JP2015004003A - Adhesive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive sheet which is excellent in followability to unevenness of a processed component when the component is processed, and is also excellent in storage stability and handling properties, when being stuck to the processed component having the unevenness (for instance, semiconductor wafer).SOLUTION: An adhesive sheet 100 includes an adhesive layer 10, an intermediate layer 20, and a substrate layer 30 in this order. A storage modulus E'(23) at 23°C of the intermediate layer is 10 MPa to 50 MPa. A ratio (E'(23)/E'(50)) between the storage modulus E'(23) at 23°C and a storage modulus E'(50) at 50°C of the intermediate layer is 5 or less. A ratio (E'(23)/E'(80)) between the storage modulus E'(23) at 23°C and a storage modulus E'(80) at 80°C of the intermediate layer is 90-200.

Description

  The present invention relates to an adhesive sheet.

  When processing semiconductor parts such as semiconductor wafers, optical parts such as lenses, and the like, an adhesive sheet is attached to these parts in order to protect them from damage. For example, in a back grinding process, a dicing process and the like when processing a semiconductor wafer, an adhesive sheet is attached to protect the pattern surface. The pressure-sensitive adhesive sheet used in this way is required to have followability (step difference followability) to the unevenness of the pattern surface from the viewpoint of adhesiveness to the pattern surface having unevenness and reliability of pattern surface protection.

  As a pressure-sensitive adhesive sheet having excellent step followability, a pressure-sensitive adhesive sheet having a flexible intermediate layer between a base material and a pressure-sensitive adhesive layer has been proposed (Patent Document 1). However, the more the step followability is improved, that is, the more flexible the intermediate layer is, the easier the unnecessary deformation of the pressure-sensitive adhesive sheet occurs, or the time of conveyance (for example, the step of sticking the pressure-sensitive adhesive sheet to a semiconductor wafer) This causes a problem in storage or handling such that the end face of the adhesive sheet adheres to the processing apparatus at the time of conveyance in (1).

JP 2007-45965 A

  The present invention has been made in order to solve the above-described conventional problems. The object of the present invention is to process a component when it is attached to a workpiece to be processed (eg, a semiconductor wafer) having irregularities. Another object of the present invention is to provide a pressure-sensitive adhesive sheet having excellent followability to the unevenness and excellent storage stability and handling properties.

The pressure-sensitive adhesive sheet of the present invention includes a pressure-sensitive adhesive layer, an intermediate layer, and a base material layer in this order, and the storage elastic modulus E ′ (23) at 23 ° C. of the intermediate layer is 10 MPa to 50 MPa. The ratio (E ′ (23) / E ′ (50)) of the storage elastic modulus E ′ (23) at 23 ° C. and the storage elastic modulus E ′ (50) at 50 ° C. of the layer is 5 or less, The ratio (E ′ (23) / E ′ (80)) of the storage elastic modulus E ′ (23) at 23 ° C. and the storage elastic modulus E ′ (80) at 80 ° C. of the layer is 90 to 200.
In one embodiment, the pressure-sensitive adhesive layer contains a polyolefin-based resin.
In one embodiment, the thickness of the said intermediate | middle layer is 60 micrometers-300 micrometers.

  According to the present invention, by providing an intermediate layer having a specific storage elastic modulus, when pasted on a workpiece having irregularities (for example, a semiconductor wafer), following the irregularities when processing the component. It is possible to provide a pressure-sensitive adhesive sheet that is excellent in properties and excellent in storage and handling properties.

It is a schematic sectional drawing of the adhesive sheet for semiconductor wafer processing by one Embodiment of this invention. It is a figure explaining the "floating width" used as the parameter | index of the level | step difference followability of the adhesive sheet of this invention.

A. Overall configuration diagram 1 of the adhesive sheet is a schematic sectional view of a pressure-sensitive adhesive sheet according to one embodiment of the present invention. The pressure-sensitive adhesive sheet 100 includes a pressure-sensitive adhesive layer 10, an intermediate layer 20, and a base material layer 30 in this order.

  The thickness of the pressure-sensitive adhesive sheet of the present invention is preferably 5 μm to 1000 μm, more preferably 100 μm to 300 μm, and particularly preferably 130 μm to 260 μm.

