Adhesive film

Abstract

An adhesive film used in a manufacturing process for an electronic device, wherein the deformation ratio at 100°C is 2.0% to 70.0%, and the deformation ratio at 150°C is 25.0% or less.

Description

adhesive film

[0001] The present invention relates to an adhesive film.

[0002] Some manufacturing methods for electronic devices include a process of forming a circuit on an electronic component, followed by a process such as backgrinding (grinding), ion implantation, laser annealing, or sputtering on the surface of the electronic component opposite the circuit-formed surface. In these processes, an adhesive film is used to protect the circuit-formed surface of the electronic component. Examples of technologies related to such adhesive films include those described in Patent Document 1 (International Publication No. 2015 / 152010).

[0003] Patent Document 1 describes a protective film that is attached to the circuit-forming surface of a semiconductor wafer, the protective film having a polyimide substrate and a thermosetting adhesive layer provided on one surface of the polyimide substrate and obtained from a composition including an acrylic polymer (a), a thermal radical generator (b) having a 1-minute half-life temperature of 140° C. or more and 200° C. or less, and a crosslinking agent (c). Patent Document 1 also describes that when the protective film is applied to a semiconductor device manufacturing method including a step of attaching the protective film to the circuit-forming surface of the semiconductor wafer, thermally curing the thermosetting adhesive layer, and then performing vacuum heating while the protective film is attached to the semiconductor wafer, the protective film can protect the circuit-forming surface of the semiconductor wafer, suppress the occurrence of lifting, and have excellent releasability when peeled from the semiconductor wafer.

[0004] International Publication No. 2015 / 152010

[0005] In such a method for manufacturing an electronic device, if the adhesion between the electronic component and the adhesive film is insufficient, water or chemicals may penetrate between the electronic component and the adhesive film, causing deterioration of the electronic component.

[0006] According to the studies of the present inventors, it has been found that in order to improve the adhesion between an electronic component and an adhesive film and to protect the electronic component, the adhesive film needs to be able to follow the irregularities of the circuit-forming surface when attached to the circuit-forming surface of the electronic component (irregularity-following ability), and also needs to be able to prevent the adhesive film attached to the electronic component from floating even in a vacuum atmosphere (vacuum resistance).

[0007] Furthermore, according to the study by the present inventors, it has been found that while a method of making the adhesive film flexible can be used to improve the conformability to uneven surfaces, the adhesive film is prone to deformation in a vacuum atmosphere and is prone to floating from electronic components. On the other hand, a method of making the adhesive film hard can be used to improve vacuum resistance, but it has been found that the conformability to uneven surfaces when attached to electronic components is insufficient. In other words, it has been found that there is a trade-off between the conformability to uneven surfaces and vacuum resistance of the adhesive film.

[0008] The present invention has been made in view of the above circumstances, and provides a pressure-sensitive adhesive film having an improved balance of conformability to irregularities and vacuum resistance.

[0009] According to the present invention, there is provided the following adhesive film.

[0010] [1] An adhesive film used in a manufacturing process for an electronic device, wherein the deformation rate at 100°C calculated by the following method 1 is 2.0% or more and 70.0% or less, and the deformation rate at 150°C calculated by the following method 2 is 25.0% or less. [Method 1] A measurement sample is prepared by stacking n sheets of the adhesive film until the thickness is 1.4±0.1 mm, and the measurement sample is cut to a width of 10 mm. The amount of deformation when a load of 10 N is continuously applied to the measurement sample using a dynamic viscoelasticity measuring device under the following conditions: temperature: 100°C, deformation mode: compression, upper jig: three-point bending (indenter tip: 2.5R), lower jig: parallel plate, measurement time: 1000 seconds, atmosphere: nitrogen, is measured, and the value calculated by the formula "(deformation amount at 600 seconds [μm] / number of stacked measurement samples n / thickness per sheet of the adhesive film [μm]) × 100" is defined as the deformation rate [%] at 100°C. [Method 2] A sample obtained by stacking n sheets of the pressure-sensitive adhesive film until the thickness reached 1.4±0.1 mm was subjected to heat treatment at 130°C for 30 minutes to prepare a measurement sample, and the measurement sample was cut to a width of 10 mm. The measurement sample was measured using a dynamic viscoelasticity measuring device under the following conditions: temperature: 150°C, deformation mode: compression, upper jig: three-point bending (indenter tip: 2.5R), lower jig: parallel plate, measurement time: 1000 seconds, atmosphere: nitrogen, and the deformation amount when a load of 5 N was continuously applied was measured. The value calculated by the formula "(deformation amount at 600 seconds [μm] / number of layers n of the measurement sample / thickness per sheet of the pressure-sensitive adhesive film [μm]) × 100" is the deformation rate [%] at 150°C. [2] An adhesive film used in the manufacturing process of an electronic device, wherein the deformation amount at 100°C calculated by the following method 3 is 1.0 μm or more and 100.0 μm or less, and the deformation amount at 150°C calculated by the following method 4 is 35.0 μm or less.[Method 3] A measurement sample is prepared by stacking n sheets of the pressure-sensitive adhesive film until the thickness reaches 1.4±0.1 mm, and the measurement sample is cut to a width of 10 mm. Using a dynamic viscoelasticity measuring device, the deformation amount when a load of 10 N is continuously applied is measured under the following conditions: temperature: 100°C, deformation mode: compression, upper jig: three-point bending (indenter tip: 2.5R), lower jig: parallel plate, measurement time: 1000 seconds, atmosphere: nitrogen, and the value calculated by the formula "deformation amount at 600 seconds [μm] / number n of stacked measurement samples" is defined as the deformation amount at 100°C [μm]. [Method 4] A sample obtained by laminating n sheets of the pressure-sensitive adhesive film until the thickness reaches 1.4±0.1 mm is subjected to heat treatment at 130°C for 30 minutes to prepare a measurement sample, and the measurement sample is cut into a width of 10 mm. The measurement sample is measured using a dynamic viscoelasticity measuring device under the following conditions: temperature: 150°C, deformation mode: compression, upper jig: three-point bending (indenter tip: 2.5R), lower jig: parallel plate, measurement time: 1000 seconds, atmosphere: nitrogen, and the deformation amount when a load of 5 N is continuously applied is measured. The value calculated by the formula "deformation amount [μm] at 600 seconds / number n of layers of the measurement sample" is defined as the deformation amount [μm] at 150°C. [3] The pressure-sensitive adhesive film according to [1] or [2] above, comprising, in this order, a base layer, an irregularity-absorbing resin layer, and a thermosetting pressure-sensitive adhesive layer. [4] The pressure-sensitive adhesive film according to [3], wherein the irregularity-absorbing resin layer and the thermosetting adhesive layer are provided so as to be in direct contact with each other. [5] The pressure-sensitive adhesive film according to [3] or [4], wherein the thermosetting adhesive layer contains a (meth)acrylic resin and a thermal polymerization initiator. [6] The pressure-sensitive adhesive film according to any one of [3] to [5], wherein the resin constituting the irregularity-absorbing resin layer contains at least one selected from the group consisting of an ethylene-vinyl acetate copolymer, a (meth)acrylic resin, an ethylene-α-olefin copolymer, and a low-density polyethylene. [7] The pressure-sensitive adhesive film according to any one of [3] to [6], wherein the thickness of the irregularity-absorbing resin layer is 20 μm or more and 500 μm or less.[8] The pressure-sensitive adhesive film according to any one of [3] to [7], wherein the resin constituting the base layer comprises at least one selected from the group consisting of polyethylene naphthalate, polyethylene terephthalate, and polyimide. [9] The pressure-sensitive adhesive film according to any one of [1] to [8], wherein the manufacturing process of the electronic device comprises: a step (A) of preparing a structure including an electronic component having a circuit-forming surface and the pressure-sensitive adhesive film attached to the circuit-forming surface side of the electronic component; and a step (B) of treating the surface of the electronic component opposite to the circuit-forming surface side in a vacuum atmosphere.

