Method for manufacturing electronic device and method for manufacturing stainless steel substrate

Abstract

This method for manufacturing an electronic device includes: a step for preparing a structure (100) which comprises an adhesive film (50) provided with an adhesive resin layer (A), a substrate layer (10), and an adhesive resin layer (B) in that order, and which comprises an electronic component (70) on the adhesive resin layer (A) side of the adhesive film (50), and a support substrate (80) on the adhesive resin layer (B) side of the adhesive film (50); and a step for reducing the adhesive strength of the adhesive resin layer (B) through a heat treatment to peel off the support substrate (80) from the structure (100). The support substrate (80) includes a stainless-steel substrate having an oxide film on a surface thereof.

Description

Method for manufacturing an electronic device and method for manufacturing a stainless steel substrate

[0001] The present invention relates to a method for manufacturing an electronic device and a method for manufacturing a stainless steel substrate.

[0002] Fan-out packaging is known as a technology that can reduce the size and weight of electronic devices (e.g., semiconductor devices). One method for fabricating a fan-out package, called an embedded wafer level ball grid array (eWLB), involves temporarily fixing a plurality of electronic components, such as semiconductor chips, spaced apart on an adhesive film attached to a support substrate, and then encapsulating the plurality of electronic components together with an encapsulant. Here, the adhesive film must be adhered to the electronic components and the support substrate during the encapsulation process, and must be removed from the encapsulated electronic components together with the support substrate after encapsulation.

[0003] Techniques relating to a method for manufacturing such a fan-out type package include, for example, the technique described in Patent Document 1 (Japanese Patent Laid-Open No. 2011-134811).

[0004] Patent Document 1 describes a heat-resistant adhesive sheet for semiconductor device manufacturing that is used by adhering when resin-encapsulating a substrateless semiconductor chip, with the aim of solving the problem of the chip not being held in place due to pressure during resin encapsulation and shifting from its designated position, or the problem of the package being damaged when the heat-resistant adhesive sheet for semiconductor device manufacturing is peeled off due to the hardening of the encapsulant or heat causing the encapsulant to become strongly adhesive to the chip surface, the heat-resistant adhesive sheet having a base layer and an adhesive layer, the adhesive layer having an adhesive strength to SUS304 after lamination of 0.5 N / 20 mm or more, and hardening due to stimuli received up to the time the resin encapsulation process is completed, so that the peel strength to the package is 2.0 N / 20 mm or less.

[0005] JP 2011-134811 A

[0006] According to the investigations of the present inventors, it has become clear that when peeling an adhesive film from a support substrate, peeling failure between the support substrate and the adhesive film may occur. The present invention has been made in view of the above circumstances, and provides a method for manufacturing an electronic device in which the thermal peelability between the support substrate and the adhesive film is improved.

[0007] The present inventors have conducted extensive research to achieve the above object, and as a result have found that the thermal peelability between the support substrate and the adhesive film can be improved by including a stainless steel substrate having an oxide film on its surface as the support substrate, thereby completing the present invention.

[0008] According to the present invention, there are provided the following methods for manufacturing an electronic device and a stainless steel substrate.

[0009] [1] A method for manufacturing an electronic device, comprising the steps of: preparing a structure including an adhesive film having an adhesive resin layer (A), a base layer, and an adhesive resin layer (B) in this order; an electronic component on the adhesive resin layer (A) side of the adhesive film; and a support substrate on the adhesive resin layer (B) side of the adhesive film; and removing the support substrate from the structure by reducing the adhesive strength of the adhesive resin layer (B) through heat treatment, wherein the support substrate includes a stainless steel substrate having an oxide film on its surface. [2] A method for manufacturing an electronic device according to [1] above, wherein the oxygen concentration on the surface of the stainless steel substrate is 45 atomic% or more and 75 atomic% or less, as determined by (Method 1) below. (Method 1) The stainless steel substrate is subjected to X-ray photoelectron spectroscopy (ESCA) using an apparatus under the following conditions: a step width of 1.0 eV, a dwell time of 50 milliseconds, two accumulations, and a wide scan measurement range of 0 to 1100 eV, to identify detected elements. Then, a spectrum of O element is acquired by narrow scanning with a step width of 0.1 eV, a dwell time of 300 milliseconds, an accumulation count of 4, and a measurement range of 523 to 543 eV. The background determined by the Shirley method is removed from the obtained spectrum, and the concentration of O element is calculated from the obtained peak area using the relative sensitivity factor method, which is used as the oxygen concentration. The instrument conditions are as follows: X-ray source: Mg-Kα radiation; X-ray source output: 15 kV, 10 mA; Analysis area: 300 × 700 μm; A neutralizing electron gun for charge correction is used during analysis. [3] The method for manufacturing an electronic device according to [1] or [2] above, including a step of heating a raw stainless steel plate to obtain the stainless steel substrate before the step of preparing the structure. [4] The method for manufacturing an electronic device according to [3] above, wherein the heating time in the step of obtaining the stainless steel substrate is 3.0 hours or more. [5] The method for manufacturing an electronic device according to [3] or [4] above, wherein the heating temperature in the step of obtaining the stainless steel substrate is 120°C or more. [6] The method for manufacturing an electronic device according to any one of [1] to [5] above, wherein the stainless steel substrate comprises one or more stainless steels selected from the group consisting of SUS304 and SUS430.[7] The method for producing an electronic device according to any one of [1] to [6] above, wherein the adhesive resin layer (A) contains one or more resins selected from the group consisting of (meth)acrylic adhesive resins, silicone adhesive resins, urethane adhesive resins, olefin adhesive resins, and styrene adhesive resins. [8] The method for producing an electronic device according to any one of [1] to [7] above, wherein the total content of the gas-generating component and heat-expandable microspheres in the adhesive resin layer (A) is 0.1% by mass or less, when the entire adhesive resin layer (A) is taken as 100% by mass. [9] The method for producing an electronic device according to any one of [1] to [8] above, wherein the adhesive resin layer (A) has a thickness of 1 μm or more and 40 μm or less.

[10] The method for producing an electronic device according to any one of [1] to [9] above, wherein the adhesive resin layer (B) contains a layer whose adhesive strength decreases by heat treatment.

[11] The method for producing an electronic device according to

[10] above, wherein the adhesive resin layer (B) contains a thermally expandable adhesive.

[12] The method for manufacturing an electronic device according to

[10] or

[11] above, wherein the adhesive strength of the adhesive resin layer (B) decreases when heated at a temperature exceeding 180°C.

[13] The method for manufacturing an electronic device according to any one of [1] to

[12] above, wherein the adhesive resin layer (B) comprises one or more resins selected from the group consisting of (meth)acrylic adhesive resins, silicone adhesive resins, urethane adhesive resins, olefin adhesive resins, and styrene adhesive resins.

[14] The method for manufacturing an electronic device according to any one of [1] to

[13] above, wherein the adhesive resin layer (B) has a thickness of 10 μm or more and 100 μm or less.

[15] The method for manufacturing an electronic device according to any one of [1] to

[14] above, wherein the base layer comprises one or more resins selected from the group consisting of polypropylene, polyethylene terephthalate, polyethylene naphthalate, polyamide, and polyimide.

[16] The method for producing an electronic device according to any one of the above [1] to

[15] , further comprising an intermediate layer (C) between the base material layer and the adhesive resin layer (A) and between the base material layer and the adhesive resin layer (B).

[17] The method for producing an electronic device according to any one of the above [1] to

[16] , further comprising a step of peeling the adhesive film from the electronic component.

[18] A method for manufacturing an electronic device according to any one of [1] to

[17] above, further comprising a step of encapsulating the electronic component with an encapsulant between the step of preparing the structure and the step of peeling the support substrate from the structure.

[19] A method for manufacturing an electronic device according to any one of [1] to

[19] above, wherein the encapsulant comprises an epoxy resin-based encapsulant.

[20] A method for manufacturing an electronic device according to any one of [1] to

[19] above, wherein the electronic device comprises a fan-out package.

[21] A method for manufacturing a stainless steel substrate used in the method for manufacturing an electronic device according to any one of [1] to

[20] above, comprising a step of heating a raw stainless steel plate to obtain the stainless steel substrate.

[22] A method for manufacturing a stainless steel substrate according to

[21] above, wherein the oxygen concentration on the surface of the stainless steel substrate is 45 atomic % or more and 75 atomic % or less, according to the following (Method 1): (Method 1) The stainless steel substrate is subjected to X-ray photoelectron spectroscopy (ESCA) using an apparatus under the following conditions: step width: 1.0 eV, dwell time: 50 milliseconds, number of integrations: 2, measurement range: 0 to 1100 eV, and a wide scan is used to identify the detected elements. Then, a spectrum of the O element is obtained using a narrow scan with a step width: 0.1 eV, dwell time: 300 milliseconds, number of integrations: 4, and measurement range: 523 to 543 eV. The background determined by the Shirley method is removed from the obtained spectrum, and the concentration of the O element is calculated from the obtained peak area using the relative response factor method, which is used as the oxygen concentration. The apparatus conditions are shown below. X-ray source: Mg-Kα rays X-ray source output: 15 kV, 10 mA Analysis area: 300 × 700 μm A neutralizing electron gun for charge correction was used during analysis

[23] The method for producing a stainless steel substrate according to

[21] or

[22] above, wherein the heating time in the step of obtaining the stainless steel substrate is 3.0 hours or more.

[24] The method for producing a stainless steel substrate according to any of

[21] to

[23] above, wherein the heating temperature in the step of obtaining the stainless steel substrate is 120°C or more.

[0010] According to the present invention, it is possible to provide a method for manufacturing an electronic device in which the thermal peelability between the support substrate and the adhesive film is improved.

