JP7760376B2 - adhesive sheet - Google Patents

Description

The present invention relates to an adhesive sheet.

Conventionally, when processing (processing) electronic components, a process is sometimes performed in which the object to be processed is temporarily fixed to a fixing table via an adhesive sheet during processing, and then the object is peeled off from the adhesive sheet after processing. The adhesive sheets used in this process are sometimes those that have a predetermined adhesive strength during processing but whose adhesive strength can decrease after processing. One such adhesive sheet has been proposed, which is an adhesive sheet containing heat-expandable microspheres in the adhesive layer (see, for example, Patent Document 1). An adhesive sheet containing heat-expandable microspheres has a predetermined adhesive strength, but when heated, the heat-expandable microspheres expand, forming irregularities on the adhesive surface and reducing the contact area, thereby reducing or eliminating the adhesive strength. Such an adhesive sheet has the advantage of allowing the object to be easily peeled off without external stress.

However, adhesive sheets containing heat-expandable microspheres have low translucency, and when such adhesive sheets are used, the problem arises that markings on the mounting base to indicate the temporary fixing positions of electronic components are difficult to see through the adhesive sheet.

Japanese Patent Application Laid-Open No. 2001-131507

The present invention has been made to solve the above-mentioned conventional problems, and its purpose is to provide an adhesive sheet that combines excellent adhesion and releasability, and also has excellent visibility of the adherend (visibility through the adhesive sheet).

The pressure-sensitive adhesive sheet of the present invention includes a gas generating layer that generates gas when irradiated with laser light, and has a haze value of 50% or less.
In one embodiment, the gas generating layer has a thickness of 0.1 μm to 50 μm.
In one embodiment, the gas generating layer is a layer capable of absorbing ultraviolet light.
In one embodiment, the gas generating layer includes an ultraviolet absorber.
In one embodiment, the pressure-sensitive adhesive sheet has an ultraviolet transmittance of 30% or less at a wavelength of 360 nm.
In one embodiment, the pressure-sensitive adhesive sheet has an ultraviolet transmittance of 500 nm wavelength of 50% to 100%.
In one embodiment, the gas generating layer is a layer that generates a hydrocarbon gas.
In one embodiment, the gasification initiation temperature of the gas generating layer is 150°C to 500°C.
In one embodiment, the pressure-sensitive adhesive sheet has a 10% weight loss temperature of 200°C to 500°C.
In one embodiment, the pressure-sensitive adhesive sheet further comprises a pressure-sensitive adhesive layer on at least one side of the gas-generating layer, and the pressure-sensitive adhesive layer is a layer whose surface is deformed when the pressure-sensitive adhesive sheet is irradiated with laser light.
In one embodiment, the pressure-sensitive adhesive layer has a thickness of 0.1 μm to 50 μm.
In one embodiment, the pressure-sensitive adhesive layer is foamed by irradiating the pressure-sensitive adhesive sheet with laser light.
According to another aspect of the present invention, there is provided a method for treating electronic components, which comprises adhering an electronic component to the pressure-sensitive adhesive sheet described above, and irradiating the pressure-sensitive adhesive sheet with laser light to peel the electronic component from the pressure-sensitive adhesive sheet.
In one embodiment, the electronic component is peeled off selectively at a position.
In one embodiment, the treatment method includes performing a predetermined treatment on the electronic component after the electronic component is attached to the pressure-sensitive adhesive sheet and before the electronic component is peeled off from the pressure-sensitive adhesive sheet.
In one embodiment, the treatment is grinding, dicing, die bonding, wire bonding, etching, deposition, molding, circuit formation, inspection, testing, cleaning, transfer, alignment, repair, or protection of a device surface.
According to another aspect of the present invention, there is provided a method for treating an electronic component, comprising peeling the electronic component from the pressure-sensitive adhesive sheet and then placing the electronic component on another sheet.

The present invention makes it possible to provide an adhesive sheet that combines excellent adhesion and releasability, and also has excellent visibility of the adherend (visibility through the adhesive sheet).

1 is a schematic cross-sectional view of a pressure-sensitive adhesive sheet according to one embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of a pressure-sensitive adhesive sheet according to another embodiment of the present invention. FIG. 2 is a schematic diagram illustrating a method for measuring puncture strength.

A. Overview of the Pressure-Sensitive Adhesive Sheet FIG. 1( a) is a schematic cross-sectional view of a pressure-sensitive adhesive sheet according to one embodiment of the present invention. The pressure-sensitive adhesive sheet 100 includes a gas-generating layer 10. The gas-generating layer 10 generates gas when irradiated with laser light. More specifically, the gas-generating layer 10 is a layer that generates gas by gasifying its components when irradiated with laser light. UV laser light is typically used as the laser light. The gas-generating layer 10 can have a predetermined adhesive strength.

Figure 1(b) is a schematic cross-sectional view of a pressure-sensitive adhesive sheet according to another embodiment of the present invention. The pressure-sensitive adhesive sheet 100' comprises a gas-generating layer 10 and at least one pressure-sensitive adhesive layer 20 disposed on one side of the gas-generating layer 10. The surface of the pressure-sensitive adhesive layer 20 can be deformed by irradiating the pressure-sensitive adhesive sheet (essentially the gas-generating layer) with laser light. In one embodiment, the deformation is caused by gas generated from the gas-generating layer 10 and can occur on the side of the pressure-sensitive adhesive layer 20 opposite the gas-generating layer 10.

The pressure-sensitive adhesive sheet of the present invention can be used by adhering a target object, such as an electronic component, to the gas-generating layer or adhesive layer. The pressure-sensitive adhesive sheet of the present invention includes a gas-generating layer that generates gas locally within a small area upon irradiation with laser light. This gas generation causes deformation of the adhesion surface, resulting in satisfactory peeling of the adherend. When the pressure-sensitive adhesive sheet includes an adhesive layer, as described above, the gas generation causes deformation of the adhesive layer, resulting in the development of releasability in the area irradiated with laser light. Typically, the laser light is irradiated from the gas-generating layer opposite the adhesive layer. According to the present invention, deformation can be caused within a small area as described above, thereby enabling satisfactory peeling of even extremely small electronic components when processing (processing) them. Furthermore, even when a small electronic component requiring peeling and a small electronic component not requiring peeling are temporarily fixed adjacent to each other, peeling occurs at the target area and not at the non-target area, i.e., only the small electronic component requiring peeling can be peeled, preventing unwanted detachment of the small electronic components. In order to allow the pressure-sensitive adhesive layer to deform satisfactorily, it is preferable that at least a portion of the generated gas is prevented from escaping from the pressure-sensitive adhesive sheet, and the pressure-sensitive adhesive layer can function as a gas barrier layer.

Deformation of the adhesive layer refers to displacement occurring in the normal direction (thickness direction) and horizontal direction (direction perpendicular to the thickness direction) of the adhesive layer. Deformation of the adhesive layer occurs, for example, by pulse scanning a UV laser beam with a wavelength of 355 nm and a beam diameter of approximately 20 μmφ at a power of 0.80 mW and a frequency of 40 kHz to generate gas from the gas-generating layer. The deformed shape is observed, for example, by measuring any pulse-scanned spot 24 hours after laser irradiation using a confocal laser microscope or a non-contact interference microscope (WYKO). The shape may be a bubble (convex), a through hole (unevenness), or a depression (concave), and these deformations can result in peelability. For efficient peeling of electronic components in the normal direction, a large change in normal displacement before and after laser irradiation is preferable, and a bubble-like shape is particularly suitable. The bubble (convex) is defined as the highest point, measured as the vertical displacement Y, and the full width at half maximum, measured as the horizontal displacement X (diameter), relative to the unirradiated portion of the adhesive sheet surface. With regard to the through-holes (concave and convex) and depressions (concave) that form holes after laser light irradiation, the difference between the highest point and the lowest point is defined as the vertical displacement Y, and the diameter of the hole is defined as the horizontal displacement X. Hereinafter, the part that has been deformed by laser light irradiation will also be referred to as the "deformed part."

Figure 2 is a schematic cross-sectional view of an adhesive sheet according to another embodiment of the present invention. The adhesive sheet 200 further comprises an intermediate layer 30 between the gas generating layer 10 and the adhesive layer 20. By providing the intermediate layer, it becomes possible to easily control the deformation of the adhesive layer (details will be described later). The intermediate layer can also function as a gas barrier layer in cooperation with the adhesive layer. Therefore, by providing the intermediate layer, the gas barrier properties are improved, and an adhesive sheet with a more favorable deformation of the adhesive layer can be obtained. The intermediate layer may be a single layer or multiple layers.

Although not shown, the pressure-sensitive adhesive sheet may further include other layers. For example, a substrate, another pressure-sensitive adhesive layer, etc. may be provided on the side of the gas-generating layer opposite the pressure-sensitive adhesive layer. The substrate may be, for example, a film formed from any suitable resin.

The pressure-sensitive adhesive sheet of the present invention is characterized by a haze value of 50% or less. In the present invention, the gas-generating layer, pressure-sensitive adhesive layer, and intermediate layer can be formed without the inclusion of insoluble fillers, etc., resulting in a pressure-sensitive adhesive sheet with a low haze value, high light transmittance, and reduced opacity. The pressure-sensitive adhesive sheet exhibits high transparency before laser irradiation (during temporary fixation). Use of such a pressure-sensitive adhesive sheet allows, for example, the adherend (e.g., a stand for temporarily fixing electronic components) to be viewed through the pressure-sensitive adhesive sheet, and allows, for example, markings on the stand to indicate the temporary fixation position of the electronic components to be clearly visible through the pressure-sensitive adhesive sheet. This is an excellent effect that cannot be obtained with pressure-sensitive adhesive sheets containing insoluble fillers (e.g., pressure-sensitive adhesive sheets containing heat-expandable microspheres in the pressure-sensitive adhesive layer as a release layer).

The haze value of the pressure-sensitive adhesive sheet of the present invention is preferably 0% to 50%, more preferably 0.01% to 40%, even more preferably 0.05% to 30%, and particularly preferably 0.1% to 20%. Within these ranges, the above-mentioned effects of the present invention become more pronounced.

The adhesive strength of the adhesive layer of the pressure-sensitive adhesive sheet of the present invention to SUS430 is preferably 0.1 N/20 mm or more, more preferably 0.2 N/20 mm to 50 N/20 mm, even more preferably 0.5 N/20 mm to 40 N/20 mm, particularly preferably 0.7 N/20 mm to 20 N/20 mm, and most preferably 1 N/20 mm to 10 N/20 mm. Within these ranges, a pressure-sensitive adhesive sheet exhibiting good adhesive properties can be obtained, for example, as a temporary fixing sheet used in the manufacture of electronic components. As used herein, "adhesive strength" refers to adhesive strength measured at 23°C using a method conforming to JIS Z 0237:2000 (lamination conditions: one round trip with a 2 kg roller, tensile speed: 300 mm/min, peel angle: 180°).

In one embodiment, the gas generation layer has a predetermined adhesive strength. The adhesive strength of the gas generation layer of the pressure-sensitive adhesive sheet of the present invention to SUS430 is preferably 0.1 N/20 mm or more, more preferably 0.5 N/20 mm to 50 N/20 mm, even more preferably 1 N/20 mm to 40 N/20 mm, particularly preferably 1.5 N/20 mm to 30 N/20 mm, and most preferably 2 N/20 mm to 20 N/20 mm. Within these ranges, a pressure-sensitive adhesive sheet exhibiting good adhesive properties can be obtained, for example, as a temporary fixing sheet used in the manufacture of electronic components.