[10] The pressure-sensitive adhesive film according to any one of [1] to [9], wherein the electronic device is a power semiconductor device.

[0011] According to the present invention, it is possible to provide a pressure-sensitive adhesive film having an improved balance of conformability to irregularities and vacuum resistance.

[0012] 1 is a cross-sectional view schematically showing a preferred layer structure of an adhesive film according to an embodiment of the present invention. 2 is a cross-sectional view schematically showing a structure in step (A) of a method for producing an electronic device according to an embodiment of the present invention.

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all drawings, similar components are designated by common symbols and their descriptions will be omitted where appropriate. The drawings are schematic and do not correspond to actual dimensional ratios. Furthermore, the numerical range "A to B" represents A or more and B or less unless otherwise specified. Furthermore, in this embodiment, "(meth)acrylic" means acrylic, methacrylic, or both acrylic and methacrylic. Furthermore, unless otherwise specified, "the adhesive film of this embodiment" means an embodiment including both the "adhesive film of the first embodiment" and the "adhesive film of the second embodiment."

[0014] <Adhesive Film> The adhesive film of the first embodiment is an adhesive film used in the manufacturing process of an electronic device, and has a deformation rate of 2.0% or more and 70.0% or less at 100°C, and a deformation rate of 25.0% or less at 150°C. Here, the deformation rate at 100°C means a value calculated by the following method 1. Also, the deformation rate at 150°C means a value calculated by the following method 2. [Method 1] A measurement sample is prepared by stacking n sheets of pressure-sensitive adhesive film until the thickness reaches 1.4±0.1 mm, and the measurement sample is cut to a width of 10 mm. The measurement sample is measured using a dynamic viscoelasticity measuring device under the following conditions: temperature: 100°C, deformation mode: compression, upper jig: three-point bending (indenter tip: 2.5R), lower jig: parallel plate, measurement time: 1000 seconds, atmosphere: nitrogen, and the deformation amount when a load of 10 N is continuously applied is measured. The value calculated by the formula "(deformation amount at 600 seconds [μm] / number of layers of the measurement sample n / thickness per sheet of the pressure-sensitive adhesive film [μm]) × 100" is defined as the deformation rate [%] at 100°C. [Method 2] A sample obtained by laminating n sheets of pressure-sensitive adhesive film until the thickness is 1.4±0.1 mm is subjected to heat treatment at 130°C for 30 minutes to prepare a measurement sample, and the measurement sample is cut to a width of 10 mm. The measurement sample is measured using a dynamic viscoelasticity measuring device under the following conditions: temperature: 150°C, deformation mode: compression, upper jig: three-point bending (indenter tip: 2.5R), lower jig: parallel plate, measurement time: 1000 seconds, atmosphere: nitrogen, and the deformation amount when a load of 5 N is continuously applied is measured. The value calculated by the formula "(deformation amount at 600 seconds [μm] / number of laminations of the measurement sample n / thickness per sheet of the pressure-sensitive adhesive film [μm]) × 100" is the deformation rate [%] at 150°C.

[0015] The pressure-sensitive adhesive film of the second embodiment is a pressure-sensitive adhesive film used in the manufacturing process of an electronic device, and has a deformation amount of 1.0 μm or more and 100.0 μm or less at 100° C. and a deformation amount of 35.0 μm or less at 150° C. Here, the deformation amount at 100° C. means a value calculated by the following method 3. The deformation amount at 150° C. means a value calculated by the following method 4. [Method 3] A measurement sample is prepared by stacking n sheets of pressure-sensitive adhesive film until the thickness reaches 1.4±0.1 mm, and the measurement sample is cut to a width of 10 mm. The measurement sample is measured using a dynamic viscoelasticity measuring device under the following conditions: temperature: 100°C, deformation mode: compression, upper jig: three-point bending (indenter tip: 2.5R), lower jig: parallel plate, measurement time: 1000 seconds, atmosphere: nitrogen, and the deformation amount when a load of 10 N is continuously applied is measured. The value calculated by the formula "deformation amount at 600 seconds [μm] / number n of stacked measurement samples" is defined as the deformation amount [μm] at 100°C. [Method 4] A sample obtained by laminating n sheets of pressure-sensitive adhesive film until the thickness reaches 1.4±0.1 mm is subjected to heat treatment at 130°C for 30 minutes to prepare a measurement sample, and the measurement sample is cut to a width of 10 mm. The measurement sample is measured using a dynamic viscoelasticity measuring device under the following conditions: temperature: 150°C, deformation mode: compression, upper jig: three-point bending (indenter tip: 2.5R), lower jig: parallel plate, measurement time: 1000 seconds, atmosphere: nitrogen, and the deformation amount when a load of 5 N is continuously applied is measured. The value calculated by the formula "deformation amount at 600 seconds [μm] / number n of laminated sheets of the measurement sample" is defined as the deformation amount at 150°C [μm].

[0016] As described above, conventional adhesive films used in the manufacturing process of electronic devices have a trade-off between conformability and vacuum resistance. The inventors conducted extensive research to achieve the above-mentioned objectives. As a result, they discovered that the measures of the deformation rate of an adhesive film at 100°C and the deformation rate at 150°C are effective design indicators for improving the balance between conformability and vacuum resistance. Furthermore, they discovered that the measures of the deformation amount of an adhesive film at 100°C and the deformation amount at 150°C are effective design indicators for improving the balance between conformability and vacuum resistance. As described above, the adhesive film of this embodiment makes it possible to improve the balance between conformability and vacuum resistance.

[0017] The pressure-sensitive adhesive film of the first embodiment has a deformation rate of 2.0% or more and 70.0% or less at 100° C., and a deformation rate of 25.0% or less at 150° C. The deformation rate of the pressure-sensitive adhesive film of the first embodiment at 100° C. is preferably 2.5% or more, more preferably 3.0% or more, even more preferably 3.5% or more, even more preferably 4.0% or more, and even more preferably 4.5% or more from the viewpoint of further improving the unevenness-following ability of the pressure-sensitive adhesive film, and is preferably 65.0% or less, more preferably 60.0% or less, even more preferably 55.0% or less, even more preferably 50.0% or less, even more preferably 45.0% or less, and even more preferably 42.0% or less from the viewpoint of further improving the handleability of the pressure-sensitive adhesive film. The deformation rate of the pressure-sensitive adhesive film of the first embodiment at 150°C is preferably 23.0% or less, more preferably 20.0% or less, even more preferably 18.0% or less, and even more preferably 15.0% or less, from the viewpoint of further improving the vacuum resistance of the pressure-sensitive adhesive film, and the lower limit is not particularly limited, but may be, for example, 0.2% or more, or 0.5% or more. The deformation rates of the pressure-sensitive adhesive film of the first embodiment at 100°C and 150°C can be controlled, for example, by the layer structure of the pressure-sensitive adhesive film, the thickness and material of each layer, etc., and specifically, by the resin used in the unevenness-absorbing resin layer, the thermal polymerization initiator contained in the thermosetting pressure-sensitive adhesive layer, etc.

