Double-sided adhesive sheet for transfer

Abstract

To provide a double-sided adhesive sheet for transfer capable of maintaining transfer accuracy because positional displacement of an electronic component hardly occurs even in the case of irradiation with ultraviolet light.SOLUTION: Provided is a double-sided adhesive sheet for transfer having a first adhesive layer, a substrate, and a second adhesive layer laminated in this order. The first adhesive layer is formed of a low adhesion adhesive layer, and the second adhesive layer is formed of a peelable adhesive layer. A ratio (Rz1 / Rz2) of a floating height Rz1 before the first adhesive layer is irradiated with an ultraviolet laser having a wavelength of 248 nm at a beam size of 130×105 μm, an output of 100 mJ / cm2, a pulse width of 10 ns, and a frequency of 100 Hz to a floating height Rz2 after irradiation with the same is 0.2-1600.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a double-sided pressure-sensitive adhesive sheet for transfer. [Background technology]

[0002] Conventionally, in the manufacturing process of semiconductor devices and the like, semiconductor chips obtained by dividing a semiconductor wafer are received on a double-sided adhesive sheet for transfer on a carrier substrate, and then transferred onto a mounting substrate (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-263876 Summary of the Invention [Problem to be solved by the invention]

[0004] In the manufacturing process of semiconductor devices and the like, marking is sometimes performed on a double-sided adhesive sheet for transfer to provide identification when the sheet is transported after receiving a semiconductor chip. However, when an ultraviolet laser is used for such marking, the marking is easily removed from the substrate 10 to the first adhesive layer 1, as shown in FIG. 1 When the adhesive peels off and floats, the flatness of the double-sided adhesive sheet for transfer is impaired, which can lead to displacement of the electronic component 21 and transfer failure.

[0005] The present invention has been made in consideration of the above problems, and aims to provide a double-sided pressure-sensitive adhesive sheet for transfer that is less likely to cause misalignment of electronic components even when irradiated with ultraviolet rays, and can maintain transfer accuracy. [Means for solving the problem]

[0006] As a result of extensive research to achieve the above object, the inventors have found that by using a double-sided PSA sheet for transfer that has a first adhesive layer for receiving fine electronic components such as semiconductor chips, a base material, and a second adhesive layer for temporarily fixing them to a carrier substrate, and that has a ratio of the lift height before irradiation to the lift height after irradiation with a specific ultraviolet laser within a specific range, it is possible to suppress misalignment of electronic components and transfer defects even when marking is performed by ultraviolet laser irradiation. The present invention was completed based on these findings.

[0007] That is, the present invention provides a double-sided PSA sheet for transfer, in which a first PSA layer, a substrate, and a second PSA layer are laminated in this order, the first pressure-sensitive adhesive layer is a low-tack pressure-sensitive adhesive layer, the second pressure-sensitive adhesive layer is a peelable pressure-sensitive adhesive layer, The first adhesive layer was irradiated with an ultraviolet laser beam of 248 nm wavelength, with a beam size of 130 × 105 μm and an output of 100 mJ / cm. 2 , frequency 100Hz, pulse width 10ns Before Floating height R z1 Irradiation After Floating height R z2 The ratio (R z2 / R z1 ) is 0.2 to 1600.

[0008] The first adhesive layer was irradiated with an ultraviolet laser beam of 248 nm wavelength, with a beam size of 130 × 105 μm and an output of 100 mJ / cm. 2 When irradiated with light at a frequency of 100 Hz and a pulse width of 10 ns, the ratio of the lifted area to the irradiated area is preferably 20.0% or less.

[0009] The present invention also provides a double-sided PSA sheet for transfer, comprising a first PSA layer, a substrate, and a second PSA layer laminated in this order, the first pressure-sensitive adhesive layer is a low-tack pressure-sensitive adhesive layer, the second pressure-sensitive adhesive layer is a peelable pressure-sensitive adhesive layer, The first adhesive layer is irradiated with an ultraviolet laser having a wavelength of 248 nm and a beam size of 130 × 105 μm and an output of 100 mJ / cm 2 The present invention provides a double-sided pressure-sensitive adhesive sheet for transfer, which has a lifted area that is 20.0% or less of the total irradiated area when irradiated with light having a pulse width of 10 ns and a frequency of 100 Hz.

[0010] the above Thickness t of the first adhesive layer 1 (μm) For the above Floating height R z2 (μm) The ratio ( R z2 / t 1) is preferably 1.0 or less. [Effects of the Invention]

[0011] The double-sided pressure-sensitive adhesive sheet for transfer of the present invention is unlikely to lose its flatness even when irradiated with an ultraviolet laser, so it is possible to suppress misalignment of electronic components and transfer defects, and maintain transfer accuracy. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view schematically illustrating one embodiment of a double-sided pressure-sensitive adhesive sheet for transfer according to the present invention. [Figure 2] FIG. 2 is a cross-sectional view schematically illustrating another embodiment of the double-sided pressure-sensitive adhesive sheet for transfer of the present invention. [Figure 3] 2 is a cross-sectional view schematically illustrating one embodiment of a first step in a method for mounting an electronic component onto a mounting substrate using the double-sided pressure-sensitive adhesive sheet for transfer shown in FIG. 1. FIG. [Figure 4] 2 is a cross-sectional view schematically illustrating one embodiment of a second step in a method for mounting an electronic component onto a mounting substrate using the double-sided pressure-sensitive adhesive sheet for transfer shown in FIG. 1. FIG. [Figure 5] FIG. 10 is a cross-sectional view showing a double-sided pressure-sensitive adhesive sheet for transfer in which flatness has been impaired by irradiation with an ultraviolet laser, causing misalignment of the received electronic component. DETAILED DESCRIPTION OF THE INVENTION

[0013] [Double-sided adhesive sheet for transfer] A double-sided pressure-sensitive adhesive sheet for transfer according to one embodiment of the present invention has a laminated structure in which a first pressure-sensitive adhesive layer, a substrate, and a second pressure-sensitive adhesive layer are laminated in this order, and is formed by irradiating the first pressure-sensitive adhesive layer with an ultraviolet laser having a wavelength of 248 nm with a beam size of 130 × 105 μm and an output of 100 mJ / cm. 2 , frequency 100Hz, pulse width 10ns Before Floating height R z1 Irradiation After Floating height R z2 The ratio (R z2 / R z1 ) is 0.2 to 1600. One embodiment of the double-sided pressure-sensitive adhesive sheet for transfer of the present invention will be described below with reference to the drawings, but the double-sided pressure-sensitive adhesive sheet for transfer of the present invention is not limited to this embodiment. FIG. 1 is a cross-sectional view showing one embodiment of the double-sided pressure-sensitive adhesive sheet for transfer of the present invention, in which 1 denotes the double-sided pressure-sensitive adhesive sheet for transfer, 10 a substrate, 11 a first pressure-sensitive adhesive layer, and 12 a second pressure-sensitive adhesive layer.

[0014] The above ratio (R z2 / R z1 ) is preferably 0.2 to 1600 from the viewpoint of the positional accuracy of the electronic component received on the first pressure-sensitive adhesive layer, more preferably 0.4 to 1500, and even more preferably 0.5 to 1400. z1 and R z2 is the maximum height of swelling in the vertical direction (Z-axis direction) of the irradiated area after laser irradiation, and can be obtained, for example, by analyzing a surface observation image obtained using a laser microscope (product name "VK-X100", manufactured by Keyence Corporation).

[0015] In the double-sided pressure-sensitive adhesive sheet for transfer of the present invention, an ultraviolet laser having a wavelength of 248 nm is applied to the first pressure-sensitive adhesive layer with a beam size of 130 × 105 μm and an output of 100 mJ / cm 2When irradiated at a frequency of 100 Hz and a pulse width of 10 ns, the area ratio of the lifted area to the irradiated area is preferably 20.0% or less. An area ratio of 20.0% or less is preferred from the viewpoint of the positional accuracy of the electronic components received by the first pressure-sensitive adhesive layer, and 15.0% or less is more preferred, and 10.0% or less is even more preferred. The lower limit of the area ratio is usually 0%. The lifted area is the area of the portion of the low-tack pressure-sensitive adhesive layer that has peeled off and lifted from the substrate, and can be determined, for example, by analyzing a surface observation image captured using a microscope.

[0016] In the double-sided pressure-sensitive adhesive sheet for transfer of the present invention, Thickness t of the first adhesive layer 1 (μm) For the above Floating height R z2 (μm) The ratio (R z2 / t1) is preferably 1.0 or less. z2 A configuration in which / t1) is 1.0 or less is preferred from the viewpoint of the positional accuracy of the electronic component received on the first pressure-sensitive adhesive layer, with 0.5 or less being more preferred, and 0.4 or less being even more preferred.

[0017] The floating height R after ultraviolet laser irradiation z2 The area ratio of the raised area can be adjusted by adjusting the adhesive strength by adjusting the type, composition, degree of crosslinking, etc. of the adhesive that constitutes the first adhesive layer, and by adjusting the type and amount of UV absorber to suppress reaction of the substrate and adjust the adhesion between the adhesive and the substrate.

[0018] A double-sided pressure-sensitive adhesive sheet for transfer according to another embodiment of the present invention has a laminated structure in which a first pressure-sensitive adhesive layer, a substrate, and a second pressure-sensitive adhesive layer are laminated in this order, and is formed by irradiating the first pressure-sensitive adhesive layer with an ultraviolet laser having a wavelength of 248 nm with a beam size of 130 × 105 μm and an output of 100 mJ / cm. 2When irradiated with light at a frequency of 100 Hz and a pulse width of 10 ns, the area ratio of the lifted area to the irradiated area is 20.0% or less. By configuring the area ratio to be 20.0% or less, the positional accuracy of the electronic component can be maintained. The area ratio is preferably 15.0% or less, and more preferably 10.0% or less.

[0019] <First adhesive layer> In the double-sided pressure-sensitive adhesive sheet for transfer of the present invention, the first pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer for receiving and holding an electronic component, and is made of a low-tack adhesive layer. The configuration in which the first pressure-sensitive adhesive layer is made of a low-tack adhesive layer is preferable because it can reduce the force applied to the electronic component during reception and suppress damage to the electronic component. Furthermore, when the first pressure-sensitive adhesive layer receives an electronic component in a non-contact manner, for example, the electronic component is peeled off from the dicing tape by pushing it with a pin member and dropped onto the first pressure-sensitive adhesive layer. However, when the dropped electronic component is received by the first pressure-sensitive adhesive layer, it may bounce and not be able to be received accurately. When this phenomenon occurs, the positional accuracy of the electronic product may decrease, resulting in poor contact. The configuration in which the first pressure-sensitive adhesive layer is made of a low-tack adhesive layer is also preferable because when the first pressure-sensitive adhesive layer receives an electronic component in a non-contact manner, the electronic component is easily caught by the first pressure-sensitive adhesive layer without bouncing, allowing it to be received with high positional accuracy. Furthermore, this is also preferable in that when the electronic component received by the double-sided pressure-sensitive adhesive sheet for transfer is mounted on a mounting substrate, the electronic component can be easily peeled off from the first pressure-sensitive adhesive layer.

[0020] The first adhesive layer can be made into a low-tack adhesive layer by adjusting the type, composition, degree of crosslinking, etc. of the adhesive that constitutes it, or by forming a WBL (Weak Boundary Layer) by incorporating a light release agent or plasticizer.

[0021] The 180° peel adhesive strength of the first pressure-sensitive adhesive layer to a PET film at 25°C is not particularly limited, but from the viewpoints of being able to receive electronic components with good positional accuracy without damage and of good transferability to a mounting substrate, it is preferably 100 mN / 25 mm or less, more preferably 50 mN / 25 mm or less, and even more preferably 10 mN / 25 mm. Furthermore, from the viewpoint of the adhesion of electronic components to the first pressure-sensitive adhesive layer, the 180° peel adhesive strength of the first pressure-sensitive adhesive layer to a glass plate at 25°C is preferably 0.1 mN / 25 mm or more, more preferably 1 mN / 25 mm or more.

[0022] The ratio (P1b / P1a) of the 180° peel adhesive strength of the first pressure-sensitive adhesive layer against a PET film at 25°C (hereinafter sometimes referred to as "P1a" in this specification) to the 180° peel adhesive strength of the first pressure-sensitive adhesive layer against a PET film after the double-sided pressure-sensitive adhesive sheet for transfer is held at 160°C for 5 minutes (hereinafter sometimes referred to as "P1b" in this specification) is not particularly limited, but is preferably 3.0 or less, more preferably 2.5 or less. A P1b / P1a ratio of 3.0 or less is preferable because, when an electronic component received by the double-sided pressure-sensitive adhesive sheet for transfer of the present invention is transferred onto a mounting substrate by thermocompression bonding and mounted, the adhesive strength of the first pressure-sensitive adhesive layer against the electronic component does not increase, allowing the electronic component to be easily peeled and transferred to the mounting substrate.

[0023] The 180° peel adhesive strength at 25°C was measured by laminating the second adhesive layer of a double-sided adhesive sheet for transfer to a glass plate, laminating a PET film to the adhesive surface of the first adhesive layer, and then compressing the sheet with a 2 kg roller, using one back-and-forth motion. The sheet was then aged for 30 minutes at 23°C and 50% RH. After aging, the double-sided adhesive sheet for transfer was peeled from the adherend in accordance with JIS Z0237 at 25°C and 50% RH, at a tensile speed of 300 mm / min and a peel angle of 180°. The 180° peel adhesive strength (mN / 25 mm) was measured. The PET film used was not particularly limited as long as it was untreated PET, but examples include the product "Lumirror #25-S10, 23 μm thick" (manufactured by Toray Industries, Inc.).

[0024] The surface strength of the first pressure-sensitive adhesive layer can be adjusted by the type and composition of the pressure-sensitive adhesive constituting the layer, the degree of crosslinking, and additives such as fatty acid esters and fluorine-based surfactants.

[0025] In the double-sided pressure-sensitive adhesive sheet for transfer of the present invention, the storage modulus (E'1a) of the first pressure-sensitive adhesive layer measured by AFM-DMA at a frequency of 1 Hz and 25°C is preferably 50 MPa or less. This configuration is preferable for reliably adhering an electronic component received by the first pressure-sensitive adhesive layer. If E'1a is too high, the adhesion of the electronic component to the first pressure-sensitive adhesive layer may decrease, resulting in problems such as displacement or dropping of the electronic component. From the viewpoint of the adhesion of the electronic component to the first pressure-sensitive adhesive layer, E'1a is preferably 40 MPa or less, more preferably 30 MPa or less. It may also be 20 MPa or less, or 10 MPa or less. On the other hand, from the viewpoint of transferability from the first pressure-sensitive adhesive layer to a circuit board, E'1a is preferably 0.1 MPa or more. If E'1a is too low, the adhesion of the electronic component to the first pressure-sensitive adhesive layer may be too high, which may impair transferability when mounting the electronic component to a mounting board. From the viewpoint of transferability of electronic components to mounting substrates, E'1a is preferably 0.2 MPa or more, and more preferably 0.5 MPa or more.

[0026] In the double-sided pressure-sensitive adhesive sheet for transfer of the present invention, the storage modulus (E'1b) of the first pressure-sensitive adhesive layer measured by AFM-DMA at a frequency of 1 kHz and 25°C is preferably 100 MPa or less. This configuration is preferable because, when the first pressure-sensitive adhesive layer receives an electronic component without contact, the electronic component is not repelled from the surface of the first pressure-sensitive adhesive layer and can be received with good positional accuracy. If the E'1b is too high, when an electronic component is dropped onto the surface of the first pressure-sensitive adhesive layer without contacting it, the electronic component is likely to be repelled and shifted from its predetermined position or turned upside down, resulting in a decrease in positional accuracy. From the viewpoint of the positional accuracy of the electronic component relative to the first pressure-sensitive adhesive layer, E'1b is preferably 90 MPa or less, more preferably 80 MPa or less. It may also be 70 MPa or less, 60 MPa or less, 50 MPa or less, 40 MPa or less, or 30 MPa or less, and particularly 20 MPa or less. On the other hand, from the viewpoint of transferability from the first pressure-sensitive adhesive layer to a mounting substrate, E'1b is preferably 0.5 MPa or more. If E'1b is too low, the adhesion of the electronic component to the first pressure-sensitive adhesive layer will be high, and the electronic component may be embedded in the first pressure-sensitive adhesive layer when dropped, impairing transferability when mounted on a mounting substrate. From the viewpoint of transferability of the electronic component to a mounting substrate, E'1b is preferably 0.7 MPa or more, and more preferably 1.0 MPa or more.