[0011] Fig. 1 is a cross-sectional view schematically showing an example of a method for manufacturing an electronic device according to an embodiment of the present invention. Fig. 2 is a cross-sectional view schematically showing an example of a method for manufacturing an electronic device according to an embodiment of the present invention. Fig. 3 is a cross-sectional view schematically showing an example of a structure of an adhesive film according to an embodiment of the present invention. Fig. 4 is a cross-sectional view schematically showing an example of a structure of an adhesive film according to an embodiment of the present invention.

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all drawings, similar components are designated by common reference numerals, and descriptions thereof will be omitted where appropriate. Furthermore, the drawings are schematic diagrams and do not necessarily correspond to actual dimensional ratios. In the specification, the expression "A to B" regarding a numerical range means A or more and B or less, unless otherwise specified. For example, 1 to 5% means 1% or more and 5% or less. In the specification, "(meth)acrylic" means acrylic, methacrylic, or both acrylic and methacrylic.

[0013] 1 , the method for manufacturing an electronic device according to the present embodiment includes the steps of preparing a structure 100 including an adhesive film 50 having an adhesive resin layer (A), a base layer 10, and an adhesive resin layer (B) in this order, an electronic component 70 on the adhesive resin layer (A) side of the adhesive film 50, and a support substrate 80 on the adhesive resin layer (B) side of the adhesive film 50, and removing the support substrate 80 from the structure 100 by reducing the adhesive strength of the adhesive resin layer (B) through heat treatment, wherein the support substrate 80 includes a stainless steel substrate having an oxide film on its surface.

[0014] As described above, it has become clear that poor peeling between the support substrate and the adhesive film may occur when peeling the adhesive film from the support substrate. The present invention can improve the thermal peelability between the support substrate and the adhesive film by including a stainless steel substrate having an oxide film on its surface as the support substrate. Although the reason for this is unclear, it is thought that the stainless steel substrate having an oxide film on its surface has an inactive surface, which can suppress the initial adhesive strength with the adhesive film and excessive adhesion caused by heating, resulting in improved thermal peelability between the support substrate and the adhesive film.

[0015] Each step of the method for manufacturing an electronic device according to this embodiment will be described in detail below.

[0016] First, a structure 100 is prepared, which includes an adhesive film 50 having an adhesive resin layer (A), a base layer 10, and an adhesive resin layer (B) in this order, an electronic component 70 on the adhesive resin layer (A) side of the adhesive film 50, and a support substrate 80 on the adhesive resin layer (B) side of the adhesive film 50.

[0017] Such a structure 100 can be produced, for example, by the following procedure. First, the adhesive film 50 is attached to the support substrate 80 so that the adhesive resin layer (B) faces the support substrate 80. A protective film called a separator may be attached to the adhesive resin layer (B), and the protective film can be peeled off to attach the exposed surface of the adhesive resin layer (B) to the surface of the support substrate 80. Next, the structure 100 can be obtained by placing the electronic component 70 on the adhesive resin layer (A) on the side of the adhesive film 50 opposite to the side to which the support substrate 80 is attached.

[0018] The surface of the electronic component 70 may have an uneven structure, for example, by having electrodes. Furthermore, for example, when mounting an electronic device on a mounting surface, the electrodes are bonded to the electrodes formed on the mounting surface to form an electrical connection between the electronic device and the mounting surface (such as the mounting surface of a printed circuit board). Examples of the electrodes include bump electrodes such as ball bumps, printed bumps, stud bumps, plated bumps, and pillar bumps. That is, the electrodes are typically convex electrodes. These bump electrodes may be used alone or in combination of two or more types. Furthermore, the metal species constituting the bump electrodes are not particularly limited, and examples include silver, gold, copper, tin, lead, bismuth, and alloys thereof. These metal species may be used alone or in combination of two or more types.

[0019] The stainless steel substrate of this embodiment preferably includes one or more selected from the group consisting of an austenitic stainless steel substrate, an austenitic-ferritic stainless steel substrate, a ferritic stainless steel substrate, and a martensitic stainless steel substrate. The austenitic stainless steel substrate of this embodiment is preferably SUS301, SUS301J1, SUS301L, SUS630, SUS631, SUS302, SUSXM15J1, SUS303, SUS303Cu, SUS304, SUS304LN, SUS304N1, SUS304N2, SUS304J1, SUS304J2, SUS305, SUS305J1, SUS The austenitic-ferritic stainless steel substrate of this embodiment preferably includes one or more selected from the group consisting of SUS309S, SUS310S, SUS312L, SUS836L, SUS890L, SUS315J1, SUS315J2, SUS316, SUS316L, SUS316N, SUS316LN, SUS316J1, SUS316J1L, SUS317, SUS317J1, SUS317L, SUS321, and SUS347. The austenitic-ferritic stainless steel substrate of this embodiment preferably includes one or more selected from the group consisting of SUS329J1, SUS329J3L, and SUS329J4L. The ferritic stainless steel substrate of this embodiment preferably contains one or more types selected from the group consisting of SUH409, SUH409L, SUS405, SUS410L, SUS429, SUS430, SUS430F, SUS430LX, SUS430J1L, SUS443J1, SUS434, SUS436J1L, SUS436L, SUS444, SUS445J1, SUSXM27, and SUS447J1. The martensitic stainless steel substrate of this embodiment preferably contains one or more types selected from the group consisting of SUS403, SUS410, SUS410S, SUS410F2, SUS416, SUS420J1, SUS420J2, SUS420F, SUS420F2, SUS440A, SUS440B, SUS440C, SUS440F, and SUS431.The stainless steel substrate of this embodiment more preferably contains one or two types selected from the group consisting of SUS304 and SUS430, from the viewpoint of further improving the thermal peelability between the support substrate 80 and the adhesive film 50.

[0020] In the method for manufacturing an electronic device of this embodiment, the oxygen concentration on the surface of the stainless steel substrate by the following (Method 1) is preferably 45 atomic% or more and 75 atomic% or less, more preferably 47 atomic% or more and 70 atomic% or less, even more preferably 49 atomic% or more and 65 atomic% or less, even more preferably 51 atomic% or more and 60 atomic% or less, even more preferably 52 atomic% or more and 58 atomic% or less, and even more preferably 53 atomic% or more and 56 atomic% or less, from the viewpoint of further improving the thermal peelability between the support substrate 80 and the adhesive film 50.

[0021] (Method 1) The above stainless steel substrate is subjected to X-ray photoelectron spectroscopy (ESCA) using an apparatus under the following conditions: step width: 1.0 eV, dwell time: 50 milliseconds, number of integrations: 2, measurement range: 0 to 1100 eV, and a wide scan is used to identify the detected elements. Then, for the O element, a spectrum is obtained using a narrow scan with a step width: 0.1 eV, dwell time: 300 milliseconds, number of integrations: 4, and measurement range: 523 to 543 eV. The background determined by the Shirley method is removed from the obtained spectrum, and the concentration of the O element is calculated from the obtained peak area using the relative sensitivity factor method, which is used as the oxygen concentration. The apparatus conditions are as follows: X-ray source: Mg-Kα radiation; X-ray source output: 15 kV, 10 mA; Analysis area: 300 × 700 μm; A neutralization electron gun for charge correction is used during analysis.

[0022] A stainless steel substrate that can be used in the method for manufacturing an electronic device of this embodiment can be obtained, for example, by the following manufacturing method. The method for manufacturing a stainless steel substrate of this embodiment preferably includes a step of heating a raw stainless steel sheet to obtain the stainless steel substrate, from the viewpoint of further improving the thermal peelability between the support substrate 80 and the adhesive film 50. The method for heating the raw stainless steel sheet is not particularly limited, and generally known heat treatment methods such as an oven, a dryer, a heating roll, or a drying furnace can be used.

[0023] In the method for producing a stainless steel substrate of this embodiment, heating is preferably performed until the oxygen concentration at the surface of the stainless steel substrate reaches the above-mentioned numerical value, from the viewpoint of further improving the thermal peelability between the support substrate 80 and the adhesive film 50. That is, in the method for producing a stainless steel substrate of this embodiment, the oxygen concentration at the surface of the stainless steel substrate by the following (Method 1) is preferably 45 atomic% or more and 75 atomic% or less, more preferably 47 atomic% or more and 70 atomic% or less, even more preferably 49 atomic% or more and 65 atomic% or less, even more preferably 51 atomic% or more and 60 atomic% or less, even more preferably 52 atomic% or more and 58 atomic% or less, and even more preferably 53 atomic% or more and 56 atomic% or less, from the viewpoint of further improving the thermal peelability between the support substrate 80 and the adhesive film 50.

[0024] (Method 1) The above stainless steel substrate is subjected to X-ray photoelectron spectroscopy (ESCA) using an apparatus under the following conditions: step width: 1.0 eV, dwell time: 50 milliseconds, number of integrations: 2, measurement range: 0 to 1100 eV, and a wide scan is used to identify the detected elements. Then, for the O element, a spectrum is obtained using a narrow scan with a step width: 0.1 eV, dwell time: 300 milliseconds, number of integrations: 4, and measurement range: 523 to 543 eV. The background determined by the Shirley method is removed from the obtained spectrum, and the concentration of the O element is calculated from the obtained peak area using the relative sensitivity factor method, which is used as the oxygen concentration. The apparatus conditions are as follows: X-ray source: Mg-Kα radiation; X-ray source output: 15 kV, 10 mA; Analysis area: 300 × 700 μm; A neutralization electron gun for charge correction is used during analysis.

[0025] In the method for producing a stainless steel substrate of this embodiment, the heating time in the step of obtaining the stainless steel substrate is preferably 3.0 hours or more, more preferably 3.5 hours or more, even more preferably 4.0 hours or more, and even more preferably 4.5 hours or more, from the viewpoint of further improving the thermal peelability between the support substrate 80 and the adhesive film 50. The upper limit of the heating time is not particularly limited, but may be, for example, 144 hours or less, 120 hours or less, 96 hours or less, 72 hours or less, 48 ​​hours or less, 24 hours or less, or 12 hours or less. Furthermore, in the method for manufacturing a stainless steel substrate of this embodiment, the heating time in the step of obtaining the stainless steel substrate is, from the viewpoint of further improving the thermal peelability between the support substrate 80 and the adhesive film 50, preferably 3.0 hours or more and 144 hours or less, more preferably 3.0 hours or more and 120 hours or less, even more preferably 3.0 hours or more and 96 hours or less, even more preferably 3.0 hours or more and 72 hours or less, even more preferably 3.5 hours or more and 48 hours or less, even more preferably 4.0 hours or more and 24 hours or less, and even more preferably 4.5 hours or more and 12 hours or less.

