains the structural unit derived from the (meth)acrylic acid alkyl ester monomer and is crosslinked with an isocyanate compound.
• the intermediate layer 4 is preferably made of an acrylic copolymer having a hydroxyl value of 45 to 100, which is composed of 70 to 95% by mass of (meth)acrylic acid alkyl ester monomers with an alkyl group having 4 or more carbon atoms and 5 to 30% by mass of 2-hydroxypropyl acrylate, and polypropylene oxide with a number average molecular weight of 3,000 to 10,000, and is crosslinked using an isocyanate-based crosslinking agent.
• an acrylic copolymer having a hydroxyl value of 45 to 100 which is composed of 70 to 95% by mass of (meth)acrylic acid alkyl ester monomers with an alkyl group having 4 or more carbon atoms and 5 to 30% by mass of 2-hydroxypropyl acrylate, and polypropylene oxide with a number average molecular weight of 3,000 to 10,000, and is crosslinked using an isocyanate-based crosslinking agent.
• examples of (meth)acrylic acid 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 (meth)acrylate, and among these, those having an alkyl group with 8 or more carbon atoms are particularly preferred.
• the copolymer constituting the intermediate layer 4 preferably contains 65 to 90 mass % of structural units derived from (meth)acrylic acid alkyl ester monomers having an alkyl group with 4 or more carbon atoms. If there are too many structural units derived from (meth)acrylic acid alkyl ester monomers, the adhesive will have fewer crosslinking points and sufficient properties will not be obtained, while if there are too few, the pot life from mixing the intermediate layer composition to applying it to the base film 2 will be shortened, causing problems when manufacturing the adhesive tape for electronic components 1 of the present invention.
• crosslinkable functional group-containing monomer 2-hydroxypropyl acrylate or 4-hydroxybutyl acrylate is preferably used, and is preferably contained in an amount of 10 to 30% by mass as a constituent unit. If a functional group-containing monomer such as 2-hydroxyethyl acrylate, which has a shorter chain length than 2-hydroxypropyl acrylate, is used, the crosslinking reaction will be faster and the pot life will be shorter, which will cause problems when manufacturing the semiconductor processing tape 1 of the present invention, and if a monomer with a longer chain length is used, the crosslinking reaction will proceed more slowly, causing a problem that it will take an extremely long time to complete.
• a functional group-containing monomer such as 2-hydroxyethyl acrylate, which has a shorter chain length than 2-hydroxypropyl acrylate
• the functional group-containing monomer is less than 10% by mass, the polarity will be low, the adhesion to the adhesive layer 3 will be reduced, and there is a risk that pieces of the adhesive layer 3 will fall off when expanding the adhesive layer 3 after it has been cured by irradiation with radiation.
• the hydroxyl value of an acrylic copolymer in which the constituent units derived from (meth)acrylic acid alkyl ester monomers having an alkyl group with 4 or more carbon atoms are 70 to 90% by mass, and the functional group-containing monomer is 2-hydroxyethyl acrylate and/or 2-hydroxypropyl acrylate is preferably 25 to 100 mgKOH/g. If the hydroxyl value is less than 25 mgKOH/g, the polarity is low, the adhesion to the adhesive layer 3 is reduced, and there is a risk that pieces of the adhesive layer 3 will fall off when expanding the adhesive layer 3 after it has been cured by irradiation with radiation.
• the polypropylene oxide having a number average molecular weight of 3000 to 10000 is not particularly limited as long as it is 3000 to 10000, and can be appropriately selected from known polypropylene oxides. If the number average molecular weight is less than 3000, low molecular weight components will migrate to the adherend surface, increasing the tendency to stain, and if it exceeds 10000, compatibility with the acrylic copolymer will deteriorate, and incompatible components will migrate to the adherend surface, increasing the tendency to stain, so the number average molecular weight is preferably in the range of 3000 to 10000.
• the amount of polypropylene oxide is not particularly limited and can be adjusted as appropriate within a range in which the desired adhesive strength is obtained, but can be selected as appropriate from the range of 0.5 to 5 parts by mass per 100 parts by mass of the acrylic copolymer. If the amount of polypropylene oxide is less than 0.5 parts, there is a risk that pieces of the adhesive layer 3 will fall off when expanding after the adhesive layer 3 is cured by irradiation with radiation.