[0027] In the double-sided pressure-sensitive adhesive sheet for transfer of the present invention, the ratio (E'1b / E'1a) of the storage modulus (E'1b) of the first pressure-sensitive adhesive layer measured by AFM-DMA at a frequency of 1 Hz and 25°C to the storage modulus (E'1a) of the first pressure-sensitive adhesive layer measured by AFM-DMA at a frequency of 1 Hz and 25°C is preferably greater than 1.00. This configuration is preferred in that it provides a good balance between the adhesion of an electronic component to the first pressure-sensitive adhesive layer, positional accuracy, and transferability to a mounting substrate. From the viewpoint of a balance between the adhesion of an electronic component, positional accuracy, and transferability to a mounting substrate, E'1b / E'1a is preferably 1.05 or greater, and more preferably 1.10 or greater. There are no particular limitations on the upper limit of E'1b / E'1a, but from the viewpoint of the above-mentioned balance, it is preferably 3.00 or less.

[0028] In the double-sided pressure-sensitive adhesive sheet for transfer of the present invention, the loss modulus (E"1a) of the first pressure-sensitive adhesive layer measured by AFM-DMA at a frequency of 1 Hz and 25°C is preferably 7 MPa or less. This configuration is preferred from the viewpoint of excellent transferability of electronic components to mounting substrates. If E"1a is too high, the adhesion of the electronic component to the first pressure-sensitive adhesive layer will be too high, which may impair transferability when mounting the electronic component to a mounting substrate. From the viewpoint of transferability of the electronic component to a mounting substrate, E"1a is preferably 5 MPa or less, and more preferably 3 MPa or less. If E"1a is too low, the adhesion of the electronic component to the first pressure-sensitive adhesive layer will be reduced, which may result in problems such as displacement or dropping of the electronic component. From the viewpoint of adhesion of the electronic component to the first pressure-sensitive adhesive layer, E"1a is preferably 0.01 MPa or more, and more preferably 0.03 MPa or more.

[0029] The storage modulus (E'1a) at a frequency of 1 Hz and 25°C, the storage modulus (E'1b) at a frequency of 1 kHz and 25°C, and the loss modulus (E"1a) at a frequency of 1 Hz and 25°C measured by AFM-DMA (nano Dynamic Mechanical Analysis (nDMA) using an atomic force microscope (AFM)) of the first adhesive layer can be adjusted by the type, composition, degree of crosslinking, etc. of the adhesive constituting the layer.

[0030] In the double-sided pressure-sensitive adhesive sheet for transfer of the present invention, the tack strength of the first pressure-sensitive adhesive layer to a stainless steel plate (diameter 5 mm) is preferably 10 to 250 gf / Φ5mmSUS. A configuration in which the tack strength is 10 gf / Φ5mmSUS or more is preferred from the viewpoints of adhesion and positional accuracy of electronic components to the first pressure-sensitive adhesive layer, and more preferably 20 gf / Φ5mmSUS or more. On the other hand, a configuration in which the tack strength is 250 gf / Φ5mmSUS or less is preferred from the viewpoint of transferability of electronic components to mounting substrates, and more preferably 200 gf / Φ5mmSUS or less.

[0031] The tackiness of the first adhesive layer to a stainless steel plate (diameter 5 mm) can be adjusted by the type and composition of the adhesive constituting it, the degree of crosslinking, and additives such as fatty acid esters and fluorine-based surfactants.

[0032] In the double-sided pressure-sensitive adhesive sheet for transfer of the present invention, the surface strength of the first pressure-sensitive adhesive layer is preferably −500 to −100 μN. A surface strength of −500 μN or more is preferred from the viewpoints of adhesion and positional accuracy of electronic components to the first pressure-sensitive adhesive layer, and is more preferably −400 μN or more. On the other hand, a surface strength of −100 μN or less is preferred from the viewpoint of transferability of electronic components to mounting substrates, and is more preferably −150 μN or less.

[0033] The surface strength of the first pressure-sensitive adhesive layer can be adjusted by the type and composition of the pressure-sensitive adhesive constituting the layer, the degree of crosslinking, and additives such as fatty acid esters and fluorine-based surfactants.

[0034] In the double-sided pressure-sensitive adhesive sheet for transfer of the present invention, the thickness t1 of the first pressure-sensitive adhesive layer is not particularly limited, but is preferably 1 μm or more, more preferably 3 μm or more. A thickness of at least a certain level is preferable because it allows the first pressure-sensitive adhesive layer to receive electronic components with precision. The upper limit of the thickness t1 of the first pressure-sensitive adhesive layer is not particularly limited, but is preferably 100 μm, more preferably 90 μm, and even more preferably 80 μm, 70 μm, 60 μm, or 50 μm. It is even more preferably 45 μm, 40 μm, 35 μm, μm, 30 μm, 25 μm, 20 μm, 15 μm, or 10 μm. A thickness of at most a certain level is preferable because it allows the electronic components to be transferred to the mounting substrate with precision.

[0035] In the double-sided pressure-sensitive adhesive sheet for transfer of the present invention, the haze (according to JIS K7136) of the first pressure-sensitive adhesive layer is not particularly limited, but is preferably 10% or less, more preferably 5.0% or less. A haze of 10% or less provides excellent transparency, and is preferable because, for example, when the double-sided pressure-sensitive adhesive sheet for transfer is attached to a carrier substrate, a pattern (e.g., a marker indicating the transfer position of an electronic component) attached to the carrier substrate can be visually recognized. The haze can be measured, for example, by forming the first pressure-sensitive adhesive layer on a separator and leaving it at room temperature (23°C, 50% RH) for at least 24 hours, peeling off the separator, and attaching the sample to a slide glass (e.g., one with a total light transmittance of 91.8% and a haze of 0.4%) using a haze meter (product name "HM-150" manufactured by Murakami Color Research Laboratory Co., Ltd.).

[0036] In the double-sided pressure-sensitive adhesive sheet for transfer of the present invention, the total light transmittance (according to JIS K7361-1) of the first pressure-sensitive adhesive layer in the visible light wavelength region is not particularly limited, but is preferably 85% or more, more preferably 88% or more. A total light transmittance of 85% or more provides excellent transparency, and is preferable because, for example, when the double-sided pressure-sensitive adhesive sheet for transfer is attached to a carrier substrate, a pattern (e.g., a marker indicating the transfer position of an electronic component) attached to the carrier substrate can be visually recognized. Note that the total light transmittance can be measured, for example, by forming the first pressure-sensitive adhesive layer on a separator and leaving it at room temperature (23°C, 50% RH) for at least 24 hours, peeling off the separator, and attaching the sample to a slide glass (e.g., one with a total light transmittance of 91.8% and a haze of 0.4%) using a haze meter (product name "HM-150" manufactured by Murakami Color Research Laboratory Co., Ltd.).

[0037] The pressure-sensitive adhesive composition constituting the first pressure-sensitive adhesive layer is not particularly limited, but may include, for example, a silicone-based pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, an acrylic-based pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, a polyester-based pressure-sensitive adhesive, a polyamide-based pressure-sensitive adhesive, an epoxy-based pressure-sensitive adhesive, a vinyl alkyl ether-based pressure-sensitive adhesive, a fluorine-based pressure-sensitive adhesive, etc. Among these, from the viewpoints of being able to hold electronic components with good positional accuracy without being damaged and further being able to be transferred well to a mounting substrate, silicone-based pressure-sensitive adhesives, urethane-based pressure-sensitive adhesives, and acrylic-based pressure-sensitive adhesives, which are easy to control to have low adhesion and low tack, are preferred, silicone-based pressure-sensitive adhesives and urethane-based pressure-sensitive adhesives are more preferred, and silicone-based pressure-sensitive adhesives are even more preferred.

[0038] (Silicone adhesive) The silicone-based adhesive is not particularly limited, and known or commonly used silicone-based adhesives can be used, such as addition-type silicone-based adhesives, peroxide-curing silicone-based adhesives, and condensation-type silicone-based adhesives. The silicone-based adhesives may be either one-component or two-component. The silicone-based adhesives can be used alone or in combination of two or more.

[0039] The addition type silicone-based pressure-sensitive adhesive is generally a pressure-sensitive adhesive that generates a silicone-based polymer by addition reaction (hydrosilylation reaction) between an organopolysiloxane having an alkenyl group such as a vinyl group on a silicon atom and an organopolysiloxane having a hydrosilyl group using a platinum compound catalyst such as chloroplatinic acid. The peroxide-curing type silicone-based pressure-sensitive adhesive is generally a pressure-sensitive adhesive that generates a silicone-based polymer by curing (crosslinking) an organopolysiloxane with a peroxide. Meanwhile, the condensation type silicone-based pressure-sensitive adhesive is generally a pressure-sensitive adhesive that generates a silicone-based polymer by dehydration or dealcoholization reaction between polyorganosiloxanes having hydrolyzable silyl groups such as silanol groups or alkoxysilyl groups at the terminals.

[0040] As the silicone-based adhesive, for example, a silicone-based adhesive containing silicone rubber and silicone resin can be used, because it is easy to control the adhesiveness and tackiness to be low.

[0041] The silicone rubber is not particularly limited as long as it contains a silicone-based rubber component, but for example, an organopolysiloxane having dimethylsiloxane, methylphenylsiloxane, or the like as its main structural unit can be used. Depending on the type of reaction, silicone rubbers having alkenyl groups bonded to silicon atoms (alkenyl-group-containing organopolysiloxanes; in the case of addition reaction types), silicone rubbers having at least methyl groups (in the case of peroxide curing types), and silicone rubbers having silanol groups or hydrolyzable alkoxysilyl groups at the terminals (in the case of condensation types) can be used. The weight-average molecular weight of the organopolysiloxane in the silicone rubber is usually 150,000 or more, preferably 280,000 to 1,000,000, and particularly preferably 500,000 to 900,000.

[0042] The silicone resin is not particularly limited as long as it is a silicone resin used in silicone adhesives. For example, a silicone resin having the structural unit "R3Si 1 / 2 " M unit consisting of the structural unit "SiO2" Q unit consisting of the structural unit "RSiO 3 / 2and silicone resins made of organopolysiloxanes composed of (co)polymers having at least one unit selected from T units consisting of "R2SiO" and D units consisting of the structural unit "R2SiO". In the structural unit, R represents a hydrocarbon group or a hydroxyl group. Examples of the hydrocarbon group include aliphatic hydrocarbon groups (e.g., alkyl groups such as methyl and ethyl), alicyclic hydrocarbon groups (e.g., cycloalkyl groups such as cyclohexyl), and aromatic hydrocarbon groups (e.g., aryl groups such as phenyl and naphthyl). The ratio (ratio) of the M units to at least one unit selected from Q units, T units, and D units is preferably about 0.3 / 1 to 1.5 / 1 (preferably 0.5 / 1 to 1.3 / 1) by mole. Various functional groups, such as vinyl groups, may be introduced into the organopolysiloxane in such silicone resins, as necessary. The introduced functional group may be a functional group capable of undergoing a crosslinking reaction. The silicone resin is preferably an MQ resin composed of M units and Q units. The weight average molecular weight of the organopolysiloxane in the silicone resin is usually 1,000 or more, preferably 1,000 to 20,000, and particularly preferably 1,500 to 10,000.

[0043] The compounding ratio of silicone rubber to silicone resin is not particularly limited, but from the viewpoint of ease of control to achieve low adhesion and low tackiness, it is preferable that the silicone resin be 100 to 220 parts by weight (particularly 120 to 180 parts by weight) per 100 parts by weight of silicone rubber.

[0044] In a silicone-based pressure-sensitive adhesive containing silicone rubber and silicone resin, the silicone rubber and silicone resin may be in a mixed state in which they are simply mixed together, or may have reacted with each other to form a condensation product (particularly a partial condensation product), a crosslinked reaction product, an addition reaction product, etc.

[0045] Furthermore, silicone-based pressure-sensitive adhesives containing silicone rubber and silicone resin usually contain a crosslinking agent to form a crosslinked structure, which makes it easier to control low adhesion and low tack. Such crosslinking agents are not particularly limited, but siloxane-based crosslinking agents (silicone-based crosslinking agents) and peroxide-based crosslinking agents can be suitably used. The crosslinking agents can be used alone or in combination of two or more.

[0046] As the siloxane-based crosslinking agent, for example, a polyorganohydrogensiloxane having two or more hydrogen atoms bonded to silicon atoms in the molecule can be suitably used. In such polyorganohydrogensiloxane, various organic groups may be bonded to the silicon atoms bonded to hydrogen atoms in addition to the hydrogen atoms. Examples of the organic group include alkyl groups such as methyl groups and ethyl groups; aryl groups such as phenyl groups, and halogenated alkyl groups, but from the viewpoint of synthesis and handling, a methyl group is preferred. Furthermore, the skeletal structure of the polyorganohydrogensiloxane may be linear, branched, or cyclic, but a linear structure is preferred.

[0047] Examples of the peroxide-based crosslinking agent that can be used include diacyl peroxide, alkyl peroxy ester, peroxydicarbonate, monoperoxycarbonate, peroxyketal, dialkyl peroxide, hydroperoxide, ketone peroxide, etc. More specific examples include benzoyl peroxide, t-butyl peroxybenzoate, dicumyl peroxide, t-butylcumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di-t-butylperoxyhexane, 2,4-dichloro-benzoyl peroxide, di-t-butylperoxy-diisopropylbenzene, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, and 2,5-dimethyl-2,5-di-t-butylperoxyhexyne-3.

[0048] Examples of commercially available addition-type silicone-based pressure-sensitive adhesives include those under the trade names "KR-3700," "KR-3701," "X-40-3237-1," "X-40-3240," "X-40-3291-1," and "X-40-3306" (all manufactured by Shin-Etsu Chemical Co., Ltd.). Examples of commercially available peroxide-curing silicone-based pressure-sensitive adhesives include those under the trade names "KR-100," "KR-101-10," and "KR-130" (all manufactured by Shin-Etsu Chemical Co., Ltd.).

[0049] The addition-type silicone-based pressure-sensitive adhesive preferably contains a curing catalyst such as a platinum catalyst. Commercially available platinum catalysts include those under the trade name "CAT-PL-50T" (manufactured by Shin-Etsu Chemical Co., Ltd.), and those under the trade names "DOWSIL NC-25 Catalyst" and "DOWSIL SRX212 Catalyst" (all manufactured by Dow-Toray Industries, Inc.). From the viewpoint of achieving a balance between the first pressure-sensitive adhesive layer's ability to accept electronic components, positional accuracy, transferability to a mounting substrate, and tackiness, the content of the curing catalyst is preferably about 0.1 to 10 parts by weight per 100 parts by weight of the silicone-based polymer (including silicone rubber, silicone resin, etc.) serving as the base polymer.

[0050] (urethane adhesive) The urethane-based adhesive is not particularly limited, and any known or commonly used urethane-based adhesive can be used. A urethane-based adhesive containing a polyol, a polyfunctional isocyanate compound, and a catalyst is preferred because it is easy to control the adhesiveness and tackiness to be low.

[0051] As the polyol, any suitable polyol can be used as long as it has two or more hydroxyl groups. Examples of such polyols include polyols (diols) having two hydroxyl groups, polyols (triols) having three hydroxyl groups, polyols (tetraols) having four hydroxyl groups, polyols (pentaols) having five hydroxyl groups, and polyols (hexaols) having six hydroxyl groups. The polyols can be used alone or in combination of two or more.

[0052] The polyol preferably contains a polyol having a number average molecular weight (Mn) of 400 to 20,000. The content of the polyol having a number average molecular weight (Mn) of 400 to 20,000 in the total amount of polyol is preferably 50 to 100 wt%, more preferably 70 to 100 wt%, even more preferably 90 to 100 wt%, particularly preferably 95 to 100 wt%, and most preferably substantially 100 wt%. By adjusting the content of the polyol having a number average molecular weight (Mn) of 400 to 20,000 in the polyol within the above range, it is possible to provide, for example, a urethane-based pressure-sensitive adhesive with controlled low adhesion and low tackiness.

