Heat-resistant adhesive film

Abstract

Provided is a heat-resistant adhesive film which is suitable for protecting the surface of plastic products, glass products, ceramic products, and the like, that have been subjected to electrical conductivity processing or decorated through printing or the like. Provided is the heat-resistant adhesive film which is suitable for use in a step for fixing and subjecting chips to a treatment at a high temperature exceeding 150°C, when obtaining chips by cutting and separating in a semiconductor production process　The heat-resistant adhesive film is characterized by having a UV (ultraviolet radiation)-curable adhesive layer on at least one surface of a film-like substrate that is a film-like substance which comprises a thermoplastic polyester-based resin having a melting point of 150°C or higher and has a tensile modulus of elasticity of 30-5500 MPa, a tensile rupture elongation of 10-1100%, and a ratio of stress F50 at 50% elongation relative to stress F25 at 25% elongation F50 / F25 of 0.95 or more, and characterized in that the adhesive force upon UV irradiation after being heat treated for 1 hour at a temperature of at least 180°C is 1.2 N / 25 mm or less.

Description

Heat-resistant adhesive film

[0001] The present invention provides a heat-resistant adhesive film suitable for protecting the surface condition of plastic products, glass products, ceramic products, etc., which have been subjected to conductive processing or decorative processing such as printing. Furthermore, the present invention relates to a heat-resistant adhesive film suitable for fixing chips and for use in a process in which the chips are cut and separated in a semiconductor manufacturing process and are subjected to high-temperature processing exceeding 150°C.

[0002] Plastic products, glass products, ceramic products, etc., are subject to surface processing, decoration, etc., and are therefore desirably protected from scratches during transportation, heating, etc. Furthermore, the surfaces to be protected after processing, decoration, etc. are not limited to flat surfaces, but can also include curved surfaces and even uneven shapes, and protecting these surfaces requires adaptability to various shapes.Furthermore, since these protections must be removed before use, adhesive films are often required for protection.

[0003] The semiconductor manufacturing process involves adhesive films used to transport semiconductor workpieces such as wafers and substrates, and involves a dicing process in which the semiconductor workpieces are cut into chips, a drying process in which the chips are rotated or otherwise subjected to cooling water removal, a heating process in which the adhesive film is heated to reduce its adhesive strength in some cases, an expanding process in which the cut chips are spaced apart to facilitate individual pick-up using a suction jig, and a pick-up process in which the chips are harvested. In particular, the dicing process requires adequate rigidity to secure the wafer or substrate and prevent misalignment during dicing by a blade or other tool, and to prevent chips from scattering. The expanding process requires extensibility to ensure uniform expansion of the spacing between the chips.

[0004] Furthermore, the obtained chips are loaded onto another wafer or semiconductor workpiece such as a substrate, and a new circuit is formed. After that, the chips are attached to an adhesive film for transport known as back tape and then resin-sealed in a mold at 160 to 170°C. The adhesive film for transport is then peeled off from the resulting resin-sealed product, and another adhesive film is used to carry out the processes after the dicing process. When high-temperature processes such as the above-mentioned chip drying process and resin-sealing of new circuits made by stacking multiple chips are performed, an adhesive film that is heat-resistant for each application is required.

[0005] Taking the semiconductor manufacturing process as an example of the substrate, a multilayer film has been disclosed in which a resin composition consisting of, for example, a vinyl aromatic hydrocarbon or a hydrogenated conjugated diene hydrocarbon copolymer and a polypropylene resin is laminated onto the substrate of a conventional surface protection film or a dicing adhesive film (Patent Document 1).

[0006] Polyester-based resins have a high glass transition temperature and are excellent heat-resistant materials, and in light of this, an amorphous polyester with a glass transition temperature of 0 to 50°C has been disclosed in order to obtain a certain level of expandability (Patent Document 2). Also, a method of laminating polyester-based resins with glass transition temperatures of -100 to 0°C and 0 to 100°C has been disclosed (Patent Document 3).

[0007] Thermoplastic polyester elastomers are known as block copolymers formed by combining hard segments consisting of polyester units composed of an aromatic dicarboxylic acid and an aliphatic diol or an alicyclic diol with soft segments consisting of an aliphatic diol or an alicyclic diol. These have higher heat resistance than polystyrene elastomers, polyolefin elastomers, polyamide elastomers, etc., and are used in a variety of applications. However, many block copolymers experience a decrease in stress when their elongation exceeds 10 to 30%, making uniform elongation difficult.

[0008] As a result of extensive research aimed at solving the above problems, the present inventors have proposed a method for increasing the ratio F50 / F25, the stress F50 at 50% elongation, which is an index of the change in stress beyond an elongation of 10 to 30%, by applying a specific soft segment to a heat-resistant thermoplastic polyester elastomer and increasing the molecular weight, without impairing extensibility (Patent Document 4).Furthermore, the present inventors have proposed a method for achieving heat resistance, a high F50 / F25, and without impairing extensibility, by setting a predetermined amount of a general soft segment (Patent Document 5).

[0009] As for pressure-sensitive adhesives, various measures have been disclosed, such as high-temperature treatment, as described above (Patent Document 6). As semiconductor manufacturing processes continue to improve, it will be necessary to make pressure-sensitive adhesives compatible with processes requiring higher expandability, processes requiring treatment at temperatures exceeding 150°C, or processes requiring both.

[0010] JP 2009-094418 A JP 2003-092273 A JP 2018-140508 A WO2021 / 246239 A WO2023 / 085175 A WO2020 / 100491 A

[0011] Regarding the substrate, the technology described in Patent Document 1 has sufficient expandability, but there is a problem that the adhesive film may develop wrinkles, pressure marks, or fusion due to the high-temperature treatment described above. The technologies described in Patent Documents 2 and 3 can handle the high-temperature treatment described above, but have issues with expandability because they basically contain a layer with a high melting point or softening point. The technology described in Patent Document 4 can achieve both expandability and heat resistance, and the technology described in Patent Document 5 is sufficient for processes requiring further improvement in extensibility.

[0012] Regarding the adhesive, the technology described in Patent Document 6 can provide sufficient functionality at temperatures of 150° C. or less in the high-temperature treatment described above, but is difficult to use in processes exceeding that temperature.

[0013] The present invention solves the above-mentioned problems and provides a heat-resistant adhesive film suitable for protecting the surface condition of plastic products, glass products, ceramic products, etc. that have been processed to be conductive or decorated by printing, etc. A further object of the present invention is to provide a heat-resistant adhesive film that is suitable for fixing chips and for use in processes in which high-temperature treatment exceeding 150°C is performed when chips are obtained by cutting and separating them in the semiconductor manufacturing process.