• the copolymer constituting the intermediate layer is crosslinked with an isocyanate compound.
• isocyanate compound there are no particular limitations on the isocyanate compound, and examples include aromatic isocyanates such as 4,4'-diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, 4,4'-diphenylether diisocyanate, and 4,4'-[2,2-bis(4-phenoxyphenyl)propane]diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethyl-hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 2,4'-dicyclohexylmethane diisocyanate, lysine diisocyanate, and lysine triisocyanate.
• Coronate L trade name, manufactured by Nippon Polyurethane Co.
• the content of the isocyanate compound in the intermediate layer 4 is preferably 1 to 12 parts by mass per 100 parts by mass of the copolymer. If the amount of the isocyanate compound exceeds 12 parts by mass, the pot life from mixing the intermediate layer composition to applying it to the base film 2 becomes short, which causes problems when manufacturing the adhesive tape 1 for electronic components.
• the intermediate layer 4 may also use a polyester polymer as the base polymer.
• the polyester resin may be a curing agent curing resin or a thermosetting resin, and preferably a curing agent curing resin.
• a curing agent curing resin When a curing agent curing resin is used, a crosslinking agent is added to the resin, and the resin is cured by curing after application and drying.
• a thermosetting resin When a thermosetting resin is used, the resin is cured by heating after application.
• the curing agent curing polyester resin composition is a composition containing a polyester resin having a functional group that can react with a curing agent, and preferably a polyester polyol having a hydroxyl group can be used.
• the curing agent is used to adjust the adhesive strength and cohesive strength by reacting with the functional group of the curing agent curing polyester resin composition.
• an isocyanate compound having two or more isocyanate groups in the molecule can be used.
• the adhesive composition for forming the intermediate layer 4 may contain known additives such as tackifiers, antioxidants, fillers, colorants, flame retardants, antistatic agents, softeners, antioxidants, plasticizers, and surfactants, as necessary.
• the intermediate layer 4 preferably has a tack strength of 200 kPa or more when laminated on the base film 2.
• the tack strength of the intermediate layer 4 is the peak value in a probe tack test.
• Probe tack can be measured, for example, using a tack tester TAC-II from Rhesca Corporation.
• the measurement mode used is "Constant Load," which presses the probe to a set pressure value and continues to control the pressure value to be maintained until a set time has elapsed.
• the laminate of the intermediate layer 4 and base film 2 is placed with the intermediate layer 4 facing up, and a cylindrical probe is brought into contact with the intermediate layer 4 from above, then peeled upwards, and the force required to peel it off is measured.
• the adhesion to the adhesive layer 3 will decrease, and there is a risk that pieces of the adhesive layer 3 will fall off when the adhesive layer 3 is expanded after being cured by irradiation.
• the tack strength of the intermediate layer 4 can be adjusted by appropriately combining the number of carbon atoms in the alkyl group, the blending ratio of the (meth)acrylic acid alkyl ester monomer and the 2-hydroxypropyl acrylate, the hydroxyl value, the number average molecular weight of the polypropylene oxide, the blending ratio of the polypropylene oxide, etc.
• the intermediate layer 4 may have a single layer form or a laminated form.
• a primer layer or the like may be provided between the base film 2 and the intermediate layer 4, if necessary.
• the tack strength of the layer in contact with the adhesive layer 3 is 200 kPa or more when the layer is laminated on the base film 2 together with other layers.
• the thickness of the intermediate layer 4 is preferably 30% or more of the sum of the thicknesses of the adhesive layer 3 and the intermediate layer 4, preferably 5 to 60 ⁇ m, preferably less than 50 ⁇ m, and more preferably 20 ⁇ m or less.
• the MD direction refers to the flow direction of the base film 2 during production, the unwinding direction of the base film 2, and the length direction when rolled.
• the intermediate layer 4 is made of a polyester-based adhesive, the kerf width in the MD direction can be well secured even if the thickness of the intermediate layer 4 is less than 30% of the sum of the thicknesses of the adhesive layer 3 and the intermediate layer 4. If the intermediate layer 4 is less than 5 ⁇ m thick, the adhesive strength with the adhesive layer 3 is weak, and there is a risk that pieces of the adhesive layer 3 may fall off when the adhesive layer 3 is expanded after being cured by radiation exposure.