The thickness of the adhesive sheet of the present invention is preferably 2 μm to 200 μm, more preferably 3 μm to 150 μm, and even more preferably 5 μm to 120 μm.

The water vapor transmission rate of the pressure-sensitive adhesive sheet of the present invention is preferably 5000 g/( ^m2 ·day) or less, more preferably 4800 g/( ^m2 ·day) or less, even more preferably 4500 g/( ^m2 ·day) or less, and even more preferably 4200 g/( ^m2 ·day) or less. In a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer (and an intermediate layer, if necessary) having a water vapor transmission rate in such a range, the escape of gas generated by laser light irradiation is prevented, and a deformed portion with an excellent shape is formed in the pressure-sensitive adhesive layer. By using such a pressure-sensitive adhesive sheet, small adherends (e.g., electronic components) can be peeled off with high accuracy. The lower the water vapor transmission rate of the pressure-sensitive adhesive sheet of the present invention, the more preferable, and the lower limit thereof is, for example, 0.1 g/( ^m2 ·day). The water vapor transmission rate can be measured in an atmosphere of 30°C and 90% RH by a measurement method in accordance with JIS K7129B.

The water vapor permeability of the laminate comprising the pressure-sensitive adhesive layer and the intermediate layer is preferably 10,000 g/(m ² ·day) or less, more preferably 7,000 g/(m ² ·day) or less, even more preferably 5,000 g/(m ² ·day) or less, even more preferably 4,800 g/(m ² ·day) or less, particularly preferably 4,500 g/(m ² ·day) or less, and most preferably 4,200 g/(m ² ·day) or less. Within this range, the laminate comprising the pressure-sensitive adhesive layer and the intermediate layer functions well as a gas barrier layer, and a deformed portion with an excellent shape is formed in the pressure-sensitive adhesive layer. By using such a pressure-sensitive adhesive sheet, small adherends (e.g., electronic components) can be peeled off with high precision. The lower the water vapor permeability of the laminate comprising the pressure-sensitive adhesive layer and the intermediate layer, the more preferable it is, and the lower limit is, for example, 1 g/(m ² ·day).

The puncture strength of the laminate comprising the pressure-sensitive adhesive layer and intermediate layer is preferably 10 mN to 5,000 mN, more preferably 30 mN to 4,000 mN, even more preferably 50 mN to 3,000 mN, and particularly preferably 100 mN to 2,000 mN. Within these ranges, the laminate comprising the pressure-sensitive adhesive layer and intermediate layer functions well as a gas barrier layer, and favorable shape change due to gas generation occurs, resulting in the formation of a deformed portion with an excellent shape in the pressure-sensitive adhesive layer. Use of such a pressure-sensitive adhesive sheet enables accurate peeling of small adherends (e.g., electronic components). As shown in Figure 3, puncture strength is measured using a compression tester 6 (manufactured by Kato Tech Co., Ltd., product name "KES-G5") by clamping sample 4 (e.g., a laminate) between sample holders 5A and 5B with circular openings each having a diameter of 11.28 mm. More specifically, at a measurement temperature of 23°C, a piercing needle (radius of curvature: 1 mm) is pierced into the sample at the center of the circular opening (piercing speed: 0.1 mm/s), and the maximum load at the breaking point can be taken as the piercing strength.

The ultraviolet transmittance at a wavelength of 360 nm of the laminate consisting of the above-mentioned adhesive layer and intermediate layer is preferably 50% to 100%, and more preferably 60% to 95%.

The transmittance of the above-mentioned pressure-sensitive adhesive sheet to ultraviolet light with a wavelength of 360 nm is preferably 30% or less, more preferably 20% or less, even more preferably 15% or less, particularly preferably 10% or less, and most preferably 5% or less. The lower limit of the transmittance of ultraviolet light with a wavelength of 360 nm to the pressure-sensitive adhesive sheet is, for example, 0% (preferably 0.05%, more preferably 0.1%).

The transmittance of the above-mentioned adhesive sheet to ultraviolet light at a wavelength of 500 nm is preferably 50% to 100%, more preferably 60% to 99%, even more preferably 70% to 98%, and particularly preferably 80% to 97%.

The 10% weight loss temperature of the above-mentioned adhesive sheet is preferably 200°C to 500°C, more preferably 220°C to 450°C, even more preferably 250°C to 400°C, and particularly preferably 270°C to 370°C. Within these ranges, an adhesive sheet capable of forming a better deformed portion upon laser light irradiation can be obtained. The 10% weight loss temperature of the adhesive sheet refers to the temperature at which, in TGA analysis when the adhesive sheet is heated, the weight has decreased by 10% compared to the weight before heating (i.e., the weight of the adhesive sheet has reached 90% of the weight before irradiation).

B. Gas Generating Layer The gas generating layer may be a layer capable of absorbing ultraviolet light. In one embodiment, the gas generating layer contains an ultraviolet absorber. By including an ultraviolet absorber, a gas generating layer capable of absorbing laser light and gasifying can be formed. Typically, the gas generating layer contains an ultraviolet absorber and a pressure-sensitive adhesive A. Preferably, the ultraviolet absorber is present in a state of being dissolved in the pressure-sensitive adhesive A. If the ultraviolet absorber is present in a state of being dissolved in the pressure-sensitive adhesive A, a deformed portion (e.g., an uneven portion) can be generated anywhere on the adhesion surface (the gas generating layer surface and/or the pressure-sensitive adhesive layer surface), and a pressure-sensitive adhesive sheet with little variation in the shape of the deformed portion (e.g., an uneven portion) can be obtained. By using such a pressure-sensitive adhesive sheet, deformed portions (e.g., an uneven portion) can be generated accurately at desired locations, thereby achieving remarkable effects of the present invention. In this specification, the state of being "present in a state of being dissolved in the pressure-sensitive adhesive" means that the ultraviolet absorber is not present as particles in the gas generating layer. More specifically, the gas generating layer preferably does not contain an ultraviolet absorber having a particle diameter of 10 μm or more when the particle distribution in the cross section of the gas generating layer is measured by X-ray CT. The gas generating layer may or may not contain a component that is insoluble in the adhesive. In one embodiment, the presence or absence and content of the insoluble component in the gas generating layer is evaluated by the haze value of the gas generating layer, and the smaller the haze value, the lower the content of the insoluble component in the gas generating layer. Preferably, the gas generating layer is substantially free of components that are insoluble in the adhesive.

The elastic modulus of the cross section of the gas generation layer measured by nanoindentation is preferably 0.01 MPa to 1000 MPa, and more preferably 0.05 MPa to 800 MPa. Within this range, the shape of the gas generation layer changes favorably due to gas generation, resulting in the formation of a deformed portion with an excellent shape on the adhesion surface (the surface of the gas generation layer and/or the pressure-sensitive adhesive layer). The elastic modulus measured by nanoindentation is determined by continuously measuring the load and indentation depth applied to the indenter when the indenter is pressed into the sample (e.g., the adhesive surface) during loading and unloading, and then deriving the resulting load-indentation depth curve. The elastic modulus measured by nanoindentation is determined by pressing a diamond Berkovich-type (triangular pyramid-shaped) probe perpendicularly against a cut-out cross section of the layer to be measured, and then numerically processing the resulting displacement-load hysteresis curve using software (triboscan) provided with the measurement device. In this specification, the elastic modulus measured by nanoindentation of a cross section refers to the elastic modulus measured using a nanoindenter (Triboindenter TI-950 manufactured by Hysitron Inc.) by a single indentation method at a predetermined temperature (25°C) under measurement conditions of an indentation speed of about 500 nm/sec, an extraction speed of about 500 nm/sec, and an indentation depth of about 1500 nm. The elastic modulus of the gas generating layer can be adjusted by the type of material contained in the corresponding layer, the structure of the base polymer constituting the material, the type and amount of additives added to the corresponding layer, etc. In this specification, when the elastic modulus measured by nanoindentation is simply referred to without mentioning a cross section or a surface, the elastic modulus refers to the elastic modulus measured by nanoindentation of a cross section.

The elastic modulus of the surface of the gas generation layer measured by nanoindentation is preferably 0.01 MPa to 1000 MPa, and more preferably 0.05 MPa to 800 MPa. Within this range, the gas generation layer deforms favorably due to gas generation, resulting in the formation of a deformed portion with an excellent shape in the adhesive layer. The elastic modulus measured by nanoindentation is determined by continuously measuring the load and indentation depth applied to the indenter when the indenter is pressed into the sample (e.g., the adhesive surface) during loading and unloading, and then calculating the elastic modulus from the load-indentation depth curve. The elastic modulus measured by nanoindentation is determined by pressing a diamond Berkovich-type (triangular pyramid-shaped) probe perpendicularly against a cut-out cross section of the layer to be measured, obtaining a displacement-load hysteresis curve, which is then numerically processed using software (triboscan) provided with the measurement device. In this specification, the elastic modulus measured by the nanoindentation method on the surface refers to the elastic modulus measured using a nanoindenter (Triboindenter TI-950 manufactured by Hysitron Inc.) by a single indentation method at a predetermined temperature (25°C) under the following measurement conditions: an indentation speed of about 500 nm/sec, a withdrawal speed of about 500 nm/sec, and an indentation depth of about 3000 nm. The elastic modulus of the gas generating layer can be adjusted by the type of material contained in the corresponding layer, the structure of the base polymer constituting the material, the type and amount of additives added to the corresponding layer, etc. In the present invention, there is no significant difference between the elastic modulus measured by the nanoindentation method using a cross section as the measurement surface and the elastic modulus measured by the nanoindentation method using a surface as the measurement surface. If it is difficult to measure from the cross section, the value measured from the surface can be used as the measurement value from the cross section.

The gasification initiation temperature of the gas generating layer is preferably 150°C to 500°C, more preferably 170°C to 450°C, even more preferably 190°C to 420°C, and particularly preferably 200°C to 400°C. Within these ranges, a pressure-sensitive adhesive sheet capable of forming a more favorable deformation portion upon laser light irradiation can be obtained. In this specification, the gasification initiation temperature of the gas generating layer refers to the gas generation onset temperature calculated from EGA analysis when the pressure-sensitive adhesive sheet is heated. The gas generation onset temperature is defined as the temperature at which the maximum gas generation peak in the EGA/MS spectrum obtained from the EGA analysis reaches half its maximum. The lower the gasification initiation temperature, the lower the temperature at which gas begins to be generated upon laser light irradiation, and a sufficient amount of gas is generated even when the laser light is irradiated at a lower power. In one embodiment, the gasification initiation temperature of the gas generating layer corresponds to the gasification initiation temperature of the ultraviolet absorber.

The 10% weight loss temperature of the gas generating layer is preferably 150°C to 500°C, more preferably 170°C to 450°C, and even more preferably 200°C to 400°C. Within these ranges, a pressure-sensitive adhesive sheet capable of forming a better deformation portion upon laser light irradiation can be obtained. The 10% weight loss temperature of the gas generating layer refers to the temperature at which, in TGA analysis when the pressure-sensitive adhesive sheet is heated (e.g., when heated by laser light irradiation), the weight of the gas generating layer has decreased by 10% by weight compared to the weight before heating (i.e., the weight of the gas generating layer has reached 90% of the weight before heating).