[0026] In the method for producing a stainless steel substrate of this embodiment, the heating temperature in the step of obtaining the stainless steel substrate is preferably 120° C. or higher, more preferably 130° C. or higher, even more preferably 140° C. or higher, and even more preferably 150° C. or higher, from the viewpoint of further improving the thermal peelability between the support substrate 80 and the adhesive film 50, and is preferably 500° C. or lower, more preferably 450° C. or lower, even more preferably 400° C. or lower, even more preferably 350° C. or lower, even more preferably 300° C. or lower, and even more preferably 250° C. or lower, from the viewpoint of production efficiency. That is, in the method for producing a stainless steel substrate of this embodiment, the heating temperature in the step of obtaining the stainless steel substrate is preferably 120° C. or higher and 500° C. or lower, more preferably 120° C. or higher and 450° C. or lower, even more preferably 130° C. or higher and 400° C. or lower, even more preferably 130° C. or higher and 350° C. or lower, even more preferably 140° C. or higher and 300° C. or lower, and even more preferably 150° C. or higher and 250° C., from the viewpoint of further improving the performance balance between the thermal peelability between the support substrate 80 and the adhesive film 50 and the production efficiency.

[0027] The method for producing a stainless steel substrate of this embodiment is preferably carried out immediately before preparing structure 100 by the method for producing an electronic device of this embodiment, from the viewpoint of further improving the thermal peelability between support substrate 80 and adhesive film 50. In other words, the method for producing an electronic device of this embodiment includes a step of heating a raw stainless steel plate to obtain the stainless steel substrate, preferably before the step of preparing structure 100, from the viewpoint of further improving the thermal peelability between support substrate 80 and adhesive film 50. The conditions for obtaining the stainless steel substrate in the method for producing an electronic device of this embodiment are the same as the conditions described above for the method for producing a stainless steel substrate of this embodiment.

[0028] Next, the adhesive strength of the adhesive resin layer (B) is reduced by heat treatment, and the support substrate 80 is peeled off from the structure 100. The support substrate 80 can be easily removed from the adhesive film 50 by heating it, for example, to a temperature exceeding 150°C or a temperature exceeding 170°C, thereby reducing the adhesive strength of the adhesive resin layer (B).

[0029] 2 , the method for manufacturing an electronic device according to this embodiment preferably further includes a step of encapsulating electronic components 70 with encapsulant 60 between the step of preparing structure 100 and the step of peeling support substrate 80 from structure 100. In the step of encapsulating electronic components 70 with encapsulant 60, electronic components 70 are encapsulated by covering them with encapsulant 60. Here, when the adhesive resin layer (B) of adhesive film 50 contains at least one selected from a gas-generating component and heat-expandable microspheres, the temperature at which encapsulant 60 is used for encapsulation is preferably within a range not exceeding the temperature at which gas is generated or the temperature at which the heat-expandable microspheres thermally expand.

[0030] In the step of sealing the electronic components 70 with the sealing material 60, the plurality of electronic components 70 may be sealed together or individually with the sealing material 60. As a method for individually covering the plurality of electronic components 70 with the sealing material 60, it is preferable to use one or more methods selected from the group consisting of a 3D printer method, a spray method, a screen printing method, and an inkjet method, and it is more preferable to use the 3D printer method.

[0031] As the sealing material 60, any known sealing material having high insulating properties can be used, but the sealing material 60 preferably includes an epoxy resin-based sealing material, which improves the affinity of the sealing material 60 to the adhesive film 50 and enables more uniform sealing of the electronic component 70. Examples of such epoxy resin-based sealing materials that can be used include the T693 / R4000 series, T693 / R1000 series, and T693 / R5000 series manufactured by Nagase ChemteX Corporation. The sealing material 60 may be solid or liquid, but is preferably liquid, from the viewpoints of enabling the sealing process to be carried out at low temperature and low pressure and further suppressing misalignment of the electronic component 70 during the sealing process.

[0032] The method for manufacturing an electronic device according to this embodiment preferably further includes, after the step of sealing the electronic components 70 with the sealing material 60, a step of curing the sealing material 60 by treating it with one or two methods selected from the group consisting of light irradiation and heat treatment. This fixes the electronic components 70 and further suppresses misalignment of the electronic components 70. Furthermore, from the viewpoint of further suppressing misalignment of the electronic components 70, the step of curing the sealing material 60 is preferably performed before the step of peeling the support substrate 80 from the structure 100.

[0033] The method of curing the encapsulant 60 by light irradiation is preferably a method of crosslinking and curing the encapsulant 60 by irradiating the encapsulant 60 with light such as ultraviolet light. The light source used in this method is preferably a light source capable of irradiating ultraviolet light containing wavelength components capable of exciting a photoinitiator, and more preferably a light source capable of irradiating ultraviolet light containing components with wavelengths of less than 300 nm. The method of curing the encapsulant 60 by heat treatment is preferably a method of curing the encapsulant 60 by thermal crosslinking using an oven, thermal crosslinking using a hot plate, or thermal crosslinking using infrared radiation. In the case of thermal crosslinking, the heating temperature is, for example, 100°C or higher and 150°C or lower, and the heating time is, for example, 10 to 180 minutes. The heating temperature is preferably a temperature that does not exceed the temperature at which gas contained in the pressure-sensitive adhesive film 50 generates or the temperature at which the heat-expandable microspheres thermally expand.

[0034] In the method for producing an electronic device of this embodiment, when the pressure-sensitive adhesive film 50 includes an intermediate layer (C) described below, a step of subjecting the structure 100 to one or more treatments selected from the group consisting of light irradiation and heat treatment is preferably carried out between the step of preparing the structure 100 and the step of sealing the electronic component 70 with the sealing material 60. In this step, the intermediate layer (C) in the structure 100 is irradiated with light or heated to provide light energy or heat energy, thereby crosslinking the intermediate layer (C).

[0035] When crosslinking the intermediate layer (C) by irradiating the structure 100 with light in a step of performing one or more treatments selected from the group consisting of light irradiation and heat treatment, the intermediate layer (C) is preferably irradiated with light such as ultraviolet light. The light source used in this step is not particularly limited, but it is preferable to use a light source capable of irradiating ultraviolet light containing wavelength components capable of exciting the photoinitiator, and it is more preferable to use a light source capable of irradiating ultraviolet light containing components with wavelengths of less than 300 nm. Examples of such light sources include high-pressure mercury lamps, low-pressure mercury lamps, metal halide lamps, and super UV lamps. The light irradiated by the above light sources may contain components with wavelengths of 300 nm or more. In the case of ultraviolet crosslinking, for example, ultraviolet light with a dominant wavelength of 365 nm is irradiated using a high-pressure mercury lamp in an environment of 0 to 60°C, with an irradiation intensity of 10 to 350 mW / cm. ２ UV dose 100-20,000 mJ / cm ２ By irradiating the intermediate layer (C) under the above conditions, the intermediate layer (C) can be crosslinked and cured.

[0036] When the intermediate layer (C) is crosslinked by heating in the step of subjecting the structure 100 to one or more treatments selected from the group consisting of light irradiation and heat treatment, the method for crosslinking the intermediate layer (C) by heating is not limited, but preferred examples include thermal crosslinking in an oven, thermal crosslinking on a hot plate, and thermal crosslinking by infrared irradiation. In the case of thermal crosslinking, the heating temperature is, for example, 100°C to 150°C, and the heat treatment time is, for example, 10 to 180 minutes. It is preferable that the heating temperature does not exceed the temperature at which gas is generated or the temperature at which the heat-expandable microspheres thermally expand.

[0037] As shown in Fig. 2, the method for manufacturing an electronic device according to this embodiment preferably further includes a step of peeling the adhesive film 50 from the electronic component 70. This step results in an electronic device 200. Examples of methods for peeling the adhesive film 50 from the electronic component 70 include a mechanical peeling method and a method of reducing the adhesive strength of the surface of the adhesive film 50 before peeling. The step of peeling the adhesive film 50 from the electronic component 70 is preferably carried out after the step of peeling the support substrate 80 from the structure 100.

[0038] <Adhesive Film> Next, a description will be given of each layer constituting the adhesive film 50 that can be used in the method for manufacturing an electronic device of this embodiment. The adhesive film 50 that can be used in the method for manufacturing an electronic device of this embodiment is an adhesive film 50 that includes an adhesive resin layer (A), a base layer 10, and an adhesive resin layer (B) in this order, as shown in Figure 3.

[0039] (Base layer) The base layer 10 is a layer provided for the purpose of improving the properties such as handleability, mechanical properties, and heat resistance of the pressure-sensitive adhesive film 50. The base layer 10 is not particularly limited, but examples thereof include a resin film.

[0040] The substrate layer 10 preferably contains a thermoplastic resin. The thermoplastic resin constituting the substrate layer 10 of this embodiment preferably contains one or more selected from the group consisting of polyolefins such as polyethylene, polypropylene, poly(4-methyl-1-pentene), and poly(1-butene); polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyamides such as nylon-6, nylon-66, and polymethaxylene adipamide; polyacrylate; polymethacrylate; polyvinyl chloride; polyvinylidene chloride; polyimide; polyetherimide; ethylene-vinyl acetate copolymer; polyacrylonitrile; polycarbonate; polystyrene; ionomer; polysulfone; polyethersulfone; and polyphenylene ether. Among these, from the viewpoint of an excellent balance of transparency, mechanical strength, price, etc., the base material layer 10 preferably contains one or more types selected from the group consisting of polypropylene, polyethylene terephthalate, polyethylene naphthalate, polyamide, and polyimide, and more preferably contains one or more types selected from the group consisting of polyethylene terephthalate and polyethylene naphthalate.