[0053] Examples of the polyol include polyester polyol, polyether polyol, polycaprolactone polyol, polycarbonate polyol, and castor oil polyol.

[0054] The polyester polyol can be obtained, for example, by an esterification reaction between a polyol component and an acid component.

[0055] Examples of the polyol component include ethylene glycol, diethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2-butyl-2-ethyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 1,8-decanediol, octadecanediol, glycerin, trimethylolpropane, pentaerythritol, hexanetriol, and polypropylene glycol.

[0056] Examples of the acid component include succinic acid, methylsuccinic acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, 1,12-dodecanedioic acid, 1,14-tetradecanedioic acid, dimer acid, 2-methyl-1,4-cyclohexanedicarboxylic acid, 2-ethyl-1,4-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, isophthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, and acid anhydrides thereof.

[0057] Examples of the polyether polyol include polyether polyols obtained by addition polymerization of alkylene oxides such as ethylene oxide, propylene oxide, and butylene oxide using as initiators water, low-molecular-weight polyols (propylene glycol, ethylene glycol, glycerin, trimethylolpropane, pentaerythritol, etc.), bisphenols (bisphenol A, etc.), dihydroxybenzenes (catechol, resorcinol, hydroquinone, etc.), etc. Specific examples include polyethylene glycol, polypropylene glycol, and polytetramethylene glycol.

[0058] Examples of the polycaprolactone polyol include caprolactone-based polyester diols obtained by ring-opening polymerization of cyclic ester monomers such as ε-caprolactone and σ-valerolactone.

[0059] Examples of the polycarbonate polyol include polycarbonate polyols obtained by polycondensation of the polyol components described above with phosgene; polycarbonate polyols obtained by transesterification of the polyol components described above with carbonate diesters such as dimethyl carbonate, diethyl carbonate, dipropyl carbonate, diisopropyl carbonate, dibutyl carbonate, ethylbutyl carbonate, ethylene carbonate, propylene carbonate, diphenyl carbonate, and dibenzyl carbonate; copolymer polycarbonate polyols obtained by combining two or more of the polyol components described above; polycarbonate polyols obtained by esterification of the various polycarbonate polyols described above with carboxyl group-containing compounds; and various polycarbonate polyols described above. Examples of the polycarbonate polyol include polycarbonate polyols obtained by etherifying polycarbonate polyols with hydroxyl group-containing compounds; polycarbonate polyols obtained by transesterifying the above-mentioned various polycarbonate polyols with ester compounds; polycarbonate polyols obtained by transesterifying the above-mentioned various polycarbonate polyols with hydroxyl group-containing compounds; polyester-based polycarbonate polyols obtained by polycondensation of the above-mentioned various polycarbonate polyols with dicarboxylic acid compounds; and copolymerized polyether-based polycarbonate polyols obtained by copolymerizing the above-mentioned various polycarbonate polyols with alkylene oxides.

[0060] Examples of the castor oil-based polyol include castor oil-based polyols obtained by reacting castor oil fatty acids with the polyol components.Specific examples include castor oil-based polyols obtained by reacting castor oil fatty acids with polypropylene glycol.

[0061] As the polyol, it is preferable to use a polyol (triol) having three hydroxyl groups as an essential component from the viewpoints of low adhesion, low tackiness, wettability, etc. of the first pressure-sensitive adhesive layer to electronic components. The content of the polyol (triol) having three hydroxyl groups is preferably 50 to 100 wt %, and more preferably 70 to 100 wt %, of the total amount of components constituting the polyol.

[0062] Examples of the polyfunctional isocyanate compound include aliphatic polyisocyanates, alicyclic polyisocyanates, and aromatic polyisocyanate compounds.

[0063] Examples of the aliphatic polyisocyanate include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate.

[0064] Examples of the alicyclic polyisocyanate include 1,3-cyclopentene diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated tolylene diisocyanate, and hydrogenated tetramethylxylylene diisocyanate.

[0065] Examples of the aromatic polyisocyanate include phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 2,2'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-toluidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, and xylylene diisocyanate.

[0066] Among these, aliphatic polyisocyanates and their modified products are preferred. Compared with other isocyanate-based crosslinking agents, aliphatic polyisocyanates and their modified products have a highly flexible crosslinked structure, and are easy to control to have low adhesiveness and low tackiness. As the aliphatic polyisocyanates and their modified products, hexamethylene diisocyanate and its modified products are particularly preferred.

[0067] From the viewpoint of low adhesion, low tackiness, and wettability of the first pressure-sensitive adhesive layer to electronic components, the polyfunctional isocyanate compound and the polyol preferably have an equivalent ratio (NCO / OH) of the isocyanate groups of the polyfunctional isocyanate compound to the hydroxyl groups of the polyol of 1 to 5, more preferably 1.1 to 3, and even more preferably 1.2 to 2.

[0068] The urethane-based adhesive preferably contains a catalyst such as an iron-based compound and / or a tin-based compound. Specifically, tin-based catalysts such as dibutyltin dilaurate and dioctyltin dilaurate, iron tris(acetylacetonate), iron tris(hexane-2,4-dionato), iron tris(heptane-2,4-dionato), iron tris(heptane-3,5-dionato), iron tris(5-methylhexane-2,4-dionato), iron tris(octane-2,4-dionato), iron tris(6-methylheptane-2,5 ... ,4-dionato)iron, tris(2,6-dimethylheptane-3,5-dionato)iron, tris(nonane-2,4-dionato)iron, tris(nonane-4,6-dionato)iron, tris(2,2,6,6-tetramethylheptane-3,5-dionato)iron, tris(tridecane-6,8-dionato)iron, tris(1-phenylbutane-1,3-dionato)iron, tris(hexafluoroacetylacetonate) ) iron, tris(ethyl acetoacetate) iron, tris(acetoacetate-n-propyl) iron, tris(isopropyl acetoacetate) iron, tris(acetoacetate-n-butyl) iron, tris(acetoacetate-sec-butyl) iron, tris(acetoacetate-tert-butyl) iron, tris(methyl propionylacetate) iron, tris(ethyl propionylacetate) iron, tris(propionylacetate-n-propyl) iron, tris(isopropyl propionylacetate) iron, tris(propionylacetate-n-butyl) iron, tris(propionylacetate-sec-butyl) iron, tris(propionylacetate-tert-butyl) iron, tris(benzyl acetoacetate) iron, tris(dimethyl malonate) iron, tris(diethyl malonate) iron, trimethoxy iron, triethoxy iron, triisopropoxy iron, and ferric chloride are examples of iron-based catalysts.

[0069] The content (amount used) of the catalyst contained in the urethane-based pressure-sensitive adhesive is preferably 0.002 to 0.5 parts by weight, more preferably 0.005 to 0.3 parts by weight, and even more preferably 0.01 to 0.1 parts by weight, relative to 100 parts by weight of the polyol. Within this range, the rate of the crosslinking reaction when the pressure-sensitive adhesive layer is formed is fast, and the pot life of the pressure-sensitive adhesive composition is also long, which is a preferred embodiment.

[0070] As the urethane-based adhesive, a urethane-based adhesive containing a urethane prepolymer is also preferred because it is easy to control the adhesiveness and tackiness to be low.

[0071] Examples of urethane-based adhesives containing urethane prepolymers include adhesives containing polyurethane polyol as the urethane prepolymer and a polyfunctional isocyanate compound. The urethane prepolymers can be used alone or in combination of two or more. The polyfunctional isocyanate compounds can be used alone or in combination of two or more.

[0072] The polyurethane polyol as the urethane prepolymer is preferably obtained by reacting a polyester polyol and a polyether polyol with an organic polyisocyanate compound in the presence or absence of a catalyst.

[0073] Any suitable polyester polyol can be used as the polyester polyol. Examples of such polyester polyols include polyester polyols obtained by reacting an acid component with a glycol component. Examples of acid components include terephthalic acid, adipic acid, azelaic acid, sebacic acid, phthalic anhydride, isophthalic acid, and trimellitic acid. Examples of glycol components include ethylene glycol, propylene glycol, diethylene glycol, butylene glycol, 1,6-hexane glycol, 3-methyl-1,5-pentanediol, 3,3'-dimethylolheptane, polyoxyethylene glycol, polyoxypropylene glycol, 1,4-butanediol, neopentyl glycol, and butylethylpentanediol. Examples of polyol components include glycerin, trimethylolpropane, and pentaerythritol. Other examples of polyester polyols include polyester polyols obtained by ring-opening polymerization of lactones such as polycaprolactone, poly(β-methyl-γ-valerolactone), and polyvalerolactone.

[0074] The molecular weight of the polyester polyol can range from low to high. The molecular weight of the polyester polyol is preferably a number average molecular weight of 500 to 5,000. If the number average molecular weight is less than 500, the reactivity may be high and gelation may occur easily. If the number average molecular weight exceeds 5,000, the reactivity may be low and the cohesive force of the polyurethane polyol itself may be reduced. The amount of polyester polyol used is preferably 10 to 90 mol % of the polyol constituting the polyurethane polyol.

[0075] Any suitable polyether polyol can be used as the polyether polyol. Examples of such polyether polyols include polyether polyols obtained by polymerizing oxirane compounds such as ethylene oxide, propylene oxide, butylene oxide, and tetrahydrofuran using low-molecular-weight polyols such as water, propylene glycol, ethylene glycol, glycerin, and trimethylolpropane as initiators. Specific examples of such polyether polyols include polyether polyols having two or more functional groups, such as polypropylene glycol, polyethylene glycol, and polytetramethylene glycol.

[0076] The molecular weight of the polyether polyol can range from low to high. The number average molecular weight of the polyether polyol is preferably 1,000 to 5,000. If the number average molecular weight is less than 1,000, the reactivity may be high and gelation may occur easily. If the number average molecular weight exceeds 5,000, the reactivity may be low and the cohesive force of the polyurethane polyol itself may be reduced. The amount of polyether polyol used is preferably 20 to 80 mol % of the polyol constituting the polyurethane polyol.

[0077] If necessary, a portion of the polyether polyol can be replaced with glycols such as ethylene glycol, 1,4-butanediol, neopentyl glycol, butylethylpentanediol, glycerin, trimethylolpropane, and pentaerythritol, or polyamines such as ethylenediamine, N-aminoethylethanolamine, isophoronediamine, and xylylenediamine, and used in combination.

[0078] The polyether polyol may be a bifunctional polyether polyol alone, or a polyether polyol having a number-average molecular weight of 1000 to 5000 and at least three hydroxyl groups per molecule may be used in part or in whole. Using a polyether polyol having an average molecular weight of 1000 to 5000 and at least three hydroxyl groups per molecule in part or in whole can improve the balance between adhesive strength and removability. If the number-average molecular weight of such polyether polyol is less than 1000, the reactivity may be high and gelation may occur easily. If the number-average molecular weight of such polyether polyol is more than 5000, the reactivity may decrease and the cohesive strength of the polyurethane polyol itself may become weak. The number-average molecular weight of such polyether polyol is more preferably 2500 to 3500.

[0079] Any appropriate organic polyisocyanate compound can be used as the organic polyisocyanate compound, such as aromatic polyisocyanates, aliphatic polyisocyanates, araliphatic polyisocyanates, and alicyclic polyisocyanates.

[0080] Examples of aromatic polyisocyanates include 1,3-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,4-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-toluidine diisocyanate, 2,4,6-triisocyanate toluene, 1,3,5-triisocyanate benzene, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate, and 4,4',4"-triphenylmethane triisocyanate.

[0081] Examples of aliphatic polyisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate.

[0082] Examples of the aromatic aliphatic polyisocyanate include ω,ω'-diisocyanate-1,3-dimethylbenzene, ω,ω'-diisocyanate-1,4-dimethylbenzene, ω,ω'-diisocyanate-1,4-diethylbenzene, 1,4-tetramethylxylylene diisocyanate, and 1,3-tetramethylxylylene diisocyanate.

[0083] Examples of alicyclic polyisocyanates include 3-isocyanatemethyl-3,5,5-trimethylcyclohexyl isocyanate, 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), 1,4-bis(isocyanatemethyl)cyclohexane, and 1,4-bis(isocyanatemethyl)cyclohexane.

[0084] As the organic polyisocyanate compound, a trimethylolpropane adduct, a biuret reacted with water, a trimer having an isocyanurate ring, etc. can also be used in combination.

[0085] Any suitable catalyst can be used to obtain the polyurethane polyol, such as a tertiary amine compound or an organometallic compound.

[0086] Examples of tertiary amine compounds include triethylamine, triethylenediamine, and 1,8-diazabicyclo(5,4,0)-undecene-7 (DBU).

[0087] Examples of organometallic compounds include tin-based compounds and non-tin-based compounds.

[0088] Examples of tin compounds include dibutyltin dichloride, dibutyltin oxide, dibutyltin dibromide, dibutyltin dimaleate, dibutyltin dilaurate (DBTDL), dibutyltin diacetate, dibutyltin sulfide, tributyltin sulfide, tributyltin oxide, tributyltin acetate, triethyltin ethoxide, tributyltin ethoxide, dioctyltin oxide, tributyltin chloride, tributyltin trichloroacetate, and tin 2-ethylhexanoate.

[0089] Examples of non-tin compounds include titanium compounds such as dibutyltitanium dichloride, tetrabutyltitanium, and butoxytitanium trichloride; lead compounds such as lead oleate, lead 2-ethylhexanoate, lead benzoate, and lead naphthenate; iron compounds such as iron 2-ethylhexanoate and iron acetylacetonate; cobalt compounds such as cobalt benzoate and cobalt 2-ethylhexanoate; zinc compounds such as zinc naphthenate and zinc 2-ethylhexanoate; and zirconium compounds such as zirconium naphthenate.

[0090] When a catalyst is used to obtain polyurethane polyol, in a system containing two types of polyols, polyester polyol and polyether polyol, problems such as gelation and cloudiness of the reaction solution can easily occur in a system using a single catalyst due to the difference in reactivity between the two polyols. Therefore, by using two types of catalysts to obtain polyurethane polyol, it becomes easier to control the reaction rate, catalyst selectivity, etc., thereby solving these problems. Examples of such combinations of two types of catalysts include tertiary amine / organometallic, tin / non-tin, and tin / tin. Tin / tin combinations are preferred, and a combination of dibutyltin dilaurate and tin 2-ethylhexanoate is more preferred. The weight ratio of tin 2-ethylhexanoate / dibutyltin dilaurate is preferably less than 1, more preferably 0.2 to 0.6. A combination ratio of 1 or more may result in gelation due to the balance of catalytic activity.

[0091] When a catalyst is used in obtaining the polyurethane polyol, the amount of the catalyst used is preferably 0.01 to 1.0% by weight based on the total amount of the polyester polyol, polyether polyol, and organic polyisocyanate compound.

[0092] When a catalyst is used to obtain a polyurethane polyol, the reaction temperature is preferably less than 100° C., and more preferably 85 to 95° C. If the temperature is 100° C. or higher, it may become difficult to control the reaction rate and crosslinked structure, and it may become difficult to obtain a polyurethane polyol having a predetermined molecular weight.

[0093] When obtaining polyurethane polyol, it is not necessary to use a catalyst. In that case, the reaction temperature is preferably 100° C. or higher, more preferably 110° C. or higher. When obtaining polyurethane polyol without a catalyst, the reaction is preferably carried out for 3 hours or longer.

[0094] Methods for obtaining polyurethane polyol include, for example, 1) a method in which a polyester polyol, a polyether polyol, a catalyst, and an organic polyisocyanate are all charged into a volumetric flask, and 2) a method in which a polyester polyol, a polyether polyol, and a catalyst are charged into a flask and an organic polyisocyanate is added dropwise. Method 2) is preferred as a method for obtaining polyurethane polyol in terms of controlling the reaction.

[0095] Any suitable solvent may be used to obtain the polyurethane polyol. Examples of such solvents include methyl ethyl ketone, ethyl acetate, toluene, xylene, and acetone. Among these solvents, toluene is preferred.

[0096] As the polyfunctional isocyanate compound, those mentioned above can be used.

[0097] As a method for producing a polyurethane-based composition obtained from a composition containing a urethane prepolymer, any appropriate production method can be adopted as long as it is a method for producing a polyurethane-based resin composition using a so-called "urethane prepolymer" as a raw material.