The thickness of the gas generating layer is preferably 0.1 μm to 50 μm, more preferably 1 μm to 40 μm, even more preferably 2 μm to 30 μm, and particularly preferably 5 μm to 20 μm. Within these ranges, a pressure-sensitive adhesive sheet can be obtained that can form better deformation portions upon laser light irradiation.

The gas generating layer has an elastic modulus Er (gas) [unit: MPa] measured by nanoindentation and a thickness h (gas) [unit: μm] that satisfy the following formula (1).
Log(Er(gas)×10 ⁶ )≧8.01×h(gas) ^-0.116 ...(1)
In the present invention, the gas generating layer is configured to satisfy the above formula (1), thereby preventing excessive deformation due to the gas generated from the gas generating layer, and the pressure-sensitive adhesive sheet deforms well when irradiated with laser light. By forming such a gas generating layer, it is possible to generate surface deformation in a small range without disposing a thick barrier layer (pressure-sensitive adhesive layer) as a layer to prevent excessive deformation. More specifically, the gas generating layer alone can cause surface deformation, or the pressure-sensitive adhesive layer (gas barrier layer) can be configured to be flexible.

In one embodiment, the elastic modulus Er(gas) [unit: MPa] and the thickness h(gas) [unit: μm] measured by nanoindentation satisfy the following formula (2): In one embodiment, the elastic modulus Er(gas) [unit: MPa] and the thickness h(gas) [unit: μm] measured by nanoindentation satisfy the following formula (3):
Log(Er(gas)×10 ⁶ )≧7.66×h(gas) ^-0.092 ...(2)
Log(Er(gas)×10 ⁶ )≧7.52×h(gas) ^-0.081 ...(3)
Within this range, the above effects become more pronounced.

In one embodiment, the elastic modulus Er(gas) [unit: MPa] and the thickness h(gas) [unit: μm] measured by nanoindentation further satisfy the following formula (4):
Log(Er(gas)×10 ⁶ )≦47.675×h(gas) ^-0.519 ...(4)

The transmittance of ultraviolet light at a wavelength of 360 nm through the gas generating layer is preferably 30% or less, more preferably 20% or less, even more preferably 15% or less, particularly preferably 10% or less, and most preferably 5% or less. The lower limit of the transmittance of ultraviolet light at a wavelength of 360 nm through the gas generating layer is, for example, 0% (preferably 0.05%, more preferably 0.1%).

The haze value of the gas generating layer is preferably 55% or less, more preferably 0.1% to 50%, and even more preferably 0.5% to 40%. This haze value serves as an indicator of the compatibility between the adhesive (essentially the base polymer) and the UV absorber in the gas generating layer. The haze value is calculated from the ratio of diffuse transmitted light to total transmitted light when light in the visible light range (wavelength: 380 nm to 780 nm) is incident. Considering the wavelength of light as the smallest unit, if the concentration and composition are uniform at or above the wavelength, transparency is high, i.e., compatibility is high. On the other hand, if the concentration and composition are non-uniform, light scattering occurs, resulting in cloudiness, i.e., compatibility is low. If the haze of the gas generating layer is within the above range, the UV absorber can be distributed evenly in the resulting pressure-sensitive adhesive sheet. Such pressure-sensitive adhesive sheets exhibit precise releasability when irradiated with laser light.

B-1. UV Absorber Any appropriate UV absorber can be used as the UV absorber as long as the effects of the present invention can be obtained. Examples of UV absorbers include benzophenone-based UV absorbers, triazine-based UV absorbers, salicylate-based UV absorbers, and cyanoacrylate-based UV absorbers. Among these, triazine-based UV absorbers are preferred. In particular, when an acrylic pressure-sensitive adhesive is used as the pressure-sensitive adhesive A, triazine-based UV absorbers are preferably used due to their high compatibility with the base polymer of the acrylic pressure-sensitive adhesive. The use of a triazine-based UV absorber enables the formation of a gas-generating layer with a low haze value. The triazine-based UV absorber is more preferably composed of a compound having a hydroxyl group, and a UV absorber composed of a hydroxyphenyltriazine-based compound (hydroxyphenyltriazine-based UV absorber) is particularly preferred.

Examples of hydroxyphenyltriazine-based ultraviolet absorbers include the reaction product of 2-(4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl)-5-hydroxyphenyl with [(C10-C16 (mainly C12-C13) alkyloxy)methyl]oxirane (trade name "TINUVIN 400", manufactured by BASF), 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl]-5-[3-(dodecyloxy)-2-hydroxypropoxy]phenol, and the reaction product of 2-(2,4-dihydroxyphenyl)-4,6-bis-(2,4-dimethylphenyl)-1,3,5-triazine with (2-ethylhexyl)glycidic acid ester (trade name "TINUVIN 405" manufactured by BASF), 2,4-bis(2-hydroxy-4-butoxyphenyl)-6-(2,4-dibutoxyphenyl)-1,3,5-triazine (trade name "TINUVIN 460" manufactured by BASF), 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[(hexyl)oxy]-phenol (trade name "TINUVIN 1577" manufactured by BASF), 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[2-(2-ethylhexanoyloxy)ethoxy]-phenol (trade name "ADK STAB LA-46, manufactured by ADEKA Corporation), 2-(2-hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine (trade name "TINUVIN 479", manufactured by BASF), and TINUVIN 477, manufactured by BASF.

Examples of benzotriazole-based ultraviolet absorbers (benzotriazole-based compounds) include 2-(2-hydroxy-5-tert-butylphenyl)-2H-benzotriazole (trade name "TINUVIN PS", manufactured by BASF), an ester compound of benzenepropanoic acid and 3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)-4-hydroxy (C7-9 side chain and linear alkyl) (trade name "TINUVIN 384-2", manufactured by BASF), and a mixture of octyl 3-[3-tert-butyl-4-hydroxy-5-(5-chloro-2H-benzotriazol-2-yl)phenyl]propionate and 2-ethylhexyl-3-[3-tert-butyl-4-hydroxy-5-(5-chloro-2H-benzotriazol-2-yl)phenyl]propionate (trade name "TINUVIN 109" (manufactured by BASF Corporation), 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (trade name "TINUVIN 900" (manufactured by BASF Corporation), 2-(2H-benzotriazol-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol (trade name "TINUVIN 928" (manufactured by BASF Corporation), reaction product of methyl 3-(3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl)propionate/polyethylene glycol 300 (trade name "TINUVIN 1130" (manufactured by BASF Corporation), 2-(2H-benzotriazol-2-yl)-p-cresol (trade name "TINUVIN P”, manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (trade name “TINUVIN 234”, manufactured by BASF), 2-[5-chloro-2H-benzotriazol-2-yl]-4-methyl-6-(tert-butyl)phenol (trade name “TINUVIN 326”, manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (trade name “TINUVIN 328”, manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol (trade name “TINUVIN 329" (manufactured by BASF Corporation), 2,2'-methylenebis[6-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol] (trade name "TINUVIN 360" (manufactured by BASF Corporation), reaction product of methyl 3-(3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl)propionate and polyethylene glycol 300 (trade name "TINUVIN 213" (manufactured by BASF Corporation), 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol (trade name "TINUVIN 571" (manufactured by BASF Corporation), 2-[2-hydroxy-3-(3,4,5,6-tetrahydrophthalimido-methyl)-5-methylphenyl]benzotriazole (trade name "Sumisorb 250" manufactured by Sumitomo Chemical Co., Ltd.), 2-(3-tert-butyl-2-hydroxy-5-methylphenyl)-5-chloro-2H-benzotriazole (trade name "SEESORB 703" manufactured by Shipro Chemical Co., Ltd.), 2-(2H-benzotriazol-2-yl)-4-methyl-6-(3,4,5,6-tetrahydrophthalimidylmethyl)phenol (trade name "SEESORB 706" manufactured by Shipro Chemical Co., Ltd.), 2-(4-benzoyloxy-2-hydroxyphenyl)-5-chloro-2H-benzotriazole (trade name "SEESORB 7012BA" manufactured by Shipro Chemical Co., Ltd.), 2-tert-butyl-6-(5-chloro-2H-benzotriazol-2-yl)-4-methylphenol (trade name "KEMISORB 73”, manufactured by Chemipro Chemical Co., Ltd.), 2,2'-methylenebis[6-(2H-benzotriazol-2-yl)-4-tert-octylphenol] (trade name “ADK STAB LA-31”, manufactured by ADEKA Corporation), 2-(2H-benzotriazol-2-yl)-p-cellulose (trade name “ADK STAB LA-32”, manufactured by ADEKA Corporation), 2-(5-chloro-2H-benzotriazol-2-yl)-6-tert-butyl-4-methylphenol (trade name “ADK STAB LA-36”, manufactured by ADEKA Corporation), and the like.

In one embodiment, an ultraviolet absorber that does not contain halogen atoms is used. Using such an ultraviolet absorber makes it possible to obtain a pressure-sensitive adhesive sheet that is less likely to contaminate adherends such as electrodes.

The molecular weight of the compound constituting the above-mentioned ultraviolet absorber is preferably 200 to 1500, more preferably 250 to 1200, and even more preferably 300 to 1000. Within this range, it is possible to obtain an adhesive sheet that can form better deformation portions upon irradiation with laser light.

The maximum absorption wavelength of the above ultraviolet absorber is preferably 300 nm to 450 nm, more preferably 320 nm to 400 nm, and even more preferably 330 nm to 380 nm.

The content of the above-mentioned ultraviolet absorber is preferably 1 to 100 parts by weight, more preferably 1 to 50 parts by weight, and even more preferably 5 to 30 parts by weight, per 100 parts by weight of the gas generating layer. Within this range, a pressure-sensitive adhesive sheet can be obtained that can form better deformation sections upon laser light irradiation.

B-2. Adhesive A
As the adhesive A contained in the gas generating layer, a pressure-sensitive adhesive A is preferably used. Examples of the adhesive A include acrylic adhesives, rubber adhesives, vinyl alkyl ether adhesives, silicone adhesives, polyester adhesives, polyamide adhesives, urethane adhesives, and styrene-diene block copolymer adhesives. Among these, acrylic adhesives or rubber adhesives are preferred, and acrylic adhesives are more preferred. The above adhesives may be used alone or in combination of two or more.

Examples of the acrylic adhesive include those based on an acrylic polymer (homopolymer or copolymer) containing one or more (meth)acrylic acid alkyl esters as monomer components. Specific examples of (meth)acrylic acid alkyl esters include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, and (meth) Examples of (meth)acrylic acid C1-20 alkyl esters include nonyl acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate. Among these, (meth)acrylic acid alkyl esters having a linear or branched alkyl group with 1 to 20 carbon atoms can be preferably used, and (meth)acrylic acid alkyl esters having a linear or branched alkyl group with 2 to 20 carbon atoms can be more preferably used.