[0041] The base layer 10 may be a single layer or two or more layers. The resin film used to form the base layer 10 may be a stretched film or a uniaxially or biaxially stretched film, but from the viewpoint of improving the mechanical strength of the base layer 10, a uniaxially or biaxially stretched film is preferred.

[0042] From the viewpoint of obtaining good film properties, the thickness of the substrate layer 10 is preferably 10 μm or more and 1000 μm or less, more preferably 20 μm or more and 500 μm or less, and even more preferably 30 μm or more and 100 μm or less. The substrate layer 10 may be subjected to a surface treatment to improve adhesion to other layers. Specifically, corona treatment, plasma treatment, undercoat treatment, primer coating treatment, etc. may be performed.

[0043] [Adhesive Resin Layer (A)] The adhesive film 50 of the present embodiment includes an adhesive resin layer (A) on one surface of the base layer 10, from the viewpoint of suppressing misalignment of the electronic component 70. The adhesive resin layer (A) is a layer that comes into contact with the surface of the electronic component to temporarily fix the electronic component when, for example, sealing the electronic component with a sealing material in the manufacturing process of the electronic device.

[0044] The adhesive resin layer (A) preferably contains an adhesive resin (Aa). The adhesive resin (Aa) preferably contains one or more selected from the group consisting of (meth)acrylic adhesive resin (a), silicone adhesive resin, urethane adhesive resin, olefin adhesive resin, and styrene adhesive resin. Among these, the adhesive resin layer (A) preferably contains a (meth)acrylic adhesive resin (a) from the viewpoint of suppressing misalignment of the electronic component 70 and improving the performance balance of adhesive strength.

[0045] The adhesive resin layer (A) may be a radiation-crosslinkable adhesive resin layer whose adhesive strength can be reduced by radiation. When the radiation-crosslinkable adhesive resin layer is irradiated with radiation, crosslinking occurs, significantly reducing the adhesive strength, making it easier to peel the adhesive film 50 from the electronic component 70. Examples of radiation include ultraviolet light, electron beams, and infrared light. The radiation-crosslinkable adhesive resin layer preferably includes an ultraviolet-crosslinkable adhesive resin layer.

[0046] The (meth)acrylic adhesive resin (a) used in the adhesive resin layer (A) of this embodiment preferably comprises a copolymer containing (meth)acrylic acid alkyl ester monomer units (a1) and monomer units (a2) having a functional group capable of reacting with a crosslinking agent. In this embodiment, the (meth)acrylic acid alkyl ester refers to an acrylic acid alkyl ester, a methacrylic acid alkyl ester, or a mixture thereof.

[0047] The (meth)acrylic adhesive resin (a) of the present embodiment can be obtained, for example, by copolymerizing a monomer mixture containing a (meth)acrylic acid alkyl ester monomer and a monomer having a functional group capable of reacting with a crosslinking agent.

[0048] The (meth)acrylic acid alkyl ester monomer of this embodiment preferably includes a (meth)acrylic acid alkyl ester having an alkyl group having about 1 to 12 carbon atoms, and more preferably includes a (meth)acrylic acid alkyl ester having an alkyl group having 1 to 8 carbon atoms. The (meth)acrylic acid alkyl ester having an alkyl group having about 1 to 12 carbon atoms preferably includes one or more selected from the group consisting of methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, and 2-ethylhexyl methacrylate. In the (meth)acrylic adhesive resin (a) of this embodiment, the content of the (meth)acrylic acid alkyl ester monomer unit (a1) is preferably 10% by mass or more and 98.9% by mass or less, more preferably 50% by mass or more and 97% by mass or less, and even more preferably 85% by mass or more and 95% by mass or less, when the total of all monomer units in the (meth)acrylic adhesive resin (a) is taken as 100% by mass.

[0049] Preferred examples of the monomer having a functional group reactive with the crosslinking agent of this embodiment include acrylic acid, methacrylic acid, itaconic acid, mesaconic acid, citraconic acid, fumaric acid, maleic acid, monoalkyl itaconic acid esters, monoalkyl mesaconic acid esters, monoalkyl citraconic acid esters, monoalkyl fumaric acid esters, monoalkyl maleic acid esters, glycidyl acrylate, glycidyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, acrylamide, methacrylamide, tert-butylaminoethyl acrylate, tert-butylaminoethyl methacrylate, etc. More preferred examples of the monomer having a functional group reactive with the crosslinking agent of this embodiment include one or more selected from the group consisting of acrylic acid, methacrylic acid, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, acrylamide, and methacrylamide. In the (meth)acrylic adhesive resin (a) of the present embodiment, the content of the monomer unit (a2) having a functional group capable of reacting with a crosslinking agent is preferably 1% by mass or more and 40% by mass or less, more preferably 1% by mass or more and 20% by mass or less, and even more preferably 1% by mass or more and 10% by mass or less, when the total of all monomer units in the (meth)acrylic adhesive resin (a) is 100% by mass.

[0050] The (meth)acrylic adhesive resin (a) of this embodiment may further contain, in addition to the (meth)acrylic acid alkyl ester monomer unit (a1) and the monomer unit (a2) having a functional group reactive with a crosslinking agent, a bifunctional monomer unit (a3) ​​or a specific comonomer unit having surfactant properties (hereinafter referred to as a polymerizable surfactant). The polymerizable surfactant has the property of copolymerizing with the (meth)acrylic acid alkyl ester monomer, the monomer having a functional group reactive with a crosslinking agent, and the bifunctional monomer, and also acts as an emulsifier when emulsion polymerization is performed.

[0051] The bifunctional monomer of the present embodiment preferably includes one or more monomers selected from the group consisting of allyl methacrylate, allyl acrylate, divinylbenzene, vinyl methacrylate, vinyl acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tetraethylene glycol di(meth)acrylate, monomers having diacrylate or dimethacrylate at both ends and a propylene glycol main chain structure (e.g., manufactured by NOF Corporation, trade names: PDP-200, PDP-400, ADP-200, ADP-400), tetramethylene glycol monomers (e.g., manufactured by NOF Corporation, trade names: ADT-250, ADT-850), and mixtures thereof (e.g., manufactured by NOF Corporation, trade names: ADET-1800, ADPT-4000).

[0052] In the (meth)acrylic adhesive resin (a) of the present embodiment, the content of the bifunctional monomer unit (a3) ​​is preferably 0.1% by mass or more and 30% by mass or less, more preferably 0.1% by mass or more and 20% by mass or less, even more preferably 0.1% by mass or more and 15% by mass or less, and still more preferably 0.1% by mass or more and 5% by mass or less, when the total of all monomer units in the (meth)acrylic adhesive resin (a) is 100% by mass.

[0053] The polymerizable surfactant of this embodiment preferably includes one or more surfactants selected from the group consisting of polyoxyethylene nonylphenyl ether having a polymerizable 1-propenyl group introduced into the benzene ring (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.; trade names: AQUALON RN-10, RN-20, RN-30, RN-50, etc.), polyoxyethylene nonylphenyl ether sulfate ammonium salt having a polymerizable 1-propenyl group introduced into the benzene ring (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.; trade names: AQUALON HS-10, HS-20, HS-1025, etc.), and sulfosuccinic acid diesters having a polymerizable double bond in the molecule (manufactured by Kao Corporation; trade names: Latemul S-120A, S-180A, etc.). In the (meth)acrylic adhesive resin (a) of the present embodiment, the content of the polymerizable surfactant is preferably 0.1% by mass or more and 30% by mass or less, more preferably 0.1% by mass or more and 20% by mass or less, even more preferably 0.1% by mass or more and 15% by mass or less, and still more preferably 0.1% by mass or more and 5% by mass or less, when the sum of all monomer units in the (meth)acrylic adhesive resin (a) is 100% by mass.

[0054] The (meth)acrylic adhesive resin (a) of the present embodiment may further contain, if necessary, a monomer unit formed from a monomer having a polymerizable double bond, such as vinyl acetate, acrylonitrile, or styrene.

[0055] The polymerization reaction mechanism of the (meth)acrylic adhesive resin (a) of this embodiment can be radical polymerization, anionic polymerization, cationic polymerization, etc. Taking into consideration the production cost of the (meth)acrylic adhesive resin (a), the influence of functional groups of the monomers, and the influence of ions on the surface of electronic components, it is preferable that the (meth)acrylic adhesive resin (a) of this embodiment be polymerized by a radical polymerization reaction. When polymerizing by a radical polymerization reaction, the (meth)acrylic adhesive resin (a) of this embodiment preferably contains a radical polymerization initiator. The radical polymerization initiator of the present embodiment is preferably benzoyl peroxide, di-t-butyl peroxide, dicumyl peroxide, 3,3,5-trimethylhexanoyl peroxide, di-2-ethylhexyl peroxydicarbonate, methyl ethyl ketone peroxide, t-butyl peroxyphthalate, t-butyl peroxybenzoate, di-t-butyl peroxyacetate, t-butyl peroxyisobutyrate, t-butylperoxy-2-hexanoate, or t-butylperoxy-2-ethylhexanoate. The peroxides may include one or more compounds selected from the group consisting of organic peroxides such as t-butylperoxy-3,5,5-trimethylhexanoate, acetyl peroxide, isobutyryl peroxide, octanoyl peroxide, t-butyl peroxide, and di-t-amyl peroxide; inorganic peroxides such as ammonium persulfate, potassium persulfate, and sodium persulfate; and azo compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis-2-methylbutyronitrile, and 4,4'-azobis-4-cyanovaleric acid.