• the intermediate layer 4 is thicker than 60 ⁇ m, 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 is not sufficiently transmitted to the wafer 6, so there is a risk that the wafer 6 cannot be chipped with a good yield.
• the total thickness of the adhesive layer 3 and the intermediate layer is preferably 5 to 100 ⁇ m, more preferably 20 ⁇ m or more, even more preferably 30 ⁇ m or more, even more preferably 40 ⁇ m or more, and even more preferably more than 50 ⁇ m. It is also preferable that it is 70 ⁇ m or less. A thickness of 4 ⁇ m or less is difficult for manufacturing reasons. If the thickness of the adhesive layer 3 is thin, when the shape of the adherend becomes complex and there is a step on the adherend surface, the adhesive layer 3 does not follow the step of the wafer, and air is caught near the step.
• the thickness of the adhesive layer 3 is too thick, the response of the push-up pin when picking up the chip may be poor, and the pick-up performance may be reduced.
• the tape is too thick, there is a risk of it coming off the jig, so it is preferable that the total thickness of the base film 2, adhesive layer 3, and intermediate layer 4 is 170 ⁇ m or less.
• the intermediate layer 4 can be formed by applying the intermediate layer composition as described above onto the base film 2 and drying it.
• the adhesive layer 3 is then bonded onto the intermediate layer 4, and the release film is peeled off to produce the adhesive tape 1 for electronic components.
• the intermediate layer 4 can be composed of the same composition as the adhesive layer 3 described above.
• the pressure-sensitive adhesive tape 1 for electronic components of the present invention is used in a method for producing electronic components, which includes a singulation step of singulating the wafer 6 (see FIG. 2) along a dividing line starting from a modified region 7 (see FIG. 2) formed inside the wafer 6 (see FIG. 2) by expanding the wafer 6 after irradiating the pressure-sensitive adhesive layer 3 with radiation. Therefore, other steps and the order of steps are not particularly limited.
• the pressure-sensitive adhesive tape 1 for electronic components can be suitably used in the following methods for producing electronic components (A) and (B).
• Manufacturing method for electronic components (A) (a) a laser processing step of irradiating a laser beam 5 to a portion of a wafer to be divided, and forming a modified region 7 inside the wafer 6 by multiphoton absorption; (b) a tape application step of applying the adhesive layer 3 of the adhesive tape 1 for electronic components to the rear surface of the wafer 6; (c) a radiation exposure step of irradiating the pressure-sensitive adhesive layer 3 with radiation; (d) a singulation step of dividing the wafer 6 along the dividing lines by expanding the adhesive tape 1 for electronic components to obtain a plurality of chips 9; (e) a pick-up step of picking up the chip 9 from the adhesive layer 3 of the adhesive tape 1 for electronic components; A method for manufacturing an electronic component comprising the steps of:
• Manufacturing method for electronic components (B) (a) a tape application step of applying an adhesive layer 3 of an adhesive tape 1 for electronic components to a rear surface of a wafer; (b) irradiating a laser beam 5 onto a portion of the wafer to be divided, thereby forming a modified region 7 inside the wafer 6 by multiphoton absorption; (c) a radiation exposure step of irradiating the pressure-sensitive adhesive layer 3 with radiation; (d) a singulation step of dividing the wafer 6 along the dividing lines by expanding the adhesive tape 1 for electronic components to obtain a plurality of chips 9; (e) a pick-up step of picking up the chip 9 from the adhesive layer 3 of the adhesive tape 1 for electronic components; A method for manufacturing an electronic component comprising the steps of:
• a laser beam 5 is irradiated onto the portion of the wafer 6 to be divided, forming a modified region 7 inside the wafer 6 through multiphoton absorption.
• 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. After that, radiation is irradiated onto the adhesive layer 3 from the side of the base film 2 of the adhesive tape 1 for electronic components, causing the adhesive layer 3 to harden.
• the adhesive tape 1 for electronic components to which the fixing jig 8 is attached and the wafer 6 with the modified region 7 is attached, is placed on the stage 10 of the expanding device with the base film 2 side facing down.
• the stage 10 of the expanding device is raised to expand the adhesive tape 1 for electronic components.
• the expansion conditions are an expansion speed of, for example, 0.1 to 20 mm/sec, and an expansion amount (push-up amount) of, for example, 1 to 70 mm.