In one embodiment, a (meth)acrylic acid alkyl ester A having a linear or branched alkyl group with 4 or more carbon atoms (preferably 4 to 20, more preferably 4 to 18) is used. Acrylic polymers formed using such monomers and having long side chains are advantageous in that they have high affinity (compatibility) with UV absorbers. The content of the (meth)acrylic acid alkyl ester A is preferably 30% by weight or more, more preferably 50% by weight or more, even more preferably 70% to 100% by weight, and particularly preferably 80% to 100% by weight, based on all structural units constituting the acrylic polymer. This range enhances the compatibility between the acrylic polymer and UV absorbers. The content of the acrylic polymer containing structural units derived from the (meth)acrylic acid alkyl ester A is preferably 30 to 100 parts by weight, more preferably 70 to 100 parts by weight, based on 100 parts by weight of the total acrylic polymer.

In one embodiment, a (meth)acrylic acid alkyl ester A having a linear or branched alkyl group with 4 or more carbon atoms (preferably 4 to 20, more preferably 4 to 18) is used in combination with a triazine-based UV absorber. The (meth)acrylic acid alkyl ester A and the triazine-based UV absorber have particularly excellent compatibility, and a pressure-sensitive adhesive sheet having a gas-generating layer formed using these compounds exhibits remarkably excellent visibility.

The above acrylic polymer may, if necessary, contain units corresponding to other monomer components copolymerizable with the above (meth)acrylic acid alkyl ester in order to modify its cohesive strength, heat resistance, crosslinkability, etc. Examples of such monomer components include carboxyl group-containing monomers such as acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid; acid anhydride monomers such as maleic anhydride and itanoic anhydride; hydroxyl group-containing monomers such as hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, hydroxyhexyl (meth)acrylate, hydroxyoctyl (meth)acrylate, hydroxydecyl (meth)acrylate, hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)methyl methacrylate; and sulfonic acid group-containing monomers such as styrenesulfonic acid, allylsulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid. (N-substituted) amide monomers such as (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-butyl(meth)acrylamide, N-methylol(meth)acrylamide, and N-methylolpropane(meth)acrylamide; aminoalkyl (meth)acrylate monomers such as aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, and t-butylaminoethyl (meth)acrylate; alkoxyalkyl (meth)acrylate monomers such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate; maleimide monomers such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, and N-phenylmaleimide; itaconimide monomers such as N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, and N-laurylitaconimide vinylimide-based monomers such as N-(meth)acryloyloxymethylene succinimide, N-(meth)acryloyl-6-oxyhexamethylene succinimide, and N-(meth)acryloyl-8-oxyoctamethylene succinimide; vinyl monomers such as vinyl acetate, vinyl propionate, N-vinylpyrrolidone, methylvinylpyrrolidone, vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyloxazole, vinylmorpholine, N-vinylcarboxylic acid amides, styrene, α-methylstyrene, and N-vinylcaprolactam; cyanoacrylate monomers such as acrylonitrile and methacrylonitrile; epoxy group-containing acrylic monomers such as glycidyl (meth)acrylate; polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, methoxyethylene glycol (meth)acrylate, and the like. p) Glycol-based acrylic ester monomers such as methoxypolypropylene glycol acrylate; acrylic ester-based monomers having a heterocycle, a halogen atom, a silicon atom, or the like, such as tetrahydrofurfuryl (meth)acrylate, fluorine (meth)acrylate, and silicone (meth)acrylate; polyfunctional monomers such as hexanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, epoxy acrylate, polyester acrylate, and urethane acrylate; olefin-based monomers such as isoprene, butadiene, and isobutylene; and vinyl ether-based monomers such as vinyl ether. These monomer components may be used alone or in combination of two or more. Among these, from the viewpoint of particularly high affinity (compatibility) with UV absorbers, carboxyl group-containing monomers such as acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid; acid anhydride monomers such as maleic anhydride and itanoic anhydride; and hydroxyl group-containing monomers such as hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, hydroxyhexyl (meth)acrylate, hydroxyoctyl (meth)acrylate, hydroxydecyl (meth)acrylate, hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)methyl methacrylate are preferably used. The content of the carboxyl group-containing monomer is preferably 0.5 to 15 parts by weight, more preferably 1 to 10 parts by weight, and even more preferably 3 to 9.5 parts by weight, relative to 100 parts by weight of the total amount of the acrylic polymer. The content of the acid anhydride monomer is preferably 0.5 to 15 parts by weight, more preferably 1 to 10 parts by weight, and even more preferably 3 to 9.5 parts by weight, relative to 100 parts by weight of the total amount of the acrylic polymer. The content of the hydroxyl group-containing monomer is preferably 0.5 to 15 parts by weight, more preferably 1 to 10 parts by weight, and even more preferably 3 to 9.5 parts by weight, relative to 100 parts by weight of the total amount of the acrylic polymer.

Examples of the above-mentioned rubber-based adhesives include rubber-based adhesives whose base polymer is natural rubber; polyisoprene rubber, styrene-butadiene (SB) rubber, styrene-isoprene (SI) rubber, styrene-isoprene-styrene block copolymer (SIS) rubber, styrene-butadiene-styrene block copolymer (SBS) rubber, styrene-ethylene-butylene-styrene block copolymer (SEBS) rubber, styrene-ethylene-propylene-styrene block copolymer (SEPS) rubber, styrene-ethylene-propylene block copolymer (SEP) rubber, reclaimed rubber, butyl rubber, polyisobutylene, and synthetic rubbers such as modified versions of these.

The gas generated from the gas generation layer is preferably a hydrocarbon (preferably an aliphatic hydrocarbon) gas. A gas generation layer capable of generating a hydrocarbon gas is composed, for example, of a hydrocarbon compound as its main component. The gas generation layer preferably does not contain a compound containing a halogen element. If the generated gas is a hydrocarbon gas, corrosion of the electronic component being processed can be prevented. This effect is more pronounced by forming a gas generation layer that does not contain a compound containing a halogen element. The formula mass of the ions generated from the gas generation layer is preferably 10 m/z to 800 m/z, more preferably 11 m/z to 700 m/z, even more preferably 12 m/z to 500 m/z, and particularly preferably 13 m/z to 400 m/z.

The above-mentioned adhesive A may contain any appropriate additives as needed. Examples of such additives include crosslinkers, tackifiers (e.g., rosin-based tackifiers, terpene-based tackifiers, hydrocarbon-based tackifiers, etc.), plasticizers (e.g., trimellitate ester-based plasticizers, pyromellitate ester-based plasticizers), pigments, dyes, antioxidants, conductive materials, antistatic agents, light stabilizers, release modifiers, softeners, surfactants, flame retardants, antioxidants, etc.

Examples of the crosslinking agent include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, melamine-based crosslinking agents, peroxide-based crosslinking agents, urea-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, carbodiimide-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, and amine-based crosslinking agents. Of these, isocyanate-based crosslinking agents and epoxy-based crosslinking agents are preferred.

Specific examples of the above-mentioned isocyanate-based crosslinking agents include lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate, and isophorone diisocyanate; aromatic isocyanates such as 2,4-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and xylylene diisocyanate; and isocyanate adducts such as trimethylolpropane/tolylene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate L"), trimethylolpropane/hexamethylene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate HL"), and hexamethylene diisocyanate isocyanurate (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate HX"). The content of the isocyanate-based crosslinking agent can be set to any appropriate amount depending on the desired adhesive strength, and is typically 0.1 to 20 parts by weight, and more preferably 0.5 to 10 parts by weight, per 100 parts by weight of the base polymer.

Examples of the epoxy-based crosslinking agent include N,N,N',N'-tetraglycidyl-m-xylylenediamine, diglycidylaniline, 1,3-bis(N,N-glycidylaminomethyl)cyclohexane (manufactured by Mitsubishi Gas Chemical Company, Inc., trade name "Tetrad C"), 1,6-hexanediol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolight 1600"), neopentyl glycol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolight 1500NP"), ethylene glycol Licor diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolite 40E"), propylene glycol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolite 70P"), polyethylene glycol diglycidyl ether (manufactured by NOF Corporation, trade name "Epiol E-400"), polypropylene glycol diglycidyl ether (manufactured by NOF Corporation, trade name "Epiol P-200"), sorbitol polyglycidyl ether (manufactured by Nagase ChemteX Corporation, trade name "Denacol") Examples of suitable crosslinking agents include glycerol polyglycidyl ether (manufactured by Nagase ChemteX Corporation, trade name "Denacol EX-314"), pentaerythritol polyglycidyl ether, polyglycerol polyglycidyl ether (manufactured by Nagase ChemteX Corporation, trade name "Denacol EX-512"), sorbitan polyglycidyl ether, trimethylolpropane polyglycidyl ether, adipic acid diglycidyl ester, o-phthalic acid diglycidyl ester, triglycidyl tris(2-hydroxyethyl)isocyanurate, resorcinol diglycidyl ether, bisphenol-S-diglycidyl ether, and epoxy resins having two or more epoxy groups in the molecule. The content of the epoxy crosslinking agent can be set at any appropriate amount depending on the desired adhesive strength, and is typically 0.01 to 10 parts by weight, and more preferably 0.03 to 5 parts by weight, per 100 parts by weight of the base polymer.

C. Adhesive Layer The adhesive layer includes any suitable adhesive B. The adhesive B may be a pressure-sensitive adhesive B1 or a curable adhesive B2.

The thickness of the pressure-sensitive adhesive layer is preferably 0.1 μm to 50 μm, more preferably 0.5 μm to 40 μm, even more preferably 1 μm to 30 μm, and particularly preferably 2 μm to 20 μm. Within this range, a pressure-sensitive adhesive layer can be formed that has desirable adhesive strength and functions well as a gas barrier layer.

The water vapor transmission rate of the pressure-sensitive adhesive layer is preferably 20,000 g/(m ² ·day) or less, more preferably 10,000 g/(m ² ·day) or less, even more preferably 7,000 g/(m ² ·day) or less, even more preferably 5,000 g/(m ² ·day) or less, particularly preferably 4,800 g/(m ² ·day) or less, and most preferably 4,500 g/(m ² ·day) or less. Within this range, the pressure-sensitive adhesive layer functions well as a gas barrier layer, and a deformed portion with an excellent shape is formed. By using such a pressure-sensitive adhesive sheet, small adherends (e.g., electronic components) can be peeled off with high precision. The lower the water vapor transmission rate of the pressure-sensitive adhesive layer, the more preferable it is, and the lower limit thereof is, for example, 100 g/(m ² ·day).

The puncture strength of the pressure-sensitive adhesive layer is preferably 10 mN to 3,000 mN, more preferably 30 mN to 2,500 mN, even more preferably 50 mN to 2,000 mN, and particularly preferably 100 mN to 2,000 mN. Within these ranges, the pressure-sensitive adhesive layer functions well as a gas barrier layer, and shape change due to gas generation occurs favorably, resulting in the formation of a deformed portion with an excellent shape. Use of such a pressure-sensitive adhesive sheet allows for accurate peeling of small adherends (e.g., electronic components).

The ultraviolet transmittance of the above adhesive layer at a wavelength of 360 nm is preferably 50% to 100%, and more preferably 60% to 95%.

C-1. Pressure-sensitive adhesive B1
Examples of the pressure-sensitive adhesive B1 include acrylic adhesives, rubber adhesives, vinyl alkyl ether adhesives, silicone adhesives, polyester adhesives, polyamide adhesives, urethane adhesives, and styrene-diene block copolymer adhesives. Of these, acrylic adhesives or rubber adhesives are preferred, and acrylic adhesives are more preferred. The adhesive B1 contained in the pressure-sensitive adhesive-containing adhesive layer can be the adhesives described in Section B-2.