[0056] When polymerized by emulsion polymerization, the (meth)acrylic adhesive resin (a) of this embodiment preferably contains one or more compounds selected from the group consisting of water-soluble inorganic peroxides such as ammonium persulfate, potassium persulfate, and sodium persulfate; and azo compounds having a carboxyl group in the molecule, such as water-soluble 4,4'-azobis-4-cyanovaleric acid. Furthermore, in consideration of the influence of ions on the surface of electronic components, the (meth)acrylic adhesive resin (a) more preferably contains an azo compound having a carboxyl group in the molecule, such as ammonium persulfate or 4,4'-azobis-4-cyanovaleric acid, and even more preferably contains an azo compound having a carboxyl group in the molecule, such as 4,4'-azobis-4-cyanovaleric acid.

[0057] From the viewpoint of suppressing misalignment of the electronic component 70 and improving the performance balance of adhesive strength, the adhesive resin layer (A) of this embodiment preferably further contains, in addition to the adhesive resin (Aa), a crosslinking agent (Ab) having two or more crosslinkable functional groups per molecule. The crosslinking agent (Ab) having two or more crosslinkable functional groups per molecule can be reacted with the functional groups of the adhesive resin (Aa) and used to adjust the adhesive strength and cohesive strength. The crosslinking agent (Ab) of the present embodiment is preferably an epoxy-based crosslinking agent such as sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, glycerol polyglycidyl ether, neopentyl glycol diglycidyl ether, or resorcinol diglycidyl ether; an isocyanate-based crosslinking agent such as tetramethylene diisocyanate, hexamethylene diisocyanate, a toluene diisocyanate triadduct of trimethylolpropane, polyisocyanate, diphenylmethane diisocyanate, or tolylene diisocyanate; trimethylolpropane-tri-β-aziridinyl propionate, tetramethylolpropane-tri-β-aziridinyl propionate, or tetramethylolpropane-tri-β-aziridinyl propionate; The crosslinking agent may comprise one or more crosslinkers selected from the group consisting of aziridine-based crosslinkers such as tyrolmethane-tri-β-aziridinylpropionate, N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxamide), N,N'-hexamethylene-1,6-bis(1-aziridinecarboxamide), N,N'-toluene-2,4-bis(1-aziridinecarboxamide), and trimethylolpropane-tri-β-(2-methylaziridine)propionate; tetrafunctional epoxy-based crosslinkers such as N,N,N',N'-tetraglycidyl-m-xylylenediamine and 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane; and melamine-based crosslinkers such as hexamethoxymethylolmelamine. Among these, the crosslinking agent (Ab) of this embodiment preferably includes one or more crosslinking agents selected from the group consisting of epoxy-based crosslinking agents, isocyanate-based crosslinking agents, and aziridine-based crosslinking agents, from the viewpoint of being able to improve the performance balance between suppressing misalignment of the electronic component 70 and adhesive strength.

[0058] The content of the crosslinking agent (Ab) is preferably within a range such that the number of functional groups in the crosslinking agent (Ab) is not greater than the number of functional groups in the adhesive resin (Aa). However, an excess amount of the crosslinking agent (Ab) may be added as necessary when new functional groups are generated by the crosslinking reaction or when the crosslinking reaction is slow. The content of the crosslinking agent (Ab) in the adhesive resin layer (A) is preferably 0.1 parts by mass or more and 15 parts by mass or less per 100 parts by mass of the adhesive resin (Aa), from the viewpoint of suppressing misalignment of the electronic component 70 in the adhesive resin layer (A) and improving the performance balance between heat resistance and adhesion.

[0059] The adhesive resin layer (A) may contain additives such as plasticizers and tackifier resins as other components. When the adhesive resin layer (A) is a radiation-crosslinkable adhesive resin layer, it may contain various additives for radiation crosslinking. The total content of the adhesive resin (Aa) and the crosslinking agent (Ab) in the adhesive resin layer (A) is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, and even more preferably 80% by mass or more, based on 100% by mass of the entire adhesive resin layer (A), from the viewpoint of suppressing misalignment of the electronic component 70. Furthermore, the upper limit of the total content of the adhesive resin (Aa) and the crosslinking agent (Ab) in the adhesive resin layer (A) is not particularly limited, but may be, for example, 100% by mass or less.

[0060] In the pressure-sensitive adhesive film 50 of the present embodiment, from the viewpoint of being able to stably hold the electronic component 70 on the pressure-sensitive adhesive resin layer (A) when the support substrate 80 is peeled off from the pressure-sensitive adhesive film 50, the total content of the gas-generating component and heat-expandable microspheres in the pressure-sensitive adhesive resin layer (A) is preferably 0.1% by mass or less, more preferably 0.05% by mass or less, even more preferably 0.01% by mass or less, based on 100% by mass of the entire pressure-sensitive adhesive resin layer (A). More preferably, the pressure-sensitive adhesive resin layer (A) does not contain any gas-generating component or heat-expandable microspheres.

[0061] The adhesive resin layer (A) may be a single layer or a multilayer. The thickness of the adhesive resin layer (A) is preferably 1 μm or more and 40 μm or less, more preferably 3 μm or more and 35 μm or less, and even more preferably 5 μm or more and 30 μm or less.

[0062] The adhesive resin layer (A) can be formed, for example, by applying an adhesive onto the substrate layer 10. The adhesive may be dissolved in a solvent and applied as a coating liquid, or may be applied as an aqueous emulsion, or the liquid adhesive may be applied directly. Among these, an aqueous emulsion coating liquid is preferred. Examples of aqueous emulsion coating liquids include coating liquids in which a (meth)acrylic adhesive resin (a), a silicone adhesive resin, a urethane adhesive resin, an olefin adhesive resin, a styrene adhesive resin, or the like is dispersed in water. An adhesive coating liquid dissolved in an organic solvent may also be used. The organic solvent is not particularly limited, and may be appropriately selected from known organic solvents in consideration of solubility and drying time. The organic solvent of the present embodiment preferably includes one or more selected from the group consisting of esters such as ethyl acetate and methyl acetate; ketones such as acetone and MEK; aromatics such as benzene, toluene, and ethylbenzene; linear or cyclic aliphatic solvents such as heptane, hexane, and cyclohexane; and alcohols such as isopropanol and butanol, and more preferably includes one or more selected from the group consisting of ethyl acetate and toluene.

[0063] 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. The drying conditions for the applied adhesive are not particularly limited, but generally, drying is preferably performed for 10 seconds to 10 minutes at a temperature range of 80 to 200°C. Drying for 15 seconds to 5 minutes at 80 to 170°C is even more preferable. To sufficiently promote the crosslinking reaction between the crosslinker and the adhesive, the adhesive coating liquid may be heated at 40 to 80°C for approximately 5 to 300 hours after drying is complete.

[0064] The adhesive resin layer (A) of this embodiment may be formed by co-extrusion molding together with the base layer 10, or may be formed by further laminating a film-like adhesive resin layer (A) on the film-like base layer 10. In the examples described later, the adhesive resin layer (A) is first formed on the surface of a separator (release film), and then the adhesive resin layer (A) is bonded to another layer to produce an adhesive film.

[0065] [Adhesive Resin Layer (B)] The adhesive film 50 of the present embodiment includes an adhesive resin layer (B) on the side opposite to the adhesive resin layer (A) of the base material layer 10, from the viewpoint of being able to suppress misalignment of the electronic component 70. The adhesive resin layer (B) is a layer for fixing the adhesive film 50 to the support substrate 80, for example, when sealing the electronic component with a sealing material in the manufacturing process of the electronic device.

[0066] The adhesive resin layer (B) preferably includes a layer whose adhesive strength decreases in response to an external stimulus, thereby enabling the adhesive film 50 to be peeled from the support substrate 80 by the external stimulus. Here, the external stimulus preferably includes one or more selected from the group consisting of light irradiation and heat treatment, and more preferably includes heat treatment.

[0067] The adhesive resin layer (B) of this embodiment preferably contains a heat-expandable adhesive from the viewpoint of further improving releasability. The heat-expandable adhesive of this embodiment preferably contains an adhesive resin (B1) and one or more components selected from the group consisting of a gas-generating component and heat-expandable microspheres, and more preferably contains an adhesive resin (B1) and heat-expandable microspheres.

[0068] The adhesive resin layer (B) of this embodiment is a layer whose adhesive strength is reduced or lost when heated at a temperature preferably exceeding 180°C, more preferably 185°C or higher, even more preferably 190°C or higher, even more preferably 195°C or higher, even more preferably 200°C or higher, even more preferably 205°C or higher, and even more preferably 210°C or higher. Such an adhesive resin layer (B) can be obtained by selecting the gas-generating component or the type of heat-expandable microspheres in the adhesive resin layer (B). The reduction or loss of adhesive strength due to heating at a temperature exceeding 180°C can be evaluated, for example, by attaching the adhesive resin layer (B) side to a stainless steel plate, heating at 120°C for 1 hour, and then heating at a temperature exceeding 180°C for 2 minutes, and then measuring the peel strength from the stainless steel plate. The specific heating temperature when heating at a temperature exceeding 180°C is set to a temperature higher than the temperature at which gas is generated or the temperature at which the heat-expandable microspheres thermally expand, and is appropriately set depending on the gas generated and the type of heat-expandable microspheres. In this embodiment, loss of adhesive strength refers to, for example, a case where the 180° peel strength measured under conditions of 23° C. and a pulling rate of 300 mm / min becomes less than 0.5 N / 25 mm.