  Although not shown, the pressure-sensitive adhesive sheet of the present invention may further include another layer as necessary. For example, the pressure-sensitive adhesive sheet of the present invention may further include a protective layer that protects the pressure-sensitive adhesive layer until it is practically used. The pressure-sensitive adhesive sheet of the present invention can be wound into a roll while being protected by a protective layer. As the protective layer, for example, a plastic (for example, polyethylene terephthalate (PET), polyethylene, polypropylene) film, non-woven fabric surface-coated with a release agent such as a silicon release agent, a fluorine release agent, or a long-chain alkyl acrylate release agent Or paper etc. are mentioned.

  For example, when the pressure-sensitive adhesive sheet of the present invention is not protected by a protective layer, the back surface treatment may be performed on the outermost layer opposite to the pressure-sensitive adhesive layer. The back surface treatment can be performed using a release agent such as a silicon release agent or a long-chain alkyl acrylate release agent. The pressure-sensitive adhesive sheet of the present invention can be wound into a roll by performing a back surface treatment.

  In the present invention, “floating width” is used as one of the indicators of the followability (step difference followability) to the unevenness of the pressure-sensitive adhesive sheet. As shown in FIG. 2, the “floating width” means that when the adhesive sheet 100 is adhered to the adherend 200 having the step x, the adhesive sheet floats in the vicinity of the step and comes into contact with the adherend 200. This means the width a of the portion not to be used. The fact that the floating width is small means that the pressure-sensitive adhesive sheet has excellent step following ability and can well fill the unevenness of the adherend. When the pressure-sensitive adhesive sheet of the present invention is attached to a silicon semiconductor mirror wafer at 80 ° C., the floating width with respect to the adherend having a step of 30 μm is preferably as small as possible, preferably 650 μm or less. Preferably it is 500 micrometers or less, Especially preferably, it is 450 micrometers or less. The pressure-sensitive adhesive sheet of the present invention has a small floating width at a temperature at a scene that actually needs protection of the adherend (for example, about 80 ° C., which is a processing temperature at the time of back grinding or dicing at the time of processing a semiconductor wafer), The unevenness of the adherend can be filled well. When such an adhesive sheet is used to protect the pattern surface during processing of a semiconductor wafer, the pressure is uniformly applied to the semiconductor wafer during the back grinding process, and the back surface of the semiconductor wafer is not affected by the unevenness of the pattern surface and is smooth. Can be ground. Moreover, it is possible to prevent the semiconductor wafer from cracking. Furthermore, it is possible to prevent grinding water from entering between the semiconductor wafer and the adhesive sheet.

  The pressure-sensitive adhesive sheet of the present invention is a method according to JIS Z 0237 (2000) using a semiconductor mirror wafer (made of silicon) as a test plate (bonding condition: 2 kg roller 1 reciprocation, peeling speed: 300 mm / min, peeling angle: 180 °, measurement temperature: 23 ° C.), preferably 0.1 N / 20 mm to 2.0 N / 20 mm, more preferably 0.15 N / 20 mm to 1.5 N / 20 mm, more preferably Is 0.15 N / 20 mm to 1.0 N / 20 mm, particularly preferably 0.25 N / 20 mm to 1.0 N / 20 mm. Within such a range, it is possible to obtain a pressure-sensitive adhesive sheet having a sufficient adhesive force and having an appropriate peelability. For example, such a pressure-sensitive adhesive sheet does not peel during processing such as a back grinding process and a dicing process when it is used for surface protection of a semiconductor wafer, and can be easily peeled after processing.

B. Intermediate Layer The storage elastic modulus E ′ (23) at 23 ° C. of the intermediate layer is 10 MPa to 50 MPa, preferably 10 MPa to 20 MPa, and more preferably 12 MPa to 18 MPa. If it is such a range, the adhesive sheet excellent in storage stability and handling property can be obtained. More specifically, unnecessary deformation of the pressure-sensitive adhesive sheet during storage or transportation can be prevented. In addition, unnecessary adhesion such as adhesion to a processing apparatus in a process of adhering an adhesive sheet to a semiconductor wafer can be prevented. The storage elastic modulus E ′ can be measured by dynamic viscoelastic spectrum measurement.