[0014] The present inventors conducted extensive research to solve the above-mentioned problems and have completed the following invention. [1] A heat-resistant adhesive film having, in this order, a substrate film made of a thermoplastic polyester resin and a pressure-sensitive adhesive layer, wherein the substrate film has a melting point of 150°C or higher, a tensile modulus of elasticity of 30 to 5,500 MPa, a tensile elongation at break of 10 to 1,100%, and a ratio F50 / F25 (stress F50 at 50% elongation to stress F25 at 25% elongation) of 0.95 or higher, the pressure-sensitive adhesive layer is an ultraviolet-curable pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer has an adhesive strength of 1.2 N / 25 mm or less when measured under conditions of heat treatment at 180°C for 1 hour and UV irradiation. [2] In one aspect, the heat-resistant adhesive film according to [1], wherein the film thickness of the substrate is 50 to 250 μm and the thickness of the pressure-sensitive adhesive layer is 5 to 50 μm. [3] In one aspect, the heat-resistant adhesive film according to [1] or [2] is provided, wherein the substrate is a thermoplastic polyester-based elastomer formed by bonding a hard segment having a polyester unit composed of an aromatic dicarboxylic acid and an aliphatic diol or an alicyclic diol to a soft segment composed of an aliphatic diol, an alicyclic diol, or an aliphatic polycarbonate, and the amount of the soft segment is 30% by mass or more relative to 100% by mass of the thermoplastic polyester-based elastomer. [4] In one aspect, the heat-resistant adhesive film according to any one of [1] to [3] is provided, wherein the thermoplastic polyester-based elastomer constituting the substrate film has a melting point of 180°C or higher, and the substrate film has undergone a heat treatment process at 110°C or higher. [5] In one aspect, the heat-resistant adhesive film according to any one of [1] to [4] is provided, wherein the surface protection film comprises the heat-resistant adhesive film according to any one of [1] to [4]. [6] In one aspect, the film for semiconductor manufacturing is provided, wherein the heat-resistant adhesive film according to any one of [1] to [4] is provided.

[0015] The present invention has an ultraviolet-curable adhesive layer, and the adhesive layer has an adhesive strength of 1.2 N / 25 mm or less when measured under conditions of heat treatment at 180°C for 1 hour and UV irradiation. Therefore, the present invention can provide a heat-resistant adhesive film that is suitable for protecting the surface condition of plastic products, glass products, ceramic products, etc. that have been processed to be conductive or decorated by printing, etc. Furthermore, the present invention can provide a heat-resistant adhesive film that is suitable for the process of fixing chips and performing high-temperature treatment exceeding 150°C when cutting and separating them to obtain chips in the semiconductor manufacturing process.

[0016] The heat-resistant adhesive film of the present invention is composed of a film-like substrate of a thermoplastic polyester resin, and therefore has excellent heat resistance, and can protect the surface condition of plastic products, glass products, ceramic products, etc., which have been processed to be conductive or decorated by printing, from scratches when they pass through processes such as annealing and drying at high temperatures, or it can provide a heat-resistant adhesive film that is suitable for preventing film tearing during resin sealing in the semiconductor manufacturing process and for annealing after resin sealing.

[0017] The heat-resistant adhesive film of the present invention has the compound and structure described below.

[0018] <Configuration of Heat-Resistant Adhesive Film> The present invention is a heat-resistant adhesive film having, in this order, a substrate film made of a thermoplastic polyester resin and an adhesive layer. An adhesive layer made of an adhesive is formed on at least one surface of the heat-resistant adhesive film according to the present invention, and the adhesive is made of an active energy ray-curable adhesive. Since the adhesive layer is made of an active energy ray-curable adhesive, the adhesive layer is cured by irradiation with active energy rays, reducing the adhesive strength between the heat-resistant adhesive film and the adherend surface, making it possible to easily peel the heat-resistant adhesive film from the adherend surface.

[0019] <Thermoplastic Polyester Resin> The thermoplastic polyester resin used as the substrate of the heat-resistant adhesive film of the present invention is preferably a polyester composed of an aromatic dicarboxylic acid and an aliphatic diol or an alicyclic diol. Conventional aromatic dicarboxylic acids are widely used as the aromatic dicarboxylic acid constituting the polyester. Specific examples include terephthalic acid and naphthalenedicarboxylic acid, with terephthalic acid being preferred from the viewpoint of versatility. These compounds can also be included as the main component of the aromatic dicarboxylic acid of the present invention. Other acid components include aromatic dicarboxylic acids such as diphenyldicarboxylic acid, isophthalic acid, and 5-sodium sulfoisophthalic acid; alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid and tetrahydrophthalic anhydride; and those obtained by adding aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, dimer acid, and hydrogenated dimer acid. These aliphatic dicarboxylic acids are used in a range that does not significantly lower the melting point of the resin, for example, in an amount of less than 30 mol %, preferably less than 20 mol %, of the total acid components. The aliphatic diol or alicyclic diol constituting the polyester is not particularly limited, but is preferably an alkylene glycol having 2 to 8 carbon atoms. Specific examples include ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, and 1,4-cyclohexanedimethanol, with 1,4-butanediol and 1,4-cyclohexanedimethanol being most preferred. These compounds may also be included as the main component of the diol according to the present invention.

[0020] <Thermoplastic polyester-based resin (elastomer)> Further examples include thermoplastic polyester-based elastomers obtained by bonding a hard segment made of the above-mentioned thermoplastic polyester-based resin to a soft segment made of an aliphatic diol, an alicyclic diol, or an aliphatic polycarbonate. In this case, the hard segment is preferably composed mainly of butylene terephthalate units or butylene naphthalate units, and more preferably composed mainly of butylene terephthalate units, from the viewpoints of physical properties, moldability, and cost performance. Examples of the aliphatic diol, alicyclic diol, or aliphatic polycarbonate constituting the soft segment include poly(alkylene oxide) glycols such as poly(ethylene oxide) glycol, poly(propylene oxide) glycol, poly(tetramethylene oxide) glycol, poly(hexamethylene oxide) glycol, copolymers of ethylene oxide and propylene oxide, ethylene oxide addition polymers of poly(propylene oxide) glycol, and copolymers of ethylene oxide and tetrahydrofuran. Aliphatic diols having 5 to 12 carbon atoms are preferred in terms of heat resistance and extensibility. Aliphatic polycarbonate diols are also preferred, and those with a low melting point (e.g., 70°C or less) and a low glass transition temperature are preferred. For example, aliphatic polycarbonate diols made from 1,6-hexanediol are suitable because they have a low glass transition temperature of around −60°C and a melting point of around 50°C, thereby providing extensibility at room temperature. Furthermore, an aliphatic polycarbonate diol obtained by copolymerizing, for example, an appropriate amount of 3-methyl-1,5-pentanediol with the above aliphatic polycarbonate diol has a glass transition temperature that is slightly higher than that of the original aliphatic polycarbonate diol, but has a lower melting point or is amorphous, and thus corresponds to a good aliphatic polycarbonate diol.Furthermore, for example, an aliphatic polycarbonate diol made from 1,9-nonanediol and 2-methyl-1,8-octanediol has a melting point of about 30°C and a glass transition temperature that are sufficiently low, around -70°C, and therefore corresponds to a good aliphatic polycarbonate diol.These aliphatic polycarbonate diols may be copolymerized with small amounts of other glycols, dicarboxylic acids, ester compounds, ether compounds, etc., and examples of copolymerization components include glycols such as dimer diol, hydrogenated dimer diol, and modified products thereof, dicarboxylic acids such as dimer acid and hydrogenated dimer acid, polyesters composed of aliphatic, aromatic, or alicyclic dicarboxylic acids and glycols, polyesters composed of oligoesters, ε-caprolactone, etc., oligoesters, polyalkylene glycols such as polytetramethylene glycol and polyoxyethylene glycol, or oligoalkylene glycols, and can be used to an extent that the effect of the aliphatic polycarbonate segment is not substantially lost. Furthermore, those primarily comprising aliphatic diol residues having 2 to 12 carbon atoms, such as ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 2,2-dimethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,9-nonanediol, and 2-methyl-1,8-octanediol, with those comprising aliphatic diol residues having 5 to 12 carbon atoms being particularly preferred from the standpoint of heat resistance and extensibility. These components may be used alone, or two or more may be used in combination as necessary. Copolymerization components such as polyalkylene glycols, such as polyethylene glycol and polyoxytetramethylene glycol, and polyesters, such as polycaprolactone and polybutylene adipate, are also applicable.