[0098] (acrylic adhesive) The acrylic pressure-sensitive adhesive is not particularly limited, and any known or commonly used acrylic pressure-sensitive adhesive can be used. For example, an acrylic pressure-sensitive adhesive containing an acrylic polymer as a base polymer is preferred because it is easy to control the adhesiveness and tackiness to be low.

[0099] The acrylic polymer is a polymer containing, as a structural unit of the polymer, a structural unit derived from an acrylic monomer (a monomer component having a (meth)acryloyl group in the molecule). The acrylic polymer is preferably a polymer containing a structural unit derived from a (meth)acrylic acid ester in the largest amount by mass. The acrylic polymer may be used alone or in combination of two or more kinds. In addition, in this specification, "(meth)acrylic" represents "acrylic" and / or "methacrylic" (either one or both of "acrylic" and "methacrylic"), and the same applies to others.

[0100] Examples of the (meth)acrylic acid ester include hydrocarbon group-containing (meth)acrylic acid esters. Examples of the hydrocarbon group-containing (meth)acrylic acid ester include (meth)acrylic acid alkyl esters, (meth)acrylic acid cycloalkyl esters, and (meth)acrylic acid aryl esters. Examples of the (meth)acrylic acid alkyl esters include the methyl ester, ethyl ester, propyl ester, isopropyl ester, butyl ester, isobutyl ester, s-butyl ester, t-butyl ester, pentyl ester, isopentyl ester, hexyl ester, heptyl ester, octyl ester, 2-ethylhexyl ester, isooctyl ester, nonyl ester, decyl ester, isodecyl ester, undecyl ester, dodecyl ester (lauryl ester), tridecyl ester, tetradecyl ester, hexadecyl ester, octadecyl ester, and eicosyl ester of (meth)acrylic acid. Examples of the (meth)acrylic acid cycloalkyl ester include the cyclopentyl ester and cyclohexyl ester of (meth)acrylic acid. Examples of the (meth)acrylic acid aryl ester include phenyl ester and benzyl ester of (meth)acrylic acid.

[0101] The hydrocarbon group-containing (meth)acrylic esters can be used alone or in combination of two or more. In order to appropriately exhibit the basic properties of the hydrocarbon group-containing (meth)acrylic esters, such as adhesion, in the first adhesive layer and to easily control low adhesion and low tackiness, the proportion of the hydrocarbon group-containing (meth)acrylic esters in all monomer components for forming the acrylic polymer is preferably 40% by mass or more, and more preferably 60% by mass or more.

[0102] The acrylic polymer may contain structural units derived from other monomer components copolymerizable with the hydrocarbon group-containing (meth)acrylic acid ester for the purpose of improving properties such as cohesive strength, heat resistance, adhesiveness, and tackiness. Examples of such other monomer components include carboxy group-containing monomers, acid anhydride monomers, hydroxy group-containing monomers, glycidyl group-containing monomers, sulfonic acid group-containing monomers, phosphate group-containing monomers, functional group-containing monomers such as acrylamide and acrylonitrile, and vinyl ester monomers. Examples of the carboxy group-containing monomers include acrylic acid, methacrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. Examples of the acid anhydride monomers include maleic anhydride and itaconic anhydride. Examples of the hydroxy group-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)methyl (meth)acrylate. Examples of the glycidyl group-containing monomer include glycidyl (meth)acrylate and methylglycidyl (meth)acrylate. Examples of the sulfonic acid group-containing monomer include styrene sulfonic acid, allyl sulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid. Examples of the phosphate group-containing monomer include 2-hydroxyethyl acryloyl phosphate. Examples of the vinyl ester monomer include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl cyclohexanecarboxylate, and vinyl benzoate. The other monomer components can be used alone or in combination of two or more.In order to properly express the basic properties such as adhesion of the hydrocarbon group-containing (meth)acrylic acid ester in the first adhesive layer and to easily control low adhesion and low tackiness, the total proportion of the above-mentioned other monomer components in all monomer components for forming the acrylic polymer is preferably 60 mass% or less, and more preferably 40 mass% or less.

[0103] The acrylic polymer may contain a structural unit derived from a polyfunctional monomer copolymerizable with the monomer components forming the acrylic polymer to form a crosslinked structure in the polymer backbone. Examples of the polyfunctional monomer include 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(meth)acrylate (e.g., polyglycidyl(meth)acrylate), polyester(meth)acrylate, and urethane(meth)acrylate, which contain a (meth)acryloyl group and other reactive functional groups in the molecule. The polyfunctional monomers may be used alone or in combination of two or more. In order to properly express the basic properties such as adhesion of the hydrocarbon group-containing (meth)acrylic acid ester in the first adhesive layer and to easily control low adhesion and low tackiness, the proportion of the above-mentioned polyfunctional monomer in all monomer components for forming the acrylic polymer is preferably 40 mass% or less, and more preferably 30 mass% or less.

[0104] Acrylic polymers can be obtained by polymerizing one or more monomer components including an acrylic monomer, using methods such as solution polymerization, emulsion polymerization, bulk polymerization, and suspension polymerization.

[0105] The mass average molecular weight of the acrylic polymer is preferably 100,000 or more, more preferably 200,000 to 3,000,000. When the mass average molecular weight is 100,000 or more, the amount of low molecular weight substances in the pressure-sensitive adhesive layer tends to be small, and contamination of electronic components and the like can be further suppressed.

[0106] The acrylic pressure-sensitive adhesive composition forming the first pressure-sensitive adhesive layer may contain a crosslinking agent. For example, by crosslinking the acrylic polymer, the amount of low-molecular-weight substances in the first pressure-sensitive adhesive layer can be further reduced. In addition, by increasing the weight-average molecular weight of the acrylic polymer, low adhesion and low tackiness can be controlled. Examples of the crosslinking agent include polyisocyanate compounds, epoxy compounds, polyol compounds (such as polyphenol compounds), aziridine compounds, and melamine compounds, with isocyanate-based crosslinking agents and / or epoxy-based crosslinking agents being preferred. When a crosslinking agent is used, the amount used is preferably about 10 parts by mass or less, more preferably 0.1 to 10 parts by mass, per 100 parts by mass of the acrylic polymer.

[0107] Examples of isocyanate crosslinking agents include aliphatic isocyanates, alicyclic isocyanates, and aromatic isocyanates. Examples of aliphatic isocyanates include trimethylene diisocyanate, butylene diisocyanate, hexamethylene diisocyanate, and dimer acid diisocyanate. Examples of alicyclic isocyanates include cyclopentylene diisocyanate, cyclohexylene diisocyanate, isophorone diisocyanate, and 1,3-bis(isocyanatomethyl)cyclohexane. Examples of aromatic isocyanates include 2,4-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and xylylene diisocyanate. Further, examples of the isocyanate crosslinking agent include a trimethylolpropane adduct of tolylene diisocyanate (trade name "Coronate L", manufactured by Tosoh Corporation) and an isocyanurate of hexamethylene diisocyanate (trade name "Coronate HX", manufactured by Tosoh Corporation).

[0108] Examples of epoxy crosslinking agents (polyfunctional epoxy compounds) include N,N,N',N'-tetraglycidyl-m-xylylenediamine, diglycidylaniline, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and sorbitol polyglycidyl ether. Examples of the epoxy crosslinking agent include glycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitan polyglycidyl ether, trimethylolpropane polyglycidyl ether, adipic acid diglycidyl ester, o-phthalic acid diglycidyl ester, triglycidyl-tris(2-hydroxyethyl)isocyanurate, resorcinol diglycidyl ether, and bisphenol-S-diglycidyl ether. Also included are epoxy resins having two or more epoxy groups in the molecule. An example of a commercially available epoxy crosslinking agent is "Tetrad C" manufactured by Mitsubishi Gas Chemical Company, Inc.

[0109] The adhesive composition constituting the first adhesive layer preferably contains a light release agent, which forms a weak boundary layer (WBL) on the surface of the first adhesive layer, making it easier to control the adhesiveness and tackiness.

[0110] The light release agent is not particularly limited, and known light release agents can be used without limitation. Examples include silicone-based release agents, fluorine-based surfactants, and aliphatic esters, which can be used alone or in combination of two or more.

[0111] The silicone-based release agent is not particularly limited, but examples thereof include heat-curable silicone-based release agents and ionizing radiation-curable silicone-based release agents. The silicone-based release agent may be either a solvent-free type that does not contain a solvent, or a solvent-based type that is dissolved or dispersed in an organic solvent. The silicone-based release agents may be used alone or in combination of two or more.

[0112] The thermosetting silicone release agent is not particularly limited, but is preferably one containing an organohydrogenpolysiloxane and an organopolysiloxane having an aliphatic unsaturated group. Furthermore, the silicone release agent is preferably a thermoaddition reaction-curable silicone release agent that cures by crosslinking caused by a thermal addition reaction.

[0113] The thermal addition reaction curable silicone release agent is not particularly limited, but a preferred example is a release agent containing a polysiloxane having a hydrogen atom (H) bonded to a silicon atom (Si) in the molecule (Si-H group-containing polysiloxane) and a polysiloxane containing a functional group (Si-H group-reactive functional group) in the molecule that is reactive with an Si-H bond (covalent bond between Si and H) (Si-H group-reactive polysiloxane). Note that this release agent cures by crosslinking caused by an addition reaction between the Si-H group and the Si-H group-reactive functional group.

[0114] In the Si-H group-containing polysiloxane, the Si bonded to H may be either Si in the main chain or Si in the side chain. The Si-H group-containing polysiloxane is preferably a polysiloxane containing two or more Si-H groups in the molecule. Preferred examples of polysiloxanes containing two or more Si-H groups include dimethylhydrogensiloxane polymers such as poly(dimethylsiloxane-methylsiloxane).

[0115] Furthermore, preferred examples of the Si-H group-reactive polysiloxane include polysiloxanes in which an Si-H group-reactive functional group or a side chain containing such a functional group is bonded to Si (e.g., Si at the terminal of the main chain, Si within the main chain) that forms the main chain (skeleton) of the siloxane-based polymer. Among these, polysiloxanes in which the Si-H group-reactive functional group is directly bonded to Si in the main chain are preferred. Furthermore, preferred examples of the Si-H group-reactive polysiloxane include polysiloxanes containing two or more Si-H group-reactive functional groups in the molecule.

[0116] Examples of the Si-H group-reactive functional group in the Si-H group-reactive polysiloxane include alkenyl groups such as vinyl and hexenyl. Examples of the siloxane-based polymer forming the main chain portion of the Si-H group-reactive polysiloxane include polydialkylsiloxanes (wherein the two alkyl groups may be the same or different) such as polydimethylsiloxane, polydiethylsiloxane, and polymethylethylsiloxane; polyalkylarylsiloxanes; poly(dimethylsiloxane / methylsiloxane); and polymers obtained by polymerizing multiple Si-containing monomers. Among these, polydimethylsiloxane is preferred as the siloxane-based polymer forming the main chain portion.

[0117] In particular, the thermal addition reaction curable silicone release agent is preferably a thermal addition reaction curable silicone release agent that contains a polysiloxane containing two or more Si-H groups in the molecule and a polysiloxane containing two or more Si-H group reactive functional groups in the molecule.

[0118] The ionizing radiation curable silicone-based release agent is not particularly limited, but a preferred example is a UV-curable silicone-based release agent that undergoes a crosslinking reaction upon exposure to ultraviolet (UV) light and is cured.

[0119] The UV-curable silicone-based release agent is a release agent that cures by UV irradiation through a chemical reaction such as cationic polymerization, radical polymerization, radical addition polymerization, hydrosilylation reaction, etc. Of the UV-curable silicone-based release agents, UV-curable silicone-based release agents that cure through cationic polymerization are particularly preferred.

[0120] The cationic polymerization type UV-curable silicone release agent is not particularly limited, but preferred examples include release agents containing an epoxy group-containing polysiloxane in which at least two epoxy groups are bonded directly or via a divalent group (e.g., alkylene groups such as methylene and ethylene; alkyleneoxy groups such as ethyleneoxy and propyleneoxy) to Si atoms forming the main chain (skeleton) of the siloxane polymer (e.g., Si atoms at the terminals of the main chain, Si atoms within the main chain) and / or Si atoms contained in the side chains. The bonding modes of these at least two epoxy groups to the Si atoms may be the same or different. That is, preferred examples include release agents containing polysiloxanes containing two or more types of epoxy group-containing side chains. Examples of epoxy group-containing side chains include glycidyl groups, glycidoxy groups (glycidyloxy groups), 3,4-epoxycyclohexyl groups, and 2,3-epoxycyclopentyl groups. The epoxy group-containing polysiloxane may be linear, branched, or a mixture thereof.

[0121] In particular, in the double-sided adhesive tape for transfer of the present invention, from the viewpoint of making it easier to control the first adhesive layer to have low adhesion and low tackiness, it is preferable that the silicone-based adhesive contain a heat-curable silicone-based release agent, and it is even more preferable that it contain a thermal addition reaction-curable silicone-based release agent.

[0122] When the first pressure-sensitive adhesive layer in the double-sided pressure-sensitive adhesive tape for transfer of the present invention contains a silicone-based pressure-sensitive adhesive, the content of the silicone-based release agent is not particularly limited, but is preferably 0.5 parts by weight or more and 100 parts by weight or less per 100 parts by weight of the silicone-based polymer base polymer. When the content is 0.5 parts by weight or more, the effect of easily controlling the first pressure-sensitive adhesive layer to have low adhesion and low tackiness is easily achieved, more preferably 1 part by weight or more, and even more preferably 3 parts by weight or more. When the content is 100 parts by weight or less, the problem of insufficient adhesion being obtained and making it difficult to receive electronic components is easily suppressed, more preferably 30 parts by weight or less, and even more preferably 25 parts by weight or less.

[0123] By using the above fluorine-based surfactant as an easy release agent, it is possible to exert an easy release effect due to the low surface free energy of the fluorine moiety.

[0124] The above-mentioned fluorine-based surfactant is not particularly limited, but can be exemplified by fluorine-based oligomer, perfluorobutane sulfonate, perfluoroalkyl group-containing carboxylate, hexafluoropentane trimer derivative-containing sulfonate, hexafluoropentane trimer derivative-containing carboxylate, hexafluoropentane trimer derivative-containing quaternary ammonium salt, hexafluoropentane trimer derivative-containing betaine, hexafluoropentane trimer derivative-containing polyoxyethylene ether, etc., and among them, fluorine-based oligomer is preferred.It should be noted that the fluorine-based surfactant can be used alone or in combination of two or more kinds.

[0125] Specific examples of the fluorine-based surfactant include, for example, commercially available products under the trade names "Megafac F-114" and "Megafac F-410" (both manufactured by DIC Corporation), product names "Surflon S-211", "Surflon S-221", "Surflon S-231", "Surflon S-232", "Surflon S-233", "Surflon S-241", "Surflon S-242", "Surflon S-243", and "Surflon S-420" (all manufactured by AGC Seimi Chemical Co., Ltd.), product names "Ftergent 100", "Ftergent 100C", "Ftergent 110", "Ftergent 150", "Ftergent 150CH", "Ftergent 300", and "Ftergent Examples of suitable compounds include Ftergent 310, Ftergent 320, Ftergent 400SW, Ftergent 251, Ftergent 212M, Ftergent 215M, Ftergent 250, Ftergent 209F, Ftergent 222F, Ftergent 245F, Ftergent 208G, Ftergent 218GL, Ftergent 240G, Ftergent 212P, Ftergent 220P, Ftergent 228P, Ftergent FTX-218, and Ftergent DFX-18 (all manufactured by Neos Corporation). These compounds may be used alone or in combination of two or more.

[0126] The weight-average molecular weight (Mw) of the fluorine-based oligomer is preferably 3,500 or more, more preferably 5,000 or more, even more preferably 10,000 or more, and particularly preferably 20,000 or more. When the weight-average molecular weight of the fluorine-based oligomer is 3,500 or more, it is easy to control the adhesiveness and tackiness. Furthermore, when the weight-average molecular weight is 20,000 or more, foaming during blending of the adhesive (composition) can be suppressed, resulting in excellent appearance after application of the adhesive, which is preferable. Furthermore, the upper limit of the weight-average molecular weight (Mw) of the fluorine-based oligomer is preferably 200,000, more preferably 100,000 or less. By setting the upper limit to 200,000, the fluorine-based oligomer is more likely to be unevenly distributed on the surface, making it easier to exhibit an easy release effect, which is preferable.