[0018] The pressure-sensitive adhesive film of the second embodiment has a deformation amount of 1.0 μm or more and 100.0 μm or less at 100 ° C., and a deformation amount of 35.0 μm or less at 150 ° C. The deformation amount of the pressure-sensitive adhesive film of the second embodiment at 100 ° C. is preferably 2.0 μm or more, more preferably 3.0 μm or more, even more preferably 4.0 μm or more, and even more preferably 5.0 μm or more from the viewpoint of further improving the unevenness-following ability of the pressure-sensitive adhesive film, and is preferably 95.0 μm or less, more preferably 90.0 μm or less, even more preferably 88.0 μm or less, even more preferably 85.0 μm or less, even more preferably 82.0 μm or less, and even more preferably 80.0 μm or less from the viewpoint of further improving the handleability of the pressure-sensitive adhesive film. The deformation amount of the pressure-sensitive adhesive film of the second embodiment at 150°C is preferably 32.0 μm or less, more preferably 30.0 μm or less, from the viewpoint of further improving the vacuum resistance of the pressure-sensitive adhesive film, and the lower limit is not particularly limited, but may be, for example, 0.1 μm or more, or 0.5 μm or more. The deformation amount of the pressure-sensitive adhesive film of the second embodiment at 100°C and at 150°C can be controlled, for example, by the layer structure of the pressure-sensitive adhesive film, the thickness and material of each layer, etc., and specifically, by the resin used in the unevenness-absorbing resin layer, the thermal polymerization initiator contained in the thermosetting pressure-sensitive adhesive layer, etc.

[0019] The overall thickness of the adhesive film of this embodiment is, from the viewpoint of further improving the handleability of the adhesive film, preferably 10 μm or more, more preferably 20 μm or more, even more preferably 40 μm or more, even more preferably 60 μm or more, even more preferably 80 μm or more, and even more preferably 100 μm or more, and from the viewpoint of further improving the unevenness-following ability of the adhesive film, is preferably 700 μm or less, more preferably 500 μm or less, even more preferably 300 μm or less, even more preferably 250 μm or less, and even more preferably 200 μm or less.

[0020] The layer structure of the pressure-sensitive adhesive film of this embodiment is not particularly limited, and may be a single-layer structure or a multi-layer structure, but a multi-layer structure is preferred. Figure 1 is a cross-sectional view schematically showing a preferred layer structure of the pressure-sensitive adhesive film of this embodiment according to the present invention. As shown in Figure 1, the pressure-sensitive adhesive film 50 of this embodiment preferably comprises a base layer 20, an irregularity-absorbing resin layer 30, and a thermosetting adhesive layer 40 in this order, and more preferably, the irregularity-absorbing resin layer 30 and the thermosetting adhesive layer 40 are provided so as to be in direct contact with each other.

[0021] Hereinafter, each layer constituting the adhesive film 50 of this embodiment will be described.

[0022] [Base layer] The base layer 20 is a layer provided for the purpose of improving the balance of performance such as handleability, mechanical properties, and heat resistance of the pressure-sensitive adhesive film 50. The base layer 20 is not particularly limited, but examples thereof include a resin film. The resin constituting the base layer 20 preferably contains at least one selected from the group consisting of polyethylene naphthalate, polyethylene terephthalate, and polyimide, and more preferably contains polyethylene naphthalate from the viewpoint of further improving vacuum resistance.

[0023] The base layer 20 may be a single layer or two or more layers. The resin film used to form the base layer 20 may be in the form of an unstretched film, or a uniaxially or biaxially stretched film.

[0024] The thickness of the base layer 20 is preferably 10 μm or more, more preferably 20 μm or more, even more preferably 30 μm or more, and even more preferably 40 μm or more, from the viewpoint of further improving the handleability of the adhesive film 50, and is preferably 500 μm or less, more preferably 300 μm or less, even more preferably 200 μm or less, even more preferably 100 μm or less, even more preferably 80 μm or less, and even more preferably 60 μm or less, from the viewpoint of further improving the conformability of the adhesive film 50 to uneven surfaces.

[0025] The substrate layer 20 may be subjected to a surface treatment in order to further improve adhesion to other layers. Specifically, corona treatment, plasma treatment, undercoat treatment, primer coat treatment, etc. may be performed.

[0026] [Irregularity-absorbing resin layer] The irregularity-absorbing resin layer 30 is a layer provided to further improve the balance of the performance of the pressure-sensitive adhesive film 50 between its ability to conform to irregularities and its vacuum resistance.

[0027] The resin constituting the unevenness-absorbing resin layer 30 preferably contains at least one selected from the group consisting of ethylene-vinyl acetate copolymer, (meth)acrylic resin, ethylene-α-olefin copolymer, and low-density polyethylene, more preferably contains one or two selected from the group consisting of ethylene-vinyl acetate copolymer and (meth)acrylic resin, and even more preferably contains ethylene-vinyl acetate copolymer.

[0028] The ethylene-vinyl acetate copolymer of this embodiment is a copolymer of ethylene and vinyl acetate, for example, a random copolymer. The content of structural units derived from vinyl acetate in the ethylene-vinyl acetate copolymer is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, from the viewpoint of further improving the balance between the conformability and vacuum resistance of the PSA film 50. Furthermore, from the viewpoint of further improving the balance between the conformability and vacuum resistance of the PSA film 50, the content is preferably 50% by mass or less, more preferably 45% by mass or less, even more preferably 40% by mass or less, even more preferably 35% by mass or less, even more preferably 30% by mass or less, and even more preferably 25% by mass or less. The vinyl acetate content can be measured in accordance with JIS K7192:1999.

[0029] The ethylene-vinyl acetate copolymer is preferably a binary copolymer consisting of only ethylene and vinyl acetate, but may also contain, in addition to ethylene and vinyl acetate, at least one copolymer component selected from the group consisting of vinyl ester monomers such as vinyl formate, vinyl glycolate, vinyl propionate, and vinyl benzoate; acrylic monomers such as acrylic acid, methacrylic acid, ethacrylic acid, or salts or alkyl esters thereof; etc. When copolymer components other than ethylene and vinyl acetate are contained, the amount of the copolymer components other than ethylene and vinyl acetate in the ethylene-vinyl acetate copolymer is preferably 0.5% by mass or more and 5% by mass or less.

[0030] The melt flow rate (MFR) of the ethylene-vinyl acetate copolymer, measured in accordance with JIS K7210:1999 under conditions of 190°C and a load of 2.16 kg, is preferably 0.1 g / 10 min or more, more preferably 0.5 g / 10 min or more, even more preferably 1.0 g / 10 min or more, even more preferably 1.5 g / 10 min or more, and even more preferably 2.0 g / 10 min or more, from the viewpoint of further improving the formability of the irregularity-absorbing resin layer 30, and is preferably 50 g / 10 min or less, more preferably 40 g / 10 min or less, even more preferably 20 g / 10 min or less, even more preferably 10 g / 10 min or less, even more preferably 5.0 g / 10 min or less, and even more preferably 3.0 g / 10 min or less, from the viewpoint of further improving the storage stability of the pressure-sensitive adhesive film 50.

[0031] The ethylene / α-olefin copolymer of this embodiment is, for example, a copolymer obtained by copolymerizing ethylene with an α-olefin having from 3 to 20 carbon atoms. As the α-olefin, for example, α-olefins having from 3 to 20 carbon atoms can be used alone or in combination of two or more. An α-olefin having from 3 to 10 carbon atoms is preferred, and an α-olefin having from 3 to 8 carbon atoms is more preferred. Specific examples of α-olefins include propylene, 1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene, 3,3-dimethyl-1-butene, 4-methyl-1-pentene, 1-octene, 1-decene, and 1-dodecene. Among these, propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, and 1-octene are preferred due to their ease of availability. The ethylene / α-olefin copolymer may be a random copolymer or a block copolymer, but a random copolymer is preferred from the viewpoint of flexibility.

[0032] The melting point of the resin constituting the unevenness-absorbing resin layer 30 is preferably 40°C or higher, more preferably 50°C or higher, even more preferably 60°C or higher, even more preferably 70°C or higher, and even more preferably 80°C or higher, from the viewpoint of further improving the storage stability of the pressure-sensitive adhesive film 50, and is preferably 100°C or lower, more preferably 95°C or lower, more preferably 90°C or lower, and even more preferably 85°C or lower, from the viewpoint of further improving the unevenness-following ability of the pressure-sensitive adhesive film 50. When two or more types of resins are used to constitute the unevenness-absorbing resin layer 30, the melting point of the resin constituting the unevenness-absorbing resin layer 30 is the peak temperature of the maximum melting peak measured by DSC.