• the adhesive layer 3 has hardened, so if the expansion amount is large, it may break due to the expansion force. However, even if it does break, the broken pieces are held by the intermediate layer 4 and do not contaminate the chip 9.
• the chip 9 is pushed up from the base film 2 side by a push-up pin 11 and picked up by a suction collet 12.
• the adhesive tape 1 for electronic components can be suitably used in an expanded state retention process in which the adhesive tape 1 for electronic components (substrate 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 using, for example, a grip ring manufactured by Technovision Co., Ltd. as a fixing jig 8 after the singulation process and before the pick-up process, thereby retaining the expanded state.
• the singulation process is carried out as follows. First, as shown in FIG. 8, the adhesive tape for electronic components 1, to which the wafer 6 provided with the modified region 7 is bonded and to which the ring frame 13 is attached, is set and fixed in an expanding device. In this state, the pressing unit 14 descends and presses the adhesive tape for electronic components 1 from the base film 2 side, pushing it downward. This causes the adhesive tape for electronic components 1 to be stretched in the radial direction of the wafer 6, and the electronic component adhesive tape 1 is cut into chips 9 starting from the wafer 6 and the modified region 7.
• an expanded state maintaining process is carried out. Specifically, referring to FIG. 9, first, the pressing portion 15 rises to press the adhesive tape 1 for electronic components, and then the outer ring 81 rises and fits into the inner ring 82 held by the pressing portion 14. As a result, the adhesive tape 1 for electronic components (the base film 2, the adhesive layer 3, and the intermediate layer 4) is sandwiched between the outer peripheral surface of the inner ring 82 and the inner peripheral surface of the outer ring 81, and the expanded state is maintained.
• the adhesive tape 1 for electronic components is cut by a cutter (not shown) near the inner ring 82 and the outer ring 81, and the adhesive tape 1 can be stored or transported while maintaining the expanded state shown in FIGS. 6 and 7 until the pick-up process is carried out.
• the adhesive tape for electronic components according to the present invention includes the following aspects:
• An adhesive tape for electronic components having a base film and an adhesive layer, the adhesive layer being a radiation-curable adhesive layer that is cured by exposure to radiation, and an intermediate layer that is not cured by exposure to radiation being provided between the base film and the adhesive layer, the adhesive tape for electronic components being used in wafer dicing, including a singulation process in which the adhesive layer is irradiated with radiation and then expanded to singulate the wafer.
• Substrate film A A film having a total thickness of 100 ⁇ m was prepared by extrusion molding, in which 10 ⁇ m of Nucrel AN4214C (trade name, Mitsui-Dow Polychemical Co., Ltd.), which is an ethylene-methacrylic acid copolymer, 80 ⁇ m of Himilan 1855 (trade name, manufactured by Mitsui-Dow Polychemical Co., Ltd.), which is an ethylene-methacrylic acid-(2-methyl-propyl acrylate) terpolymer-Zn ++ ionomer resin, and 10 ⁇ m of Nucrel AN4214C were laminated. This was used as the substrate film.
• Nucrel AN4214C trade name, Mitsui-Dow Polychemical Co., Ltd.
• Substrate film B A film having a total thickness of 150 ⁇ m was prepared by extrusion molding, in which 15 ⁇ m of Nucrel AN4214C (trade name, Mitsui-Dow Polychemical Co., Ltd.), which is an ethylene-methacrylic acid copolymer, 120 ⁇ m of Himilan 1855 (trade name, manufactured by Mitsui-Dow Polychemical Co., Ltd.), which is an ethylene-methacrylic acid-(2-methyl-propyl acrylate) terpolymer-Zn ++ ionomer resin, and 15 ⁇ m of Nucrel AN4214C were laminated. This was used as the substrate film.
• Nucrel AN4214C trade name, Mitsui-Dow Polychemical Co., Ltd.
• Substrate film C A film having a total thickness of 80 ⁇ m was prepared by extrusion molding, in which 10 ⁇ m of Nucrel AN4214C (trade name, Mitsui-Dow Polychemical Co., Ltd.), which is an ethylene-methacrylic acid copolymer, 60 ⁇ m of Himilan 1855 (trade name, manufactured by Mitsui-Dow Polychemical Co., Ltd.), which is an ethylene-methacrylic acid-(2-methyl-propyl acrylate) terpolymer-Zn ++ ionomer resin, and 10 ⁇ m of Nucrel AN4214C were laminated. This was used as the substrate film.