  The storage elastic modulus E ′ (50) at 50 ° C. of the intermediate layer is preferably 2 MPa to 50 MPa, more preferably 3 MPa to 20 MPa, and particularly preferably 4.5 MPa to 10 MPa. If it is such a range, the adhesive sheet which is excellent by storage stability and handling property can be obtained.

  The storage elastic modulus E ′ (80) at 80 ° C. of the intermediate layer is preferably 0.05 MPa to 0.6 MPa, more preferably 0.07 MPa to 0.3 MPa, and particularly preferably 0.1 MPa to 0 MPa. .25 MPa. If it is such a range, the unevenness | corrugation of a to-be-adhered body can be satisfactorily filled at the temperature (for example, about 80 degreeC as mentioned above) in the scene (for example, about 80 degreeC as mentioned above) in which a to-be-adhered body is actually required.

  The ratio ((E ′ (23) / E ′ (50)) of the storage elastic modulus E ′ (23) at 23 ° C. and the storage elastic modulus E ′ (50) at 50 ° C. of the intermediate layer is 5 or less. The pressure-sensitive adhesive sheet is preferably 4 or less, and more preferably 3.5 or less.Within such a range, a pressure-sensitive adhesive sheet excellent in storage stability and handling properties can be obtained. Adhesive sheets have moderate flexibility when the storage elastic modulus of the intermediate layer is controlled at the ambient temperature (room temperature to about 50 ° C.) during storage or when handling is required. It is possible to prevent problems such as unnecessary deformation of the pressure-sensitive adhesive sheet, unnecessary adhesion, etc. The lower limit of E ′ (23) / E ′ (50) is usually 2 or more.

  The ratio (E ′ (23) / E ′ (80)) of the storage elastic modulus E ′ (23) at 23 ° C. and the storage elastic modulus E ′ (80) at 80 ° C. of the intermediate layer is 90 to 200. , Preferably 110 to 150. If it is such a range, the adhesive sheet which was compatible with handling property and the level | step difference followability at the time of a process can be obtained.

  The thickness of the intermediate layer is preferably 60 μm to 300 μm, more preferably 80 μm to 250 μm, and particularly preferably 90 μm to 200 μm. If it is such a range, the adhesive sheet which was compatible with handling property and the level | step difference followability at the time of a process can be obtained.

  As the material constituting the intermediate layer, any appropriate material can be adopted as long as the storage elastic modulus E ′ within the above range is satisfied. As the material constituting the intermediate layer, a resin capable of extrusion molding is preferably used, and more preferably a resin capable of co-extrusion with the resin constituting the pressure-sensitive adhesive layer and the resin constituting the base material layer is used. . Specific examples of the resin constituting the intermediate layer include ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer, polyester resin (polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polybutylene naphthalate, etc.) , Polyolefin resin (polyethylene, polypropylene, ethylene-propylene copolymer, etc.), polyvinyl alcohol, polyvinylidene chloride, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyamide, polyimide, celluloses, fluorine Resin, polyether, polystyrene resin (polystyrene, etc.), polycarbonate, polyethersulfone and the like. These resins may be used alone or in combination of two or more.

  From the viewpoint of the resin structure, a copolymer is preferably used as the resin constituting the intermediate layer. The storage elastic modulus E ′ (23), storage elastic modulus E ′ (50) and storage elastic modulus E ′ (80) of the intermediate layer are controlled by adjusting the type and content ratio of the structural units constituting the copolymer. can do.

  In one embodiment, an ethylene-methyl methacrylate copolymer is preferably used as the resin constituting the intermediate layer. When an ethylene-methyl methacrylate copolymer is used, the storage elastic modulus E ′ (23) and storage elastic modulus E of the intermediate layer are prepared by adjusting the content ratio of the structural unit derived from ethylene and the structural unit derived from methyl methacrylate. '(50) and storage elastic modulus E' (80) can be controlled, and the more structural units derived from methyl methacrylate, the lower the storage elastic modulus E '. The content ratio of the structural unit derived from methyl methacrylate in the ethylene-methyl methacrylate copolymer is preferably more than 15% by weight, more preferably 20% by weight to 30% by weight, and particularly preferably 25% by weight to 30%. % By weight.

