resin composition

Abstract

To provide a resin composition that is appropriate for forming an adhesive layer suitable as a shock-absorbing layer endowed with both shock absorption properties and heat resistance.SOLUTION: The present invention relates to a resin composition for forming an adhesive layer. A storage modulus G'(100k) of the adhesive layer at 100 kHz and 25°C is 60 MPa or less. The resin composition contains an active-energy-ray-curable compound.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resin composition. More specifically, the present invention relates to a resin composition that can be suitably used to form an adhesive layer useful as a shock-absorbing layer used for transferring small electronic components such as semiconductor chips and LED chips. [Background technology]

[0002] In the manufacturing process of semiconductor devices, semiconductor wafers are generally diced into individual pieces while temporarily fixed on a dicing tape. The individual semiconductor chips are then pushed from the dicing tape side on the back of the wafer using a pin member, picked up by a suction jig called a collet, and mounted on a mounting substrate such as a circuit board (for example, Patent Document 1).

[0003] However, advances in microfabrication technology have led to the miniaturization and thinning of semiconductor chips, making it difficult to pick them up individually with collets. Furthermore, the miniaturization of semiconductor devices has progressed, requiring the dense mounting of numerous tiny semiconductor chips on a substrate, and individual mounting with collets has become inefficient.

[0004] As a means of solving the above problems, a technique called laser transfer is being considered (see, for example, Patent Documents 2 and 3). In laser transfer, first, small electronic components such as semiconductor chips (for example, rectangular with sides of 100 μm or less) are arranged in a grid pattern on a temporary fixing material, with the side on which the electronic components are arranged facing downwards. Next, a transfer substrate for transferring (receiving) the electronic components is placed opposite the side of the temporary fixing material on which the electronic components are arranged, with a gap between them. Next, by irradiating the electronic components with laser light from the temporary fixing material side, the temporary fixing is released and the components are peeled off and dropped onto the transfer substrate, thereby transferring them. The electronic components transferred to the transfer substrate can be transferred to another carrier substrate and mounted on a mounting substrate, or they can be mounted by transferring them directly from the transfer substrate to the mounting substrate.

[0005] In laser transfer, there is no need to mechanically pick up small electronic components using a collet or the like. Instead, by irradiating a plurality of electronic components with laser light and sweeping it, transfer can be performed on an optical time scale, resulting in a dramatic improvement in efficiency. In addition, by arranging the temporary fixing material and the transfer substrate with a gap (clearance), there is also an advantage that the electronic components can be adjusted to a desired interval and arranged.

[0006] In laser transfer, since the temporary fixing material and the transfer substrate are arranged with a gap (clearance), there are problems such as damage due to impact when the peeled-off electronic component collides with the transfer substrate, displacement due to bouncing, or turning over, which reduces the transferability. Therefore, an impact absorption layer for alleviating the impact when the electronic component collides with the transfer substrate is provided on the surface of the transfer substrate (for example, see Patent Document 2). Such an impact absorption layer is designed to have flexibility by reducing elasticity so that it can sufficiently absorb the impact when the electronic component collides.

[0007] On the other hand, in laser transfer, when transferring an electronic component to a mounting substrate, thermocompression bonding is performed to improve the connection reliability of the electronic component to the electronic circuit provided on the mounting substrate (for example, see Patent Document 3). In particular, when connecting an electronic component to a circuit on a mounting substrate via a protruding electrode (connection metal) called a bump, it is also known to perform thermocompression bonding at a high temperature of 250°C or higher in order to sufficiently plastically deform the bump and ensure electrical connection to the circuit and improve the connection reliability (for example, see Patent Document 4).

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

[0009] In the transfer (mounting) of electronic components onto a mounting substrate, a method is preferably used in which electronic components are transferred directly from a transfer substrate to the mounting substrate without using another carrier substrate, in order to reduce the number of processes and thus reduce costs, and to prevent a decrease in the positional accuracy of electronic components on the circuit on the mounting substrate due to repeated transfers (for example, Patent Document 3). However, shock-absorbing layers with improved shock absorption due to reduced elasticity have low heat resistance, which can cause expansion or outgassing during thermocompression bonding, leading to misalignment of electronic components and deterioration of connection reliability. On the other hand, increasing the elasticity of the shock-absorbing layer to improve heat resistance reduces shock absorption and impairs transferability. Thus, the shock absorption and heat resistance of the shock-absorbing layer are in a trade-off relationship, and achieving both simultaneously has been a difficult challenge.