[0021] When the thermoplastic polyester resin used in the heat-resistant film of the present invention is an elastomer, it is preferably a thermoplastic polyester elastomer formed by combining hard segments made of a polyester composed of an aromatic dicarboxylic acid and an aliphatic diol or an alicyclic diol with soft segments made of an aliphatic diol, an aliphatic diol, or an aliphatic polycarbonate, and optional copolymerization components. In this case, the mass ratio of the soft segments (sometimes referred to as the soft segment amount) is preferably 30% by mass or more per 100% by mass of the elastomer, which can provide good extensibility and further improve heat resistance. Preferably, the hard segment:soft segment (mass ratio) is 40:60 to 70:30. Preferably, the weight ratio of the hard segments contained in the thermoplastic polyester elastomer is greater than the weight ratio of the soft segments, and from the viewpoint of heat resistance, the weight ratio of the hard segments contained in the thermoplastic polyester elastomer is 45% or more. For example, the hard segment:soft segment ratio is 45:55 to 70:30, preferably 48:52 to 70:30. In one embodiment, the hard segment:soft segment ratio is 51:49 to 70:30. Having such a mass ratio allows for better heat resistance and expandability. In particular, in the semiconductor manufacturing process, having such a mass ratio allows for the properties required of an adhesive film that fixes semiconductor wafers, substrates, etc. when cutting and separating them to obtain chips. Furthermore, heat treatment of the substrate is possible during the coating process of the adhesive layer, etc., and the excellent extensibility provides sufficient expandability, making it applicable to surface protection films that protect the surface condition of plastic products, glass products, ceramic products, etc. that have been processed for conductivity or decorated by printing, and to transport films that carry semiconductor wafers, substrates, etc. during the semiconductor manufacturing process.

[0022] The melting point of the thermoplastic polyester resin is 150°C or higher, for example, 180°C or higher, or may be 190°C or higher. Furthermore, from the viewpoint of temperature control in general extrusion equipment, the melting point is preferably 260°C or lower. In particular, when the thermoplastic polyester resin is an elastomer, such a melting point results in good film strength, tensile elongation at break, and elastic modulus, and furthermore, higher heat resistance and expandability. By using such a thermoplastic polyester resin, the melting point of the substrate film of the present invention can be set to 150°C or higher, 180°C or higher, or 190°C or higher, and the melting point can be set to 260°C or lower.

[0023] The thermoplastic polyester resin used in the present invention can be produced by known methods such as a method of obtaining it by esterifying dimethyl terephthalate or terephthalic acid with a diol such as ethylene glycol, or a method of obtaining it by transesterification thereof.

[0024] Similarly, when the thermoplastic polyester resin used in the present invention is an elastomer, it can be produced by a known method, such as a method of transesterifying a lower alcohol diester of a dicarboxylic acid, an excess amount of a low-molecular-weight glycol, and a soft segment component in the presence of a catalyst, followed by polycondensation of the resulting reaction product, or a method of esterifying a dicarboxylic acid, an excess amount of a glycol, and a soft segment component in the presence of a catalyst, followed by polycondensation of the resulting reaction product. The hard segment and soft segment in the thermoplastic polyester-based elastomer can be bonded to each other using a chain extender such as an isocyanate compound. In this case, the polycarbodiimide compound can be contained in an amount of 0.5 to 10 parts by mass, and for example, 0.5 to 6 parts by mass, more preferably 1.0 to 3.0 parts by mass, relative to 100 parts by mass of a product (hereinafter sometimes referred to as a blocked reaction product) obtained by repeatedly carrying out a transesterification reaction and a depolymerization reaction for a certain period of time in a melt of the polyester constituting the hard segment, the aliphatic diol or alicyclic diol or aliphatic polycarbonate constituting the soft segment, and, if necessary, various copolymerization components.

[0025] In this case, if the reduced viscosity of the elastomer is low, the tensile elongation at break decreases, and if it is high, the fluidity in the melt decreases, which may make molding such as extrusion difficult. Therefore, although it largely depends on the composition and mass ratio of the hard segment and soft segment, the reduced viscosity is preferably 1.0 to 2.5 dl / g, and more preferably 1.0 to 2.3 dl / g.

[0026] The thermoplastic polyester resin used in the present invention can contain, to the extent that the object is not impaired, particles of known inorganic compounds such as silica, talc, zeolite, and aluminum borate, and particles of organic compounds such as polymethyl methacrylate, melamine formalin resin, melamine urea resin, and polyester resin. The resin may also contain additives such as flame retardants, plasticizers, antistatic agents, lubricants, antioxidants, colorants, infrared absorbers, and ion scavengers. The content of these additives is not particularly limited, but is preferably within a range that allows the substrate to exhibit the desired functions. In addition, organic slip agents such as hydrocarbon-based agents such as liquid paraffin, paraffin wax, and synthetic polyethylene wax; aliphatic and higher alcohol-based agents such as stearic acid and stearyl alcohol; and fatty acid amide-based agents such as stearic acid amide, oleic acid amide, and erucic acid amide are likely to bleed and cause contamination, so it is important that the amount of such agents extracted by Soxhlet extraction with chloroform in accordance with JIS K 6229 "Determination of rubber - solvent extractables (quantitative)" is 1 wt % or less, and that they are essentially not contained. If added, the amount of each organic slip agent should be 0.5 wt % or less, and preferably 0.1 wt % or less.

[0027] The raw materials used for the thermoplastic polyester resin used in the present invention are not particularly limited and may be derived from petroleum or plants, but are preferably derived from plants from an environmental point of view.

[0028] <Film Formation> The substrate used in the heat-resistant adhesive film of the present invention can be obtained by forming the above-mentioned thermoplastic polyester resin into a film by melt extrusion or the like.