  In another embodiment, an ethylene-vinyl acetate copolymer is preferably used as the resin constituting the intermediate layer. When an ethylene-vinyl acetate copolymer is used, the storage elastic modulus E ′ (23) and storage elastic modulus E ′ () of the intermediate layer are prepared by adjusting the content ratio of the structural unit derived from ethylene and the structural unit derived from vinyl acetate. 50) and storage elastic modulus E ′ (80) can be controlled, and the more structural units derived from vinyl acetate, the lower the storage elastic modulus E ′. The content ratio of the structural unit derived from vinyl acetate in the ethylene-vinyl acetate copolymer is preferably 15% by weight to 50% by weight, and more preferably 25% by weight to 35% by weight.

  The melt flow rate at 190 ° C. and 2.16 kgf of the resin constituting the intermediate layer is preferably 2 g / 10 min to 20 g / 10 min, more preferably 5 g / 10 min to 15 g / 10 min, and particularly preferably 7 g / min. 10 min to 15 g / 10 min. If it is such a range, an intermediate | middle layer can be formed without processing defect by co-extrusion molding. The melt flow rate can be measured by a method according to JISK7210.

  The intermediate layer may further contain other components as long as the effects of the present invention are not impaired. Examples of the other components include an antioxidant, an ultraviolet absorber, a light stabilizer, a heat resistance stabilizer, and an antistatic agent. The kind and usage-amount of another component can be suitably selected according to the objective.

C. Pressure-sensitive adhesive layer The pressure-sensitive adhesive layer contains any appropriate pressure-sensitive adhesive resin. Examples of the adhesive resin include thermoplastic resins such as polyolefin resins, acrylic resins, and styrene resins. Preferably, a polyolefin resin is used. If a thermoplastic polyolefin-based resin is used, co-extrusion with the resin constituting the intermediate layer and the resin constituting the base material layer described later becomes possible, and a pressure-sensitive adhesive sheet having excellent interlayer adhesion can be obtained. Further, by combining the intermediate layer whose storage elastic modulus is adjusted as described above and the pressure-sensitive adhesive layer composed of the polyolefin-based resin, more preferable flexibility can be realized as the whole pressure-sensitive adhesive sheet, and as a result. , The step following ability is remarkably improved.

  Specific examples of the polyolefin resin include low density polyethylene, ultra low density polyethylene, amorphous polypropylene resin (for example, amorphous propylene- (1-butene) copolymer, amorphous propylene-ethylene copolymer). Etc.), ionomer resin, ethylene-vinyl acetate copolymer, ethylene- (meth) acrylic acid copolymer, ethylene- (meth) acrylic acid ester-maleic anhydride copolymer, ethylene-glycidyl methacrylate copolymer, etc. And ethylene copolymers and polyolefin-modified polymers. Among these, an amorphous polypropylene resin is preferable. In this specification, “amorphous” means a property that does not have a clear melting point such as crystalline.

  The melt flow rate at 230 ° C. and 2.16 kgf of the adhesive resin is preferably 1 g / 10 min to 50 g / 10 min, more preferably 5 g / 10 min to 30 g / 10 min, and particularly preferably 5 g / 10 min to 20 g. / 10 min.

  The amorphous polypropylene-based resin can be preferably obtained by polymerizing propylene and an olefin other than propylene using a metallocene catalyst. Preferred examples of the olefin other than propylene include 1-butene and ethylene. Amorphous polypropylene resin polymerized using a metallocene catalyst exhibits a narrow molecular weight distribution. Specifically, the molecular weight distribution (Mw / Mn) of the amorphous polypropylene resin is 2.5 or less, preferably 1.0 to 2.3, more preferably 1.0 to 2.1. It is. Amorphous polypropylene resin having a narrow molecular weight distribution has few low molecular weight components, and thus using such an amorphous polypropylene resin provides an adhesive sheet that can prevent contamination of the adherend due to bleeding of low molecular weight components. be able to.

  The content ratio of the structural unit derived from propylene in the amorphous polypropylene resin is preferably 70 mol% to 99 mol%, more preferably 75 mol% to 99 mol%, and particularly preferably 78 mol% to 99 mol%. Mol%.