C-2. Curing adhesive B2
Examples of the curable adhesive B2 include a heat-curable adhesive and an active energy ray-curable adhesive. Preferably, an active energy ray-curable adhesive is used. The adhesive layer formed from the active energy ray-curable adhesive is an adhesive layer formed by irradiating with active energy rays, i.e., an adhesive layer having a predetermined adhesive strength after irradiating with active energy rays.

Examples of resin materials constituting the above-mentioned active energy ray-curable adhesive include those described in Ultraviolet Curing System (by Kiyomi Kato, published by the General Technology Center (1989)), Photocuring Technology (edited by the Technical Information Association (2000)), JP 2003-292916 A, and Japanese Patent No. 4151850. More specifically, examples include resin materials (B2-1) containing a polymer as a base material and an active energy ray-reactive compound (monomer or oligomer), and resin materials (B2-2) containing an active energy ray-reactive polymer.

Examples of polymers that can serve as the base material include rubber-based polymers such as natural rubber, polyisobutylene rubber, styrene-butadiene rubber, styrene-isoprene-styrene block copolymer rubber, reclaimed rubber, butyl rubber, polyisobutylene rubber, and nitrile rubber (NBR); silicone-based polymers; and acrylic-based polymers. These polymers may be used alone or in combination of two or more.

Examples of the active energy ray-reactive compound include photoreactive monomers or oligomers having multiple functional groups with carbon-carbon multiple bonds, such as acryloyl groups, methacryloyl groups, vinyl groups, allyl groups, and acetylene groups. Among these, compounds with ethylenically unsaturated functional groups are preferred, and (meth)acrylic compounds with ethylenically unsaturated functional groups are even more preferred. Compounds with ethylenically unsaturated functional groups readily generate radicals when exposed to ultraviolet light, making it possible to form a pressure-sensitive adhesive layer that can be cured in a short period of time. Furthermore, using a (meth)acrylic compound with an ethylenically unsaturated functional group makes it possible to form a pressure-sensitive adhesive layer that has appropriate hardness after curing. Specific examples of photoreactive monomers or oligomers include (meth)acryloyl group-containing compounds such as trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, and urethane (meth)acrylate compounds; dimers to pentamers of the (meth)acryloyl group-containing compounds; and the like. These compounds may be used alone or in combination of two or more.

The active energy ray-reactive compound may also be a monomer such as epoxidized butadiene, glycidyl methacrylate, acrylamide, or vinyl siloxane; or an oligomer composed of such a monomer. Resin materials (B2-1) containing these compounds can be cured by high-energy rays such as ultraviolet rays or electron beams.

Furthermore, the active energy ray-reactive compound may be a mixture of an organic salt such as an onium salt and a compound having multiple heterocycles in the molecule. When irradiated with active energy rays (e.g., ultraviolet light or an electron beam), the organic salt in the mixture cleaves to generate ions, which act as initiating species to trigger a ring-opening reaction of the heterocycles, forming a three-dimensional network structure. Examples of the organic salt include iodonium salts, phosphonium salts, antimonium salts, sulfonium salts, and borate salts. Examples of heterocycles in the compound having multiple heterocycles in the molecule include oxirane, oxetane, oxolane, thiirane, and aziridine.

In the resin material (B2-1) containing the above-mentioned base polymer and an active energy ray reactive compound, the content of the active energy ray reactive compound is preferably 0.1 to 500 parts by weight, more preferably 1 to 300 parts by weight, and even more preferably 10 to 200 parts by weight, per 100 parts by weight of the base polymer.

Examples of the active energy ray-reactive polymer include polymers having active energy ray-reactive functional groups with carbon-carbon multiple bonds, such as acryloyl groups, methacryloyl groups, vinyl groups, allyl groups, and acetylene groups. Preferably, a compound (polymer) having an ethylenically unsaturated functional group is used, and more preferably, a (meth)acrylic polymer having an acryloyl group or methacryloyl group is used. Specific examples of polymers having active energy ray-reactive functional groups include polymers composed of polyfunctional (meth)acrylates. The polymers composed of such polyfunctional (meth)acrylates preferably have alkyl esters with 4 or more carbon atoms in their side chains, more preferably alkyl esters with 6 or more carbon atoms, even more preferably alkyl esters with 8 or more carbon atoms, particularly preferably alkyl esters with 8 to 20 carbon atoms, and most preferably alkyl esters with 8 to 18 carbon atoms.

The resin material (B2-2) containing the above-mentioned active energy ray-reactive polymer may further contain the above-mentioned active energy ray-reactive compound (monomer or oligomer).

The active energy ray-curable adhesive can be cured by irradiation with active energy rays. In the pressure-sensitive adhesive sheet of the present invention, an adherend can be attached to the sheet before curing the adhesive, and then the adhesive can be cured by irradiating the sheet with active energy rays, thereby adhering the adherend to the sheet. Examples of active energy rays include gamma rays, ultraviolet rays, visible light, infrared rays (heat rays), radio waves, alpha rays, beta rays, electron beams, plasma flow, ionizing rays, and particle beams. Conditions such as the wavelength and dose of the active energy rays can be set as appropriate depending on the type of resin material used. For example, the adhesive can be cured by irradiating the sheet with ultraviolet rays at a dose of 10 to 1,000 mJ/ ^cm² .

D. Intermediate Layer The intermediate layer may be in the form of, for example, a resin layer or an adhesive layer.

In one embodiment, the intermediate layer includes a thermoplastic resin. Such an intermediate layer may be a resin film including a thermoplastic resin, a layer including an adhesive C composed of a thermoplastic resin, or the like. In another embodiment, the intermediate layer includes a curable resin (e.g., an ultraviolet-curable resin, a thermosetting resin). Such an intermediate layer may be a resin film including a curable resin, a layer including a curable adhesive D, or the like.

The thickness of the intermediate layer is preferably 0.1 μm to 50 μm, more preferably 1 μm to 40 μm, and even more preferably 1.5 μm to 30 μm. Within this range, an intermediate layer that functions well as a gas barrier layer can be formed.

The water vapor permeability of the intermediate layer is preferably 5000 g/( ^m2 ·day) or less, more preferably 4800 g/( ^m2 ·day) or less, even more preferably 4500 g/( ^m2 ·day) or less, and even more preferably 4200 g/( ^m2 ·day) or less. Within this range, the intermediate layer functions well as a gas barrier layer, and a deformed portion with an excellent shape is formed. By using such a pressure-sensitive adhesive sheet, small adherends (e.g., electronic components) can be peeled off with high precision. The lower the water vapor permeability of the intermediate layer, the better, and the lower limit is, for example, 0.1 g/( ^m2 ·day).

The puncture strength of the intermediate layer is preferably 300 mN to 5000 mN, more preferably 500 mN to 4500 mN, and even more preferably 1000 mN to 4000 mN. Within this range, the intermediate layer functions well as a gas barrier layer, and shape change due to gas generation occurs favorably, resulting in the formation of a deformed portion with an excellent shape. Use of such an adhesive sheet allows for accurate peeling of small adherends (e.g., electronic components).

The ultraviolet transmittance of the intermediate layer at a wavelength of 360 nm is preferably 50% to 100%, and more preferably 60% to 95%.

D-1. Intermediate layer as a resin layer The intermediate layer as a resin layer is formed, for example, from a resin film. Examples of resins that form the resin film include polyethylene terephthalate resins, polyolefin resins, styrene elastomer resins (e.g., SEBS, etc.), ultraviolet-curable resins, thermosetting resins, urethane resins, and epoxy resins. In one embodiment, the resin film is made of a thermoplastic resin.

The thickness of the above resin film is preferably 0.1 μm to 50 μm, more preferably 0.5 μm to 30 μm, and even more preferably 1 μm to 20 μm.

D-2. Intermediate layer as adhesive layer Examples of intermediate layers as adhesive layers include intermediate layers containing a pressure-sensitive adhesive and intermediate layers containing a curable adhesive. Preferably, an intermediate layer containing curable adhesive D is disposed. In particular, by combining an adhesive layer containing pressure-sensitive adhesive A with an intermediate layer containing curable adhesive D as the adhesive layer, it is possible to obtain a pressure-sensitive adhesive sheet that can form a better deformation portion upon laser light irradiation. The adhesives described in Section C-2 can be used as the curable adhesive D.

The thickness of the intermediate layer as an adhesive layer is preferably 5 μm to 50 μm, and more preferably 5 μm to 30 μm.

E. Method for Producing Pressure-Sensitive Adhesive Sheet The pressure-sensitive adhesive sheet of the present invention can be produced by any appropriate method. For example, the pressure-sensitive adhesive sheet of the present invention can be produced by a method in which a gas-generating layer-forming composition containing pressure-sensitive adhesive A and an ultraviolet absorber is applied directly onto a predetermined substrate to form a gas-generating layer, and then a pressure-sensitive adhesive layer-forming composition containing pressure-sensitive adhesive B is applied onto the gas-generating layer to form a pressure-sensitive adhesive layer. In one embodiment, when the pressure-sensitive adhesive sheet has an intermediate layer, before forming the pressure-sensitive adhesive layer, a composition for forming an intermediate layer is applied onto the gas-generating layer to form the intermediate layer, and then a pressure-sensitive adhesive layer-forming composition is applied onto the intermediate layer to form the pressure-sensitive adhesive layer. Alternatively, each layer may be formed separately and then bonded together to form a pressure-sensitive adhesive sheet.

Any appropriate coating method can be used to apply the composition. For example, each layer can be formed by coating and then drying. Examples of coating methods include coating methods using a multi-coater, die coater, gravure coater, applicator, etc. Examples of drying methods include natural drying and heat drying. When heat drying is performed, the heating temperature can be set to any appropriate temperature depending on the properties of the material to be dried. In addition, active energy ray irradiation (e.g., ultraviolet irradiation) can be performed depending on the form of each layer.

F. Method for Treating Electronic Components The method for treating electronic components of the present invention includes adhering electronic components to the pressure-sensitive adhesive sheet and irradiating the pressure-sensitive adhesive sheet with laser light to peel the electronic components from the pressure-sensitive adhesive sheet. Examples of electronic components include semiconductor chips, LED chips, and MLCCs.

The electronic components can be peeled off selectively. Specifically, multiple electronic components can be attached and fixed to an adhesive sheet, and then some of the electronic components can be peeled off while the other electronic components remain fixed.

In one embodiment, the method for processing electronic components of the present invention involves applying a predetermined process to the electronic component after the electronic component has been attached to the adhesive sheet and before the electronic component is peeled from the adhesive sheet. The process is not particularly limited, and examples include grinding, dicing, die bonding, wire bonding, etching, vapor deposition, molding, circuit formation, inspection, quality control, cleaning, transfer, alignment, repair, and device surface protection.

The size of the electronic component (area of the adhesive surface) is, for example, 1 μm ² to 250,000 μm ^2. In one embodiment, electronic components having a size (area of the adhesive surface) of 1 μm ² to 6,400 μm ² may be subjected to the treatment. In another embodiment, electronic components having a size (area of the adhesive surface) of 1 μm ² to 2,500 μm ² may be subjected to the treatment.

In one embodiment, as described above, multiple electronic components can be placed on the adhesive sheet. The spacing between the electronic components is, for example, 1 μm to 500 μm. This is advantageous in that the spacing can be narrowed to temporarily fix the object to be treated.