[0029] For melt extrusion, the extrusion is carried out as a sheet from a T-die through a single-screw or twin-screw extruder. A feed block or multi-manifold can be used to obtain a heat-resistant film of heterogeneous multilayers. The extruded sheet is then pressed against the surface of a metal roll, through which cooling water or oil circulates, using an air knife, air chamber, hard rubber roll, steel belt, metal roll, or the like, to cool and solidify. Alternatively, the sheet can be sandwiched between steel belts on both sides to cool and solidify. The surface of the metal roll, hard rubber roll, or steel belt can be modified and then transferred to the surface of the sheet to form a film. The film can be constructed in a layer structure such as A: monolayer, A / B, A / B / A, or A / B / C, using similar thermoplastic polyester resins, different resins, thermoplastic polyester elastomers, or different elastomers. To prevent problems such as delamination, an additional resin layer can be added between the aforementioned layers. The resulting film can also be stretched uniaxially or biaxially. In this case, a high total stretching ratio may impair extensibility, while a low total stretching ratio may result in significant thickness variation. Therefore, a total stretching ratio of 3 to 12 times is preferred, and biaxial stretching is preferred to achieve uniform extensibility. A low static friction coefficient on at least one side of the heat-resistant film obtained in this manner can cause problems such as slippage during winding, while a high static friction coefficient can lead to wrinkles. Therefore, the lower limit is preferably 0.10 or more, more preferably 0.15 or more. The upper limit is preferably 0.9 or less, and more preferably 0.5 or less, since uniform expandability may not be achieved during the expanding step in semiconductor manufacturing processes. Furthermore, if necessary, the surface of the substrate may be subjected to a known treatment such as corona treatment, plasma treatment, ozone treatment, flame treatment, primer treatment, vapor deposition treatment, or alkali treatment to improve wettability with the pressure-sensitive adhesive, thereby improving adhesion to the pressure-sensitive adhesive.

[0030] <Thickness of the substrate> The thickness of the substrate of the heat-resistant adhesive film of the present invention depends on the usage, but if it is too thin, it will have little stiffness and be prone to breakage, while if it is too thick, problems with handling may occur. Therefore, when used as a protective film, it is preferably 50 μm or more. When used in a semiconductor manufacturing process, it is preferably 80 μm or more, although this depends on the cutting method for semiconductor wafers, substrates, etc. In addition, when using resin encapsulation, it is preferably 100 μm or more, although this depends on the fluidity of the encapsulation resin. In addition, from the viewpoint of handleability, it is preferably 250 μm or less, more preferably 180 μm or less.

[0031] <Mechanical Properties of the Substrate> Depending on the usage, a low modulus of elasticity of the substrate of the heat-resistant adhesive film of the present invention can result in poor stiffness and susceptibility to breakage, while a high modulus can cause problems with handling and expandability. Therefore, when used as a protective film, if the target is flat and prone to scratches, a modulus of elasticity of 700 to 1,100 MPa is preferred, and if the target is uneven, a modulus of elasticity of 30 to 800 MPa is preferred. Furthermore, if an expansion step is required in the semiconductor manufacturing process, a modulus of elasticity of 30 to 500 MPa is preferred. Considering transport for resin encapsulation, including a subsequent process that includes an expansion step, a modulus of elasticity of 30 to 1,100 MPa is preferred, and for simple transport for resin encapsulation, a modulus of elasticity of 800 to 5,500 MPa is preferred. For example, when used in a semiconductor manufacturing process, the modulus of elasticity may be, for example, 50 to 500 MPa, 65 to 400 MPa, or 65 to 350 MPa.

[0032] The substrate of the heat-resistant adhesive film of the present invention is used in the same manner as described above, but the tensile elongation at break is preferably 10 to 250% when used as a protective film on a flat surface where problems such as deformation may occur, or in the case of simple transport for resin encapsulation, and is preferably 200 to 1,100% when there are irregularities and a certain degree of conformability is required, or when cutting and expanding processes are required in the semiconductor manufacturing process.

[0033] When an expanding process is required in a semiconductor manufacturing process, the substrate of the heat-resistant adhesive film of the present invention has a ratio (F50 / F25) of the stress (F50) at 50% elongation to the stress (F25) at 25% elongation of 0.95 or more, for example, 1.50 or less. In one embodiment, F50 / F25 may be 1.05 or more and 1.30 or less. When F50 / F25 is within this range, abnormalities such as wrinkles and distortion are less likely to occur when stretched in one direction or multiple directions. Furthermore, when the thermoplastic polyester resin is an elastomer, wrinkles and distortion can be suppressed even when stretched in multiple directions.

[0034] <Heat Treatment of Substrate> When the thermoplastic polyester resin used contains an elastomer as one of its constituent elements, the substrate of the heat-resistant adhesive film of the present invention is desirably heat-treated. Without heat treatment, high expandability (expandability) may not be achieved. Furthermore, depending on the elastomer used, if the temperature is high, the substrate may fuse to the heat treatment base or roll. Therefore, the heat treatment temperature is desirably 100°C or higher (particularly 110°C or higher) but not more than 25°C lower than the resin melting point. Alternatively, the heat treatment temperature may be 100°C or higher (particularly 110°C or higher) but not more than 30°C lower than the resin melting point. For example, if the heat treatment temperature is outside the above range, thermal properties such as heat resistance and coatability may not meet the requirements of the present invention. In addition, the time after the substrate reaches a predetermined temperature depends on the thickness of the substrate and the heating method, but is preferably 1 to 180 seconds, more preferably 2 to 180 seconds.

[0035] Although the mechanism of such heat treatment is unclear, for example, in terms of the relationship between stress and strain, even if a decrease in stress is observed at strains of 30% or less, the ratio of the stress F50 at an elongation of 50% to the stress F25 at an elongation of 25% increases, and extensibility is obtained. Note that heat treatment methods include contact heating using a heated roll or the like, and non-contact heating using hot air or an IR heater, but are not particularly limited thereto. Furthermore, these can also be used in drying processes such as coating and printing, and in heat treatment of any layer laminated on the substrate, as long as the heat treatment temperature and heat treatment time are suitable.

[0036] In a preferred embodiment, the heat-resistant adhesive film of the present invention is provided for by undergoing a heat treatment process at 110°C or higher, as described above. This provision corresponds to the case where a claim for a product describes a manufacturing method for the product, and the claim description may be deemed to be inconsistent with the requirement that the invention be clear. However, as described herein, although significant effects can be obtained by subjecting the heat-resistant film of the present invention to the heat treatment, the mechanism has not been elucidated, and it is difficult to "directly identify" the heat-resistant film obtained through the heat treatment by its structure or properties. Therefore, the above provision is considered to include "circumstances (impossible or impractical circumstances) in which it is impossible or practical to directly identify the product by its structure or properties at the time of filing."

[0037] <Adhesive: Acrylic Acid Ester Polymer> The adhesive used in the heat-resistant adhesive film of the present invention is a UV (ultraviolet) curable adhesive, and preferably contains a mixture of an acrylic polymer and an energy ray-polymerizable oligomer, or a copolymerized base agent, a crosslinking agent, and a polymerization initiator.