[0127] Furthermore, examples of the fluorine-based oligomer include commercially available products under the trade names "Megafac F-251", "Megafac F-253", "Megafac F-281", "Megafac F-410", "Megafac F-430", "Megafac F-444", "Megafac F-477", "Megafac F-510", "Megafac F-511", "Megafac F-551", "Megafac F-552", "Megafac F-553", "Megafac F-554", "Megafac F-555", "Megafac F-556", "Megafac F-557", "Megafac F-558", "Megafac F-559", "Megafac F-560", "Megafac F-561", and "Megafac F-562". Examples of such compounds include "Megafac F-562," "Megafac F-563," "Megafac F-565," "Megafac F-568," "Megafac F-569," "Megafac F-570," "Megafac F-571," and "Megafac F-572" (all manufactured by DIC Corporation), trade names "Surflon S-611," "Surflon S-651," and "Surflon S-386" (all manufactured by AGC Seimi Chemical Co., Ltd.), and trade names "Ftergent 610FM," "Ftergent 710FL," "Ftergent 710FM," "Ftergent 710FS," "Ftergent 730FL," and "Ftergent 730LM" (all manufactured by Neos Corporation). These compounds may be used alone or in combination of two or more.

[0128] When the first pressure-sensitive adhesive layer of the double-sided pressure-sensitive adhesive tape for transfer of the present invention contains a fluororesin surfactant, the content of the fluororesin surfactant is not particularly limited, but is preferably 0.01 to 5 parts by weight per 100 parts by weight of the silicone polymer base polymer. A content of 0.01 parts by weight or more facilitates the effect of easily controlling the first pressure-sensitive adhesive layer to have low adhesion and low tackiness, and is more preferably 0.05 parts by weight or more, and even more preferably 0.1 parts by weight or more. Furthermore, a content of 5 parts by weight or less facilitates the suppression of problems such as insufficient adhesion and difficulty in receiving electronic components, and from the viewpoint of suppressing a decrease in transparency, is more preferably 3 parts by weight or less, and even more preferably 2 parts by weight or less.

[0129] When the pressure-sensitive adhesive composition constituting the first pressure-sensitive adhesive layer contains a fatty acid ester, the first pressure-sensitive adhesive layer body can be expected to have low adhesion, low tackiness, and wettability to electronic components.

[0130] Examples of the fatty acid esters include polyoxyethylene bisphenol A laurate, butyl stearate, 2-ethylhexyl palmitate, 2-ethylhexyl stearate, behenic acid monoglyceride, cetyl 2-ethylhexanoate, isopropyl myristate, isopropyl palmitate, cholesteryl isostearate, lauryl methacrylate, coconut fatty acid methyl ester, methyl laurate, methyl oleate, methyl stearate, myristyl myristate, octyldodecyl myristate, pentaerythritol monooleate, pentaerythritol monostearate, pentaerythritol tetrapalmitate, stearyl stearate, isotridecyl stearate, 2-ethylhexanoic acid triglyceride, butyl laurate, octyl oleate, and tridecyl isononanoate. The fatty acid esters can be used alone or in combination of two or more.

[0131] The content of the fatty acid ester contained in the above urethane-based pressure-sensitive adhesive composition is, for example, preferably 1 to 50 parts by weight, more preferably 2 to 40 parts by weight, and even more preferably 3 to 30 parts by weight, per 100 parts by weight of polyol, from the viewpoints of low adhesion, low tack, and wettability of the first pressure-sensitive adhesive layer to electronic components and contamination of the adherend.

[0132] When the pressure-sensitive adhesive composition constituting the first pressure-sensitive adhesive layer contains an easy-release agent, the content (total amount) thereof is, for example, preferably 0.1 parts by weight or more, more preferably 1 part by weight or more, and even more preferably 3 parts by weight or more, relative to 100 parts by weight of the base polymer, from the viewpoints of low adhesion, low tack, wettability, and contamination prevention of the first pressure-sensitive adhesive layer to electronic components. From the viewpoint of preventing discoloration of the first pressure-sensitive adhesive layer, the content is preferably 50 parts by weight or less, more preferably 30 parts by weight or less, and even more preferably 10 parts by weight or less.

[0133] The ultraviolet absorber is not particularly limited, but examples thereof include triazine-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, oxybenzophenone-based ultraviolet absorbers, salicylic acid ester-based ultraviolet absorbers, cyanoacrylate-based ultraviolet absorbers, etc., which can be used alone or in combination of two or more. Among these, benzotriazole-based ultraviolet absorbers and triazine-based ultraviolet absorbers are preferred from the viewpoint of their high ultraviolet absorption ability at a wavelength of around 250 nm.

[0134] Specific examples of triazine-based ultraviolet absorbers having two or less hydroxyl groups in one molecule include 2,4-bis-[{4-(4-ethylhexyloxy)-4-hydroxy}-phenyl]-6-(4-methoxyphenyl)-1,3,5-triazine (trade name "Tinosorb S", 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-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl)-5-hydroxyphenyl and [(C 10 -C16 (Mainly C 12 -C 13 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine-2-yl]-5-[3-(dodecyloxy)-2-hydroxypropoxy]phenol), 2-(2,4-dihydroxyphenyl)-4,6-bis-(2,4-dimethylphenyl)-1,3,5-triazine and (2-ethylhexyloxy)methyl]oxirane (trade name "TINUVIN400", manufactured by BASF), 2-[4,6-bis ... Examples of suitable esters include a reaction product of 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[(hexyl)oxy]-glycidic acid ester (trade name "TINUVIN 405", 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 LA46", manufactured by ADEKA), and 2-(2-hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine (trade name "TINUVIN 479", manufactured by BASF).

[0135] Furthermore, examples of benzotriazole-based ultraviolet absorbers having one benzotriazole skeleton per molecule include 2-(2H-benzotriazol-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol (trade name "TINUVIN 928" manufactured by BASF), 2-(2-hydroxy-5-tert-butylphenyl)-2H-benzotriazole (trade name "TINUVIN PS" manufactured by BASF), benzenepropanoic acid and 3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)-4-hydroxy(C 7-9ester compound of 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (trade name "TINUVIN 900" manufactured by BASF), 2-(2H-benzotriazol-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol (trade name "TINUVIN 928" manufactured by BASF), reaction product of methyl-3-(3-(2H-benzotriazol-2-yl)-5-t-butyl-4-hydroxyphenyl)propionate / polyethylene glycol 300 (trade name "TINUVIN 1130" manufactured by BASF), 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 "TIN Examples of suitable hydroxybenzoates include methyl 3-(3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl)propionate and polyethylene glycol 300 reaction products (trade name "TINUVIN213" manufactured by BASF), 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol (trade name "TINUVIN571" manufactured by BASF), and 2-[2-hydroxy-3-(3,4,5,6-tetrahydrophthalimido-methyl)-5-methylphenyl]benzotriazole (trade name "Sumisorb250" manufactured by Sumitomo Chemical Co., Ltd.).

[0136] Furthermore, examples of the benzophenone-based ultraviolet absorbers (benzophenone-based compounds) and oxybenzophenone-based ultraviolet absorbers (oxybenzophenone-based compounds) include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid (anhydrous and trihydrate), 2-hydroxy-4-octyloxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, 4-benzyloxy-2-hydroxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, and 2,2'-dihydroxy-4,4-dimethoxybenzophenone.

[0137] Examples of the salicylate ester-based ultraviolet absorbers (salicylate ester-based compounds) include phenyl-2-acryloyloxybenzoate, phenyl-2-acryloyloxy-3-methylbenzoate, phenyl-2-acryloyloxy-4-methylbenzoate, phenyl-2-acryloyloxy-5-methylbenzoate, phenyl-2-acryloyloxy-3-methoxybenzoate, phenyl-2-hydroxybenzoate, phenyl-2-hydroxy-3-methylbenzoate, phenyl-2-hydroxy-4-methylbenzoate, phenyl-2-hydroxy-5-methylbenzoate, phenyl 2-hydroxy-3-methoxybenzoate, and 2,4-di-tert-butylphenyl-3,5-di-tert-butyl-4-hydroxybenzoate (trade name "TINUVIN120", manufactured by BASF).

[0138] Examples of the cyanoacrylate ultraviolet absorber (cyanoacrylate compound) include alkyl-2-cyanoacrylate, cycloalkyl-2-cyanoacrylate, alkoxyalkyl-2-cyanoacrylate, alkenyl-2-cyanoacrylate, and alkynyl-2-cyanoacrylate.

[0139] The above ultraviolet absorbents may be used alone or in combination of two or more.

[0140] The maximum absorption wavelength of the absorption spectrum of the ultraviolet absorber is preferably in the wavelength range of 200 to 400 nm, more preferably in the wavelength range of 240 to 380 nm. Examples of such ultraviolet absorbers include "Tinuvin 384-2" (maximum absorption wavelength 345 nm, manufactured by BASF).

[0141] The ultraviolet transmittance TUV1 of the first pressure-sensitive adhesive layer to ultraviolet light with a wavelength of 248 nm is preferably 75% or less (more preferably 70% or less, even more preferably 50% or less, with the lower limit usually being 5%), although this varies depending on the thickness of the first pressure-sensitive adhesive layer. The ultraviolet transmittance can be measured, for example, by measuring the transmittance of ultraviolet light with a wavelength of 248 nm incident perpendicularly on the first pressure-sensitive adhesive layer using a spectrophotometer (product name "U-4100", manufactured by Hitachi High-Tech Science Corporation).

[0142] Furthermore, the value (TUV1 / t1) obtained by dividing the ultraviolet transmittance TUV1 of the first adhesive layer at a wavelength of 248 nm by the thickness t1 of the first adhesive layer is preferably 5.00 or less, more preferably 4.90 or less, and even more preferably 4.80 or less, and the lower limit is preferably 0.50, more preferably 0.70, and even more preferably 1.00.

[0143] The content of the ultraviolet absorber in the pressure-sensitive adhesive composition constituting the first pressure-sensitive adhesive layer varies depending on the thickness of the first pressure-sensitive adhesive layer, but when the thickness is 15 μm, for example, the content is preferably 0.05 to 1.5 parts by weight, more preferably 0.07 to 1.2 parts by weight, and even more preferably 1.0 to 1.0 parts by weight per 100 parts by weight of the pressure-sensitive adhesive.

[0144] The PSA composition constituting the first PSA layer may contain an antioxidant, which can suppress deterioration such as discoloration of the double-sided PSA sheet for transfer during storage and can also improve processability, such as making the double-sided PSA sheet for transfer easier to cut.

[0145] Examples of the antioxidant include phenol-based, phosphorus-based, sulfur-based, and amine-based antioxidants, and at least one selected from these is used. Among these, phenol-based antioxidants are preferred, and hindered phenol-based antioxidants are particularly preferred.

[0146] Specific examples of the phenolic antioxidant include monocyclic phenolic compounds such as 2,6-di-t-butyl-p-cresol, 2,6-di-t-butyl-4-ethylphenol, 2,6-dicyclohexyl-4-methylphenol, 2,6-diisopropyl-4-ethylphenol, 2,6-di-t-amyl-4-methylphenol, 2,6-di-t-octyl-4-n-propylphenol, and 2,6-dicyclohexyl-4-n-octylphenol. phenol, 2-isopropyl-4-methyl-6-t-butylphenol, 2-t-butyl-4-ethyl-6-t-octylphenol, 2-isobutyl-4-ethyl-6-t-hexylphenol, 2-cyclohexyl-4-n-butyl-6-isopropylphenol, styrenated mixed cresol, DL-α-tocopherol, stearyl β-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, etc., The phenol compounds include 2,2'-methylenebis(4-methyl-6-t-butylphenol), 4,4'-butylidenebis(3-methyl-6-t-butylphenol), 4,4'-thiobis(3-methyl-6-t-butylphenol), 2,2'-thiobis(4-methyl-6-t-butylphenol), 4,4'-methylenebis(2,6-di-t-butylphenol), 2,2'-methylenebis[6-(1-methylcyclohexyl) -p-cresol], 2,2'-ethylidenebis(4,6-di-t-butylphenol), 2,2'-butylidenebis(2-t-butyl-4-methylphenol), 3,6-dioxaoctamethylenebis[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionate], triethylene glycol bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanediol Bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 2,2'-thiodiethylenebis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], etc. are used as tricyclic phenolic compounds, and 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane, 1,3,5-tris(2,6-dimethyl-3-hydroxy-4-t-butylbenzyl)isocyanurate, 1,3,5-tris[(3,Examples of suitable phenol compounds include tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxyethyl]isocyanurate, tris(4-t-butyl-2,6-dimethyl-3-hydroxybenzyl)isocyanurate, 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, and the like. Examples of suitable phenol compounds include tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane, and the like. Examples of suitable phenol compounds containing phosphorus include bis(3,5-di-t-butyl-4-hydroxybenzylphosphonate)calcium and bis(3,5-di-t-butyl-4-hydroxybenzylphosphonate)nickel.

[0147] The antioxidants may be used alone or in combination of two or more. From the viewpoints of suppressing deterioration such as discoloration during storage and the processability of the double-sided pressure-sensitive adhesive sheet for transfer, the content of the deterioration inhibitor contained in the pressure-sensitive adhesive composition is, for example, preferably 0.01 to 10 parts by weight, more preferably 0.03 to 5 parts by weight, and even more preferably 0.1 to 3 parts by weight, relative to 100 parts by weight of the first pressure-sensitive adhesive composition.

[0148] The PSA composition constituting the first PSA layer may contain any appropriate other components within the scope of not impairing the effects of the present invention, such as tackifiers, inorganic fillers, organic fillers, metal powders, pigments, foil-like materials, softeners, plasticizers, conductive agents, surface lubricants, leveling agents, heat stabilizers, polymerization inhibitors, lubricants, solvents, etc.

[0149] <Second adhesive layer> In the double-sided pressure-sensitive adhesive sheet for transfer of the present invention, the second pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer for temporarily fixing to a carrier substrate, and is made of a peelable pressure-sensitive adhesive layer. The configuration in which the second pressure-sensitive adhesive layer is made of a peelable pressure-sensitive adhesive layer is preferable in that the second pressure-sensitive adhesive layer can be peeled off from the carrier substrate without leaving any contamination such as adhesive residue, thereby improving reworkability.

[0150] The second adhesive layer can be made into a peelable adhesive layer by adjusting the adhesiveness by the type, composition, degree of crosslinking, etc. of the adhesive, or by reducing the adhesive strength by physical stimuli such as heat or electromagnetic waves such as ultraviolet rays.

[0151] The 180° peel adhesive strength of the second pressure-sensitive adhesive layer from a glass plate at 25°C is not particularly limited, but from the viewpoints of peeling from the carrier substrate without leaving any contamination such as adhesive residue and improving reworkability, it is preferably 5000 mN / 25 mm or less, more preferably 3000 mN / 25 mm or less, and even more preferably 1000 mN / 25 mm or less. Furthermore, from the viewpoint of adhesion of the carrier substrate to the second pressure-sensitive adhesive layer, the 180° peel adhesive strength of the second pressure-sensitive adhesive layer from a glass plate at 25°C is preferably 1 mN / 25 mm or more, more preferably 5 mN / 25 mm or more.

[0152] The ratio (P2b / P2a) of the 180° peel adhesive strength of the second pressure-sensitive adhesive layer against a glass plate at 25°C after the double-sided pressure-sensitive adhesive sheet for transfer is held at 160°C for 5 minutes (hereinafter sometimes referred to as "P2b") to the 180° peel adhesive strength of the second pressure-sensitive adhesive layer against a glass plate at 25°C (hereinafter sometimes referred to as "P2a") is not particularly limited, but is preferably 2 or less, more preferably 2.5 or less. A P2b / P2a ratio of 3 or less is preferred because, when an electronic component received by the double-sided pressure-sensitive adhesive sheet for transfer of the present invention is transferred and mounted on a mounting substrate by thermocompression bonding, the adhesive strength of the second pressure-sensitive adhesive layer against the carrier substrate does not increase, resulting in good peeling and excellent reworkability.