  The content rate of the structural unit derived from olefins other than propylene in the amorphous polypropylene resin is preferably 1 mol% to 30 mol%, more preferably 1 mol% to 12 mol%. If it is such a range, the adhesive sheet excellent in the balance of toughness and a softness | flexibility and excellent in level | step difference followable | trackability can be obtained.

  The amorphous polypropylene resin may be a block copolymer or a random copolymer.

  The amorphous polypropylene resin has a weight average molecular weight (Mw) of 100,000 or more, preferably 100,000 to 500,000, more preferably 100,000 to 300,000. If the weight average molecular weight (Mw) of the amorphous polypropylene resin is in such a range, it is low compared with a general styrene thermoplastic resin and acrylic thermoplastic resin (Mw is 100,000 or less). A pressure-sensitive adhesive sheet having a low molecular weight component and capable of preventing contamination of the adherend can be obtained.

  The amorphous polypropylene-based resin may further contain a constituent unit derived from another monomer as long as the effects of the present invention are not impaired. Examples of other monomers include α-olefins such as 1-pentene, 1-hexene, 1-octene, 1-decene, 4-methyl-1-pentene, and 3-methyl-1-pentene.

  Preferably, the pressure-sensitive adhesive layer further includes a non-adhesive resin. By including an adhesive resin and a non-adhesive resin and adjusting the type and content ratio of these resins, the adhesive strength of the adhesive sheet can be controlled.

  As the non-adhesive resin, any appropriate resin can be used as long as it is well mixed with the adhesive resin and does not exhibit adhesiveness.

  Examples of the non-adhesive resin include ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer, polyester resin (polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polybutylene naphthalate, etc.), polyolefin Resin (polyethylene, polypropylene, ethylene-propylene copolymer, etc.), polyvinyl alcohol, polyvinylidene chloride, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyamide, polyimide, celluloses, fluorine resin , Polyether, polystyrene resin (polystyrene and the like), polycarbonate, polyethersulfone and the like. Among these, a polypropylene resin is preferable, and a crystalline polypropylene resin is more preferable.

  The melt flow rate of the non-adhesive resin at 230 ° C. and 2.16 kgf is preferably 1 g / 10 min to 50 g / 10 min, more preferably 5 g / 10 min to 30 g / 10 min, and particularly preferably 5 g / 10 min to 20 g / 10 min.

  The polypropylene resin may be a homopolymer or a copolymer having a propylene-derived structural unit as a main structural unit. The copolymer is derived from a monomer copolymerizable with propylene such as ethylene, 1-pentene, 1-hexene, 1-octene, 1-decene, 4-methyl-1-pentene, α-olefin, and the like. Includes building blocks. The polypropylene resin is preferably obtained by polymerization using a metallocene catalyst, like the amorphous polypropylene resin.

  The mixing ratio of the adhesive resin and the non-adhesive resin can be any appropriate mixing ratio depending on the desired adhesive strength. For example, the content ratio of the non-adhesive resin is preferably 70% by weight or less, more preferably 50% by weight or less, and particularly preferably 18% with respect to the total weight of the adhesive resin and the non-adhesive resin. % By weight to 30% by weight. More specifically, when an amorphous polypropylene resin and a crystalline polypropylene resin are used in combination, the content ratio of the crystalline polypropylene resin is preferably the amorphous polypropylene resin and the crystalline polypropylene. Preferably it is 50 weight% or less with respect to the total weight with a system resin, More preferably, it is 15 to 40 weight%, Most preferably, it is 18 to 30 weight%.

  The pressure-sensitive adhesive layer may further contain other components as long as the effects of the present invention are not impaired. Examples of the other components include an antioxidant, an ultraviolet absorber, a light stabilizer, a heat resistance stabilizer, and an antistatic agent. The kind and usage-amount of another component can be suitably selected according to the objective.

  The thickness of the pressure-sensitive adhesive layer is preferably 5 μm to 30 μm, more preferably 10 μm to 20 μm.