[0069] Examples of gas-generating components that can be used include azo compounds, azide compounds, Meldrum's acid derivatives, etc. Examples of gas-generating components include inorganic blowing agents such as ammonium carbonate, ammonium bicarbonate, sodium bicarbonate, ammonium nitrite, sodium boron hydroxide, and various azides; water; fluorinated alkane compounds such as trichloromonofluoromethane and dichloromonofluoromethane; azo compounds such as azobisisobutyronitrile, azodicarbonamide, and barium azodicarboxylate; paratoluenesulfonylhydrazide, diphenylsulfone-3,3'-disulfonylhydrazide, 4,4'-oxo-2,4'-dimethylaminobenzoate, and the like; Other examples of organic blowing agents that can be used include hydrazine compounds such as bis(benzenesulfonylhydrazide) and allylbis(sulfonylhydrazide); semicarbazide compounds such as p-toluylenesulfonylsemicarbazide and 4,4'-oxybis(benzenesulfonylsemicarbazide); triazole compounds such as 5-morpholyl-1,2,3,4-thiatriazole; and N-nitroso compounds such as N,N'-dinitrosopentamethylenetetramine and N,N'-dimethyl-N,N'-dinitrosoterephthalamide. The gas-generating component may be mixed with the adhesive resin (B1) or may be directly bonded to the adhesive resin (B1).

[0070] Heat-expandable microspheres can be prepared using, for example, microencapsulated blowing agents. Examples of such heat-expandable microspheres include microspheres in which a substance that easily gasifies and expands upon heating, such as isobutane, propane, or pentane, is encapsulated in an elastic shell. Examples of materials constituting the shell include vinylidene chloride-acrylonitrile copolymer, polyvinyl alcohol, polyvinyl butyral, polymethyl methacrylate, polyacrylonitrile, polyvinylidene chloride, and polysulfone. Heat-expandable microspheres can be produced by, for example, coacervation or interfacial polymerization.

[0071] To further improve thermal peelability, the total content of the gas-generating component and heat-expandable microspheres in the adhesive resin layer (B) is preferably 1 to 150 parts by mass, more preferably 3 to 150 parts by mass, even more preferably 5 to 100 parts by mass, even more preferably 7 to 50 parts by mass, even more preferably 11 to 25 parts by mass, even more preferably 12 to 20 parts by mass, and even more preferably 14 to 18 parts by mass, per 100 parts by mass of the adhesive resin (B1) in the adhesive resin layer (B). It is preferable to design the temperature at which gas is generated and the temperature at which the heat-expandable microspheres thermally expand are above 150°C.

[0072] The adhesive resin (B1) of this embodiment preferably comprises one or more selected from the group consisting of (meth)acrylic adhesive resins, silicone adhesive resins, urethane adhesive resins, olefin adhesive resins, polyester adhesive resins, polyamide adhesive resins, fluorine adhesive resins and styrene adhesive resins, and from the viewpoint of further improving the releasability, more preferably comprises one or more selected from the group consisting of (meth)acrylic adhesive resins, silicone adhesive resins, urethane adhesive resins, olefin adhesive resins and styrene adhesive resins, and from the viewpoint of easily adjusting the adhesive strength, more preferably comprises a (meth)acrylic adhesive resin. As the (meth)acrylic adhesive resin that can be used for the adhesive resin (B1) of this embodiment, for example, the above-mentioned (meth)acrylic adhesive resin (a) can be used.

[0073] The adhesive resin layer (B) of this embodiment preferably further contains, in addition to the adhesive resin (B1), a crosslinking agent (B2) having two or more crosslinkable functional groups per molecule. The crosslinking agent (B2) having two or more crosslinkable functional groups per molecule is used to adjust the adhesive strength and cohesive strength by reacting with the functional groups of the adhesive resin (B1). The crosslinking agent (B2) of this embodiment is preferably an epoxy-based crosslinking agent such as sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, glycerol polyglycidyl ether, neopentyl glycol diglycidyl ether, or resorcinol diglycidyl ether; an isocyanate-based crosslinking agent such as tetramethylene diisocyanate, hexamethylene diisocyanate, a toluene diisocyanate triadduct of trimethylolpropane, polyisocyanate, diphenylmethane diisocyanate, or tolylene diisocyanate; trimethylolpropane-tri-β-aziridinylpropionate, tetramethylolmethane-tri-β-aziridinylpropionate, N,N'-diphenylmethane-4,4'- The adhesive composition contains one or more crosslinkers selected from the group consisting of aziridine crosslinkers such as bis(1-aziridinecarboxamide), N,N'-hexamethylene-1,6-bis(1-aziridinecarboxamide), N,N'-toluene-2,4-bis(1-aziridinecarboxamide), and trimethylolpropane-tri-β-(2-methylaziridine)propionate; tetrafunctional epoxy crosslinkers such as N,N,N',N'-tetraglycidyl-m-xylylenediamine and 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane; and melamine crosslinkers such as hexamethoxymethylolmelamine. From the viewpoint of further improving the performance balance between adhesive strength and releasability, the adhesive composition contains more preferably one or more crosslinkers selected from the group consisting of epoxy crosslinkers, isocyanate crosslinkers, and aziridine crosslinkers.

[0074] The content of the crosslinking agent (B2) in the adhesive resin layer (B) is preferably within a range such that the number of functional groups in the crosslinking agent (B2) is not greater than the number of functional groups in the adhesive resin (B1). However, if necessary, an excess amount may be added when new functional groups are generated by the crosslinking reaction or when the crosslinking reaction is slow. The lower limit of the content of the crosslinking agent (B2) in the adhesive resin layer (B) is preferably 0.1 parts by mass or more and 10.0 parts by mass or less, more preferably 0.5 parts by mass or more and 8.0 parts by mass or less, even more preferably 1.0 parts by mass or more and 6.0 parts by mass or less, and even more preferably 2.0 parts by mass or more and 4.0 parts by mass or less, per 100 parts by mass of the adhesive resin (B1), in order to further improve the performance balance of adhesive strength, peelability, and storage stability.

[0075] The adhesive resin layer (B) of this embodiment preferably contains a tackifier resin in addition to the adhesive resin (B1) from the viewpoint of further improving adhesive strength. By incorporating a tackifier resin into the adhesive resin layer (B), it becomes easier to adjust the adhesion to the support substrate 80 at around room temperature. The tackifier resin preferably has a softening point of 100°C or higher. Specific examples of tackifier resins include rosin-based resins such as rosin derivatives treated by esterification or the like; terpene-based resins such as α-pinene, β-pinene, dipentene, and terpene phenol; natural rosins such as gum, wood, and tall oil; petroleum resins obtained by hydrogenating, disproportionating, polymerizing, or maleating these natural rosins; and coumarone-indene resins. Among these tackifier resins, the adhesive resin layer (B) of this embodiment preferably contains a tackifier resin having a softening point in the range of 100 to 160°C, more preferably in the range of 120 to 150°C.

[0076] The content of the tackifier resin in the adhesive resin layer (B) is preferably 1 part by mass or more and 100 parts by mass or less, more preferably 2 parts by mass or more and 50 parts by mass or less, even more preferably 3 parts by mass or more and 30 parts by mass or less, and even more preferably 5 parts by mass or more and 10 parts by mass or less, relative to 100 parts by mass of the adhesive resin (B1), from the viewpoint of further improving adhesion to the support substrate 80 during operation.

[0077] The adhesive resin layer (B) may contain additives such as plasticizers as other components. The lower limit of the total content of the adhesive resin (B1), crosslinking agent (B2), tackifier resin, gas-generating component, and heat-expandable microspheres in the adhesive resin layer (B), when the entire adhesive resin layer (B) is taken as 100% by mass, is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more. The upper limit is not particularly limited, but is, for example, 100% by mass or less.

[0078] The adhesive resin layer (B) may be a single layer or a multilayer. The thickness of the adhesive resin layer (B) is preferably 10 μm or more and 100 μm or less, more preferably 15 μm or more and 90 μm or less, even more preferably 20 μm or more and 80 μm or less, and still more preferably 25 μm or more and 70 μm or less, from the viewpoint of further improving the balance of the handling properties, adhesiveness, and peelability of the adhesive film 50.

[0079] [Intermediate layer (C)] From the viewpoint of being able to suppress misalignment of the electronic component 70 and to improve the performance balance of the conformability and adhesion of the adhesive film 50 to the electronic component 70 and the support substrate 80, the adhesive film 50 of the present embodiment preferably further includes an intermediate layer (C) in at least one selected from the group consisting of between the base layer 10 and the adhesive resin layer (A) and between the base layer 10 and the adhesive resin layer (B), as shown in Fig. 4, and more preferably further includes an intermediate layer (C) between the base layer 10 and the adhesive resin layer (B). The intermediate layer (C) of the present embodiment is, for example, a layer for imparting conformability and adhesion to the electronic component 70 and the support substrate 80 to the adhesive film 50.

[0080] The intermediate layer (C) of this embodiment preferably contains a thermoplastic resin (C1). The thermoplastic resin (C1) of this embodiment preferably contains one or more selected from the group consisting of polyolefin resins, ethylene-carboxylic anhydride copolymers, ethylene-epoxy copolymers, ethylene-(meth)acrylic acid ester copolymers, ethylene-ethylenically unsaturated acid copolymers, ethylene-vinyl ester copolymers, polystyrene resins, and (meth)acrylic resins, and more preferably contains a (meth)acrylic resin from the viewpoint of further improving releasability. Examples of the (meth)acrylic resin that can be used for the thermoplastic resin (C1) of this embodiment include the (meth)acrylic adhesive resin (a) described above.