[0038] <Adhesive: Acrylic Polymer> The acrylic polymer is preferably obtained by copolymerizing an acrylic ester as the main component with a hydroxyl group-containing monomer copolymerizable with the acrylic ester, or by copolymerizing an acrylic ester as the main component with a copolymerizable hydroxyl group- and carboxyl group-containing monomer. The mass ratio of the hydroxyl group-containing monomer to the carboxyl group-containing monomer is preferably adjusted within the range of 51:49 to 100:0. The acrylic polymer is not particularly limited, and examples include acrylic ester copolymers obtained by copolymerizing an acrylic ester with other monomers. Examples of acrylic esters include ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, isononyl acrylate, hydroxyethyl acrylate, propylene glycol acrylate, acrylamide, and glycidyl acrylate. These may be used alone or in combination of two or more. Among the above acrylic acid esters, n-butyl acrylate and 2-ethylhexyl acrylate are preferred in the present invention because they are excellent in transparency, heat resistance, moist heat resistance, durability, and coatability, and are also low in cost. Examples of other monomers include methyl acrylate, methyl methacrylate, styrene, acrylonitrile, vinyl acetate, acrylic acid, methacrylic acid, itaconic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, propylene glycol acrylate, acrylamide, methacrylamide, glycidyl acrylate, glycidyl methacrylate, dimethylaminoethyl methacrylate, tert-butylaminoethyl methacrylate, and 2-ethylhexyl methacrylate, which can be used alone or in combination of two or more. Among the above other monomers, 2-ethylhexyl methacrylate is preferred.

[0039] Alternatively, the acrylic polymer preferably has an acrylic acid ester as the main component and is obtained by copolymerizing the aforementioned acrylic acid ester with a copolymerizable hydroxyl group-containing monomer, or has an acrylic acid ester as the main component and is obtained by copolymerizing the aforementioned acrylic acid ester with a copolymerizable hydroxyl group- and carboxyl group-containing monomer, and by adjusting the mass ratio of the aforementioned hydroxyl group-containing monomer to the aforementioned carboxyl group-containing monomer to be 51:49 to 100:0, it is expected that adhesive residue will be reduced and that the adhesive strength due to UV irradiation will be effectively reduced, which is preferable. The copolymerizable hydroxyl group-containing monomer is not particularly limited as long as it has a copolymerizable polymerizable group and a hydroxyl group in its structure, and examples thereof include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, 3-chloro-2-hydroxypropyl acrylate, and polyethylene glycol acrylate. The copolymerizable carboxyl group-containing monomer is not particularly limited as long as it has a copolymerizable polymerizable group and a carboxyl group in its structure, and examples thereof include acrylic acid, methacrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid.

[0040] The mass average molecular weight (Mw) of such an acrylic polymer is preferably in the range of 100,000 to 1,100,000, and in order to further improve heat resistance, it is preferably in the range of 300,000 to 1,100,000. The mass average molecular weight is a polystyrene-equivalent value measured by gel permeation chromatography (GPC), and such an acrylic polymer can be obtained by free radical polymerization or living radical polymerization, but the latter is preferred because it produces less low-molecular-weight substances and can be expected to improve adhesive holding power and reduce adhesive residue.

[0041] <Adhesive: Energy Ray Polymerizable Oligomer> The energy ray polymerizable oligomer can be used as an acrylic polymer obtained by reacting an acrylic copolymer containing the energy ray polymerizable oligomer as a monomer unit with an unsaturated group-containing compound having a functional group. The energy ray polymerizable oligomer is not particularly limited as long as it can be polymerized by energy ray irradiation, and examples thereof include photoradical polymerizable oligomers, photocationic polymerizable oligomers, and photoanionic polymerizable oligomers. Photoradical polymerizable oligomers are particularly preferred because they have a fast curing rate, can be selected from a wide variety of compounds, and can easily control the adhesive strength before and after curing to the desired level. Examples of photoradical polymerizable oligomers include urethane (meth)acrylate, polyester (meth)acrylate, epoxy (meth)acrylate, polyol (meth)acrylate, polyether (meth)acrylate, melamine (meth)acrylate, and silicone (meth)acrylate. These may be used alone or in combination of two or more.

[0042] The content of the energy beam-polymerizable oligomer is preferably 10 to 60 parts by mass, more preferably 20 to 50 parts by mass, per 100 parts by mass of the acrylic polymer, and adjusting this amount makes it possible to control the adhesive strength after energy beam irradiation. In addition, a decrease in cohesive strength can be expected to reduce adhesive residue on the adherend.

[0043] Furthermore, it is possible to contain a polyfunctional acrylate or polyfunctional methacrylate, which is a photoradical polymerizable monomer, and it is also possible to use trimethylolmethane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, pentaerythritol tri(meth)acrylate, or ethylene oxide or propylene oxide adducts thereof, which have three or more (meth)acryloyl groups in one molecule.

[0044] When the energy ray-polymerizable oligomer and the energy ray-polymerizable monomer are contained, the total amount thereof is preferably 10 to 60 parts by mass, more preferably 20 to 50 parts by mass, per 100 parts by mass of the acrylic polymer. By adjusting the total content of these within the above range, it becomes possible to control the adhesive strength after energy ray irradiation. Furthermore, the reduced cohesive strength can be expected to reduce adhesive residue on the adherend.

[0045] <Adhesive: Crosslinking Agent> The crosslinking agent constituting the adhesive used in the heat-resistant adhesive film of the present invention is not particularly limited, and examples thereof include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, etc. Examples of the isocyanate-based crosslinking agent include a polyisocyanate compound, a trimer of a polyisocyanate compound, a urethane prepolymer having an isocyanate group at its terminal obtained by reacting a polyisocyanate compound with a polyol compound, and a trimer of the urethane prepolymer. Examples of polyisocyanate compounds include 2,4-tolylene diisocyanate, 2,5-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, diphenylmethane-4,4'-diisocyanate, 3-methyldiphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, dicyclohexylmethane-2,4'-diisocyanate, and lysine isocyanate.

[0046] Furthermore, examples of the epoxy crosslinking agent include polyfunctional epoxy compounds such as sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, glycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and polybutadiene diglycidyl ether.

[0047] The crosslinking agents can be used alone or in combination of two or more, and can be selected appropriately depending on the type of acrylic ester polymer, etc. A small content can result in insufficient adhesion to the substrate and insufficient strength of the adhesive layer, while a large content can cause problems such as adhesive residue due to the generation of unreacted substances, so the content is preferably 0.01 to 15 parts by mass per 100 parts by mass of the acrylic polymer, depending on the type of crosslinking agent. In addition, additives such as silane coupling agents, tackifiers, metal chelating agents, surfactants, antioxidants, pigments, dyes, colorants, antistatic agents, preservatives, antifoaming agents, and wettability adjusters can be added as needed within a range that does not impair the object of the present invention.

[0048] <Adhesive: Polymerization Initiator> The polymerization initiator constituting the adhesive used in the heat-resistant adhesive film of the present invention increases the sensitivity of the energy ray-polymerizable oligomer described above, making it possible to reduce the polymerization and curing time due to energy rays and the amount of energy ray irradiation. Examples of the polymerization initiator include benzoin derivatives, acylphosphine oxides such as monoacylphosphine oxide and bisacylphosphine oxide, benzil ketal compounds such as 2,2-dimethoxy-2-phenylacetophenone, and diallyl ketones such as benzophenone. The polymerization initiator is selected depending on the type of acrylic ester polymer, and it is preferable to select one with a long limit absorption wavelength, as this will result in stable polymerization initiation. Furthermore, if the content of the polymerization initiator is low, the polymerization initiation reaction will be insufficient and the adhesive strength will not decrease sufficiently. If the content is high, the energy rays will only reach the vicinity of the energy ray-irradiated surface, resulting in insufficient curing and the adhesive strength will not decrease sufficiently. Therefore, the content of the polymerization initiator is preferably 0.01 to 10 parts by mass per 100 parts by mass of the acrylic polymer and the energy ray-polymerizable oligomer combined.