[0033] The irregularity-absorbing resin layer 30 can be obtained, for example, by dry-blending or melt-kneading a resin and an additive to obtain a resin composition, and then extruding or coating and drying the resin composition. Additives may be added as needed. Specific examples of additives include a crosslinking agent and an antioxidant.

[0034] The content of the thermal polymerization initiator contained in the resin composition for forming the irregularity-absorbing resin layer 30 is preferably less than 0.3 parts by mass, more preferably less than 0.1 parts by mass, even more preferably less than 0.01 parts by mass, and even more preferably 0.00 parts by mass, when the entire resin composition for forming the irregularity-absorbing resin layer 30 is taken as 100 parts by mass. If the content of the thermal polymerization initiator contained in the resin composition for forming the irregularity-absorbing resin layer 30 is less than the above-mentioned upper limit, the formability can be further improved when the irregularity-absorbing resin layer 30 is extrusion-molded, and the irregularity-following ability of the adhesive film 50 can also be further improved. Note that the thermal polymerization initiator means the same as the thermal polymerization initiator contained in the thermosetting adhesive layer described below.

[0035] It is preferable that the layer in direct contact with the irregularity-absorbing resin layer 30 contains a thermal polymerization initiator. When the layer in direct contact with the irregularity-absorbing resin layer 30 contains a thermal polymerization initiator, the vacuum resistance of the adhesive film 50 is further improved. Although the exact mechanism is unknown, the inventors believe that this is because, during the manufacturing process of an electronic device, when the temperature of the adhesive film 50 attached to an electronic component becomes high (for example, 150°C or higher), the thermal polymerization initiator contained in the layer in direct contact with the irregularity-absorbing resin layer 30 diffuses into the irregularity-absorbing resin layer 30, hardening the resin that makes up the irregularity-absorbing resin layer 30, hardening the entire adhesive film 50, and making it difficult for the adhesive film 50 attached to the electronic component to lift off.

[0036] The thickness of the unevenness-absorbing resin layer 30 is preferably 20 μm or more, more preferably 30 μm or more, from the viewpoint of further improving the handleability of the adhesive film 50, and is preferably 500 μm or less, more preferably 300 μm or less, even more preferably 200 μm or less, and even more preferably 150 μm or less, from the viewpoint of further improving the performance balance between the unevenness-following ability and vacuum resistance of the adhesive film 50.

[0037] [Thermosetting adhesive layer] The thermosetting adhesive layer 40 is a layer provided for bonding the adhesive film 50 to the circuit-forming surface of an electronic component. The thermosetting adhesive layer 40 can be composed of, for example, a known adhesive, and preferably contains a (meth)acrylic resin and a thermal polymerization initiator.

[0038] Examples of resins contained in the thermosetting adhesive layer 40 include (meth)acrylic resins, silicone resins, urethane resins, olefin resins, and styrene resins. Among these, it is preferable to use a (meth)acrylic resin as the base polymer because it allows for easy adjustment of the adhesive strength.

[0039] Examples of the (meth)acrylic resin of this embodiment include homopolymers of (meth)acrylic acid ester compounds and copolymers of (meth)acrylic acid ester compounds and comonomers. Examples of (meth)acrylic acid ester compounds include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, and glycidyl (meth)acrylate. These (meth)acrylic acid ester compounds may be used alone or in combination of two or more. Examples of comonomers constituting the (meth)acrylic copolymer include vinyl acetate, (meth)acrylonitrile, styrene, (meth)acrylic acid, itaconic acid, (meth)acrylamide, methylol (meth)acrylamide, and maleic anhydride. These comonomers may be used alone or in combination of two or more.

[0040] The thermosetting adhesive layer 40 preferably contains a thermal polymerization initiator. The thermal polymerization initiator of the present embodiment is, for example, at least one selected from the group consisting of a thermal radical polymerization initiator, a thermal cationic polymerization initiator, and a thermal anionic polymerization initiator, and is preferably a thermal radical polymerization initiator.

[0041] The thermal radical polymerization initiator of the present embodiment is at least one selected from the group consisting of peroxides and azo compounds, and is preferably a peroxide. The peroxide of the present embodiment is preferably 1,1-di(t-butylperoxy)-2-methylcyclohexane, 1,1-di(t-butylperoxy)-cyclohexane, 2,2-di(4,4-di-(t-butylperoxy)cyclohexyl)propane, t-butylperoxymaleic acid, t-butylperoxy-3,3,5-trimethylhexanoate, t-butylperoxylaurate, t-butylperoxyisopropyl monocarbonate, t-butylperoxy-2-ethylhexyl monocarbonate, or t-hexylperoxybenzone. The peroxyalkylene oxide contains at least one selected from the group consisting of butyl peroxide, t-butyl peroxyacetate, 2,2-di(t-butylperoxy)butane, t-butylperoxybenzonate, n-butyl-4,4-di-(t-butylperoxy)valerate, di(2-t-butylperoxyisopropyl)benzene, dicumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, t-butylcumyl peroxide, di-t-butyl peroxide, and 2,5-dimethyl-2,5-di(t-butylperoxy)-3-hexyne.

[0042] The peroxide of the present embodiment preferably contains at least one structure selected from the group consisting of the following formula (I) and the following formula (II) in the molecule, and more preferably contains the following structure of formula (II) in the molecule.

[0043]

[0044] In formula (I), the wavy line indicates the point of attachment.

[0045]

[0046] In formula (II), the wavy line indicates the point of attachment.

[0047] The one-minute half-life temperature of the thermal radical polymerization initiator of this embodiment is preferably 140°C or higher, more preferably 145°C or higher, even more preferably 150°C or higher, and preferably 200°C or lower, more preferably 195°C or lower, even more preferably 190°C or lower, even more preferably 185°C or lower, and even more preferably 180°C or lower. When the one-minute half-life temperature of the thermal radical polymerization initiator is equal to or higher than the above-mentioned lower limit, the thermal radical polymerization initiator is less likely to thermally decompose when forming the thermosetting adhesive layer 40 in the manufacturing process of the adhesive film 50, and the unevenness-following ability of the adhesive film 50 is further improved, which is preferable. When the one-minute half-life temperature of the thermal radical polymerization initiator is equal to or lower than the above-mentioned upper limit, the thermal radical polymerization initiator decomposes at a temperature lower than the temperature at which the resin contained in the adhesive film 50 excessively softens, and the vacuum resistance of the adhesive film 50 is further improved, which is preferable.

[0048] The hydrogen abstraction capacity of the thermal radical polymerization initiator of this embodiment is preferably 20% or more, more preferably 25% or more, and even more preferably 30% or more. The upper limit is not particularly limited, but may be 90% or less, or may be 80% or less. When the hydrogen abstraction capacity of the thermal radical polymerization initiator of this embodiment is equal to or greater than the above-mentioned lower limit, the resin contained in the pressure-sensitive adhesive film 50 is more easily crosslinked, and the vacuum resistance of the pressure-sensitive adhesive film 50 is further improved, which is preferable. Here, the hydrogen abstraction capacity refers to a value calculated by a radical trapping method using α-methylstyrene dimer as a radical trapping agent. More specifically, first, the thermal radical polymerization initiator is decomposed in the presence of α-methylstyrene dimer and cyclohexane. Of the radicals generated from the thermal radical polymerization initiator, radicals with weak hydrogen abstraction capacity are captured by α-methylstyrene dimer. On the other hand, radicals with strong hydrogen abstraction capacity abstract hydrogen from cyclohexane, generating cyclohexyl radicals. The cyclohexyl radical is trapped by the α-methylstyrene dimer and converted into a cyclohexyl radical trapping product. The hydrogen abstraction capacity is the ratio (molar fraction) of the amount of the cyclohexyl radical trapping product to the theoretical amount of radicals produced.