As the laser light, for example, UV laser light can be used. The irradiation output of the laser light is, for example, 1 μJ to 1000 μJ. The wavelength of the UV laser light is, for example, 240 nm to 380 nm.

In one embodiment, the method for processing the electronic component includes, after peeling the electronic component, placing the electronic component on another sheet (e.g., an adhesive sheet, a substrate, etc.).

The present invention will be explained in more detail below using examples, but the present invention is not limited to these examples. The evaluation methods used in the examples are as follows. In the evaluations below, pressure-sensitive adhesive sheets from which the separator had been peeled off were used. In the examples, "parts" and "%" are by weight unless otherwise specified.

(1) Transmittance In the case of a pressure-sensitive adhesive sheet having an intermediate layer, the pressure-sensitive adhesive sheet was set in a spectrophotometer (trade name "UV-VIS ultraviolet-visible spectrophotometer SolidSpec3700", manufactured by Shimadzu Corporation) so that incident light was perpendicular to the gas barrier layer side of the sample, and the light transmittance in the wavelength region of 300 nm to 800 nm was measured. The transmittance at wavelengths of 360 nm and 500 nm was extracted from the obtained transmission spectrum. In the case of a pressure-sensitive adhesive sheet consisting only of a pressure-sensitive adhesive layer, the sheet was set in the spectrophotometer with one release liner remaining and measured, and then the transmission spectrum of the release liner alone was measured and subtracted to obtain the transmission spectrum of the pressure-sensitive adhesive layer alone. The transmittance at wavelengths of 360 nm and 500 nm was extracted from the obtained transmission spectrum.

(2) Maximum gas generation peak temperature Approximately 0.5 mg of a pressure-sensitive adhesive sheet sample was placed in a heating furnace pyrolyzer, and a mass chromatogram was obtained by EGA-MS analysis, which involves mass analyzing the components volatilized by heating. The temperature was increased from 40 ° C. to 500 ° C. at a rate of 10 ° C./min using a heating furnace pyrolyzer (manufactured by Frontier Labs, product name "PY2020iD"), and the maximum gas generation peak temperature was calculated from the mass chromatogram in the mass range m / z = 10 to 800 using a GC / MS analyzer (manufactured by JEOL, product name "JMS-T100GCV").

(3) Gasification initiation temperature The PSA sheet was heated in the same manner as in (2) above, and the gas generation onset temperature calculated from EGA analysis was defined as the temperature at which the maximum gas generation peak in the EGA/MS chromatogram obtained from the EGA analysis reached half its maximum.

(4) Species of evolved gases The PSA sheet sample was placed in an automatic sample combustion device (manufactured by Mitsubishi Chemical Analytech Co., Ltd., product name "AQF-2100H") and heated at 400°C for 30 minutes to collect the evolved gas. The collected liquid was analyzed by ion chromatography to identify the species of evolved gases.

(5) 5% Weight Loss Temperature Using a differential thermal analyzer (manufactured by TA Instruments, trade name "Discovery TGA"), the pressure-sensitive adhesive sheet was heated at a rate of 10°C/min in a _N2 atmosphere at a flow rate of 25 ml/min, and the temperature at which the weight lost 5% was measured.

(6) 10% Weight Loss Temperature Using a differential thermal analyzer (manufactured by TA Instruments, trade name "Discovery TGA"), the pressure-sensitive adhesive sheet was heated at a rate of 10°C/min in a _N2 atmosphere at a flow rate of 25 ml/min, and the temperature at which the weight lost 10% was measured.
The 10% weight loss temperature was measured for each of the pressure-sensitive adhesive sheet and the gas-generating layer (UV absorber).

(7) Water Vapor Transmission Rate A measurement sample was prepared by attaching a sample to an Al jig having an opening of 10 mm x 10 mm so as to cover the opening, and the measurement sample was placed between the first and second chambers of a water vapor transmission rate measuring device (manufactured by MOCON, product name "PERMATRAN-W3/34G") and evaluated by the MOCON measurement method. The temperature and humidity conditions were 30°C/90% RH, the gas (water vapor) flow rate was 10.0±0.5 cc/min, and the measurement time was 20 hours.
The water vapor transmission rate was measured for each of the pressure-sensitive adhesive sheet, the pressure-sensitive adhesive layer, and the intermediate layer.

(8) Change in Surface Shape A measurement sample was obtained by attaching a glass plate (large slide glass S9112 (standard large white edge polished No. 2) manufactured by Matsunami Glass Co., Ltd.) to the gas generating layer side (opposite side to the adhesive layer) of the adhesive sheet. A UV laser beam with a wavelength of 355 nm and a beam diameter of approximately 20 μmφ was used from the glass plate side of the measurement sample to pulse scan at an output of 0.80 mW and a frequency of 40 kHz to generate gas from the gas generating layer. The adhesive layer surface (the gas generating layer surface in Example 1 and Comparative Example 1) corresponding to any one pulse scanned spot was observed with a confocal laser microscope 24 hours after laser beam irradiation, and the vertical displacement Y and horizontal displacement X (diameter; full width at half maximum) were measured.
When the displacement Y is 8 μm or more, the releasability is remarkably excellent (◎ in the table); when the displacement Y is 0.6 μm or more and less than 8 μm, the releasability is good (◯ in the table); and when the displacement Y is less than 0.6 μm, the releasability is insufficient (× in the table).

(9) Haze Value In the case of a pressure-sensitive adhesive sheet having an intermediate layer, the release liner was peeled off, the sheet was set in a haze meter, and the haze value was measured with incident light perpendicular to the sample. In the case of a pressure-sensitive adhesive sheet consisting of only a pressure-sensitive adhesive layer, the sheet was set in the haze meter with one release liner remaining, and then the haze value of the release liner alone was measured and subtracted to obtain the haze value of the pressure-sensitive adhesive layer alone.
When the haze value was 20% or less, the adherend visibility was evaluated as good (marked ◯ in the table); when the haze value was 20% or more and 50% or less, the adherend visibility was evaluated as fair (marked △ in the table); and when the haze value was more than 50%, the adherend visibility was evaluated as poor (marked × in the table).

(10) Adhesion (gas generating layer side)
A measurement sample was obtained by laminating PET#25 to the pressure-sensitive adhesive layer side of the pressure-sensitive adhesive sheet. The adhesive strength of the gas-generating layer side of the measurement sample to SUS430 was measured according to JIS Z 0237:2000 (lamination conditions: one reciprocal stroke with a 2 kg roller, tensile speed: 300 mm/min, peel angle: 180°).

(11) Adhesive strength (adhesive layer)
A measurement sample was obtained by laminating PET#25 to the gas generating layer side of the pressure-sensitive adhesive sheet. The adhesive strength of the pressure-sensitive adhesive layer side of the measurement sample to SUS430 was measured according to JIS Z 0237:2000 (lamination conditions: one reciprocating stroke with a 2 kg roller, tensile speed: 300 mm/min, peel angle: 180°).

(12) In-plane uniformity of deformation The gas generating layer was irradiated with UV laser light as described above in (8).
A randomly selected deformed area of 2 mm x 2 mm was observed under a microscope, and the results were rated as good (◯ in the table) if 90% or more of the protrusions were the same size, fair (Δ in the table) if 80% or more but less than 90% of the protrusions were the same size, and poor (× in the table) if less than 80% of the protrusions were the same size. "Same size" means that the difference in displacement X was within ±20%.

(13) Position Selectivity of Deformation The gas generating layer was irradiated with UV laser light as in (8) above.
A single deformation in the laser irradiated area was evaluated as pass (◯), and multiple deformations in the periphery of the laser irradiated area were evaluated as fail (×).

(14) Elastic Modulus Using a nanoindenter (Triboindenter TI-950 manufactured by Hysitron Inc.), the elastic modulus was measured by a single indentation method at a predetermined temperature (25°C) under the following measurement conditions: an indentation speed of about 500 nm/sec, an extraction speed of about 500 nm/sec, and an indentation depth of about 1500 nm.

[Production Example 1] Preparation of gas generating layer-forming composition a 30 parts by weight of 2-ethylhexyl acrylate, 70 parts by weight of ethyl acrylate, 4 parts by weight of 2-hydroxyethyl acrylate, 5 parts by weight of methyl methacrylate, and 0.2 parts by weight of benzoyl peroxide as a polymerization initiator were added to toluene, and the mixture was heated to 70°C to obtain a toluene solution of an acrylic copolymer (polymer A).
A toluene solution of polymer A (polymer A: 100 parts by weight), 1.5 parts by weight of an isocyanate-based crosslinking agent (manufactured by Nippon Polyurethane Co., Ltd., trade name "Coronate L"), and 20 parts by weight of an ultraviolet absorber (manufactured by BASF, trade name "Tinuvin 477", structure: [Chemical Formula 1]) were mixed to prepare a gas-generating layer-forming composition a. The composition of gas-generating layer-forming composition a is shown in Table 1.

[Production Example 2] Preparation of gas generating layer-forming composition b A gas generating layer-forming composition b was prepared in the same manner as in Production Example 1, except that the blending amount of the UV absorber was 10 parts by weight. The composition of gas generating layer-forming composition b is shown in Table 1.

[Production Example 3] Preparation of gas generating layer-forming composition c A gas generating layer-forming composition c was prepared in the same manner as in Production Example 1, except that 10 parts by weight of 2,4-bis(2-hydroxy-4-butoxyphenyl)-6-(2,4-dibutoxyphenyl)-1,3,5-triazine (trade name "TINUVIN 460", manufactured by BASF, structure: [Chemical Formula 2]) was used as the UV absorber. The composition of gas generating layer-forming composition c is shown in Table 1.

Production Example 4 Preparation of Gas Generating Layer-Forming Composition d Gas generating layer-forming composition d was prepared in the same manner as in Production Example 1, except that 20 parts by weight of a reaction product of 2-(4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl)-5-hydroxyphenyl and [(C10-C16 (mainly C12-C13) alkyloxy)methyl]oxirane (trade name "TINUVIN 400", manufactured by BASF, structure: [Chemical Formula 3]) was used as the UV absorber. The composition of gas generating layer-forming composition d is shown in Table 1.

[Production Example 5] Preparation of composition e for forming gas generating layer 30 parts by weight of 2-ethylhexyl acrylate, 70 parts by weight of methyl acrylate, 10 parts by weight of acrylic acid, and 0.2 parts by weight of benzoyl peroxide as a polymerization initiator were added to ethyl acetate, and the mixture was heated to 70°C to obtain an ethyl acetate solution of an acrylic copolymer (polymer B).
A gas-generating layer-forming composition e was prepared by mixing an ethyl acetate solution of polymer B (polymer B: 100 parts by weight), 1 part by weight of an isocyanate-based crosslinking agent (manufactured by Nippon Polyurethane Co., Ltd., trade name "Coronate L"), and 20 parts by weight of an ultraviolet absorber (manufactured by BASF, trade name "Tinuvin 477"). The composition of gas-generating layer-forming composition e is shown in Table 1.