• Nucrel AN4214C trade name, Mitsui-Dow Polychemical Co., Ltd.
• Polymer A An acrylic copolymer (glass transition temperature: -70°C) having structural units of 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 was synthesized.
• Polymer B 2-methacryloyloxyethyl isocyanate was added to an acrylic copolymer (glass transition temperature: ⁇ 64° C.) having as constituent units 78% by weight of 2-ethylhexyl acrylate, 21% by weight of 2-hydroxyethyl acrylate, and 1% by weight of methacrylic acid so that the amount of double bonds was 0.59 (meq/g).
• Polymer C An acrylic copolymer (glass transition temperature: ⁇ 64° C.) having as constituent units 78% by weight of 2-ethylhexyl acrylate, 21% by weight of 2-hydroxyethyl acrylate, and 1% by weight of methacrylic acid was added with 2-methacryloyloxyethyl isocyanate so that the amount of double bonds was 0.30 (meq/g).
• Polymer D Polyester resin composition (weight average molecular weight: 15,000, glass transition point: -50°C)
• Coronate L isocyanate-based hardener, product name, manufactured by Tosoh Corporation
• Adhesive composition a 5% by weight of a photopolymerization initiator (Irgacure 184 (trade name), manufactured by Ciba-Geigy Japan Ltd.) and 1% by weight of an isocyanate-based curing agent (Coronate L (trade name), manufactured by Tosoh Corporation) were mixed with respect to the weight of polymer A to obtain adhesive composition a.
• a photopolymerization initiator Irgacure 184 (trade name), manufactured by Ciba-Geigy Japan Ltd.
• an isocyanate-based curing agent Coronate L (trade name), manufactured by Tosoh Corporation
• Adhesive composition b was obtained by mixing 5% by weight of a photopolymerization initiator (Irgacure 184 (product name), manufactured by Nippon Ciba-Geigy Ltd.) and 8% by weight of an isocyanate-based curing agent (Coronate L (product name), manufactured by Tosoh Corporation) relative to the weight of polymer A.
• a photopolymerization initiator Irgacure 184 (product name), manufactured by Nippon Ciba-Geigy Ltd.
• an isocyanate-based curing agent Coronate L (product name), manufactured by Tosoh Corporation
• Adhesive composition c was obtained by mixing 5% by weight of a photopolymerization initiator (Irgacure 184 (product name), manufactured by Nippon Ciba-Geigy Ltd.) and 2% by weight of an isocyanate-based curing agent (Coronate L (product name), manufactured by Tosoh Corporation) relative to the weight of polymer B.
• a photopolymerization initiator Irgacure 184 (product name), manufactured by Nippon Ciba-Geigy Ltd.
• an isocyanate-based curing agent Coronate L (product name), manufactured by Tosoh Corporation
• Adhesive composition d was obtained by mixing 5% by weight of a photopolymerization initiator (Irgacure 184 (product name), manufactured by Nippon Ciba-Geigy Ltd.) and 2% by weight of an isocyanate-based curing agent (Coronate L (product name), manufactured by Tosoh Corporation) relative to the weight of polymer C.
• a photopolymerization initiator Irgacure 184 (product name), manufactured by Nippon Ciba-Geigy Ltd.
• an isocyanate-based curing agent Coronate L (product name), manufactured by Tosoh Corporation
• Adhesive composition e 2% by weight of an isocyanate-based curing agent (Coronate L (product name), manufactured by Tosoh Corporation) was added to the weight of polymer D to obtain adhesive composition e.
• an isocyanate-based curing agent Coronate L (product name), manufactured by Tosoh Corporation
• Example 1 The pressure-sensitive adhesive composition a was applied to the surface of the substrate film A so that the film thickness after drying would be 10 ⁇ m, and then dried to form an intermediate layer, and a release separator was attached onto the intermediate layer. Thereafter, while peeling off the release separator, the pressure-sensitive adhesive composition c was applied to the intermediate layer so that the film thickness after drying would be 30 ⁇ m, and then dried to form a pressure-sensitive adhesive layer, thereby producing the pressure-sensitive adhesive tape for electronic components according to Example 1.