[0153] The 180° peel adhesive strength at 25° C. of the second pressure-sensitive adhesive layer can be measured in the same manner as for the first pressure-sensitive adhesive layer.

[0154] The adhesive strength of the second adhesive layer can be adjusted by adjusting the type, composition, degree of crosslinking, etc. of the adhesive that constitutes it, or by forming a WBL (Weak Boundary Layer) by blending a light release agent or plasticizer.

[0155] In the double-sided pressure-sensitive adhesive sheet for transfer of the present invention, the thickness of the second pressure-sensitive adhesive layer is not particularly limited, but is preferably 1 μm or more, more preferably 3 μm or more. When the thickness is at least a certain level, the second pressure-sensitive adhesive layer is easily and stably fixed to the carrier substrate, which is preferable. Furthermore, the upper limit of the thickness of the second pressure-sensitive adhesive layer is not particularly limited, but is preferably 30 μm, more preferably 20 μm. When the thickness is less than a certain level, the second pressure-sensitive adhesive layer is easily peeled from the carrier substrate, which improves reworkability, which is preferable.

[0156] In the double-sided pressure-sensitive adhesive sheet for transfer of the present invention, the haze (according to JIS K7136) of the second pressure-sensitive adhesive layer is not particularly limited, but is preferably 10% or less, more preferably 5% or less. A haze of 10% or less provides excellent transparency, and is preferable because, for example, when the double-sided pressure-sensitive adhesive sheet for transfer is attached to a carrier substrate, a pattern (e.g., a marker indicating the receiving position of an electronic component) on the carrier substrate can be visually recognized. The haze can be measured, for example, by forming the second pressure-sensitive adhesive layer on a separator and leaving it at room temperature (23°C, 50% RH) for at least 24 hours, peeling off the separator, and attaching the resulting sample to a slide glass (e.g., one with a total light transmittance of 91.8% and a haze of 0.4%) using a haze meter (product name "HM-150" manufactured by Murakami Color Research Laboratory Co., Ltd.).

[0157] In the double-sided pressure-sensitive adhesive sheet for transfer of the present invention, the total light transmittance (according to JIS K7361-1) of the second pressure-sensitive adhesive layer in the visible light wavelength region is not particularly limited, but is preferably 85% or more, more preferably 88% or more. A total light transmittance of 85% or more provides excellent transparency, and is preferable because, for example, when the double-sided pressure-sensitive adhesive sheet for transfer is attached to a carrier substrate, a pattern (e.g., a marker indicating the receiving position of an electronic component) attached to the carrier substrate can be visually recognized. The total light transmittance can be measured, for example, by forming the second pressure-sensitive adhesive layer on a separator and leaving it at room temperature (23°C, 50% RH) for at least 24 hours, peeling off the separator, and attaching the sample to a slide glass (e.g., one with a total light transmittance of 91.8% and a haze of 0.4%) using a haze meter (product name "HM-150" manufactured by Murakami Color Research Laboratory Co., Ltd.).

[0158] The adhesive constituting the second adhesive layer is not particularly limited, and examples thereof include the silicone-based adhesives, urethane-based adhesives, acrylic-based adhesives, rubber-based adhesives, polyester-based adhesives, polyamide-based adhesives, epoxy-based adhesives, vinyl alkyl ether-based adhesives, fluorine-based adhesives, etc., which are used in the first adhesive layer. Among these, from the viewpoints of peeling from the carrier substrate without leaving any contamination such as adhesive residue and improving reworkability, silicone-based adhesives, urethane-based adhesives, and acrylic-based adhesives are preferred, urethane-based adhesives and acrylic-based adhesives are more preferred, and acrylic-based adhesives are even more preferred.

[0159] The second adhesive layer in the double-sided adhesive sheet for transfer of the present invention may be an adhesive layer (adhesive strength-reducible adhesive layer) whose adhesive strength can be intentionally reduced by external action during use of the double-sided adhesive sheet for transfer, or an adhesive layer (adhesive strength-non-reducible adhesive layer) whose adhesive strength is hardly or not reduced at all by external action during use of the double-sided adhesive sheet for transfer, and can be selected appropriately depending on the method and conditions for transferring electronic components using the double-sided adhesive sheet for transfer of the present invention.

[0160] When the second pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer with reducible adhesive strength, the second pressure-sensitive adhesive layer can be selectively used in two states, one exhibiting relatively high adhesive strength and the other exhibiting relatively low adhesive strength, during the manufacturing and use processes of the double-sided pressure-sensitive adhesive sheet for transfer of the present invention. For example, during the process of using the double-sided pressure-sensitive adhesive sheet for transfer of the present invention, in which the first pressure-sensitive adhesive layer receives an electronic component, the state in which the second pressure-sensitive adhesive layer exhibits relatively high adhesive strength can be utilized to suppress or prevent the double-sided pressure-sensitive adhesive sheet for transfer from the carrier substrate. On the other hand, during the subsequent process of peeling the double-sided pressure-sensitive adhesive sheet for transfer of the present invention from the carrier substrate, the adhesive strength of the second pressure-sensitive adhesive layer can be reduced, thereby improving reworkability.

[0161] Examples of adhesives that form such an adhesive strength-reducible adhesive layer include radiation-curable adhesives, heat-foamable adhesives, etc. The adhesives that form the adhesive strength-reducible adhesive layer can be used alone or in combination of two or more.

[0162] The radiation-curable adhesive may be, for example, an adhesive that cures upon irradiation with electron beams, ultraviolet rays, α rays, β rays, γ rays, or X-rays, and it is particularly preferable to use an adhesive that cures upon irradiation with ultraviolet rays (ultraviolet-curable adhesive).

[0163] Examples of the radiation-curable adhesive include additive-type radiation-curable adhesives containing a base polymer such as an acrylic polymer and a radiation-polymerizable monomer component or oligomer component having a functional group such as a radiation-polymerizable carbon-carbon double bond.

[0164] The base polymer can be the same acrylic polymer as in the first pressure-sensitive adhesive layer. In order to allow the basic properties such as adhesiveness of the hydrocarbon group-containing (meth)acrylic acid ester to be appropriately exhibited in the second pressure-sensitive adhesive layer and to facilitate control of adhesiveness and peelability, the proportion of the hydrocarbon group-containing (meth)acrylic acid ester in all monomer components for forming the acrylic polymer is preferably 40% by mass or more, more preferably 60% by mass or more.

[0165] The acrylic polymer may contain a hydroxy group-containing monomer. When the acrylic polymer in the second pressure-sensitive adhesive layer contains a hydroxy group-containing monomer, the second pressure-sensitive adhesive layer is likely to have an appropriate cohesive strength. From the viewpoint of realizing appropriate adhesiveness and cohesive strength in the second pressure-sensitive adhesive layer, the proportion of the hydroxy group-containing monomer in the acrylic polymer is, for example, 0.1 to 30 mass %, and preferably 0.5 to 20 mass %.

[0166] The acrylic polymer may contain a carboxyl group-containing monomer. When the acrylic polymer in the second pressure-sensitive adhesive layer contains a carboxyl group-containing monomer, the second pressure-sensitive adhesive layer is more likely to have adequate adhesive reliability. From the viewpoint of realizing adequate adhesive reliability in the second pressure-sensitive adhesive layer, the proportion of the carboxyl group-containing monomer in the acrylic polymer is, for example, 0.1 to 30 mass %, and preferably 0.5 to 20 mass %.

[0167] The acrylic polymer may contain a vinyl ester monomer. When the acrylic polymer in the second pressure-sensitive adhesive layer contains a vinyl ester monomer, the second pressure-sensitive adhesive layer is likely to have an appropriate cohesive strength. From the viewpoint of realizing an appropriate cohesive strength in the second pressure-sensitive adhesive layer, the proportion of the vinyl ester monomer in the acrylic polymer is, for example, 0.1 to 60 mass %, and preferably 0.5 to 50 mass %.

[0168] The acrylic pressure-sensitive adhesive composition forming the second pressure-sensitive adhesive layer may contain a crosslinking agent. For example, by crosslinking the acrylic polymer, the amount of low-molecular-weight substances in the second pressure-sensitive adhesive layer can be further reduced. In addition, by increasing the weight-average molecular weight of the acrylic polymer, low adhesion and releasability can be controlled. Examples of the crosslinking agent include polyisocyanate compounds, epoxy compounds, polyol compounds (such as polyphenol compounds), aziridine compounds, and melamine compounds. When an isocyanate-based crosslinking agent and / or an epoxy-based crosslinking agent is used, the amount used is preferably about 10 parts by mass or less, more preferably 0.1 to 10 parts by mass, per 100 parts by mass of the acrylic polymer.

[0169] The acrylic pressure-sensitive adhesive composition forming the second pressure-sensitive adhesive layer may contain a crosslinking accelerator. The type of crosslinking accelerator can be appropriately selected depending on the type of crosslinking agent used. In this specification, the crosslinking accelerator refers to a catalyst that increases the rate of the crosslinking reaction caused by the crosslinking agent. Examples of such crosslinking accelerators include tin (Sn)-containing compounds such as dioctyltin dilaurate, dibutyltin dilaurate, dibutyltin diacetate, dibutyltin diacetylacetonate, tetra-n-butyltin, and trimethyltin hydroxide; amines such as N,N,N',N'-tetramethylhexanediamine and triethylamine; and N-containing compounds such as imidazoles. Among these, Sn-containing compounds are preferred. The use of these crosslinking accelerators is particularly effective when a hydroxyl group-containing monomer is used as the secondary monomer and an isocyanate-based crosslinking agent is used as the crosslinking agent. The amount of the crosslinking accelerator contained in the pressure-sensitive adhesive composition can be, for example, about 0.001 to 0.5 parts by mass (preferably about 0.001 to 0.1 parts by mass) relative to 100 parts by mass of the acrylic polymer.

[0170] Examples of the radiation-polymerizable monomer component include urethane (meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and 1,4-butanediol di(meth)acrylate. Examples of the radiation-polymerizable oligomer component include various oligomers such as urethane-based, polyether-based, polyester-based, polycarbonate-based, and polybutadiene-based oligomers, with those having a molecular weight of approximately 100 to 30,000 being preferred. The content of the radiation-curable monomer component and oligomer component in the radiation-curable adhesive that forms the second adhesive layer is, for example, 5 to 500 parts by mass, and preferably about 40 to 150 parts by mass, per 100 parts by mass of the base polymer. Furthermore, as the additive type radiation curable adhesive, for example, the one disclosed in Japanese Patent Application Laid-Open No. 60-196956 may be used.

[0171] The radiation-curable adhesive also includes an intrinsic radiation-curable adhesive containing a base polymer having a functional group such as a radiation-polymerizable carbon-carbon double bond on a polymer side chain or in the polymer main chain or at the end of the polymer main chain. The use of such an intrinsic radiation-curable adhesive tends to suppress unintended changes in adhesive properties over time due to migration of low-molecular-weight components within the formed second adhesive layer.

[0172] The base polymer contained in the inherent radiation-curable pressure-sensitive adhesive is preferably an acrylic polymer. A method for introducing a radiation-polymerizable carbon-carbon double bond into an acrylic polymer includes, for example, polymerizing (copolymerizing) a raw material monomer containing a monomer component having a first functional group to obtain an acrylic polymer, and then subjecting the acrylic polymer to a condensation reaction or addition reaction with a compound having a second functional group reactive with the first functional group and a radiation-polymerizable carbon-carbon double bond while maintaining the radiation-polymerizability of the carbon-carbon double bond.

[0173] Examples of combinations of the first functional group and the second functional group include a carboxy group and an epoxy group, an epoxy group and a carboxy group, a carboxy group and an aziridyl group, an aziridyl group and a carboxy group, a hydroxy group and an isocyanate group, and an isocyanate group and a hydroxy group. Among these, from the viewpoint of ease of reaction tracking, a combination of a hydroxy group and an isocyanate group and a hydroxy group is preferred. While producing a polymer having a highly reactive isocyanate group is technically difficult, from the viewpoint of ease of production and availability of an acrylic polymer having a hydroxy group, a combination in which the first functional group is a hydroxy group and the second functional group is an isocyanate group is preferred. Examples of compounds having an isocyanate group and a radiation-polymerizable carbon-carbon double bond, i.e., radiation-polymerizable unsaturated functional group-containing isocyanate compounds, include, for example, methacryloyl isocyanate, 2-methacryloyloxyethyl isocyanate, and m-isopropenyl-α,α-dimethylbenzyl isocyanate. Examples of acrylic polymers having a hydroxy group include those containing structural units derived from the above-mentioned hydroxy group-containing monomers and ether compounds such as 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, and diethylene glycol monovinyl ether.

[0174] The radiation-curable adhesive preferably contains a photopolymerization initiator. Examples of the photopolymerization initiator include α-ketol compounds, acetophenone compounds, benzoin ether compounds, ketal compounds, aromatic sulfonyl chloride compounds, photoactive oxime compounds, benzophenone compounds, thioxanthone compounds, camphorquinone, halogenated ketones, acylphosphinoxides, and acylphosphonates. Examples of the α-ketol compounds include 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone, α-hydroxy-α,α'-dimethylacetophenone, 2-methyl-2-hydroxypropiophenone, and 1-hydroxycyclohexylphenyl ketone. Examples of the acetophenone-based compounds include methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, 2-methyl-1-[4-(methylthio)-phenyl]-2-morpholinopropane-1, and the like. Examples of the benzoin ether-based compounds include benzoin ethyl ether, benzoin isopropyl ether, and anisoin methyl ether. Examples of the ketal-based compounds include benzyl dimethyl ketal. Examples of the aromatic sulfonyl chloride-based compounds include 2-naphthalenesulfonyl chloride. Examples of the photoactive oxime-based compounds include 1-phenyl-1,2-propanedione-2-(O-ethoxycarbonyl)oxime. Examples of the benzophenone-based compounds include benzophenone, benzoylbenzoic acid, and 3,3'-dimethyl-4-methoxybenzophenone. Examples of the thioxanthone compound include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, etc. The content of the photopolymerization initiator in the radiation-curable adhesive is, for example, 0.05 to 20 parts by mass per 100 parts by mass of the base polymer.

[0175] The heat-foamable pressure-sensitive adhesive is a pressure-sensitive adhesive containing a component that foams or expands upon heating (foaming agent, heat-expandable microspheres, etc.). Examples of the foaming agent include various inorganic and organic foaming agents. Examples of the inorganic foaming agent include ammonium carbonate, ammonium bicarbonate, sodium bicarbonate, ammonium nitrite, sodium borohydride, and azides. Examples of the organic blowing agent include fluorinated alkanes such as trichloromonofluoromethane and dichloromonofluoromethane; azo compounds such as azobisisobutyronitrile, azodicarbonamide, and barium azodicarboxylate; hydrazine compounds such as paratoluenesulfonylhydrazide, diphenylsulfone-3,3'-disulfonylhydrazide, 4,4'-oxybis(benzenesulfonylhydrazide), and allylbis(sulfonylhydrazide); semicarbazide compounds such as p-toluylenesulfonylsemicarbazide and 4,4'-oxybis(benzenesulfonylsemicarbazide); triazole compounds such as 5-morpholyl-1,2,3,4-thiatriazole; and N-nitroso compounds such as N,N'-dinitrosopentamethylenetetramine and N,N'-dimethyl-N,N'-dinitrosoterephthalamide. Examples of the heat-expandable microspheres include microspheres whose shell contains a substance that readily gasifies and expands upon heating. Examples of such substances include isobutane, propane, and pentane. Heat-expandable microspheres can be produced by encapsulating such substances within a shell-forming substance using a coacervation method or interfacial polymerization method. Examples of the shell-forming substance include substances that exhibit thermal melting properties and substances that can be ruptured by the thermal expansion of the encapsulated substance. Examples of such substances include vinylidene chloride-acrylonitrile copolymer, polyvinyl alcohol, polyvinyl butyral, polymethyl methacrylate, polyacrylonitrile, polyvinylidene chloride, and polysulfone.