The storage elastic modulus E ′ at 23 ° C. of the pressure-sensitive adhesive layer is preferably 0.5 × 10 ⁶ Pa to 1.0 × 10 ⁸ Pa, more preferably 0.8 × 10 ⁶ Pa to 3.0 ×. 10 ⁷ Pa. When the storage elastic modulus of the pressure-sensitive adhesive layer is within such a range, a pressure-sensitive adhesive sheet that can achieve both sufficient adhesive force and moderate releasability for an adherend having irregularities on the surface can be obtained. Moreover, when an adhesive sheet having an adhesive layer having such a storage elastic modulus is used for semiconductor wafer processing, it can contribute to achieving excellent grinding accuracy in the back grinding process of the wafer.

  In the pressure-sensitive adhesive layer, an elastic value that is a product of the thickness of the pressure-sensitive adhesive layer and the storage elastic modulus E ′ of the pressure-sensitive adhesive layer at 70 ° C. is preferably 0.7 N / mm or less, more preferably 0.01 N. / Mm to 0.7 N / mm, particularly preferably 0.01 N / mm to 0.25 N / mm. When the elastic value of the pressure-sensitive adhesive layer is within such a range, the unevenness of the adherend can be satisfactorily filled at a temperature at a scene where the adherend is actually required to be protected.

D. Base material layer The base material layer may be composed of any appropriate resin. As the resin constituting the base layer, a resin capable of extrusion molding is preferably used, and more preferably a resin capable of co-extrusion with the resin constituting the adhesive layer and the resin constituting the intermediate layer is used. . Specific examples of the resin constituting the base layer include ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer, polyester resin (polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polybutylene naphthalate, etc. ), Polyolefin resin (polyethylene, polypropylene, ethylene-propylene copolymer, etc.), polyvinyl alcohol, polyvinylidene chloride, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyamide, polyimide, celluloses, Fluorine resin, polyether, polystyrene resin (polystyrene, etc.), polycarbonate, polyethersulfone and the like can be mentioned.

  Preferably, a resin having excellent heat resistance is used as the resin constituting the base material layer. For example, a resin having a melting point of 100 ° C. or higher is used as the resin constituting the base material layer. Melting | fusing point of resin which comprises a base material layer becomes like this. Preferably it is 100 to 150 degreeC, More preferably, it is 110 to 140 degreeC. A base material layer composed of a resin having a melting point in such a range sufficiently functions as a support even at high temperatures. Further, if the melting point of the resin constituting the base material layer is in the above range, the function of the intermediate layer can be achieved at a temperature (for example, about 80 ° C. as described above) at a scene where the protection of the adherend is actually required. A pressure-sensitive adhesive sheet that can satisfactorily fill the unevenness of the adherend without being hindered can be obtained.

  The melt flow rate at 230 ° C. and 2.16 kgf of the resin constituting the base material layer is preferably 1 g / 10 min to 50 g / 10 min, more preferably 5 g / 10 min to 30 g / 10 min, and particularly preferably 5 g. / 10 min to 25 g / 10 min.

  The base material layer may further contain other components as long as the effects of the present invention are not impaired. Examples of the other components include an antioxidant, an ultraviolet absorber, a light stabilizer, a heat resistance stabilizer, and an antistatic agent. The kind and usage-amount of another component can be suitably selected according to the objective.

  The thickness of the base material layer is preferably 10 μm to 200 μm, more preferably 20 μm to 150 μm. The pressure-sensitive adhesive sheet of the present invention can control the pressure-sensitive adhesive force by adjusting the thickness of the base material layer. If the thickness of the base material layer is reduced, the pressure-sensitive adhesive force becomes weaker, and if it is increased, the pressure-sensitive adhesive force becomes stronger. .

  The storage elastic modulus E ′ at 23 ° C. of the base material layer is preferably 300 MPa to 1500 MPa, more preferably 500 MPa to 1000 MPa. If the storage elastic modulus is provided with the base material layer in such a range, more preferable flexibility can be realized as the entire pressure-sensitive adhesive sheet, and as a result, the step following ability is remarkably improved.

E. Manufacturing method of pressure-sensitive adhesive sheet The pressure-sensitive adhesive sheet of the present invention is preferably manufactured by co-extrusion forming materials for each layer (for example, pressure-sensitive adhesive layer, intermediate layer, base material layer) constituting the pressure-sensitive adhesive sheet. By coextrusion molding, a pressure-sensitive adhesive sheet having good interlayer adhesion can be produced with a small number of steps and without using an organic solvent.