[0081] The intermediate layer (C) of this embodiment preferably further contains, in addition to the thermoplastic resin (C1), a crosslinking agent (C2) having two or more crosslinkable functional groups per molecule. The crosslinking agent (C2) having two or more crosslinkable functional groups per molecule is reacted with the functional groups of the thermoplastic resin (C1) to adjust the adhesive strength and cohesive strength. The crosslinking agent (C2) of the present embodiment is preferably an epoxy-based crosslinking agent such as sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, glycerol polyglycidyl ether, neopentyl glycol diglycidyl ether, or resorcinol diglycidyl ether; an isocyanate-based crosslinking agent such as tetramethylene diisocyanate, hexamethylene diisocyanate, a toluene diisocyanate triadduct of trimethylolpropane, polyisocyanate, diphenylmethane diisocyanate, or tolylene diisocyanate; trimethylolpropane-tri-β-aziridinylpropionate, tetramethylolmethane-tri-β-aziridinylpropionate, N,N'-diphenylmethane-4,4'- The adhesive composition contains one or more crosslinkers selected from the group consisting of aziridine crosslinkers such as bis(1-aziridinecarboxamide), N,N'-hexamethylene-1,6-bis(1-aziridinecarboxamide), N,N'-toluene-2,4-bis(1-aziridinecarboxamide), and trimethylolpropane-tri-β-(2-methylaziridine)propionate; tetrafunctional epoxy crosslinkers such as N,N,N',N'-tetraglycidyl-m-xylylenediamine and 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane; and melamine crosslinkers such as hexamethoxymethylolmelamine. From the viewpoint of further improving the performance balance between adhesive strength and releasability, the adhesive composition contains more preferably one or more crosslinkers selected from the group consisting of epoxy crosslinkers, isocyanate crosslinkers, and aziridine crosslinkers.

[0082] The content of the crosslinking agent (C2) in the intermediate layer (C) of this embodiment is preferably within a range such that the number of functional groups in the crosslinking agent (C2) is not greater than the number of functional groups in the thermoplastic resin (C1). However, an excess amount may be added as necessary when new functional groups are generated in the crosslinking reaction or when the crosslinking reaction is slow. From the viewpoint of further improving the performance balance of adhesive strength, peelability, and storage stability, the content of the crosslinking agent (C2) in the intermediate layer (C) of this embodiment is preferably 0.1 parts by mass or more and 10.0 parts by mass or less, more preferably 0.5 parts by mass or more and 8.0 parts by mass or less, even more preferably 1.0 parts by mass or more and 6.0 parts by mass or less, and even more preferably 2.0 parts by mass or more and 4.0 parts by mass or less, per 100 parts by mass of the thermoplastic resin (C1).

[0083] The intermediate layer (C) of this embodiment preferably contains a tackifier resin in addition to the thermoplastic resin (C1) from the viewpoint of further improving adhesive strength. By incorporating a tackifier resin into the intermediate layer (C), it becomes easier to adjust the adhesion to the support substrate 80 at around room temperature. The tackifier resin preferably has a softening point of 100°C or higher. Specific examples of tackifier resins include rosin-based resins such as rosin derivatives treated by esterification or the like; terpene-based resins such as α-pinene, β-pinene, dipentene, and terpene phenol; natural rosins such as gum, wood, and tall oil; petroleum resins obtained by hydrogenating, disproportionating, polymerizing, or maleating these natural rosins; and coumarone-indene resins. Among these tackifier resins, the intermediate layer (C) of this embodiment preferably contains a tackifier resin having a softening point in the range of 100 to 160°C, more preferably in the range of 120 to 150°C.

[0084] In order to further improve adhesion to the support substrate 80 during operation, the content of the tackifier resin in the intermediate layer (C) of this embodiment is preferably 1 part by mass or more and 100 parts by mass or less, more preferably 2 parts by mass or more and 50 parts by mass or less, even more preferably 3 parts by mass or more and 30 parts by mass or less, and even more preferably 3 parts by mass or more and 10 parts by mass or less, relative to 100 parts by mass of the thermoplastic resin (C1).

[0085] The intermediate layer (C) of this embodiment may contain additives such as plasticizers as other components. The total content of the thermoplastic resin (C1), crosslinking agent (C2), tackifier resin, gas-generating component, and heat-expandable microspheres in the intermediate layer (C) of this embodiment is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more, based on 100% by mass of the entire intermediate layer (C). The upper limit is not particularly limited, but is, for example, 100% by mass or less.

[0086] The thickness of the intermediate layer (C) in this embodiment is preferably 1 μm or more and 500 μm or less, more preferably 5 μm or more and 300 μm or less, and even more preferably 10 μm or more and 100 μm or less, from the viewpoint of improving the unevenness absorbency of the adhesive film 50.

[0087] [Other Layers] The pressure-sensitive adhesive film 50 of this embodiment may further include, for example, an easy-adhesion layer or the like between the layers, as long as the effect of this embodiment is not impaired.

[0088] The method for manufacturing an electronic device according to this embodiment can be preferably used to manufacture an electronic device including a fan-out package. That is, the electronic device obtained by the method for manufacturing an electronic device according to this embodiment includes a fan-out package. In a fan-out package, terminals can be extended to the outside of the chip (fan out), so it can be used in applications where the number of terminals is large compared to the chip area. Furthermore, since a package substrate is not required, it can also be made thinner.

[0089] 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.

[0090] 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.

[0091] The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. Details of the method for producing an adhesive film are as follows.

[0092] <Raw Material Components> (Resin Emulsion 1) Using 0.5 parts by mass of ammonium peroxodisulfate as a polymerization initiator, 63 parts by mass of 2-ethylhexyl acrylate, 21 parts by mass of butyl acrylate, 9 parts by mass of methyl methacrylate, 3 parts by mass of 2-hydroxyethyl methacrylate, 2 parts by mass of methacrylic acid, 1 part by mass of acrylamide, 1 part by mass of polytetramethylene glycol diacrylate (manufactured by NOF Corporation, product name: Blemmer ADT-250), and 2 parts by mass of an aqueous solution of polyoxyethylene nonylpropenyl phenyl ether ammonium sulfate (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., product name: Aqualon HS-1025) were emulsion-polymerized in deionized water at 70°C for 8 hours. After completion of polymerization, the pH was adjusted to 7 with aqueous ammonia. As a result, a (meth)acrylic resin emulsion 1 with a solids concentration of 56.5% by mass was obtained.

[0093] (Resin Emulsion 2) Using 0.5 parts by mass of 4,4'-azobis-4-cyanovaleric acid (manufactured by Otsuka Chemical Co., Ltd., product name: ACVA) as a polymerization initiator, 74 parts by mass of butyl acrylate, 14 parts by mass of methyl methacrylate, 9 parts by mass of 2-hydroxyethyl methacrylate, 2 parts by mass of methacrylic acid, 1 part by mass of acrylamide, and 3 parts by mass of an aqueous solution of polyoxyethylene nonylpropenylphenyl ether ammonium sulfate (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., product name: Aqualon HS-1025) were emulsion-polymerized in deionized water at 70°C for 8 hours. After completion of polymerization, the pH was adjusted to 7 with aqueous ammonia. As a result, a (meth)acrylic resin emulsion 2 with a solids concentration of 42.5% by mass was obtained.

[0094] (Resin Solution 1) 0.536 parts by mass of t-butylperoxy-2-ethylhexanoate (manufactured by NOF Corporation, trade name: Perbutyl O (registered trademark)) as a polymerization initiator, 34.9 parts by weight of 2-ethylhexyl acrylate, 41 parts by mass of n-butyl acrylate, 14.7 parts by mass of ethyl acrylate, and 9.4 parts by mass of 2-hydroxyethyl methacrylate were added to a mixed solvent containing ethyl acetate and toluene, and solution polymerization was carried out at 83 to 87°C for 11 hours with stirring to obtain an acrylic resin solution (resin solution 1) with a solids concentration of 45% by mass.

[0095] (Adhesive coating solution A for forming adhesive resin layer (A)) 42.6 parts by mass of resin emulsion 1, 57.4 parts by mass of resin emulsion 2, 0.4 parts by mass of dimethylethanolamine, 5 parts by mass of an epoxy compound (manufactured by Nagase ChemteX Corporation, product name: EX-1610) as a crosslinking agent, 13 parts by mass of diethylene glycol monobutyl ether, and ２ 20 parts by mass of O were mixed to prepare a pressure-sensitive adhesive coating solution A.

[0096] (Adhesive Coating Solution B for Forming Adhesive Resin Layer (B)) 100 parts by mass of resin solution 1, 2.25 parts by weight (5 parts by mass per 100 parts by mass of adhesive resin) of a polymerized rosin ester-based tackifier (manufactured by Arakawa Chemical Industries, Ltd., trade name: Pencel D-125), 1.2 parts by mass (2.7 parts by mass per 100 parts by mass of adhesive resin) of an isocyanate-based crosslinking agent (manufactured by Mitsui Chemicals, Inc., trade name: Olester P49-75S), and 6.75 parts by mass (15 parts by mass per 100 parts by mass of adhesive resin) of heat-expandable microspheres (manufactured by Sekisui Chemical Co., Ltd., trade name: Advancell EM-503) were mixed, and the solids concentration was adjusted to 30% with ethyl acetate to prepare adhesive coating solution B.

[0097] <Preparation of adhesive film> First, adhesive coating liquid B was applied to a silicone-release-treated separator and dried at 120 ° C. for 3 minutes to form a resin film B with a thickness of 47 μm. Then, this resin film B was attached to the second surface of a polyethylene terephthalate film (manufactured by Toray Industries, Inc., product name: Lumirror S10, thickness: 38 μm, double-sided corona-treated product) serving as a substrate layer to obtain an adhesive resin layer (B). Furthermore, adhesive coating liquid A was applied to a silicone-release-treated separator and dried at 120 ° C. for 3 minutes to form a resin film A with a thickness of 13 μm. This resin film A was attached to the first surface of the substrate layer (the surface opposite to the surface on which the adhesive resin layer (B) of the substrate layer was provided). This resulted in an adhesive resin layer (A). As a result, an adhesive film having, in this order, an adhesive resin layer (A), a substrate layer, and an adhesive resin layer (B) was obtained. The resulting adhesive film was heated at 60° C. for 5 days.

[0098] <Treatment of Stainless Steel Substrate> (Example 1) A SUS430 plate measuring 300 cm x 300 cm x 1.5 mm thick was fired at 230°C for 8.0 hours to obtain a stainless steel substrate with an oxidized surface.

[0099] Example 2 A stainless steel substrate with an oxidized surface was obtained in the same manner as in Example 1, except that the firing conditions were changed to 190° C. and 5.0 hours.