[0176] Examples of the non-reduced adhesive layer include a pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer includes an adhesive layer formed from the radiation-curable adhesive described above for the adhesive-reducible adhesive layer, which has been cured by irradiation in advance and still retains a certain level of adhesive strength. The adhesives forming the non-reduced adhesive layer can be used alone or in combination of two or more. The second adhesive layer may be entirely or partially a non-reduced adhesive layer. For example, when the second adhesive layer has a monolayer structure, the entire second adhesive layer may be a non-reduced adhesive layer, or a specific portion of the second adhesive layer may be a non-reduced adhesive layer and the other portion may be a reducible adhesive layer. When the second adhesive layer has a laminate structure, all of the adhesive layers in the laminate structure may be non-reduced adhesive layers, or some of the adhesive layers in the laminate structure may be non-reduced adhesive layers.

[0177] A pressure-sensitive adhesive layer (irradiated radiation-curable pressure-sensitive adhesive layer) formed by previously curing a pressure-sensitive adhesive layer (unirradiated radiation-curable pressure-sensitive adhesive layer) from a radiation-curable pressure-sensitive adhesive by irradiation (irradiated radiation-curable pressure-sensitive adhesive layer) exhibits adhesiveness attributable to the polymer component contained therein, even if its adhesive strength has been reduced by radiation irradiation, and is capable of exhibiting the minimum adhesive strength required for the double-sided pressure-sensitive adhesive sheet for transfer of the present invention. When an irradiated radiation-curable pressure-sensitive adhesive layer is used, the entire second pressure-sensitive adhesive layer in the surface extension direction of the second pressure-sensitive adhesive layer may be an irradiated radiation-curable pressure-sensitive adhesive layer, or a portion of the second pressure-sensitive adhesive layer may be an irradiated radiation-curable pressure-sensitive adhesive layer and the other portion may be an unirradiated radiation-curable pressure-sensitive adhesive layer. In this specification, the term "radiation-curable pressure-sensitive adhesive layer" refers to a pressure-sensitive adhesive layer formed from a radiation-curable pressure-sensitive adhesive, and includes both an unirradiated radiation-curable pressure-sensitive adhesive layer that has radiation curability and a radiation-cured radiation-curable pressure-sensitive adhesive layer obtained after the pressure-sensitive adhesive layer has been cured by radiation irradiation.

[0178] The pressure-sensitive adhesive layer may be formed from a known or commonly used pressure-sensitive adhesive, preferably an acrylic adhesive having an acrylic polymer as a base polymer. When the second pressure-sensitive adhesive layer contains an acrylic polymer as a pressure-sensitive adhesive, the acrylic polymer is preferably a polymer containing a structural unit derived from a (meth)acrylic acid ester as the structural unit with the largest mass ratio. As the acrylic polymer, for example, the acrylic polymer described above as an acrylic polymer that can be contained in the additive-type radiation-curable adhesive may be used.

[0179] <Base material> The substrate in the double-sided pressure-sensitive adhesive sheet for transfer of the present invention is an element that functions as a support for the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer. Examples of the substrate include plastic substrates (particularly plastic films). The substrate may be a single layer or a laminate of the same or different types of substrates.

[0180] Examples of resins that constitute the plastic substrate include polyolefin resins such as low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene, very low-density polyethylene, random copolymer polypropylene, block copolymer polypropylene, homopolypropylene, polybutene, polymethylpentene, ethylene-vinyl acetate copolymer (EVA), ionomer, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic acid ester (random, alternating) copolymer, ethylene-butene copolymer, and ethylene-hexene copolymer; polyurethane; polyesters such as polyethylene terephthalate (PET), polyethylene naphthalate, and polybutylene terephthalate (PBT); polycarbonate; polyimide; polyether ether ketone; polyetherimide; polyamides such as aramid and wholly aromatic polyamide; polyphenyl sulfide; fluororesin; polyvinyl chloride; polyvinylidene chloride; cellulose resin; and silicone resin. When an electronic component received by the double-sided pressure-sensitive adhesive sheet for transfer of the present invention is transferred onto a mounting substrate by thermocompression bonding (e.g., at 150°C) for mounting, the substrate exhibits good heat resistance that is less susceptible to thermal expansion or contraction, enabling accurate mounting. From this viewpoint, the substrate preferably contains a heat-resistant resin such as polyimide (PI), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyamide (PA), or polyether ether ketone (PEEK) as its main component, and more preferably contains polyimide as its main component. The main component of the substrate refers to the component that accounts for the largest mass percentage of the constituent components. The above resins can be used alone or in combination of two or more. When the second pressure-sensitive adhesive layer is a radiation-curable pressure-sensitive adhesive layer as described above, the substrate is preferably radiation-transparent.

[0181] When the substrate is a plastic film, the plastic film may be non-oriented or may be oriented in at least one direction (uniaxial, biaxial, etc.), but non-oriented plastic films are preferred because they are less likely to exhibit heat shrinkage.

[0182] The surface of the substrate facing the first pressure-sensitive adhesive layer and / or the second pressure-sensitive adhesive layer may be subjected to a surface treatment, such as a physical treatment such as corona discharge treatment, plasma treatment, sand matting treatment, ozone exposure treatment, flame exposure treatment, high-voltage shock exposure treatment, or ionizing radiation treatment; a chemical treatment such as chromic acid treatment; a coating agent (primer); or an adhesion-enhancing treatment using a silicone primer, in order to enhance adhesion and retention with the pressure-sensitive adhesive layer. Furthermore, to impart antistatic properties, the substrate surface may be provided with a conductive vapor deposition layer containing a metal, alloy, or oxide thereof, or may be coated with a conductive polymer such as PEDOT-PSS. The surface treatment for enhancing adhesion is preferably applied to the entire surface of the substrate facing the pressure-sensitive adhesive layer.

[0183] From the viewpoint of ensuring the strength required for the substrate to function as a support in the double-sided pressure-sensitive adhesive sheet for transfer of the present invention, the thickness of the substrate is preferably 5 μm or more, more preferably 10 μm or more, even more preferably 15 μm or more, and particularly preferably 20 μm or more. Furthermore, from the viewpoint of realizing appropriate flexibility in the double-sided pressure-sensitive adhesive sheet for transfer of the present invention, the thickness of the substrate is preferably 200 μm or less, more preferably 180 μm or less, and even more preferably 150 μm or less.

[0184] In the double-sided pressure-sensitive adhesive sheet for transfer of the present invention, the haze of the substrate (according to JIS K7136) is not particularly limited, but is preferably 10% or less, more preferably 5.0% or less. A haze of 10% or less provides excellent transparency, and is preferable because, for example, when the double-sided pressure-sensitive adhesive sheet for transfer is attached to a carrier substrate, a pattern (e.g., a marker indicating the receiving position of an electronic component) on the carrier substrate can be visually recognized. The haze can be measured using a haze meter (product name "HM-150", manufactured by Murakami Color Research Laboratory Co., Ltd.).

[0185] In the double-sided pressure-sensitive adhesive sheet for transfer of the present invention, the total light transmittance (according to JIS K7361-1) of the substrate in the visible light wavelength region is not particularly limited, but is preferably 85% or more, more preferably 88% or more. A total light transmittance of 85% or more provides excellent transparency, and is preferable because, for example, when the double-sided pressure-sensitive adhesive sheet for transfer is attached to a carrier substrate, a pattern (e.g., a marker indicating the receiving position of an electronic component) on the carrier substrate can be visually recognized. The total light transmittance can be measured using a haze meter (product name "HM-150", manufactured by Murakami Color Research Laboratory Co., Ltd.).

[0186] <separator> The surface of the pressure-sensitive adhesive layer (the adhesive surface of the first pressure-sensitive adhesive layer and / or the second pressure-sensitive adhesive layer) of the double-sided pressure-sensitive adhesive sheet for transfer of the present invention may be protected by a release liner (separator) until use. The separator is used as a protective material for the pressure-sensitive adhesive layer and is peeled off when the pressure-sensitive adhesive sheet is attached to an adherend. Figure 2 is a cross-sectional schematic diagram showing one embodiment of the double-sided pressure-sensitive adhesive sheet for transfer of the present invention, in which 1 denotes the double-sided pressure-sensitive adhesive sheet for transfer, 10 denotes a substrate, 11 denotes the first pressure-sensitive adhesive layer, 12 denotes the second pressure-sensitive adhesive layer, and 110 and 120 denote separators. Note that the separator does not necessarily have to be provided.

[0187] As the separator, a conventional release paper or the like can be used. Specifically, for example, in addition to a substrate having a release treatment layer made of a release agent on at least one surface, a low-adhesion substrate made of a fluorine-based polymer (e.g., polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, chlorofluoroethylene-vinylidene fluoride copolymer, etc.) or a low-adhesion substrate made of a non-polar polymer (e.g., an olefin-based resin such as polyethylene or polypropylene, etc.) can be used.

[0188] The separator may preferably have a release treatment layer formed on at least one surface of the separator substrate. Examples of such separator substrates include plastic substrate films (synthetic resin films) such as polyester films (polyethylene terephthalate films, etc.), olefin resin films (polyethylene films, polypropylene films, etc.), polyvinyl chloride films, polyimide films, polyamide films (nylon films), and rayon films, as well as papers (high-quality paper, Japanese paper, kraft paper, glassine paper, synthetic paper, top-coated paper, etc.), and composites (2- to 3-layer composites) of these substrates formed by lamination, co-extrusion, etc.

[0189] The release treatment agent constituting the release treatment layer is not particularly limited, but examples thereof include silicone-based release treatment agents, fluorine-based release treatment agents, long-chain alkyl-based release treatment agents, etc. The release treatment agents can be used alone or in combination of two or more. Since the first pressure-sensitive adhesive layer is composed of a low-tack pressure-sensitive adhesive layer, it is also possible to use a substrate that is not treated with a release agent as the separator.

[0190] The separator may have an antistatic layer formed on at least one surface of the separator substrate to prevent adverse effects on electronic components. The antistatic layer may be formed on one surface of the separator (the release-treated surface or the untreated surface) or on both surfaces of the separator (the release-treated surface and the untreated surface).

[0191] Examples of antistatic agents contained in antistatic resins include cationic antistatic agents having cationic functional groups such as quaternary ammonium salts, pyridinium salts, and primary, secondary, and tertiary amino groups; anionic antistatic agents having anionic functional groups such as sulfonates, sulfate ester salts, phosphonates, and phosphate ester salts; amphoteric antistatic agents such as alkylbetaine and its derivatives, imidazoline and its derivatives, and alanine and its derivatives; nonionic antistatic agents such as aminoalcohols and their derivatives, glycerin and its derivatives, and polyethylene glycol and its derivatives; and ionic conductive polymers obtained by polymerizing or copolymerizing monomers having the above-mentioned cationic, anionic, or amphoteric ionic conductive groups. These compounds may be used alone or in combination of two or more.

[0192] The thickness of the separator is not particularly limited and may be appropriately selected from the range of 5 to 100 μm.

[0193] The method for producing the double-sided pressure-sensitive adhesive sheet for transfer of the present invention varies depending on the composition of the pressure-sensitive adhesive composition, and is not particularly limited. Any known forming method can be used, and examples thereof include the following methods (1) to (4). (1) A method for producing a pressure-sensitive adhesive sheet by applying (coating) the pressure-sensitive adhesive composition onto a substrate to form a composition layer, and then curing the composition layer (for example, by heat curing or curing by irradiation with active energy rays such as ultraviolet rays) to form a pressure-sensitive adhesive layer. (2) A method of applying (coating) the pressure-sensitive adhesive composition onto a separator to form a composition layer, curing the composition layer (for example, by heat curing or by irradiation with active energy rays such as ultraviolet rays) to form a pressure-sensitive adhesive layer, and then transferring the pressure-sensitive adhesive layer onto a substrate to produce a pressure-sensitive adhesive sheet. (3) A method of producing a pressure-sensitive adhesive sheet by applying (coating) the pressure-sensitive adhesive composition onto a substrate and drying it to form a pressure-sensitive adhesive layer. (4) A method of producing a pressure-sensitive adhesive sheet by applying (coating) the pressure-sensitive adhesive composition onto a separator and drying it to form a pressure-sensitive adhesive layer, and then transferring the pressure-sensitive adhesive layer onto a substrate.

[0194] As the curing method in the above (1) to (4), a thermal curing method is preferred in terms of excellent productivity and the ability to form a homogeneous pressure-sensitive adhesive layer with a smooth surface.

[0195] The method for applying (coating) the pressure-sensitive adhesive composition onto a predetermined surface can be any known coating method, and is not particularly limited. Examples include roll coating, kiss roll coating, gravure coating, reverse coating, roll brush, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, lip coating, and extrusion coating using a die coater or the like.

[0196] The thickness (total thickness) of the double-sided pressure-sensitive adhesive sheet for transfer of the present invention is not particularly limited, but is preferably 10 μm or more, more preferably 15 μm or more. A thickness of at least a certain level is preferred because it allows the first pressure-sensitive adhesive layer to receive electronic components with precision. The upper limit of the thickness (total thickness) of the double-sided pressure-sensitive adhesive sheet for transfer of the present invention is also not particularly limited, but is preferably 500 μm, more preferably 300 μm. A thickness of at most a certain level is preferred because it allows electronic components to be transferred to a mounting substrate with precision. The thickness of the double-sided pressure-sensitive adhesive sheet for transfer of the present invention does not include the thickness of the separator.

[0197] The haze (according to JIS K7136) of the double-sided pressure-sensitive adhesive sheet for transfer of the present invention is not particularly limited, but is preferably 10% or less, more preferably 5.0% or less. A haze of 10% or less provides excellent transparency, and is preferable because, for example, when the double-sided pressure-sensitive adhesive sheet for transfer is attached to a carrier substrate, a pattern (e.g., a marker indicating the receiving position of an electronic component) on the carrier substrate can be visually recognized. The haze can be measured, for example, by leaving the double-sided pressure-sensitive adhesive sheet for transfer at normal conditions (23°C, 50% RH) for at least 24 hours, peeling off the separator if present, and attaching the sheet to a slide glass (e.g., one with a total light transmittance of 91.8% and a haze of 0.4%) as a sample, using a haze meter (product name "HM-150" manufactured by Murakami Color Research Laboratory Co., Ltd.).

[0198] The total light transmittance (according to JIS K7361-1) in the visible light wavelength region of the double-sided pressure-sensitive adhesive sheet for transfer of the present invention is not particularly limited, but is preferably 85% or more, more preferably 88% or more. A total light transmittance of 85% or more provides excellent transparency, and is preferable because, for example, when the double-sided pressure-sensitive adhesive sheet for transfer is attached to a carrier substrate, a pattern on the carrier substrate (e.g., a marker indicating the receiving position of an electronic component) can be visually recognized. The total light transmittance can be measured, for example, by leaving the double-sided pressure-sensitive adhesive sheet for transfer at normal conditions (23°C, 50% RH) for at least 24 hours, peeling off the separator if present, and bonding the sheet to a slide glass (e.g., one with a total light transmittance of 91.8% and a haze of 0.4%) as a sample using a haze meter (product name "HM-150" manufactured by Murakami Color Research Laboratory Co., Ltd.).

[0199] The double-sided pressure-sensitive adhesive sheet for transfer of the present invention is suitable for use in a method for mounting electronic components on a mounting substrate. The method for mounting electronic components on a mounting substrate using the double-sided pressure-sensitive adhesive sheet for transfer of the present invention preferably includes the following steps: A step in which the diced electronic components are received by the first adhesive layer of the double-sided adhesive sheet for transfer (first step). a step (second step) of transferring the electronic component received by the first adhesive layer onto a mounting substrate;

[0200] FIG. 3 is a cross-sectional view showing one embodiment of the first step in the method for mounting an electronic component on a mounting board using the double-sided pressure-sensitive adhesive sheet for transfer of the present invention.

[0201] 3(a), the double-sided pressure-sensitive adhesive sheet for transfer 1 is attached to a carrier substrate 22 via the adhesive surface of the second pressure-sensitive adhesive layer 12. A marking pattern for arranging electronic components may be provided on the surface of the carrier substrate 22 that is attached to the second pressure-sensitive adhesive layer 12. Because the double-sided pressure-sensitive adhesive sheet for transfer 1 is highly transparent, the marking pattern provided on the carrier substrate 22 can be seen.

[0202] On the top of the adhesive surface of the first adhesive layer 11 of the transfer double-sided adhesive sheet 1, multiple electronic components 21 that have been diced into individual pieces are attached to a dicing tape 20 and are arranged facing and spaced apart from the adhesive surface of the first adhesive layer 11.