• Example 2 The pressure-sensitive adhesive composition a was applied to the surface of the substrate film A so that the film thickness after drying would be 20 ⁇ m, and then dried to form an intermediate layer, and a release separator was attached onto the intermediate layer. Thereafter, while peeling off the release separator, the pressure-sensitive adhesive composition c was applied to the intermediate layer so that the film thickness after drying would be 30 ⁇ m, and then dried to form a pressure-sensitive adhesive layer, thereby producing the pressure-sensitive adhesive tape for electronic components according to Example 2.
• Example 3 The pressure-sensitive adhesive composition a was applied to the surface of the substrate film A so that the thickness after drying would be 50 ⁇ m, and then dried to form an intermediate layer, and a release separator was attached onto the intermediate layer. Thereafter, while peeling off the release separator, the pressure-sensitive adhesive composition c was applied to the intermediate layer so that the thickness after drying would be 60 ⁇ m, and then dried to form a pressure-sensitive adhesive layer, thereby producing the pressure-sensitive adhesive tape for electronic components according to Example 3.
• Example 4 The pressure-sensitive adhesive composition a was applied to the surface of the base film B so that the film thickness after drying would be 20 ⁇ m, and then dried to form an intermediate layer, and a release separator was attached onto the intermediate layer. Thereafter, while peeling off the release separator, the pressure-sensitive adhesive composition c was applied to the intermediate layer so that the film thickness after drying would be 30 ⁇ m, and then dried to form a pressure-sensitive adhesive layer, thereby producing the pressure-sensitive adhesive tape for electronic components according to Example 4.
• Example 5 The pressure-sensitive adhesive composition b was applied to the surface of the base film A so that the film thickness after drying would be 20 ⁇ m, and then dried to form an intermediate layer, and a release separator was attached onto the intermediate layer. Thereafter, while peeling off the release separator, the pressure-sensitive adhesive composition c was applied to the intermediate layer so that the film thickness after drying would be 30 ⁇ m, and then dried to form a pressure-sensitive adhesive layer, thereby producing the pressure-sensitive adhesive tape for electronic components according to Example 5.
• Example 6 The pressure-sensitive adhesive composition e was applied to the surface of the base film A so that the film thickness after drying would be 5 ⁇ m, and then dried to form an intermediate layer, and a release separator was attached onto the intermediate layer. Thereafter, while peeling off the release separator, the pressure-sensitive adhesive composition b was applied to the intermediate layer so that the film thickness after drying would be 40 ⁇ m, and then dried to form a pressure-sensitive adhesive layer, thereby producing the pressure-sensitive adhesive tape for electronic components according to Example 6.
• Example 7 The pressure-sensitive adhesive composition e was applied to the surface of the substrate film A so that the film thickness after drying would be 5 ⁇ m, and then dried to form an intermediate layer, and a release separator was attached onto the intermediate layer. Thereafter, while peeling off the release separator, the pressure-sensitive adhesive composition c was applied to the intermediate layer so that the film thickness after drying would be 40 ⁇ m, and then dried to form a pressure-sensitive adhesive layer, thereby producing the pressure-sensitive adhesive tape for electronic components according to Example 7.
• the pressure-sensitive adhesive composition c was applied to the surface of the base film A so that the film thickness after drying would be 20 ⁇ m, and then dried to form an intermediate layer, and a release separator was attached onto the intermediate layer. Thereafter, while peeling off the release separator, the pressure-sensitive adhesive composition c was applied to the intermediate layer so that the film thickness after drying would be 20 ⁇ m, and then dried to form a pressure-sensitive adhesive layer, thereby producing the pressure-sensitive adhesive tape for electronic components according to Comparative Example 1.
• the pressure-sensitive adhesive composition c was applied to the surface of the base film A so that the film thickness after drying would be 5 ⁇ m, and then dried to form an intermediate layer, and a release separator was attached onto the intermediate layer. Thereafter, while peeling off the release separator, the pressure-sensitive adhesive composition c was applied to the intermediate layer so that the film thickness after drying would be 40 ⁇ m, and then dried to form a pressure-sensitive adhesive layer, thereby producing a pressure-sensitive adhesive tape for electronic components according to Comparative Example 8.
• step (a) the adhesive tapes for electronic components according to the examples and comparative examples were laminated to the glass wafer at a lamination pressure of 0.3 MPa and 5 mm/sec using a lamination machine DR3000II (product name, manufactured by Nitto Seiki Co., Ltd.) manufactured by Lintec Corporation.