[Production Example 6] Preparation of gas generating layer-forming composition f 95 parts by weight of 2-ethylhexyl acrylate, 5 parts by weight of acrylic acid, and 0.15 parts by weight of benzoyl peroxide as a polymerization initiator were added to ethyl acetate, and the mixture was heated to 70°C to obtain an ethyl acetate solution of an acrylic copolymer (polymer C).
A gas-generating layer-forming composition f was prepared by mixing an ethyl acetate solution of polymer C (polymer C: 100 parts by weight), 1 part by weight of an isocyanate-based crosslinking agent (manufactured by Nippon Polyurethane Co., Ltd., trade name "Coronate L"), and 20 parts by weight of an ultraviolet absorber (manufactured by BASF, trade name "Tinuvin 477"). The composition of gas-generating layer-forming composition g is shown in Table 1.

[Production Example 7] Preparation of composition g for forming gas generating layer 95 parts by weight of 2-ethylhexyl acrylate, 5 parts by weight of acrylic acid, and 0.15 parts by weight of benzoyl peroxide as a polymerization initiator were added to ethyl acetate, and the mixture was heated to 70°C to obtain an ethyl acetate solution of an acrylic copolymer (polymer C).
A gas generating layer-forming composition g was prepared by mixing an ethyl acetate solution of polymer C (polymer C: 100 parts by weight), 0.1 parts by weight of an epoxy-based crosslinking agent (manufactured by Mitsubishi Gas Chemical Company, Inc., trade name "TETRAD-C"), and 20 parts by weight of an ultraviolet absorber (manufactured by BASF, trade name "Tinuvin 477"). The composition of gas generating layer-forming composition g is shown in Table 3.

Production Example 8 Preparation of Gas Generating Layer-Forming Composition h A gas generating layer-forming composition h was prepared by mixing 100 parts by weight of a maleic acid-modified styrene-ethylene-butylene-styrene block copolymer (SEBS: styrene moiety/ethylene-butylene moiety (weight ratio) = 30/70, acid value: 10 (mg-CH ₃ ONa/g), manufactured by Asahi Kasei Chemicals Corporation, trade name "Tuftec M1913"), 3 parts by weight of an epoxy-based crosslinking agent (manufactured by Mitsubishi Gas Chemical Company, Inc., trade name "TETRAD-C"), 20 parts by weight of an ultraviolet absorber (manufactured by BASF Corporation, trade name "Tinuvin 477"), and toluene as a solvent. The composition of gas generating layer-forming composition h is shown in Table 3.

[Production Example 8'] Preparation of composition i for forming gas generating layer 100 parts by weight of butyl acrylate, 5 parts by weight of acrylic acid, and 0.2 parts by weight of benzoyl peroxide as a polymerization initiator were added to toluene, and the mixture was heated to 70°C to obtain a toluene solution of an acrylic copolymer (polymer D).
A toluene solution of polymer D (polymer D: 100 parts by weight), 0.1 parts by weight of an epoxy-based crosslinking agent (manufactured by Mitsubishi Gas Chemical Company, Inc., trade name "TETRAD-C"), and 20 parts by weight of an ultraviolet absorber (manufactured by BASF SE, trade name "Tinuvin 400") were mixed together to prepare gas-generating layer-forming composition i. The composition of gas-generating layer-forming composition i is shown in Table 3.

[Production Example 8″] Preparation of Gas Generating Layer-Forming Composition j In the same manner as in Production Example 5, an ethyl acetate solution of an acrylic copolymer (Polymer B) was obtained.
A gas-generating layer-forming composition e was prepared by mixing an ethyl acetate solution of polymer B (polymer B: 100 parts by weight), 1 part by weight of an epoxy-based crosslinking agent (manufactured by Nippon Polyurethane Co., Ltd., trade name "Coronate L"), and 20 parts by weight of an ultraviolet absorber (manufactured by BASF, trade name "Tinuvin 477"). The composition of gas-generating layer-forming composition e is shown in Table 1.
A gas generating layer-forming composition i was prepared by mixing an ethyl acetate solution of polymer B (polymer B: 100 parts by weight), 0.1 parts by weight of an epoxy-based crosslinking agent (manufactured by Mitsubishi Gas Chemical Company, Inc., trade name "TETRAD-C"), and 20 parts by weight of an ultraviolet absorber (manufactured by BASF SE, trade name "Tinuvin 400"). The composition of gas generating layer-forming composition j is shown in Table 3.

[Production Example 8'''] Preparation of Gas Generating Layer-Forming Composition k To toluene were added 50 parts by weight of butyl acrylate, 50 parts by weight of ethyl acrylate, 5 parts by weight of acrylic acid, 0.1 parts by weight of 2-hydroxyethyl acrylate, 0.3 parts by weight of trimethylolpropane triacrylate, and 0.1 parts by weight of benzoyl peroxide as a polymerization initiator, and the mixture was heated to 70°C to obtain a toluene solution of an acrylic copolymer (polymer E).
A toluene solution of polymer E (polymer E: 100 parts by weight), 0.1 parts by weight of an epoxy-based crosslinking agent (manufactured by Mitsubishi Gas Chemical Company, Inc., trade name "TETRAD-C"), and 20 parts by weight of an ultraviolet absorber (manufactured by BASF SE, trade name "Tinuvin 400") were mixed to prepare a gas-generating layer-forming composition i. The composition of gas-generating layer-forming composition k is shown in Table 3.

[Production Example 9] Preparation of gas generating layer-forming composition I A gas generating layer-forming composition e was prepared in the same manner as in Production Example 1, except that 20 parts by weight of 2-[5-chloro-2H-benzotriazol-2-yl]-4-methyl-6-(tert-butyl)phenol (trade name "TINUVIN 326", manufactured by BASF) was used as the UV absorber. The composition of gas generating layer-forming composition I is shown in Table 1.

Production Example 10 Preparation of Heat-Expandable Microsphere-Containing Composition II Heat-expandable microsphere-containing composition II was prepared in the same manner as in Production Example 5, except that no ultraviolet absorber was added, the amount of crosslinking agent was 1.4 parts by weight, 30 parts by weight of heat-expandable microspheres (manufactured by Matsumoto Yushi Pharmaceutical Co., Ltd., trade name "Matsumoto Microsphere F-50D"), and 10 parts by weight of a terpene phenol-based tackifying resin (manufactured by Sumitomo Bakelite Co., Ltd., trade name "Sumilite Resin PR51732") were added.

Production Example 11 Preparation of Heat-Expandable Microsphere-Containing Composition III Heat-expandable microsphere-containing composition III was prepared in the same manner as in Production Example 8, except that 20 parts by weight of a terpene phenol-based tackifying resin (manufactured by Yasuhara Chemical Co., Ltd., product name "YS Polystar T160") was used instead of 10 parts by weight of a terpene phenol-based tackifying resin (manufactured by Sumitomo Bakelite Co., Ltd., product name "Sumilite Resin PR51732").

[Production Example 12] Preparation of Pressure Sensitive Adhesive a In the same manner as in Production Example 1, a toluene solution of an acrylic copolymer (Polymer A) was obtained.
A toluene solution of polymer A (polymer A: 100 parts by weight), 3 parts by weight of an isocyanate-based crosslinking agent (manufactured by Nippon Polyurethane Co., Ltd., trade name "Coronate L"), and 5 parts by weight of a surfactant (manufactured by Kao Corporation, trade name "Exsepal IPP") were mixed to prepare adhesive a. The composition of adhesive a is shown in Table 2.

[Production Example 12'] Preparation of Pressure Sensitive Adhesive b In the same manner as in Production Example 6, a toluene solution of an acrylic copolymer (Polymer C) was obtained.
A toluene solution of polymer C (polymer C: 100 parts by weight), 3 parts by weight of an isocyanate-based crosslinking agent (manufactured by Nippon Polyurethane Co., Ltd., trade name "Coronate L"), and 1 part by weight of an epoxy-based crosslinking agent (manufactured by Mitsubishi Gas Chemical Company, Inc., trade name "TETRAD-C") were mixed to prepare adhesive b. The composition of adhesive b is shown in Table 2.

[Production Example 13] Preparation of Pressure-Sensitive Adhesive I Pressure-Sensitive Adhesive I was prepared in the same manner as in Production Example 10, except that the amount of crosslinking agent was 1 part by weight and no surfactant was added. The composition of Pressure-Sensitive Adhesive I is shown in Table 2.

Production Example 14 Preparation of intermediate layer-forming composition a In the same manner as in Production Example 5, an ethyl acetate solution of an acrylic copolymer (polymer B) was obtained.
An ethyl acetate solution of polymer B (polymer B: 100 parts by weight), 1 part by weight of an epoxy-based crosslinking agent (manufactured by Mitsubishi Gas Chemical Co., Inc., trade name "Tetrad C"), 50 parts by weight of a UV oligomer (manufactured by Mitsubishi Chemical Corporation, trade name "Shikou UV-1700B"), and 3 parts by weight of a photopolymerization initiator (manufactured by BASF Corporation, trade name "Omnirad 127") were mixed to prepare an intermediate layer-forming composition a. The composition of intermediate layer-forming composition a is shown in Table 3.

[Production Example 15] Preparation of intermediate layer-forming composition b [0111] Composition b for forming an intermediate layer was obtained by mixing 100 parts by weight of a maleic acid-modified styrene-ethylene-butylene-styrene block copolymer (SEBS: styrene moiety/ethylene-butylene moiety (weight ratio) = 30/70, acid value: 10 (mg-CH ₃ ONa/g), manufactured by Asahi Kasei Chemicals Corporation, product name "Tuftec M1913"), 3 parts by weight of an epoxy-based crosslinking agent (manufactured by Mitsubishi Gas Chemical Company, Inc., product name "TETRAD-C"), 3 parts by weight of a fatty acid ester-based surfactant (manufactured by Kao Corporation, product name "Exsepal IPP", molecular weight: 298.5, alkyl group carbon number: 16), and toluene as a solvent. The composition of composition b for forming an intermediate layer is shown in Table 3.

[Example 1]
The gas generating layer forming composition a obtained in Production Example 1 was applied to a polyethylene terephthalate film (manufactured by Toray Industries, Inc., product name "Cerapeel", thickness: 38 μm) with a silicone release agent treated surface so that the thickness after solvent evaporation (drying) would be 7 μm, and then dried to obtain an adhesive sheet consisting of only a gas generating layer on the polyethylene terephthalate film.
The obtained pressure-sensitive adhesive sheet was subjected to the above evaluations (1) to (13). The results are shown in Table 4.

[Example 2]
The adhesive a obtained in Production Example 10 was applied to a polyethylene terephthalate film (thickness: 75 μm) with a silicone release agent-treated surface so that the thickness after solvent evaporation (drying) would be 15 μm, and then dried to form an adhesive layer precursor layer a on the polyethylene terephthalate film.
The gas generating layer forming composition a obtained in Production Example 1 was applied to a polyethylene terephthalate film (manufactured by Toray Industries, Inc., product name "Cerapeel", thickness: 38 μm) with a surface treated with a silicone release agent so that the thickness after solvent evaporation (drying) would be 7 μm, and then dried to form a gas generating layer precursor layer a on the polyethylene terephthalate film.
The pressure-sensitive adhesive layer precursor layer a and the gas-generating layer precursor layer a were laminated together between rolls to obtain a pressure-sensitive adhesive sheet (pressure-sensitive adhesive layer/gas-generating layer) sandwiched between polyethylene terephthalate films with silicone release agent-treated surfaces.
The obtained pressure-sensitive adhesive sheet was subjected to the above evaluations (1) to (13). The results are shown in Table 4.