[0203] In FIG. 3( b), the pin member 23 pushes the electronic component 21 against the side of the dicing tape 20 on which the electronic component 21 is not attached, bringing the electronic component 21 close to the adhesive surface of the first adhesive layer 11, and the electronic component 21 is received by the adhesive surface of the first adhesive layer 11. The receiving may be performed by contacting the electronic component 21 with the first adhesive layer 11 or non-contacting. In non-contact receiving, the electronic component 21 is pushed until it peels off from the dicing tape 20, and then dropped onto the adhesive surface of the electronic component 21. In contact receiving, the adhesive surface of the first adhesive layer 11 has low adhesiveness, so that the stress applied when the electronic component 21 is received is low, and therefore damage to the electronic component 21 can be suppressed. In non-contact receiving, the adhesive surface of the first adhesive layer 11 has low adhesiveness, so that the dropped electronic component 21 can be caught with high positional accuracy. Instead of using the pin members 23, the electronic components 21 may be peeled off from the dicing tape 20 by irradiating them with radiation such as ultraviolet rays or laser beams.

[0204] The electronic components 21 may be received individually or multiple electronic components may be received collectively on the first adhesive layer 11. Fig. 3(c) is a cross-sectional schematic diagram showing a state in which all electronic components 21 on the dicing tape 20 are received on the adhesive surface of the first adhesive layer 11 of the double-sided adhesive sheet 1 for transfer.

[0205] FIG. 4 is a cross-sectional view showing a second step in the method for mounting an electronic component onto a mounting board using the double-sided pressure-sensitive adhesive sheet for transfer of the present invention.

[0206] As shown in Fig. 4(a), electronic components 21 arranged on the adhesive surface of the first adhesive layer 11 of the double-sided adhesive sheet 1 for transfer are placed opposite to, but spaced apart from, the circuit surface 31 (circuit pattern not shown) of the mounting substrate 30. Next, as shown in Fig. 4(b), the circuit surface 31 of the mounting substrate 30 and the electronic components 21 arranged on the adhesive surface of the first adhesive layer 11 of the double-sided adhesive sheet 1 for transfer are brought close to each other, and the electronic components 21 and the circuit surface 31 of the mounting substrate 30 are brought into contact with each other.

[0207] The electronic component 21 may be transferred to the circuit surface 31 of the mounting substrate 30 by thermocompression bonding (for example, at 150°C for 1 minute). The substrate 10, first adhesive layer 11, and / or second adhesive layer 12 constituting the double-sided adhesive sheet for transfer 1 have excellent heat resistance and are therefore unlikely to expand or contract or have their adhesive strength changed by thermocompression bonding, allowing the electronic component 21 to be transferred to the circuit surface 31 of the mounting substrate 30 with high accuracy.

[0208] 4(c), the double-sided adhesive sheet for transfer 1 and the mounting substrate 30 are separated, whereby the electronic component 21 is peeled from the first adhesive layer 11 and transferred to the circuit surface 31 of the mounting substrate 30. Because the first adhesive layer 11 is composed of a low-tack adhesive layer, the electronic component 21 peels easily and can be efficiently mounted on the mounting substrate 30 without being damaged.

[0209] 4(c) after the electronic component 21 has been mounted on the mounting substrate 30, the transfer double-sided adhesive sheet 1 may be peeled off (not shown) from the carrier substrate 22. Because the second adhesive layer 12 is composed of a peelable adhesive layer, it can be peeled off without leaving any adhesive residue, and has excellent reworkability, allowing the carrier substrate 22 to be easily reused.

[0210] The electronic components to be mounted on the mounting substrate are not particularly limited, but can be suitably used for fine, thin semiconductor chips and LED chips. [Example]

[0211] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples in any way.

[0212] Example 1 100 parts by weight of a silicone-based adhesive (an addition reaction type silicone-based adhesive, product name "X-40-3306", manufactured by Shin-Etsu Chemical Co., Ltd.), 1.4 parts by weight of a platinum-based catalyst 1 (product name "CAT-PL-50T", manufactured by Shin-Etsu Chemical Co., Ltd.), 5 parts by weight of a silicone-based release agent 1 (an addition reaction type silicone-based release agent mainly composed of dimethylpolysiloxane, product name "KS-776A", manufactured by Shin-Etsu Chemical Co., Ltd.), and 0.2 parts by weight of an ultraviolet absorber (product name "Tinuvin 384-2", maximum absorption wavelength 345 nm, manufactured by BASF) were blended, diluted with toluene to a total solids content of 25% by weight, and mixed using a disperser to prepare a silicone-based adhesive composition (1).

[0213] Silicone-based pressure-sensitive adhesive composition (1) was applied to the silicone-primed surface of a substrate film (polyester film with one side treated with a silicone primer, thickness 75 μm, product name "Diafoil MRF#75", manufactured by Mitsubishi Plastics, Inc.) so that the adhesive thickness after drying would be 15 μm, and the film was cured and dried under conditions of a drying temperature of 120° C. and a drying time of 5 minutes. In this way, a film having a silicone-based pressure-sensitive adhesive layer on the silicone-primed layer of the substrate film was obtained.

[0214] In addition, a separator (1) (a polyethylene terephthalate film without release treatment, thickness 25 μm, product name "Lumirror S10#25", manufactured by Toyobo Co., Ltd.) was attached to the adhesive surface of the silicone-based adhesive film to protect the silicone-based adhesive layer, and a laminate (1) having a laminate structure of [separator (1) layer] / [silicone-based adhesive (1) layer] / [base film layer]] was obtained.

[0215] Next, 100 parts by weight of 2-ethylhexyl acrylate (2EHA) (manufactured by Nippon Shokubai Co., Ltd.), 4 parts by weight of 2-hydroxyethyl acrylate (HEA) (manufactured by Toagosei Co., Ltd.), 0.02 parts by weight of 2,2'-azobisisobutyronitrile (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as a polymerization initiator, and 180 parts by weight of ethyl acetate were charged into a four-neck flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser. Nitrogen gas was introduced while gently stirring, and the liquid temperature in the flask was maintained at around 65°C, allowing the polymerization reaction to take place for 6 hours, producing a solution of an acrylic copolymer (solid content 35% by weight) with a weight-average molecular weight of 560,000.

[0216] To the prepared acrylic copolymer solution, 4.0 parts by weight of a crosslinking agent, Coronate HX (manufactured by Tosoh Corporation), and 0.02 parts by weight of a crosslinking catalyst, Envirizer OL-1 (manufactured by Tokyo Fine Chemical Co., Ltd.), were added per 100 parts by weight of the solid content, diluted with toluene to a total solid content of 25% by weight, and the acrylic pressure-sensitive adhesive composition was stirred with a disperser. The resulting composition was applied to the release-treated layer side of separator (2) (release-treated polyethylene terephthalate film, thickness 38 μm, product name "MRF #38", manufactured by Mitsubishi Chemical Corporation) with a fountain roll to a thickness of 20 μm after drying, and then cured and dried under conditions of a drying temperature of 130 ° C. and a drying time of 30 seconds. In this way, an acrylic pressure-sensitive adhesive layer was formed on separator (2).

[0217] Next, the substrate film side (the side not treated with silicone primer) of the laminate (1) obtained above was bonded to the surface of the acrylic pressure-sensitive adhesive layer to obtain a double-sided pressure-sensitive adhesive sheet for transfer having a laminate structure of [separator (1) layer] / [silicone pressure-sensitive adhesive (1) layer (first pressure-sensitive adhesive layer)] / [substrate film layer] / [acrylic pressure-sensitive adhesive layer (second pressure-sensitive adhesive layer)] / [separator (2) layer].

[0218] <Examples 2 to 6, Comparative Examples 1 and 2> In the same manner as in Example 1, a first pressure-sensitive adhesive layer was formed to the thickness shown in Table 1 using a silicone-based pressure-sensitive adhesive composition containing an ultraviolet absorber (product name "Tinuvin 384-2, maximum absorption wavelength 345 nm, manufactured by BASF) blended in the amount shown in Table 1, to obtain each double-sided pressure-sensitive adhesive sheet for transfer.

[0219] <Evaluation> The double-sided pressure-sensitive adhesive sheets for transfer obtained in the examples and comparative examples were subjected to the following measurements and evaluations. The results are shown in Table 1.

[0220] (UV transmittance) A thin section was cut from the first adhesive layer of the double-sided adhesive sheet for transfer using a microtome, and the transmittance was measured in the wavelength range of 200 to 800 nm using a microscopic ultraviolet-visible-near-infrared spectrophotometer (product name "MSV-5200 DGK", manufactured by JASCO Corporation). The value at a wavelength of 248 nm was taken as the ultraviolet transmittance TUV1.

[0221] (floating height) The double-sided adhesive sheet for transfer from which the separator (1) layer has been peeled is irradiated with an ultraviolet laser (wavelength 248 nm, laser beam spot cross-sectional area 15300 μm) from the silicone adhesive layer side. 2 , output 100mJ / cm 2 ) with a pulse time of 10 nsec, a frequency of 100 Hz, and a pulse width of 1 mm 2 9 dots (average irradiation area 15300 μm 2 The surface observation images of these nine dots were obtained using a laser microscope (product name "VK-X100", manufactured by Keyence Corporation) and analyzed to determine the lift height R after irradiation. z2 The lift height R before irradiation was also calculated from the surface observation image of the double-sided adhesive sheet for transfer before irradiation with the ultraviolet laser at a location equivalent to 9 dots. z1 obtained.

[0222] (floating area) The double-sided adhesive sheet for transfer from which the separator (1) layer has been peeled is irradiated with an ultraviolet laser (wavelength 248 nm, laser beam size 130 × 105 μm (laser light spot cross-sectional area 13650 μm) from the silicone adhesive layer side. 2 , output 100mJ / cm 2 ) with a pulse time of 10 nsec and a frequency of 100 Hz, 2 9 dots (average irradiation area 15300 μm 2 ) for each of the nine dots. A surface observation image was taken at a magnification of 200x using a digital microscope (product name "VHX-700F", manufactured by Keyence Corporation), and this was analyzed using the image processing software ImageJ. The area where lifting occurred (lifted area) was calculated as the average value of the nine dots. The area percentage (%) of the lifted area was calculated based on the laser irradiation area of 15,300 μm. 2 The area ratio of the floating area to the surface area was calculated.

[0223] (transcription accuracy) The double-sided adhesive sheet for transfer from which the separator (1) had been peeled off was attached to a dicing ring with the first adhesive layer facing outwards, and the surface of the double-sided adhesive sheet was diced to a depth of 10 μm, thereby making multiple markings with sides of 1 mm square.

[0224] The semiconductor wafer was pre-treated with laser light so that it would be cut into 1 mm x 1 mm pieces when expanded, and then polished to a thickness of 30 μm. The wafer was then bonded to a dicing die-bonding film to obtain a dicing die-bonding film with a semiconductor wafer attached. The dicing die bond film with the semiconductor wafer attached was held on the dicing ring of a die separator (product name "DDS2300", manufactured by Disco Corporation), and cool expanded in a cool expander unit under conditions of an expansion temperature of -15°C, an expansion speed of 200 mm / sec, and an expansion amount of 11 mm to cleave the semiconductor wafer and die bond layer. After that, room temperature expansion was performed under conditions of an expansion speed of 1 mm / sec, and an expansion amount of 7 mm. Furthermore, while maintaining the expanded state, the dicing tape on the outer periphery of the semiconductor chip was thermally shrunk under conditions of a heat temperature of 200°C, an air volume of 40 L / min, a heat distance of 20 mm, and a rotation speed of 3° / sec to obtain a dicing die bond film having a semiconductor chip with a die bond layer, in which the semiconductor wafer and die bond layer were maintained in a cleaved state.

[0225] A dicing die bond film with the side having the semiconductor chip with a die bond layer facing downwards and a transfer double-sided adhesive sheet with the marked first adhesive layer facing upwards were placed opposite each other with a clearance of 1 mm, with the semiconductor chip with a die bond layer and the marking aligned, and a needle was used to push the dicing die bond film from the top (back side) to drop 10 semiconductor chips with a die bond layer onto the adhesive surface of the first adhesive layer exactly at the marking positions, thereby obtaining a transfer double-sided adhesive sheet that received the semiconductor chips.

[0226] The double-sided adhesive sheet for transfer that received the semiconductor chip was irradiated with an ultraviolet laser (wavelength 248 nm, laser beam spot cross-sectional area 15300 μm) on the area other than the area that received the semiconductor chip with the die bond layer. 2 , output 100mJ / cm 2, frequency 100 Hz, pulse width 10 ns) was irradiated so as to form an alignment mark, and a mounting substrate with a corresponding marking was placed and aligned using the alignment mark as a reference, and a semiconductor chip with a die bond layer was transferred to the aligned mounting substrate, and the semiconductor chip with a die bond layer was observed using a microscope and evaluated according to the following criteria.

[0227] ○: No semiconductor chips with die bond layers were found to be misaligned with the marking position on the mounting board. ×: A semiconductor chip with a die bond layer was confirmed to be misaligned with respect to the marking position on the mounting substrate.

[0228] In all of the double-sided pressure-sensitive adhesive sheets for transfer according to Examples 1 to 6, which had the configuration of the present invention, the positional displacement of the semiconductor chip due to irradiation with an ultraviolet laser was suppressed. z2 / R z1 In the double-sided pressure-sensitive adhesive sheets for transfer of Comparative Examples 1 and 2, in which the above-mentioned point 1) does not fall within the scope of the present invention, misalignment of the semiconductor chip occurred.

[0229] [Table 1] [Explanation of symbols]

[0230] 1 Double-sided adhesive sheet for transfer 10 Base material 11 First adhesive layer 12 Second adhesive layer 110,120 Separator 20 Dicing tape 21 Electronic Components 22 Carrier board 23 Pin member 30 Mounting board 31 Circuit side

Claims

1. a double-sided PSA sheet for transfer in which a first PSA layer, a substrate, and a second PSA layer are laminated in this order; the first adhesive layer is a low-tack adhesive layer containing an adhesive and an ultraviolet absorber, and having a 180° peel adhesive strength from a glass plate at 25°C of 0.1 mN / 25 mm or more; the second pressure-sensitive adhesive layer is a releasable pressure-sensitive adhesive layer having a 180° peel adhesive strength from a glass plate at 25°C of 1 mN / 25 mm or more; The first adhesive layer was irradiated with an ultraviolet laser having a wavelength of 248 nm and a beam size of 130 × 105 μm and an output of 100 mJ / cm ２ The double-sided pressure-sensitive adhesive sheet for transfer has a ratio (Rz2 / Rz1) of a lifting height Rz2 after irradiation with a pulse width of 10 ns and a frequency of 100 Hz to a lifting height Rz1 before irradiation of 0.2 to 1600.

2. The first adhesive layer was irradiated with an ultraviolet laser having a wavelength of 248 nm and a beam size of 130 × 105 μm and an output of 100 mJ / cm ２ 2. The double-sided pressure-sensitive adhesive sheet for transfer according to claim 1, wherein the area ratio of the lifted area to the entire irradiated area is 20.0% or less when irradiated with light having a pulse width of 10 ns and a frequency of 100 Hz.

3. a double-sided PSA sheet for transfer in which a first PSA layer, a substrate, and a second PSA layer are laminated in this order; the first adhesive layer is a low-tack adhesive layer containing an adhesive and an ultraviolet absorber, and having a 180° peel adhesive strength from a glass plate at 25°C of 0.1 mN / 25 mm or more; the second pressure-sensitive adhesive layer is a releasable pressure-sensitive adhesive layer having a 180° peel adhesive strength from a glass plate at 25°C of 1 mN / 25 mm or more; The first adhesive layer was irradiated with an ultraviolet laser having a wavelength of 248 nm and a beam size of 130 × 105 μm and an output of 100 mJ / cm ２ The double-sided pressure-sensitive adhesive sheet for transfer has an area ratio of the lifted area to the entire irradiated area of 20.0% or less when irradiated with light having a pulse width of 10 ns and a frequency of 100 Hz.

4. The ratio (R ｚ２ / t １ 3. The double-sided pressure-sensitive adhesive sheet for transfer according to claim 1, wherein the value of (a) is 1.0 or less.

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