[0100] Example 3 A stainless steel substrate with an oxidized surface was obtained in the same manner as in Example 1, except that the firing conditions were changed to 150° C. and 8.0 hours.

[0101] Example 4 A stainless steel substrate having an oxidized surface was obtained in the same manner as in Example 1, except that SUS430 in Example 1 was changed to SUS304.

[0102] Comparative Example 1 The SUS430 used in Example 1 was used as it was without being sintered.

[0103] Comparative Example 2 A stainless steel substrate having an oxidized surface was obtained in the same manner as in Example 1, except that the firing conditions were changed to 100° C. and 16.0 hours.

[0104] <Evaluation> [Oxygen Concentration (X-ray Photoelectron Spectroscopy (ESCA))] X-ray photoelectron spectroscopy (ESCA) was performed on a stainless steel substrate using an apparatus under the following conditions: step width: 1.0 eV, dwell time: 50 milliseconds, number of integrations: 2, measurement range: 0 to 1100 eV. The detected elements were identified by wide scanning under the conditions shown in Table 1. Then, a spectrum of the identified O element was obtained by narrow scanning under the conditions shown in Table 1. The background determined by the Shirley method was removed from the obtained spectrum, and the concentration of each detected element was calculated from the obtained peak area using the relative sensitivity factor method, which was used as the oxygen concentration. The apparatus conditions are as follows: Apparatus: X-ray photoelectron spectroscopy apparatus (ESCA3400, manufactured by Shimadzu Corporation) X-ray source: Mg-Kα radiation X-ray source output: 15 kV, 10 mA Analysis area: 300 × 700 μm A neutralization electron gun for charge correction was used during analysis.

[0105]

[0106] [Thermal Peelability] The adhesive resin layer (B) side of the pressure-sensitive adhesive film was attached to a stainless steel substrate of each Example and Comparative Example under conditions of a temperature of 25°C, a pressure of 0.5 MPa, and an attachment speed of 10 mm / sec, to obtain a structure. The structure was then heated at 150°C for 1 hour and allowed to stand at 25°C for 1 hour. Next, using a debonder (DT-SDB2050, manufactured by Dynatech Corporation), the pressure-sensitive adhesive film was peeled from the stainless steel substrate under conditions of a bottom chuck of 170°C, a top chuck of 200°C, and a peel time of 60 seconds. The thermal peelability was then evaluated according to the following criteria. The results are shown in Table 2. A: The pressure-sensitive adhesive film was peeled from the stainless steel substrate. B: A part of the pressure-sensitive adhesive resin layer (B) remained on the stainless steel substrate, or the pressure-sensitive adhesive film could not be peeled from the stainless steel substrate.

[0107]

[0108] As in each example, by including a stainless steel substrate having an oxide film on its surface as the support substrate, the thermal peelability between the support substrate and the adhesive film could be improved. On the other hand, as in the comparative example, the stainless steel substrate having no oxide film on its surface had poor thermal peelability. Note that the oxygen concentration on the surface of the SUS430 in Example 1 was 54 atomic %, confirming that an oxide film had been formed on the surface.

[0109] This application claims priority based on Japanese Patent Application No. 2024-047205, filed March 22, 2024, the disclosure of which is incorporated herein by reference in its entirety.

[0110] A: adhesive resin layer B: adhesive resin layer C: intermediate layer 10: base layer 50: adhesive film 60: sealing material 70: electronic component 80: supporting substrate 100: structure 200: electronic device

Claims

1. A method for manufacturing an electronic device, comprising: a step of preparing a structure comprising an adhesive film having an adhesive resin layer (A), a base layer, and an adhesive resin layer (B) in this order, an electronic component on the adhesive resin layer (A) side of the adhesive film, and a support substrate on the adhesive resin layer (B) side of the adhesive film; and a step of reducing the adhesive strength of the adhesive resin layer (B) by heat treatment to peel off the support substrate from the structure, wherein the support substrate comprises a stainless steel substrate having an oxide film on its surface.

2. The method for manufacturing an electronic device according to claim 1, wherein the oxygen concentration on the surface of the stainless steel substrate is 45 atomic % or more and 75 atomic % or less, as determined by the following (Method 1). (Method 1) The stainless steel substrate is subjected to X-ray photoelectron spectroscopy (ESCA) using an apparatus under the following conditions: a step width of 1.0 eV, a dwell time of 50 milliseconds, two accumulations, and a measurement range of 0 to 1100 eV, with a wide scan to identify the detected elements. Then, a spectrum of the O element is obtained using a narrow scan with a step width of 0.1 eV, a dwell time of 300 milliseconds, four accumulations, and a measurement range of 523 to 543 eV. The background determined by the Shirley method is subtracted from the obtained spectrum, and the concentration of the O element is calculated from the obtained peak area using the relative sensitivity factor method, which is used to determine the oxygen concentration. The apparatus conditions are as follows: X-ray source: Mg-Kα ray X-ray source output: 15 kV, 10 mA Analysis area: 300 x 700 μm A neutralization electron gun is used for charge correction during analysis.

3. The method for manufacturing an electronic device according to claim 1 or 2, further comprising the step of heating a raw stainless steel plate to obtain the stainless steel substrate before the step of preparing the structure.

4. The method for manufacturing an electronic device according to claim 3, wherein the heating time in the step of obtaining the stainless steel substrate is 3.0 hours or more.

5. The method for manufacturing an electronic device according to claim 3 or 4, wherein the heating temperature in the step of obtaining the stainless steel substrate is 120° C. or higher.

6. The method for manufacturing an electronic device according to any one of claims 1 to 5, wherein the stainless steel substrate comprises one or two selected from the group consisting of SUS304 and SUS430.

7. A method for manufacturing an electronic device according to any one of claims 1 to 6, wherein the adhesive resin layer (A) contains one or more resins selected from the group consisting of (meth)acrylic adhesive resins, silicone adhesive resins, urethane adhesive resins, olefin adhesive resins, and styrene adhesive resins.

8. The method for manufacturing an electronic device according to any one of claims 1 to 7, wherein the total content of the gas-generating component and the heat-expandable microspheres in the adhesive resin layer (A) is 0.1 mass % or less, when the entire adhesive resin layer (A) is taken as 100 mass %.

9. The method for manufacturing an electronic device according to any one of claims 1 to 8, wherein the thickness of the adhesive resin layer (A) is 1 μm or more and 40 μm or less.

10. The method for manufacturing an electronic device according to any one of claims 1 to 9, wherein the adhesive resin layer (B) includes a layer whose adhesive strength decreases upon heat treatment.

11. The method for manufacturing an electronic device according to claim 10, wherein the adhesive resin layer (B) contains a thermally expandable adhesive.

12. The method for manufacturing an electronic device according to claim 10 or 11, wherein the adhesive strength of the adhesive resin layer (B) is reduced by heating at a temperature exceeding 180°C.

13. A method for manufacturing an electronic device according to any one of claims 1 to 12, wherein the adhesive resin layer (B) contains one or more resins selected from the group consisting of (meth)acrylic adhesive resins, silicone adhesive resins, urethane adhesive resins, olefin adhesive resins, and styrene adhesive resins.

14. The method for manufacturing an electronic device according to any one of claims 1 to 13, wherein the thickness of the adhesive resin layer (B) is 10 μm or more and 100 μm or less.

15. The method for manufacturing an electronic device according to any one of claims 1 to 14, wherein the base layer comprises one or more materials selected from the group consisting of polypropylene, polyethylene terephthalate, polyethylene naphthalate, polyamide, and polyimide.

16. The method for manufacturing an electronic device according to any one of claims 1 to 15, further comprising an intermediate layer (C) between the base material layer and the adhesive resin layer (A) and between the base material layer and the adhesive resin layer (B).

17. The method for manufacturing an electronic device according to any one of claims 1 to 16, further comprising the step of peeling the adhesive film from the electronic component.

18. The method for manufacturing an electronic device according to any one of claims 1 to 17, further comprising a step of encapsulating the electronic component with an encapsulant between the step of preparing the structure and the step of peeling the support substrate from the structure.

19. The method for manufacturing an electronic device according to claim 18, wherein the encapsulant comprises an epoxy resin-based encapsulant.

20. The method for manufacturing an electronic device according to any one of claims 1 to 19, wherein the electronic device comprises a fan-out package.

21. A method for producing a stainless steel substrate for use in the method for producing an electronic device according to any one of claims 1 to 20, comprising the step of heating a raw stainless steel plate to obtain the stainless steel substrate.

22. The method for producing a stainless steel substrate according to claim 21, wherein the oxygen concentration on the surface of the stainless steel substrate is 45 atomic % or more and 75 atomic % or less, as determined by the following (Method 1). (Method 1) The stainless steel substrate is subjected to X-ray photoelectron spectroscopy (ESCA) using an apparatus under the following conditions: a step width of 1.0 eV, a dwell time of 50 milliseconds, two accumulations, and a measurement range of 0 to 1100 eV, with a wide scan to identify detected elements. Then, a spectrum of oxygen element is obtained using a step width of 0.1 eV, a dwell time of 300 milliseconds, four accumulations, and a narrow scan to 523 to 543 eV. The background determined by the Shirley method is removed from the obtained spectrum, and the concentration of oxygen element is calculated from the obtained peak area using the relative response factor method, which is taken as the oxygen concentration. The apparatus conditions are as follows: X-ray source: Mg-Kα ray X-ray source output: 15 kV, 10 mA Analysis area: 300 x 700 μm A neutralization electron gun is used for charge correction during analysis.

23. The method for producing a stainless steel substrate according to claim 21 or 22, wherein the heating time in the step of obtaining the stainless steel substrate is 3.0 hours or longer.

24. The method for producing a stainless steel substrate according to any one of claims 21 to 23, wherein the heating temperature in the step of obtaining the stainless steel substrate is 120°C or higher.

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