[Example 3]
The adhesive a obtained in Production Example 10 was applied to a polyethylene terephthalate film (thickness: 75 μm) with a silicone release agent-treated surface so that the thickness after solvent evaporation (drying) would be 15 μm, and then dried to form an adhesive layer precursor layer a on the polyethylene terephthalate film.
The intermediate layer forming composition a obtained in Production Example 12 was applied to a polyethylene terephthalate film (manufactured by Toray Industries, Inc., product name "Cerapeel", thickness: 38 μm) with a silicone release agent treated surface so that the thickness after solvent evaporation (drying) would be 15 μm, and then dried to form an intermediate layer precursor layer a on the polyethylene terephthalate film.
Next, the pressure-sensitive adhesive layer precursor layer a and the intermediate layer precursor layer a were laminated together between rolls, and then irradiated with UV light from the intermediate layer precursor layer side at 500 mJ/ ^cm2 to obtain a laminate precursor layer a sandwiched between polyethylene terephthalate films with surfaces treated with a silicone release agent.
The gas generating layer forming composition a obtained in Production Example 1 was applied to a polyethylene terephthalate film (manufactured by Toray Industries, Inc., product name "Cerapeel", thickness: 38 μm) with a surface treated with a silicone release agent so that the thickness after solvent evaporation (drying) would be 7 μm, and then dried to form a gas generating layer precursor layer a on the polyethylene terephthalate film.
After peeling off the polyethylene terephthalate film with a silicone release agent-treated surface on the intermediate layer precursor layer a side of the laminate precursor layer a, the intermediate layer precursor layer a of the laminate precursor layer a and the gas-generating layer precursor layer a were laminated together between rolls to obtain an adhesive sheet (adhesive layer/intermediate layer/gas-generating layer) sandwiched between polyethylene terephthalate films with silicone release agent-treated surfaces.
The obtained pressure-sensitive adhesive sheet was subjected to the above evaluations (1) to (13). The results are shown in Table 4.

[Example 4]
The adhesive a obtained in Production Example 10 was applied to a polyethylene terephthalate film (thickness: 75 μm) with a silicone release agent-treated surface so that the thickness after solvent evaporation (drying) would be 15 μm, and then dried to form an adhesive layer precursor layer a on the polyethylene terephthalate film.
The intermediate layer forming composition b obtained in Production Example 13 was applied to a polyethylene terephthalate film (manufactured by Toray Industries, Inc., product name "Cerapeel", thickness: 38 μm) with a silicone release agent treated surface so that the thickness after solvent evaporation (drying) would be 15 μm, and then dried to form an intermediate layer precursor layer a on the polyethylene terephthalate film.
Next, the pressure-sensitive adhesive layer precursor layer a and the intermediate layer precursor layer b were laminated together between rolls to obtain a laminate precursor layer b sandwiched between polyethylene terephthalate films with surfaces treated with a silicone release agent.
The gas generating layer forming composition a obtained in Production Example 1 was applied to a polyethylene terephthalate film (manufactured by Toray Industries, Inc., product name "Cerapeel", thickness: 38 μm) with a surface treated with a silicone release agent so that the thickness after solvent evaporation (drying) would be 7 μm, and then dried to form a gas generating layer precursor layer a on the polyethylene terephthalate film.
After peeling off the polyethylene terephthalate film with a silicone release agent-treated surface on the intermediate layer precursor layer b side of the laminate precursor layer b, the intermediate layer precursor layer b of the laminate precursor layer b and the gas generating layer precursor layer a were laminated together between rolls to obtain an adhesive sheet (adhesive layer/intermediate layer/gas generating layer) sandwiched between polyethylene terephthalate films with silicone release agent-treated surfaces.
The obtained pressure-sensitive adhesive sheet was subjected to the above evaluations (1) to (13). The results are shown in Table 4.

[Example 5]
The adhesive a obtained in Production Example 10 was applied to a polyethylene terephthalate film (thickness: 75 μm) with a silicone release agent-treated surface so that the thickness after solvent evaporation (drying) would be 15 μm, and then dried to form an adhesive layer precursor layer a on the polyethylene terephthalate film.
The gas generating layer forming composition a obtained in Production Example 1 was applied to a polyethylene terephthalate film (manufactured by Toray Industries, Inc., product name "Cerapeel", thickness: 38 μm) with a surface treated with a silicone release agent so that the thickness after solvent evaporation (drying) would be 7 μm, and then dried to form a gas generating layer precursor layer a on the polyethylene terephthalate film.
The pressure-sensitive adhesive layer precursor layer a was laminated between rolls onto one side of a polyethylene terephthalate film (manufactured by Toray Industries, Inc., trade name "Lumirror #2F51N", thickness: 2 μm).
Next, the gas generating layer precursor layer a was laminated between rolls onto the side of the polyethylene terephthalate film opposite to the pressure-sensitive adhesive layer precursor layer a.
In this way, a pressure-sensitive adhesive sheet (pressure-sensitive adhesive layer/intermediate layer/gas-generating layer) sandwiched between polyethylene terephthalate films each having a surface treated with a silicone release agent was obtained.
The obtained pressure-sensitive adhesive sheet was subjected to the above evaluations (1) to (13). The results are shown in Table 4.

[Example 6]
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 5, except that gas-generating layer-forming composition b was used instead of gas-generating layer-forming composition a. The pressure-sensitive adhesive sheet obtained was subjected to the above-mentioned evaluations (1) to (13). The results are shown in Table 5.

[Example 7]
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 5, except that gas-generating layer-forming composition c was used instead of gas-generating layer-forming composition a. The pressure-sensitive adhesive sheet obtained was subjected to the above-mentioned evaluations (1) to (13). The results are shown in Table 5.

[Example 8]
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 5, except that gas-generating layer-forming composition d was used instead of gas-generating layer-forming composition a. The pressure-sensitive adhesive sheet obtained was subjected to the above-mentioned evaluations (1) to (13). The results are shown in Table 5.

[Example 9]
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 5, except that gas-generating layer-forming composition e was used instead of gas-generating layer-forming composition a. The pressure-sensitive adhesive sheet obtained was subjected to the above-mentioned evaluations (1) to (13). The results are shown in Table 5.

[Example 10]
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 5, except that gas-generating layer-forming composition f was used instead of gas-generating layer-forming composition a. The pressure-sensitive adhesive sheet obtained was subjected to the above-mentioned evaluations (1) to (13). The results are shown in Table 5.

[Example 11]
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1, except that composition g for forming a gas-generating layer was used instead of composition a for forming a gas-generating layer. The pressure-sensitive adhesive sheet obtained was subjected to the above-mentioned evaluations. The results are shown in Table 6.

[Example 12]
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1, except that gas-generating layer-forming composition h was used instead of gas-generating layer-forming composition a. The obtained pressure-sensitive adhesive sheet was subjected to the above-mentioned evaluations. The results are shown in Table 6.

[Comparative Example 1]
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1, except that gas-generating layer-forming composition I was used instead of gas-generating layer-forming composition a. The pressure-sensitive adhesive sheet obtained was subjected to the above-mentioned evaluations (1) to (13). The results are shown in Table 7.

[Comparative Example 2]
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 5, except that gas-generating layer-forming composition I was used instead of gas-generating layer-forming composition a. The pressure-sensitive adhesive sheet obtained was subjected to the above-mentioned evaluations (1) to (13). The results are shown in Table 7.

[Comparative Example 3]
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 5, except that Pressure-sensitive Adhesive I was used instead of Pressure-sensitive Adhesive a, the pressure-sensitive adhesive layer was 10 μm thick, a 188 μm thick PET film was used as the intermediate layer, and a 48 μm thick gas-generating layer was formed using Heat-Expandable Microsphere-Containing Composition II instead of Gas-Generating Layer-Forming Composition a. The obtained pressure-sensitive adhesive sheet was subjected to the above-mentioned Evaluations (1) to (13). The results are shown in Table 7.

[Comparative Example 4]
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 5, except that Pressure-sensitive Adhesive I was used instead of Pressure-sensitive Adhesive a, the pressure-sensitive adhesive layer was 10 μm thick, a 100 μm thick PET film was used as the intermediate layer, and a 48 μm thick gas-generating layer was formed using Heat-Expandable Microsphere-Containing Composition III instead of Gas-Generating Layer-Forming Composition a. The obtained pressure-sensitive adhesive sheet was subjected to the above-mentioned Evaluations (1) to (13). The results are shown in Table 7.

10 Gas generating layer 20 Pressure sensitive adhesive layer 30 Intermediate layer 100, 100', 200 Pressure sensitive adhesive sheet

Claims (15)

A pressure-sensitive adhesive sheet having a gas generating layer that generates gas when irradiated with laser light,
The haze value is 50% or less,
the gas generating layer contains an ultraviolet absorber;
the ultraviolet absorber is a benzotriazole-based ultraviolet absorber, a benzophenone-based ultraviolet absorber, a triazine-based ultraviolet absorber, a salicylate-based ultraviolet absorber, or a cyanoacrylate-based ultraviolet absorber;
The pressure-sensitive adhesive sheet has an ultraviolet transmittance of 30% or less at a wavelength of 360 nm.
Adhesive sheet. The pressure-sensitive adhesive sheet of claim 1, wherein the gas generating layer has a thickness of 0.1 μm to 50 μm. The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the gas-generating layer is a layer capable of absorbing ultraviolet light. The pressure-sensitive adhesive sheet according to any one of claims 1 to 3 , wherein the transmittance at a wavelength of 500 nm is 50% to 100%. The pressure-sensitive adhesive sheet according to claim 1 , wherein the gas generating layer is a layer that generates a hydrocarbon gas. 6. The pressure-sensitive adhesive sheet according to claim 1, wherein the gas generation layer has a gasification initiation temperature of 150°C to 500°C. The pressure-sensitive adhesive sheet according to any one of claims 1 to 6 , wherein the 10% weight loss temperature is 200°C to 500°C. A pressure-sensitive adhesive layer is further provided on at least one side of the gas generating layer,
The pressure-sensitive adhesive sheet according to claim 1 , wherein the pressure-sensitive adhesive layer is a layer whose surface is deformed by irradiation of the pressure-sensitive adhesive sheet with laser light. The pressure-sensitive adhesive sheet according to claim 8 , wherein the pressure-sensitive adhesive layer has a thickness of 0.1 μm to 50 μm. The pressure-sensitive adhesive sheet according to claim 8 , wherein the pressure-sensitive adhesive layer foams when irradiated with laser light. A method for treating electronic components, comprising: adhering an electronic component to the adhesive sheet according to claim 1 ; and irradiating the adhesive sheet with laser light to peel the electronic component from the adhesive sheet. The method for processing an electronic component according to claim 11 , wherein the peeling of the electronic component is performed selectively at a position. After the electronic component is attached to the pressure-sensitive adhesive sheet, and before the electronic component is peeled off from the pressure-sensitive adhesive sheet,
performing a predetermined process on the electronic component;
The method for processing electronic components according to claim 12 . The method for processing electronic components according to claim 13 , wherein the processing is grinding, dicing, die bonding, wire bonding, etching, vapor deposition, molding, circuit formation, inspection, testing, cleaning, transfer, alignment, repair, or device surface protection. The method for treating an electronic component according to claim 11 , further comprising the step of: peeling the electronic component from the adhesive sheet, and then placing the electronic component on another sheet.