[0049] <Adhesive Layer: Layer Thickness> The thickness of the adhesive layer is 5 to 50 μm. The preferred range varies depending on the method of use, but is usually 10 to 30 μm. However, in the case of an uneven surface, 20 to 50 μm is preferred in order to conform to the unevenness. Within the above range, the adhesive properties are stable. Note that if the thickness is less than 5 μm, sufficient adhesive strength may not be obtained, and if it exceeds 50 μm, energy rays may not sufficiently penetrate into the adhesive layer, resulting in a loss of adhesive strength.

[0050] UV (ultraviolet rays) are commonly used as energy rays, and examples include high-pressure mercury lamps, ultra-high-pressure mercury lamps, carbon arc lamps, metal halide lamps, xenon lamps, and chemical lamps that emit light in the wavelength range of 150 to 450 nm. Although it depends on the thickness of the adhesive layer, the cumulative light amount is 50 mJ / cm. 2 More than 150 mJ / cm 2 or more, and even more, 300 mJ / cm 2 A stable decrease in adhesive strength can be obtained when the temperature is above this level.

[0051] <Adhesive Layer: Adhesive Strength> The adhesive strength of a typical adhesive film is measured by attaching the adhesive surface of the adhesive film to a target SUS-BA plate, pressing it from the substrate side with a 2 kg roller, and then performing the specified treatment. Then, the adhesive strength is measured using a universal testing machine (JIS Z0237 compliant: peel speed 300 mm / min, peel distance 50 mm, peel angle 180°). The initial adhesive strength is measured after 20 minutes of standing at room temperature and humidity. Generally, a SUS-BA plate is used as the target, but as long as there are no significant differences in surface properties such as unevenness, high adhesive strength is exhibited for highly flat targets such as silicon wafers, dummy wafers, and mirror-finished wafers. Furthermore, high adhesive strength is exhibited when the adhesive film substrate has a low modulus of elasticity and / or a small thickness.

[0052] The adhesive strength of the heat-resistant adhesive film of the present invention is measured by the method described above. While the value varies depending on the application and the surface properties of the bonding surface, an initial adhesive strength of 2.0 N / 25 mm to 20 N / 25 mm is preferred to prevent slippage of the adhesive surface, and 2.0 N / 25 mm to 15 N / 25 mm is preferred to facilitate re-application and other operations. Furthermore, when using porous or polymeric materials that do not provide sufficient flatness during cutting in the semiconductor manufacturing process, the cut chips may peel off, so an initial adhesive strength of 4.0 N / 25 mm to 15 N / 25 mm is preferred.

[0053] The adhesive strength of the heat-resistant adhesive film of the present invention is preferably 2.0 N / 25 mm to 20 N / 25 mm even when heated as a predetermined treatment, and the adhesive strength after heating preferably does not exceed twice the initial adhesive strength. In the present invention, the adhesive strength after heat treatment is measured by evaluating the adhesive layer that has been heat-treated at 180°C for 1 hour.

[0054] In the heat-resistant adhesive film of the present invention, the adhesive layer has an adhesive strength of 1.2 N / 25 mm or less, for example, 1.0 N / 25 mm or less, or 0.9 N / 25 mm or less, or even 0.85 N / 25 mm or less, measured under conditions of heat treatment at 180°C for 1 hour and UV irradiation. The adhesive layer may also have an adhesive strength of 0.1 N / 25 mm or more, measured under conditions of heat treatment at 180°C for 1 hour and UV irradiation. In the present invention, UV irradiation during adhesive strength measurement is performed with an integrated light dose of 300 mJ / cm. 2 The pressure-sensitive adhesive layer of the present invention can exhibit adhesive strength within the above range after heat treatment at 180°C for 1 hour and UV irradiation, meaning that both the substrate and the pressure-sensitive adhesive layer exhibit excellent heat resistance. Furthermore, in the present invention, even when treatment and processing are performed at temperatures exceeding 150°C, the substrate film can retain the adhesive layer without deformation. Furthermore, since the adhesive strength can be reduced by UV irradiation, semiconductor products can be processed at temperatures exceeding 150°C, for example, at 180°C to 200°C, and the semiconductor products can also be easily removed from the pressure-sensitive adhesive layer by UV irradiation.

[0055] The adhesive layer has an adhesive strength of 1.5 N / 25 mm or less, for example, 1.3 N / 25 mm or less, or 1.1 N / 25 mm or less, or even 1.0 N / 25 mm or less, measured under conditions of heat treatment at 200°C for 1 hour and UV irradiation. The adhesive layer may also have an adhesive strength of 0.1 N / 25 mm or more, measured under conditions of heat treatment at 200°C for 1 hour and UV irradiation. For example, the adhesive strength measured under conditions of heat treatment at 200°C for 1 hour and UV irradiation may be higher than the adhesive strength measured under conditions of heat treatment at 180°C for 1 hour and UV irradiation. The present invention can exhibit excellent heat resistance and expandability not only after heating to 180°C but also after heating to 200°C.

[0056] When the heat-resistant adhesive film of the present invention is subjected to a heat treatment such as drying or annealing before UV irradiation, a heating temperature of 110°C or higher is effective, and depending on the situation, 160°C or higher is preferred, and 180°C or higher can shorten the heat treatment time. The upper limit is below the melting point of the substrate of the heat-resistant adhesive film. Furthermore, depending on the method and temperature of the heat treatment, the continuous treatment time can be 15 minutes or more, and even 60 minutes is possible.

[0057] In another aspect, the present invention provides a surface protection film having the heat-resistant adhesive film of the present invention. Also, the present invention provides a film for semiconductor manufacturing having the heat-resistant adhesive film of the present invention.

[0058] This application claims the benefit of priority based on Japanese Patent Application No. 2023-200755, filed on November 28, 2023. The entire contents of the specification of Japanese Patent Application No. 2023-200755, filed on November 28, 2023, are incorporated herein by reference.

[0059] The present invention will be described in more detail below with reference to examples. Note that the present invention is not limited to the following examples, and modifications can be made within the scope of the present invention, and all such modifications are included in the technical scope of the present invention.

[0060] The physical properties in the examples were evaluated as follows.

[0061] (1) Number average molecular weight: Elastomer An aliphatic polycarbonate diol sample was dissolved in deuterated chloroform (CDCl), and the number of terminal groups was calculated by measuring H-NMR, and the number average molecular weight was determined using the following formula: Number average molecular weight = 1,000,000 / ((amount of terminal groups (equivalents / ton)) / 2)

[0062] (2) Reduced viscosity: Elastomer In accordance with JIS K 7367-5:1998 “Plastics—Method for determining viscosity of diluted polymer solutions using a capillary viscometer,” a mixed solvent of phenol / tetrachloroethane=60 / 40 (mass%) was used, and the viscosity number obtained by measurement using an Ostwald viscometer was defined as the reduced viscosity.