  In the co-extrusion molding, as a material for forming each layer constituting the pressure-sensitive adhesive sheet, a material obtained by mixing the components of each layer by any appropriate method can be used. When using 2 or more types of resin as a forming material of an adhesive layer, it is preferable to melt and mix this resin. As a method of mixing two or more kinds of resins constituting the pressure-sensitive adhesive layer, for example, a method in which resin pellets blended in a pellet state is supplied from a single hopper to an extruder and mixed at the time of melt extrusion molding, A method in which the flow rate is controlled from two or more hoppers and supplied to an extruder and mixed at the time of melt extrusion molding. A master batch in which resin pellets are blended together in a kneader is prepared and supplied from a single hopper to the extruder. And a method of mixing at the time of melt extrusion molding.

  As a specific method of the co-extrusion molding, for example, a material for forming each layer constituting the pressure-sensitive adhesive sheet is supplied to each of a plurality of extruders connected to dies, and after melting, extruded, and taken out by a touch roll molding method. And a method of forming a laminate.

  The molding temperature in the coextrusion molding is preferably 160 ° C to 220 ° C, more preferably 170 ° C to 200 ° C. Within such a range, the molding stability is excellent.

  The film forming speed in the coextrusion molding is preferably 3 m / min to 30 m / min.

  The temperature of the touch roll in the coextrusion molding is preferably 15 ° C to 80 ° C.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to these Examples at all. In addition, a part means a weight part.

[Example 1]
As an adhesive layer forming material, an amorphous propylene- (1-butene) copolymer polymerized by a metallocene catalyst as an adhesive resin (manufactured by Sumitomo Chemical Co., Ltd., trade name “Tufselen H5002”, propylene-derived structural unit 90 mol% / 1-butene-derived structural unit 10 mol%, Mw = 230,000, Mw / Mn = 1.8) and propylene-ethylene random copolymer polymerized by a metallocene catalyst as a non-adhesive resin (Nippon Polypropylene) And a product name “Wintech WFX4”, a propylene-derived structural unit 96 mol% / ethylene-derived structural unit 4 mol%, melting point: 125 ° C., softening point 115 ° C. 20 parts. Amorphous propylene- (1-butene) copolymer and propylene-ethylene copolymer are mixed by mixing resin pellets in a pellet state from a single hopper to an extruder and mixing at the time of melt extrusion molding. It went by the method.
As an intermediate layer forming material, ethylene-methyl methacrylate copolymer (EMMA) (manufactured by Sumitomo Chemical Co., Ltd., trade name “Aklift WK307”, ethylene-derived constitutional unit: 75 wt%, methyl methacrylate-derived constitutional unit: 25 wt. %)) Was used.
A polypropylene-ethylene copolymer polymerized by a metallocene catalyst (manufactured by Nippon Polypropylene, trade name “WINTEC WSX02”, melting point: 125 ° C.) was used as the base material layer forming material.
The pressure-sensitive adhesive forming material, the intermediate layer forming material, and the base material layer forming material are subjected to T-die melt co-extrusion (extrusion temperature: 180 ° C., film forming speed: 5 m / min), and the molten resin and the touch roll After laminating a Si-coated PET separator (trade name “Tetron Film G2”, manufactured by Teijin DuPont Co., Ltd.) passed through a molding part (touch roll temperature: 50 ° C.), it was cooled and an adhesive sheet (base layer (thickness) : 30 μm) / intermediate layer (thickness: 90 μm) / adhesive layer (thickness: 10 μm) / protective layer (thickness: 50 μm).