[0049] The content of the thermal polymerization initiator contained in the thermosetting adhesive layer 40 is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, and even more preferably 0.5 parts by mass or more, from the viewpoint of further improving the vacuum resistance of the adhesive film 50, relative to 100 parts by mass of the (meth)acrylic resin contained in the thermosetting adhesive layer 40. Furthermore, from the viewpoint of further improving the conformability of the adhesive film 50, the content is preferably 2.0 parts by mass or less, more preferably 1.8 parts by mass or less, and even more preferably 1.5 parts by mass or less. Here, the content of the thermal polymerization initiator contained in the thermosetting adhesive layer 40 refers to the content of the thermal polymerization initiator in the adhesive used to form the thermosetting adhesive layer 40. In other words, the content of the thermal polymerization initiator in this specification refers to the amount charged when forming the thermosetting adhesive layer 40. The contents of the crosslinking agent and polyfunctional acrylate described below also refer to the amount charged, as with the thermal polymerization initiator.

[0050] The thermosetting adhesive layer 40 may contain a crosslinking agent. Examples of the crosslinking agent in this embodiment include epoxy compounds such as sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, and diglycerol polyglycidyl ether; aziridine compounds such as tetramethylolmethane-tri-β-aziridinyl propionate, trimethylolpropane-tri-β-aziridinyl propionate, N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxamide), and N,N'-hexamethylene-1,6-bis(1-aziridinecarboxamide); and isocyanate compounds such as tetramethylene diisocyanate, hexamethylene diisocyanate, and polyisocyanate.

[0051] When the content of the (meth)acrylic resin contained in the thermosetting adhesive layer 40 is taken as 100 parts by mass, the content of the crosslinking agent contained in the thermosetting adhesive layer 40 is, from the viewpoint of further improving the performance balance of the adhesive film 50's ability to follow uneven surfaces and vacuum resistance, preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, even more preferably 0.5 parts by mass or more, even more preferably 1.0 parts by mass or more, even more preferably 1.5 parts by mass or more, even more preferably 2.0 parts by mass or more, and even more preferably 2.3 parts by mass or more; and, from the viewpoint of further improving the performance balance of the adhesive film 50's ability to follow uneven surfaces and vacuum resistance, preferably 10.0 parts by mass or less, more preferably 7.0 parts by mass or less, even more preferably 5.0 parts by mass or less, even more preferably 4.0 parts by mass or less, and even more preferably 3.0 parts by mass or less.

[0052] The thermosetting adhesive layer 40 may further contain a polyfunctional acrylate in addition to the (meth)acrylic resin. The polyfunctional acrylate of this embodiment is an acrylate having two or more radically reactive double bonds. Examples of the polyfunctional acrylate of this embodiment include urethane acrylate, epoxy acrylate, polyester acrylate, polyether acrylate, pentaerythritol polyacrylate, dipentaerythritol polyacrylate, ethoxylated isocyanuric acid triacrylate, trimethylolpropane triacrylate, and ditrimethylolpropane tetraacrylate.

[0053] When the content of the (meth)acrylic resin contained in the thermosetting adhesive layer 40 is taken as 100 parts by mass, the content of the polyfunctional acrylate contained in the thermosetting adhesive layer 40 is preferably 2.0 parts by mass or more, more preferably 3.0 parts by mass or more, and even more preferably 4.0 parts by mass or more, from the viewpoint of further improving the performance balance of the adhesive film 50's ability to follow uneven surfaces and vacuum resistance; and from the viewpoint of further improving the performance balance of the adhesive film 50's ability to follow uneven surfaces and vacuum resistance, the content of the polyfunctional acrylate contained in the thermosetting adhesive layer 40 is preferably 20.0 parts by mass or less, more preferably 15.0 parts by mass or less, and even more preferably 12.0 parts by mass or less.

[0054] The thickness of the thermosetting adhesive layer 40 is not particularly limited, but is preferably 1 μm or more, more preferably 5 μm or more, even more preferably 10 μm or more, even more preferably 15 μm or more, and is preferably 100 μm or less, more preferably 50 μm or less, even more preferably 30 μm or less, even more preferably 25 μm or less.

[0055] The thermosetting adhesive layer 40 can be formed, for example, by applying an adhesive coating liquid onto the roughness-absorbing resin layer 30. The adhesive coating liquid can be applied using conventional coating methods such as a roll coater method, a reverse roll coater method, a gravure roll method, a bar coater method, a comma coater method, or a die coater method. There are no particular restrictions on the drying conditions for the applied adhesive, but it is generally preferable to dry it at a temperature range of 80 to 200°C for 10 seconds to 10 minutes. It is more preferable to dry it at 80 to 170°C for 15 seconds to 5 minutes.

[0056] [Other Layers] An adhesive layer may be provided between each layer of the pressure-sensitive adhesive film 50. This adhesive layer can improve the adhesion between each layer.

[0057] An example of a method for manufacturing the adhesive film 50 according to this embodiment will be described. First, the irregularity-absorbing resin layer 30 is formed by extrusion molding on one surface of the base layer 20. Next, an adhesive coating liquid is applied to the irregularity-absorbing resin layer 30 and dried to form the thermosetting adhesive layer 40, thereby obtaining the adhesive film 50.

[0058] Next, a method for manufacturing the electronic device of this embodiment will be described. The electronic device of this embodiment means elements, devices, and final products to which electronic engineering technology is applied, such as semiconductor devices, power semiconductor devices, semiconductor chips, semiconductor elements, printed wiring boards, electric circuit display devices, information and communication terminals, light-emitting diodes, physical batteries, and chemical batteries. The electronic device of this embodiment is preferably a power semiconductor device. A power semiconductor device is a semiconductor device that controls and converts electric power, and generally has a rated current of 1 A or more.

[0059] The method for manufacturing an electronic device according to the present embodiment is not particularly limited, but preferably includes the steps of: (A) preparing a structure including an electronic component having a circuit-forming surface and the pressure-sensitive adhesive film attached to the circuit-forming surface side of the electronic component; and (B) treating the surface of the electronic component opposite to the circuit-forming surface side in a vacuum atmosphere. Each step of the method for manufacturing an electronic device will be described below.

[0060] 2 is a cross-sectional view schematically illustrating structure 100 in step (A). In step (A), structure 100 is prepared, which includes electronic component 10 having circuit-forming surface 10A and adhesive film 50 attached to the side of electronic component 10 on which circuit is formed 10A.

[0061] Such a structure 100 can be produced by laminating an adhesive film 50 to the circuit-forming surface 10A of the electronic component 10. The method for laminating the adhesive film 50 to the circuit-forming surface 10A of the electronic component 10 is not particularly limited, and the lamination can be performed by a known method. For example, the lamination may be performed manually, or may be performed using a device called an automatic laminating machine to which a roll of adhesive film 50 is attached.

[0062] The circuit formation surface 10A of the electronic device 10 is bonded, for example, while heating the adhesive film 50. The heating temperature is set appropriately depending on the type of adhesive film 50 and is not particularly limited, but may be, for example, 40°C or higher, 45°C or higher, and 120°C or lower, or 110°C or lower.

[0063] The electronic component 10 is not particularly limited as long as it has a circuit-forming surface 10A, and examples thereof include a semiconductor wafer, a sapphire substrate, a lithium tantalate substrate, a mold wafer, a mold panel, a mold array package, a semiconductor substrate, etc., with a semiconductor wafer being preferred. Examples of semiconductor wafers include a silicon wafer, a sapphire wafer, a germanium wafer, a germanium-arsenic wafer, a gallium-phosphorus wafer, a gallium-arsenic-aluminum wafer, a gallium-arsenic wafer, and a lithium tantalate wafer, with a silicon wafer being preferred.