[0063] (3) Soft (segment) content: elastomer Using a Fourier transform nuclear magnetic resonance spectrometer (AVANCE-NEO500 manufactured by BRUKER, Germany), the elastomer was dissolved in a solvent (deuterated chloroform / trifluoroacetic acid = 85 / 15 vol %) to a concentration of 3 to 5 vol %, and then subjected to proton NMR measurement at 25°C. The mass ratio of the hard segment to the soft segment was calculated from the signal intensity ratio of the methylene peaks adjacent to various oxygen atoms in the molecular structure.

[0064] (4) Film Thickness: Measured in accordance with JIS K 7130:1999 "Method for measuring thickness of plastic films and sheets (Method A)."

[0065] (5) Tm (melting point) and heat resistance According to JIS K 7121:1987 "Method for measuring transition temperatures of plastics," the melting peak temperature in the curve obtained by DSC (differential scanning calorimetry) was used. The obtained melting points were evaluated as follows. [Evaluation] ◎: Melting point is 200°C or higher ○: Melting point is 190°C or higher but lower than 200°C △: Melting point is 180°C or higher but lower than 190°C ×: Melting point is lower than 180°C

[0066] (6) Strength, elongation, modulus of elasticity, F25, F50 According to JIS K 7127:1999 "Plastics - Testing methods for tensile properties", strength, elongation, and modulus of elasticity were determined from tensile strength, tensile elongation at break, and tensile modulus of elasticity. The specified strains were set to 25% and 50%, and the tensile stresses were designated as F25 and F50. The index of extensibility is expressed as the ratio of stresses at the specified strains, F50 / F25. Since the longitudinal and transverse directions of the film are almost equivalent, the longitudinal direction was used as the representative value.

[0067] (7) Extensibility The target film was attached to a frame with an inner diameter of 220 mm with double-sided tape and pressed with a rubber ring to fix it on the outer periphery of the stage described below. The center point and the intersection points of four lines at 45-degree intervals from the center and a circle with a diameter of 100 mm were used as rating points. The film was expanded by raising the stage (diameter 200 mm, rising speed 50 mm / min, held for 60 seconds) so that the set elongation calculated on the stage by the following formula was 20%, and the resulting elongation between the rating points was evaluated as follows. Set elongation (%) = (amount of stage rise × 2) / stage diameter × 100 [Evaluation] ◎: Reached 45% or more of the set elongation in all directions, with a maximum difference of less than 2%. ○: Reached 45% or more of the set elongation in all directions, with a maximum difference of 2 to 5%. △: Reached 25% or more but less than 45% of the set elongation in some or all directions, with a maximum difference of 2 to 5%. ×: Reached less than 25% of the set elongation in some or all directions, or with a maximum difference of 5% or more.

[0068] (8) Coatability In the following examples and comparative examples, the prepared coating liquid was applied to a polyethylene terephthalate release film having a silicone-based release agent layer, dried to form an adhesive layer, and then laminated to a substrate to obtain a process, and the resulting A4-sized cut adhesive film was evaluated for the following items. [Evaluation] ◎: No curling in the adhesive sheet sheets ○: Curling occurs in the adhesive sheet sheets, but this can be addressed by adjusting the tension of the sheet-like material △: Curling occurs in the adhesive sheet sheets, and this can be addressed by adjusting the tension of the sheet-like material ×: It is difficult to adjust the tension of the sheet-like material when laminating, and unevenness in the adhesive thickness occurs in the adhesive sheet sheets

[0069] (9) Adhesive strength The adhesive surface of the adhesive film was attached to a target SUS-BA plate, pressed from the substrate side with a 2 kg roller, and after performing the specified treatment, the adhesive strength was measured using a universal material testing machine in accordance with JIS Z 0237:2009 "Test method for adhesive tapes and adhesive sheets" (peel speed 300 mm / min, peel distance 50 mm, peel angle 180°). When heat treatment was performed, the film was treated for 1 hour in a hot air oven set at a specified temperature, and then exposed to a high-pressure mercury lamp with an integrated light intensity of 300 mJ / cm. 2 The sample was subjected to UV irradiation.

[0070] (10) Post-process evaluation For the adhesive films obtained in the following examples and comparative examples, the release film was peeled off and the adhesive surface was attached to the #2,000 polished surface of a 300 μm thick 6-inch silicon wafer on a tape mounter, and nine of the silicon wafers were cut into chips measuring 2 mm × 2 mm using a dicing device, and spin-cleaned and dried using a cleaning device. Chip flying was visually confirmed and the following judgment was made. [Evaluation] ○: No chip flying △: Chip flying occurred on two or less silicon wafers ×: Chip flying occurred on three or more silicon wafers The silicon wafers were then irradiated with a UV irradiation device using a high-pressure mercury lamp at an integrated light intensity of 300 mJ / cm 2 The silicon wafer was irradiated with UV at 180°C, chips were picked up using a pick-up device attached to the expanding equipment, and the following judgment was made visually. Furthermore, the silicon wafer was separately heat-treated in a 180°C hot air oven for 1 hour, and thereafter UV was irradiated and chips were picked up in the same manner, and the following judgment was made visually. Furthermore, the silicon wafer was separately heat-treated in a 200°C hot air oven for 1 hour, and thereafter UV was irradiated and chips were picked up in the same manner, and the following judgment was made visually. [Evaluation] ○: No failure in picking up △: There was a failure in picking up, and picking continued after adjusting the conditions ×: There was a failure in picking up, and picking was difficult even after adjusting the conditions

[0071] Next, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0072] Examples 1 to 4, Comparative Example 1, Reference Example 1 A mixture of commercially available 1,6-hexanediol-type aliphatic polycarbonate diol (molecular weight 2,000) and diphenyl carbonate was reacted at 205°C and 130 Pa for 2 hours to obtain a mixture (number average molecular weight 2,000). Polybutylene terephthalate (PBT) was then condensed under elevated temperature and reduced pressure to obtain a resin having a predetermined soft segment mass ratio. The resulting resin was extruded from a T-die through an extruder and pressed against an embossed metal cooling roll with a nip roll to obtain a 100 μm-thick film-like material made of a thermoplastic polyester-based resin elastomer. The thicker end of this film was then trimmed off, and the resulting material was heat-treated at a predetermined temperature by contact with an electric heating roll (approximately 2 seconds) in the process to obtain a substrate. Next, a solution (solids content 50% by weight) of a mixture mainly composed of an energy beam polymerizable oligomer of an acrylic polymer containing a hydroxyl group-containing monomer and a carboxyl group-containing monomer as the main agent of the adhesive, and an epoxy (meth)acrylate oligomer was added to 100 parts by weight of a solution of a crosslinking agent mainly composed of tolylene diisocyanate (solids content 75% by weight), 0.12 parts by weight, and 0.9 parts by weight of a polymerization initiator (solids content 100% by weight) mainly composed of a benzyl ketal compound, and the resulting mixture was diluted with a mixed solvent of ethyl methyl ketone and ethyl acetate to prepare an adhesive coating liquid. The adhesive coating liquid was applied to a polyethylene terephthalate release film having a silicone-based release agent layer, and after drying at 100 to 120 ° C., the adhesive layer thickness was adjusted to 10 μm, and then the adhesive was bonded to the above-mentioned substrate and aged for 3 days under conditions of 40 ° C. to obtain samples of Examples 1 to 4 and Comparative Example 1. In Comparative Example 1, the adhesive was not contacted with the electric heating roll, and the F50 / F25 value was outside the range of the present invention. Also, an adhesive tape was obtained as Reference Example 1 using a 100 μm thick substrate made of a polyethylene resin film coated with 10 μm of a commercially available UV-curable acrylic adhesive.