[Examples 2 to 4, Comparative Examples 1 to 6]
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the resin constituting the pressure-sensitive adhesive layer, the thickness of the pressure-sensitive adhesive layer and the resin constituting the intermediate layer, and the thickness of each layer were set as shown in Table 1. .
The details of the resins described in Table 1 are as follows.
(Adhesive resin)
“H6822S”: a resin mixture containing a propylene- (1-butene) copolymer, a styrene polymer, an ethylene polymer, and a butadiene polymer (manufactured by Sumitomo Chemical Co., Ltd., trade name “Tough Selenium H6822S”)
(Non-adhesive resin)
“FLX80E4”: Homopolypropylene (manufactured by Sumitomo Chemical Co., Ltd., trade name “FLX80E4”)
“XM7070”: α-olefin elastomer (Mitsui Chemicals, trade name “Toughmer XM7070”)
“BL3450”: α-olefin elastomer (trade name “Tuffmer BL3450” manufactured by Mitsui Chemicals, Inc.)
“A4070S”: α-olefin elastomer (Mitsui Chemicals, trade name “Toughmer A4070S”)
(Resin constituting the intermediate layer)
“V523”: ethylene-vinyl acetate copolymer (manufactured by Mitsui DuPont, trade name “Evaflex V523”, ethylene-derived structural unit: 67% by weight, vinyl acetate-derived structural unit: 33% by weight)
“EV250”: ethylene-vinyl acetate copolymer (manufactured by Mitsui DuPont, trade name “Evaflex EV250”, ethylene-derived structural unit: 72 wt%, vinyl acetate-derived structural unit: 28 wt%)
“P1007”: ethylene-vinyl acetate copolymer (manufactured by Mitsui DuPont, trade name “Evaflex”, ethylene-derived structural unit: 90% by weight, vinyl acetate-derived structural unit: 10% by weight)
“Vistamax 6202”: Low crystalline polypropylene (trade name “Vistamax 6202” manufactured by ExxonMobil Corporation)
(Resin constituting the base material layer)
"WSX02": Propylene-ethylene random copolymer polymerized by metallocene catalyst (trade name "Wintech WSX02" manufactured by Nippon Polypropylene Co., Ltd.)

[Evaluation]
The pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples were subjected to the following evaluation. The results are shown in Table 1. The storage elastic modulus of the intermediate layer was measured at 23 ° C., 50 ° C., and 80 ° C. at a frequency of 1 Hz using a dynamic viscoelasticity measuring apparatus (trade name “ARES” manufactured by Rheometric Scientific Co., Ltd.). The storage modulus was measured.
(1) Handling property When the adhesive sheet is passed through the pass line of a back grind tape pasting machine (DR-3000III, manufactured by Nitto Seiki Co., Ltd.) at 23 ° C., depending on the occurrence of trouble that the adhesive sheet adheres to the device. Handling was evaluated.
(2) Step following ability (bump filling ability)
Using a back grind tape applicator (DR-3000III, manufactured by Nitto Seiki Co., Ltd.), a semiconductor wafer (height 15 μm / interval 30 μm bump) under conditions of pressure-sensitive adhesive sheet conveyance speed of 10 mm / sec and pressurization pressure of 0.20 MPa A 4 inch silicon mirror wafer formed with a sticking sheet was attached. After sticking, place the semiconductor wafer with the adhesive sheet in an environment of 80 ° C, and evaluate the step following ability with an optical microscope (250 times) depending on whether or not the adhesive sheet is stuck in the space between the bumps. did. In Table 1, the case where the adhesive sheet has stuck in this space is set as (circle) and the case where it is not stuck is set as x.
Further, the same evaluation as described above was performed using a semiconductor wafer (a 4-inch silicon mirror wafer on which bumps having a height of 50 μm / interval of 50 μm were formed) as adherends.

  The pressure-sensitive adhesive sheet of the present invention can be suitably used, for example, for protecting a semiconductor wafer.

DESCRIPTION OF SYMBOLS 10 Adhesive layer 20 Intermediate | middle layer 30 Base material layer 100 Adhesive sheet

Claims (3)

A pressure-sensitive adhesive layer, an intermediate layer, and a base material layer are provided in this order,
The storage elastic modulus E ′ (23) at 23 ° C. of the intermediate layer is 10 MPa to 50 MPa,
The ratio of the storage elastic modulus E ′ (23) at 23 ° C. and the storage elastic modulus E ′ (50) at 50 ° C. of the intermediate layer (E ′ (23) / E ′ (50)) is 5 or less,
The ratio (E ′ (23) / E ′ (80)) of the storage elastic modulus E ′ (23) at 23 ° C. and the storage elastic modulus E ′ (80) at 80 ° C. of the intermediate layer is 90 to 200. ,
Adhesive sheet.   The pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive layer contains a polyolefin-based resin. The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the intermediate layer has a thickness of 60 µm to 300 µm.

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