[0064] The circuit-forming surface 10A of the electronic component 10 has, for example, circuits such as wiring, capacitors, diodes, or transistors formed on its surface. The circuit-forming surface may also be plasma-treated. The circuit-forming surface 10A of the electronic component 10 may also have bump electrodes, making it uneven. The bump electrodes are bonded to electrodes formed on the mounting surface when mounting an electronic device on the mounting surface, forming an electrical connection between the electronic device and the mounting surface (such as the mounting surface of a printed circuit board). Examples of bump electrodes include ball bumps, printed bumps, stud bumps, plated bumps, and pillar bumps. In other words, bump electrodes are typically convex electrodes. These bump electrodes may be used alone or in combination. The height and diameter of the bump electrodes are not particularly limited, but are preferably 10 μm or more, more preferably 50 μm or more, and preferably 400 μm or less, more preferably 300 μm or less. The bump pitch is not particularly limited, but is preferably 20 μm or more, more preferably 100 μm or more, and preferably 600 μm or less, more preferably 500 μm or less. The metal constituting the bump electrodes is not particularly limited, and examples thereof include solder, silver, gold, copper, tin, lead, bismuth, and alloys thereof. The adhesive film 50 is preferably used when the bump electrodes are solder bumps. These metals may be used alone or in combination.

[0065] [Step (B)] In step (B), surface 10B of electronic component 10 opposite circuit-forming surface 10A is treated in a vacuum atmosphere. Step (B) is a step that follows step (A). Therefore, in step (B), surface 10B of electronic component 10 in structure 100 opposite circuit-forming surface 10A is treated.

[0066] In step (B), the vacuum atmosphere means a low-pressure state obtained by reducing the pressure below atmospheric pressure using a vacuum device, and may be, for example, 1000 Pa or less, 100 Pa or less, or 10 Pa or less.

[0067] Step (B) may be performed under high-temperature conditions. When step (B) is performed under high-temperature conditions, the temperature of the structure 100 in step (B) is preferably 60°C or higher, more preferably 80°C or higher, even more preferably 100°C or higher, even more preferably 120°C or higher, even more preferably 140°C or higher, and preferably 230°C or lower, more preferably 210°C or lower, even more preferably 190°C or lower, even more preferably 170°C or lower.

[0068] In step (B), the method for treating surface 10B opposite circuit-forming surface 10A of electronic component 10 is not particularly limited, and may be a step in a known method for manufacturing an electronic device. Step (B) is preferably at least one selected from the group consisting of an ion implantation step, a metal film formation step, and an annealing treatment step.

[0069] The method for manufacturing an electronic device according to the present embodiment preferably further includes a step of heating structure 100 as a step prior to step (B). By further including a step of heating structure 100 as a step prior to step (B), the resin contained in adhesive film 50 is thermally cured, and lifting of adhesive film 50 from electronic component 10 in step (B) is more effectively prevented, which is preferable. The temperature of structure 100 in the step of heating structure 100 is preferably 60°C or higher, more preferably 80°C or higher, even more preferably 100°C or higher, even more preferably 120°C or higher, even more preferably 140°C or higher, and preferably 230°C or lower, more preferably 210°C or lower, even more preferably 190°C or lower, even more preferably 170°C or lower.

[0070] [Step (C)] The method for manufacturing an electronic device according to the present embodiment preferably further includes step (C) of removing the adhesive film 50 from the electronic component 10. Step (C) is a step subsequent to step (B). That is, in step (C), the adhesive film 50 is removed from the electronic component 10 in the structure 100.

[0071] The method for removing the adhesive film 50 from the electronic component 10 is not particularly limited, and can be performed, for example, by a known method of peeling the adhesive film 50 from the electronic component 10. The peeling method may be, for example, manual or by a device called an automatic peeler.

[0072] The temperature at which the adhesive film 50 is peeled off from the electronic component 10 may be room temperature (around 25°C), or if the automatic peeling machine is equipped with a heating function, the adhesive film 50 may be peeled off after the structure 100 has been heated to a predetermined temperature (for example, 40°C or higher and 90°C or lower).

[0073] The surface of the electronic component 10 after peeling off the adhesive film 50 may be cleaned as needed. Examples of cleaning methods include wet cleaning such as water cleaning or solvent cleaning, and dry cleaning such as plasma cleaning. In the case of wet cleaning, ultrasonic cleaning may be used in combination. The cleaning method can be appropriately selected depending on the degree of contamination on the surface of the electronic component 10.

[0074] [Step (D)] The method for manufacturing an electronic device according to this embodiment preferably further includes step (D) of backgrinding the surface 10B of the electronic component 10 opposite the circuit-forming surface 10A. Step (D) is performed between steps (A) and (B). "Backgrinding" refers to thinning the electronic component 10 to a predetermined thickness without damaging it. For example, the structure 100 is fixed to a chuck table or the like of a grinding machine, and the surface 10B of the electronic component 10 opposite the circuit-forming surface 10A is ground.

[0075] In this backside grinding operation, the electronic component 10 is ground until its thickness is equal to or less than a desired thickness. The thickness of the electronic component 10 before grinding is determined appropriately depending on the diameter, type, etc. of the electronic component 10, and the thickness of the electronic component 10 after grinding is determined appropriately depending on the size of the resulting chip, type of circuit, etc. Furthermore, if the electronic component 10 is half-cut or has a modified layer formed by laser irradiation, the electronic component 10 is singulated into individual chips.

[0076] The backside grinding method is not particularly limited, and known grinding methods can be used. Grinding can be performed by pouring water over the electronic component 10 and the grinding stone to cool them. If necessary, a dry polishing process, which is a grinding method that does not use grinding water, can be performed at the end of the grinding process. After backside grinding is completed, chemical etching can be performed as needed. Chemical etching can be performed by immersing the electronic component 10 with the adhesive film 50 attached in an etching solution selected from the group consisting of acidic aqueous solutions, such as hydrofluoric acid, nitric acid, sulfuric acid, and acetic acid, alone or in combination, and alkaline aqueous solutions, such as potassium hydroxide and sodium hydroxide. Etching is performed for the purposes of removing distortion on the backside of the electronic component 10, further thinning the electronic component 10, removing oxide films, and pretreatment for forming electrodes on the backside. The etching solution is appropriately selected depending on the purpose.

[0077] [Other Steps] The method for manufacturing an electronic device according to this embodiment may include other steps in addition to those described above. These other steps may be any known method for manufacturing electronic devices. For example, any step commonly performed in the manufacturing process of electronic components, such as a resist step, a developing step, an ashing step, a sputtering step, a dicing step, a die bonding step, a wire bonding step, a flip-chip connection step, a cure heating test step, a sealing step, or a reflow step, may be further included.

[0078] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations can also be adopted.

[0079] The present invention is not limited to the above-described embodiment, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention.

[0080] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited thereto. Details regarding the preparation of adhesive films are as follows.