• the glass wafer was laminated to an optical filter with a mask having a height of 10 ⁇ m (manufactured by Tanaka Giken Co., Ltd.).
• the glass wafer was laminated to the adhesive tape for electronic components so that the dividing lines of the glass wafer were aligned with the MD and TD directions of the base film.
• process (d) the outer periphery of the adhesive tape for electronic components was clamped by a grip ring consisting of an inner ring and an outer ring, and the stage of a Technovision wafer expansion device (EX-300: manufacturer's model number) was raised to stretch the adhesive tape for electronic components, thereby expanding it.
• the conditions for process (d) were an expansion speed of 1 mm/sec, and an expansion amount of 20 mm.
• the expansion amount refers to the amount of change in the relative position between the grip ring and the stage before and after the stage was raised.
• the chip size was set to 4 x 4 mm square.
• step (b) After carrying out step (b), the conformability was evaluated by the following method. With the adhesive tape for electronic components attached, the diameter of the air that had entered was observed from the side opposite to the side where the tape was attached using a laser microscope. Products with no air at all were evaluated as good products with a rating of ⁇ , products with an air diameter of less than 100 ⁇ m were evaluated as acceptable products with a rating of ⁇ , and products with an air diameter of 100 ⁇ m or more were evaluated as defective products with a rating of ⁇ .
• step (d) After the above step (d) was performed, it was confirmed whether the glass wafer was divided into chips.
• the glass wafer in which the entirety was divided along the intended dividing line was evaluated as a good product with a rating of ⁇ , and the glass wafer in which a part or the entirety was not divided along the intended dividing line was evaluated as a defective product with a rating of ⁇ .
• step (d) After carrying out step (d), the distance between the chips in the MD direction of the tape was observed using a Mitutoyo measuring microscope. If the average distance between five randomly selected chips was 201 ⁇ m or more, it was evaluated as excellent with a ⁇ , if it was 101 to 200 ⁇ m, it was evaluated as good with a ⁇ , and if it was 100 ⁇ m or less, it was evaluated as acceptable with a ⁇ .
• step (d) After carrying out step (d), the grip ring was removed from the tape, and the degree of scattering of the adhesive layer at the portion of the adhesive tape for electronic components where the grip ring had been in contact was visually confirmed. Products with nine or fewer pieces of scattered adhesive layer outside the area where the grip ring had been in contact were evaluated as good products with a rating of ⁇ , and products with ten or more pieces of scattered adhesive layer outside the area where the grip ring had been in contact were evaluated as defective products with a rating of ⁇ .
• the adhesive layer is cured by irradiation with radiation, but the intermediate layer is not cured by irradiation with radiation, so that the adhesive tapes obtained good results in the evaluation of the conformability, the ability to be separated, and the degree of shedding of pieces of the adhesive layer.
• the thickness of the intermediate layer is 30% or more of the total thickness of the adhesive layer and the intermediate layer, so that the adhesive tape obtained good results in the evaluation of the kerf width, compared with Example 1, which has the same configuration as Example 2 except that the thickness of the intermediate layer is less than 30% of the total thickness of the adhesive layer and the intermediate layer.
• Example 3 the adhesive layer that is cured by irradiation with radiation is thick, so that the kerf width opening is inferior to Examples 1 and 2, but is within the acceptable range.
• Example 4 the base film is thick, so that the kerf width opening is inferior to Examples 1 and 2, but is within the acceptable range.
• Example 5 the intermediate layer is hard, so that the kerf width opening is inferior to Examples 1 and 2, but is within the acceptable range.
• the adhesive tapes for electronic components according to Examples 1, 2, and 5 had a combined thickness of the base film, adhesive layer, and intermediate layer of 170 ⁇ m or less, and therefore performed better than Examples 3 and 4 in the evaluation of grip ring detachment.
• the adhesive tapes for electronic components according to Comparative Examples 1 to 8 had inferior results in the evaluation of the shedding of adhesive layer fragments because the intermediate layer was cured by exposure to radiation.
• Adhesive tape for electronic components 2 Base film 3: Adhesive layer 4: Intermediate layer 5: Laser light 6: Wafer 7: Modified region 8: Fixing jig 81: Outer ring 82: Inner ring 9: Chip 10: Stage 11: Push-up pin 12: Suction collet 13: Ring frame 14: Pressing portion 15: Pressing portion

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