[0073]

[0074] Examples 5-8, Comparative Examples 2-3: Dimethyl terephthalate and 1,4-butanediol were charged together with a catalyst, and transesterified using conventional methods. Polytetramethylene glycol with a number-average molecular weight of 1,000 was then added, and polycondensation was carried out while increasing the temperature and reducing the pressure, yielding a resin with a predetermined soft segment mass ratio. The resulting resin was extruded through a T-die in an extruder and pressed against an embossed metal cooling roll with a nip roll to obtain a 100 μm-thick film-like material in which the thermoplastic polyester resin was an elastomer. The thicker end of the film was trimmed off, and then the film was heat-treated at a predetermined temperature by contact with an electric heating roll (approximately 2 seconds) in the process to obtain a substrate. Subsequently, as in Examples 1-4 and Comparative Example 1, a release film was coated with a pressure-sensitive adhesive coating solution to a thickness of 10 μm, and then laminated to the above-mentioned substrate to obtain samples for Examples 5-8 and Comparative Examples 2-3. In Comparative Example 2, the resin melting point was 180°C or lower, and the heat treatment temperature was 22°C lower than the resin melting point, so the two conditions of the present invention, i.e., the resin melting point and the heat treatment temperature, were not satisfied, resulting in inferior heat resistance and coatability compared to the examples of the present invention.

[0075]

[0076] Post-process evaluation was performed on the adhesive tapes of Examples 1 to 8, Comparative Examples 1 to 3, and Reference Example 1 described above. As a result, it was found that Examples 1 to 8, in which an elastomer was applied to a thermoplastic polyester resin, can be used in processes that involve heat treatment, and are suitable as heat-resistant adhesive films that are suitable for processes in which chips are cut and separated to fix them and are subjected to high-temperature treatment exceeding 150°C during the semiconductor manufacturing process.

[0077]

[0078] Example 9 A biaxially stretched film (thickness 100 μm, strength 200 MPa, elongation 160%, elastic modulus 4,300 MPa) of polyethylene terephthalate, a commonly available thermoplastic polyester resin, was used as a film-like substrate, and thereafter, in the same manner as in Examples 1 to 8 and Comparative Examples 1 to 3, a pressure-sensitive adhesive coating liquid was applied to a release film to a layer thickness of 10 μm, and then this was laminated to the above-mentioned substrate to obtain a sample of Example 9 (adhesive strength: initial 5.8 N / 25 mm, after 180°C UV 0.38 N / 25 mm, after 200°C UV 0.42 N / 25 mm).

[0079] The adhesive films obtained in Examples 1, 8, and 9 above were attached with a 100 mm x 100 mm x 800 μm thick epoxy resin GFRP (glass fiber reinforced plastic) on the adhesive surface after the release film had been peeled off. The film was then placed in a transfer molding machine (mold temperature 160°C), epoxy resin was filled into the mold, and the film was removed from the mold after about 3 minutes. The film was then cut into chips measuring 10 mm square using a dicing machine, dried, and heat-treated in a hot air oven at 200°C for 1 hour. The film was then irradiated with a UV irradiator using a high-pressure mercury lamp at an integrated light dose of 300 mJ / cm. 2 The adhesive film was irradiated with UV light and chips were picked up using a pick-up device, but no abnormalities were found on the cut surface of any of the adhesive films, and there were no failures in picking up chips.

[0080] The heat-resistant film of the present invention uses a thermoplastic polyester resin and a polyester elastomer that uses a resin composed of a hard segment made of a polyester composed of an aromatic dicarboxylic acid and an aliphatic diol or an alicyclic diol, and a soft segment formed by bonding a soft segment made of an aliphatic diol or an alicyclic diol, thereby achieving high heat resistance. Furthermore, when the thermoplastic polyester resin is an elastomer, the specified mass ratio of the hard segment to the soft segment provides extensibility, and further, even higher extensibility can be achieved by subjecting the film to a specified heat treatment.

[0081] The heat-resistant adhesive film of the present invention uses a thermoplastic polyester resin and has its characteristic high heat resistance. Furthermore, when the thermoplastic polyester resin is an elastomer, by adjusting the amount of the soft segment constituting the resin to an appropriate level, high extensibility can be achieved, and a stable adhesive film can be obtained even in processing steps such as coating. For these reasons, the film is suitable as a surface protection film for protecting the surface condition of plastic products, glass products, ceramic products, etc., which have been processed to be conductive or decorated by printing, etc. In particular, the film is suitable as a transport film for fixing chips during cutting and separation in the semiconductor manufacturing process, and for use in processes where high-temperature processing exceeding 150°C is performed.

Claims

1. A heat-resistant adhesive film having, in that order, a base film made of a thermoplastic polyester resin and an adhesive layer, wherein the base film has a melting point of 150°C or higher, a tensile modulus of elasticity of 30 to 5,500 MPa, a tensile breaking elongation of 10 to 1,100%, and a ratio F50 / F25 of a stress F50 at 50% elongation to a stress F25 at 25% elongation of 0.95 or higher, the adhesive layer is an ultraviolet-curing adhesive layer, and the adhesive layer has an adhesive strength of 1.2 N / 25 mm or less when measured under conditions of heat treatment at 180°C for 1 hour and UV irradiation.

2. The heat-resistant adhesive film according to claim 1, wherein the thickness of the base film is 50 to 250 μm, and the thickness of the adhesive layer is 5 to 50 μm.

3. The heat-resistant adhesive film according to claim 1, wherein the base film is a thermoplastic polyester-based elastomer comprising a hard segment having a polyester unit composed of an aromatic dicarboxylic acid and an aliphatic diol or an alicyclic diol, and a soft segment composed of an aliphatic diol, an alicyclic diol, or an aliphatic polycarbonate, and the amount of the soft segment is 30% by mass or more in 100% by mass of the thermoplastic polyester-based elastomer.

4. The heat-resistant adhesive film according to claim 3, wherein the melting point of the thermoplastic polyester elastomer constituting the base film is 180°C or higher, and the base film is a base material that has undergone a heat treatment process at 110°C or higher.

5. A surface protection film having the heat-resistant adhesive film according to any one of claims 1 to 4.

6. A film for semiconductor manufacturing, comprising the heat-resistant adhesive film according to any one of claims 1 to 4.