[0081] <Materials> Base layer 1: polyethylene naphthalate film (manufactured by Toyobo Film Solutions Co., Ltd., trade name: Teonex Q81, thickness: 50 μm) Resin 1: ethylene-vinyl acetate copolymer (manufactured by Mitsui-Dow Polychemicals, trade name: Evaflex EV460, melting point: 84°C, content of structural units derived from vinyl acetate: 19% by mass, MFR (190°C, 2.16 kg): 2.5 g / 10 min) Crosslinking agent 1: isocyanate-based crosslinking agent (manufactured by Mitsui Chemicals, Inc., trade name: Olester P49-75S) Thermal polymerization initiator 1: peroxide (manufactured by Kayaku Nouryon, trade name: Perkadox 12-XL25) Photopolymerization initiator 1: α-aminoketone (manufactured by IGM Resins B.V., trade name: Omnirad 379) Multifunctional acrylate 1: ditrimethylolpropane tetraacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., product name: AD-TMP)

[0082] <Preparation of (meth)acrylic polymer solution a> n-Butyl acrylate (77 parts by mass), methyl methacrylate (16 parts by mass), 2-hydroxyethyl acrylate (7 parts by mass), and t-butylperoxy-2-ethylhexanoate (0.3 parts by mass) as a polymerization initiator were reacted in toluene (20 parts by mass) and ethyl acetate (80 parts by mass) at 85° C. for 10 hours. After completion of the reaction, the solution was cooled, and toluene (30 parts by mass), methacryloyloxyethyl isocyanate (7 parts by mass), and dibutyltin dilaurate (0.05 parts by mass) were added thereto. The mixture was reacted at 85° C. for 12 hours while blowing air into it, yielding (meth)acrylic polymer solution a.

[0083] <Preparation of (meth)acrylic polymer solution b> n-Butyl acrylate (72 parts by mass), methyl methacrylate (18 parts by mass), 2-hydroxyethyl methacrylate (7 parts by mass), acrylic acid (3 parts by mass), and t-butylperoxy-2-ethylhexanoate (0.3 parts by mass) as a polymerization initiator were reacted in toluene (36 parts by mass) and ethyl acetate (53 parts by mass) at 85° C. for 10 hours. After completion of the reaction, the solution was cooled, and toluene (34 parts by mass) was added to obtain (meth)acrylic polymer solution b.

[0084] [Example 1] (Preparation of adhesive coating liquid for thermosetting adhesive layer) To 100 parts by mass of (meth)acrylic polymer solution a (solid content), thermal polymerization initiator 1 (0.8 parts by mass), crosslinking agent 1 (2.56 parts by mass), and polyfunctional acrylate 1 (10 parts by mass) were added to obtain an adhesive coating liquid for a thermosetting adhesive layer.

[0085] (Preparation of adhesive film) Using an extrusion molding machine, resin 1 (100 parts by mass) was extruded onto substrate layer 1. A laminated film was obtained in which a 70 μm thick irregularity-absorbing resin layer was laminated on the substrate layer. Next, the adhesive coating liquid for the thermosetting adhesive layer was applied to a silicone release-treated polyethylene terephthalate film (38 μm) and dried to form a 20 μm thick thermosetting adhesive layer. Next, the obtained thermosetting adhesive layer was attached to the irregularity-absorbing resin layer side of the above-mentioned laminated film to obtain an adhesive film.

[0086] [Examples 2 to 4 and Comparative Example 2] (Preparation of adhesive coating liquid for thermosetting adhesive layer) An adhesive coating liquid for a thermosetting adhesive layer was obtained in the same manner as in Example 1, except that the formulation of the adhesive coating liquid was set to the formulation shown in Table 1. (Production of adhesive film) An adhesive film was obtained in the same manner as in Example 1, except that the thickness of the irregularity-absorbing resin layer was set to the thickness shown in Table 1.

[0087] Example 5 (Preparation of adhesive coating liquid for thermosetting adhesive layer) An adhesive coating liquid for a thermosetting adhesive layer was obtained in the same manner as in Example 1.

[0088] (Preparation of coating liquid for roughness-absorbing resin layer) Crosslinking agent 1 (0.3 parts by mass) was added to (meth)acrylic polymer solution a (50 parts by mass) and (meth)acrylic polymer solution b (50 parts by mass) to obtain a coating liquid for roughness-absorbing resin layer.

[0089] (Preparation of adhesive film) The coating liquid for the irregularity-absorbing resin layer was applied to the base layer 1 and dried to form an irregularity-absorbing resin layer with a thickness of 40 μm, thereby obtaining a laminated film. Next, the adhesive coating liquid for the thermosetting adhesive layer was applied to a silicone release-treated polyethylene terephthalate film (38 μm) and dried to form a thermosetting adhesive layer with a thickness of 20 μm. Next, the obtained thermosetting adhesive layer was attached to the irregularity-absorbing resin layer side of the above-mentioned laminated film, thereby obtaining an adhesive film.

[0090] Comparative Example 1 Preparation of Coating Solution for Thermosetting Adhesive Layer An adhesive coating solution for a thermosetting adhesive layer was obtained in the same manner as in Example 1, except that the formulation of the adhesive coating solution was as shown in Table 1.

[0091] (Preparation of adhesive film) The adhesive coating liquid for the thermosetting adhesive layer was applied to a silicone release-treated polyethylene terephthalate film (38 μm) and dried to form a thermosetting adhesive layer having a thickness of 20 μm. The obtained thermosetting adhesive layer was then bonded to the base layer 1 to obtain an adhesive film.

[0092] <Measurement and Evaluation Methods> (1) Measurement of Deformation Ratio and Deformation Amount of Pressure-Sensitive Adhesive Film at 100°C A measurement sample was prepared by laminating n sheets of pressure-sensitive adhesive film until a thickness of 1.4±0.1 mm was reached. Here, the measurement sample was laminated so that the base layer of the pressure-sensitive adhesive film and the thermosetting adhesive layer of the adjacent pressure-sensitive adhesive film were in direct contact with each other. The number of laminated pressure-sensitive adhesive films was determined so that the thickness of the measurement sample approached 1.4 mm. In other words, the number of laminated pressure-sensitive adhesive films differs depending on the thickness of the pressure-sensitive adhesive film, and therefore the number of laminated pressure-sensitive adhesive films differs depending on the sample. The measurement sample was cut to a width of 10 mm and measured for deformation amount when a load of 10 N was continuously applied using a dynamic viscoelasticity measuring device (EPLEXOR 500N, manufactured by Netsch-Gabo) under the following conditions: temperature: 100°C, deformation mode: compression, upper jig: three-point bending (indenter tip: 2.5R), lower jig: parallel plate, measurement time: 1000 seconds, and atmosphere: nitrogen. The measurement sample was placed so that the long axis direction of the indenter in the upper jig was the same as the width direction of the measurement sample, and a load was continuously applied in the thickness direction of the measurement sample. The deformation rate [%] at 100 ° C was calculated using the formula "(deformation amount [μm] at 600 seconds / number of layers n of the measurement sample / thickness per layer [μm] of the pressure-sensitive adhesive film) × 100". The deformation amount [μm] at 100 ° C was calculated using the formula "deformation amount [μm] at 600 seconds / number of layers n of the measurement sample".

[0093] (2) Measurement of the deformation rate and deformation amount of the adhesive film at 150 ° C. (1) A measurement sample was prepared by the method described above. Then, using a constant temperature dryer (manufactured by Yamato Scientific Co., Ltd., DN-63H), the measurement sample was heated at 130 ° C. for 30 minutes. A measurement sample cut to a width of 10 mm was measured using a dynamic viscoelasticity measuring device (manufactured by Netsch-Gabo, EPLEXOR 500N) under the following conditions: temperature: 150 ° C., deformation mode: compression, upper jig: three-point bending (indenter tip: 2.5R), lower jig: parallel plate, measurement time: 1000 seconds, atmosphere: nitrogen. The deformation amount when a load of 5 N was continuously applied was measured. The measurement sample was placed so that the long axis direction of the indenter in the upper jig and the width direction of the measurement sample were in the same direction, and a load was continuously applied in the thickness direction of the measurement sample. The deformation rate [%] at 150°C was calculated by the formula "(deformation amount at 600 seconds [μm] / number of layers of the measurement sample n / thickness per layer of the pressure-sensitive adhesive film [μm]) × 100". The deformation amount [μm] at 150°C was calculated by the formula "deformation amount at 600 seconds [μm] / number of layers of the measurement sample n".

[0094] (3) Evaluation of Conformity to Irregularities A bonding device (manufactured by Takatori Corporation, trade name: TPL-0612W) was used to bond a circuit formation surface of a wafer (8-inch power device simulated wafer, height of circuit formation surface (thickness of polyimide): 10 μm, chip size: 10 mm × 10 mm, small pad size: 1 mm × 1 mm) under the conditions of SP1: 800 Pa, SP2: 300 Pa, SP3: 100 Pa, bonding pressure: 0.2 MPa, bonding temperature: 100 ° C. An adhesive film was bonded to the circuit formation surface of the wafer using a bonding device (manufactured by Keyence Corporation, trade name: VK-X1000). Two arbitrary locations on the wafer to which the adhesive film was bonded were observed using a laser microscope (manufactured by Keyence Corporation, trade name: VK-X1000), and the results were evaluated according to the following criteria. A (Good): No lifting was observed near the 10 μm step of the polyimide. B (Poor): Lifting was observed near the 10 μm step of the polyimide.

[0095] (4) Evaluation of Vacuum Resistance Using the method described in (3), an adhesive film was attached to the circuit-formed surface of the wafer, and after leaving it for at least 1 hour, it was pre-baked at 130°C for 30 minutes using a constant temperature dryer (manufactured by Yamato Scientific Co., Ltd., DN-63H). Next, the wafer with the adhesive film attached was heated in a vacuum constant temperature dryer (manufactured by Shimizu Rikagaku Kiki Seisakusho Co., Ltd., VOD6-4H) under conditions of vacuum pressure: 100 to 150 Pa, temperature: 150°C, and time: 15 minutes. During the heating process under reduced pressure, the presence or absence of lifting of the film was visually observed and evaluated according to the following criteria. A (Good): No lifting of 0.5 mm or more in diameter was visually observed. B (Bad): Lifting of 0.5 mm or more in diameter was visually observed.

[0096] Evaluations were carried out for Examples 1 to 5 and Comparative Examples 1 and 2. The results are shown in Table 1.

[0097]

[0098] It can be seen from Table 1 that the pressure-sensitive adhesive films of the examples were good in both the evaluation of the conformability to uneven surfaces and the evaluation of the vacuum resistance. That is, it can be seen that the pressure-sensitive adhesive film of the present embodiment has an improved balance of the performance of the conformability to uneven surfaces and the vacuum resistance.

[0099] REFERENCE SIGNS LIST 10 Electronic component 10A Circuit formation surface of electronic component 10B Surface opposite to circuit formation surface of electronic component 20 Base layer 30 Irregularity-absorbing resin layer 40 Thermosetting adhesive layer 50 Adhesive film 100 Structure

Claims

1. An adhesive film used in the manufacturing process of an electronic device, wherein the deformation rate at 100°C calculated by the following method 1 is 2.0% or more and 70.0% or less, and the deformation rate at 150°C calculated by the following method 2 is 25.0% or less. [Method 1] A measurement sample is prepared by stacking n sheets of the adhesive film until the thickness is 1.4±0.1 mm, and the measurement sample is cut to a width of 10 mm. The deformation amount when a load of 10 N is continuously applied to the measurement sample using a dynamic viscoelasticity measuring device under the following conditions: temperature: 100°C, deformation mode: compression, upper jig: three-point bending (indenter tip: 2.5R), lower jig: parallel plate, measurement time: 1000 seconds, atmosphere: nitrogen, is measured, and the value calculated by the formula "(deformation amount at 600 seconds [μm] / number of stacked measurement samples n / thickness per sheet of the adhesive film [μm]) × 100" is defined as the deformation rate at 100°C [%]. [Method 2] A sample obtained by stacking n sheets of the pressure-sensitive adhesive film until the thickness reached 1.4±0.1 mm was subjected to heat treatment at 130°C for 30 minutes to prepare a measurement sample, and the measurement sample was cut to a width of 10 mm. The measurement sample was measured using a dynamic viscoelasticity measuring device under the following conditions: temperature: 150°C, deformation mode: compression, upper jig: three-point bending (indenter tip: 2.5R), lower jig: parallel plate, measurement time: 1000 seconds, atmosphere: nitrogen, and the deformation amount when a load of 5 N was continuously applied was measured. The value calculated by the formula "(deformation amount at 600 seconds [μm] / number of layers n of the measurement sample / thickness per sheet of the pressure-sensitive adhesive film [μm]) × 100" is the deformation rate [%] at 150°C.

2. An adhesive film used in the manufacturing process of an electronic device, wherein the deformation amount at 100°C calculated by the following method 3 is 1.0 μm or more and 100.0 μm or less, and the deformation amount at 150°C calculated by the following method 4 is 35.0 μm or less. [Method 3] A measurement sample is prepared by stacking n sheets of the adhesive film until the thickness is 1.4±0.1 mm, and the measurement sample is cut to a width of 10 mm. Using a dynamic viscoelasticity measuring device, the deformation amount when a load of 10 N is continuously applied is measured under the following conditions: temperature: 100°C, deformation mode: compression, upper jig: three-point bending (indenter tip: 2.5R), lower jig: parallel plate, measurement time: 1000 seconds, atmosphere: nitrogen, and the value calculated by the formula "deformation amount at 600 seconds [μm] / number n of stacked sheets of the measurement sample" is defined as the deformation amount at 100°C [μm]. [Method 4] A sample obtained by laminating n sheets of the pressure-sensitive adhesive film until the thickness reaches 1.4±0.1 mm is subjected to heat treatment at 130°C for 30 minutes to prepare a measurement sample, and the measurement sample is cut to a width of 10 mm. The measurement sample is measured using a dynamic viscoelasticity measuring device under the conditions of temperature: 150°C, deformation mode: compression, upper jig: three-point bending (indenter tip: 2.5R), lower jig: parallel plate, measurement time: 1000 seconds, and atmosphere: nitrogen, and the deformation amount when a load of 5 N is continuously applied is measured. The value calculated by the formula "deformation amount at 600 seconds [μm] / number n of laminated sheets of the measurement sample" is defined as the deformation amount at 150°C [μm].

3. An adhesive film according to claim 1 or 2, comprising a base layer, an irregularity-absorbing resin layer, and a thermosetting adhesive layer in this order.

4. The adhesive film according to claim 3, wherein the irregularity-absorbing resin layer and the thermosetting adhesive layer are provided so as to be in direct contact with each other.

5. The adhesive film according to claim 3 or 4, wherein the thermosetting adhesive layer contains a (meth)acrylic resin and a thermal polymerization initiator.

6. An adhesive film according to any one of claims 3 to 5, wherein the resin constituting the irregularity-absorbing resin layer comprises at least one selected from the group consisting of ethylene-vinyl acetate copolymer, (meth)acrylic resin, ethylene-α-olefin copolymer, and low-density polyethylene.

7. The adhesive film according to any one of claims 3 to 6, wherein the thickness of the irregularity-absorbing resin layer is 20 μm or more and 500 μm or less.

8. The adhesive film according to any one of claims 3 to 7, wherein the resin constituting the base layer comprises at least one selected from the group consisting of polyethylene naphthalate, polyethylene terephthalate, and polyimide.

9. The adhesive film according to any one of claims 1 to 8, wherein the manufacturing process for the electronic device includes the steps of: (A) preparing a structure comprising an electronic component having a circuit formation surface and the adhesive film attached to the circuit formation surface side of the electronic component; and (B) treating the surface of the electronic component opposite the circuit formation surface side in a vacuum atmosphere.

10. The adhesive film according to any one of claims 1 to 9, wherein the electronic device is a power semiconductor device.

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