[0010] The present invention has been made in view of the above problems, and its object is to provide a resin composition suitable for forming an adhesive layer that is suitable as an impact-absorbing layer that achieves both impact absorption and heat resistance. [Means for solving the problem]

[0011] A first aspect of the present invention provides a resin composition. The resin composition of the first aspect of the present invention is used to form an adhesive layer. In this specification, the resin composition of the first side of the present invention may be referred to as "the resin composition of the present invention," and the adhesive layer formed by the resin composition of the first side of the present invention may be referred to as "the adhesive layer of the present invention."

[0012] The adhesive layer of the present invention can be suitably used as a shock-absorbing layer for receiving electronic components placed on a temporary fixing material, and more specifically, it can be suitably used in the following steps. - The process of placing an adhesive layer (shock-absorbing layer) on the temporary fixing material, with a gap between it and the surface on which the electronic components are placed, and receiving the electronic components. The process of transferring electronic components received by the adhesive layer (shock-absorbing layer) to another carrier substrate, or directly to a mounting substrate. From the viewpoint of reducing costs by minimizing the number of processes and preventing a decrease in the positional accuracy of electronic components on the circuit board due to repeated transfers, a process of directly transferring electronic components from a transfer substrate to the mounting substrate without using another carrier substrate is preferred.

[0013] Therefore, the adhesive layer of the present invention possesses both shock absorption properties to mitigate the impact when receiving the electronic components, and excellent heat resistance that suppresses expansion and outgassing during thermocompression bonding when transferring electronic components to a mounting substrate. The resin composition of the present invention can be suitably used to form the adhesive layer of the present invention that possesses such shock absorption properties and heat resistance.

[0014] The adhesive layer of the present invention has a storage modulus G'(100k) of 60 MPa or less at 100 kHz and 25°C. In the laser transfer process, the transfer of electronic components is completed on an optical timescale, making the shock absorption characteristics of the adhesive on this timescale crucial. Specifically, the optical timescale is correlated with the frequency at which the laser light is swept, for example, 100 kHz. Converted to a timescale, this is approximately 10 microseconds, and the adhesive needs to respond to shocks on this timescale by deforming.

[0015] In the adhesive layer of the present invention, the configuration in which G'(100k) is 60 MPa or less is preferable because it realizes excellent shock absorption of the adhesive layer on an optical time scale and provides excellent transferability when the adhesive layer of the present invention is used as a shock absorption layer for a transfer substrate.

[0016] The resin composition of the present invention contains an active energy ray-curable compound. The configuration of the resin composition of the present invention, which contains an active energy ray-curable compound, is advantageous because, before irradiation with active energy rays, the adhesive layer of the present invention exhibits excellent shock absorption, and after irradiation with active energy rays, the elastic modulus of the adhesive layer of the present invention is improved by the formation of a crosslinked structure due to the reaction of the active energy ray-curable compound, resulting in excellent heat resistance that can suppress expansion and outgassing during thermocompression bonding when transferring electronic components to a mounting substrate, and also because the adhesive strength is reduced, preventing adhesive residue on electronic components and poor transfer of electronic components.

[0017] Gel fraction G of the adhesive layer of the present invention before irradiation with active energy rays 0 Gel fraction G after active energy ray irradiation (%) 1 (%) ratio (G 1 / G 0 ) is preferably 1.1 or higher. 1 / G 0 A configuration in which is 1.1 or higher is preferable because, before irradiation with active energy rays, the adhesive layer of the present invention exhibits excellent shock absorption, and after irradiation with active energy rays, the elastic modulus of the adhesive layer of the present invention is improved by the formation of a crosslinked structure due to the reaction of the active energy ray-curable compound, resulting in excellent heat resistance that can suppress expansion and outgassing during thermocompression bonding when transferring electronic components to a mounting substrate.

[0018] The coefficient of linear expansion α(200-210°C) of the adhesive layer of the present invention at 200-210°C after irradiation with active energy rays is 500 × 10⁻⁶ -5 It is preferable that the value of α(200~210) is 500 × 10 -5The configuration of being below / K means that after the active energy ray irradiation, the adhesive layer of the present invention forms a crosslinked structure with an active energy ray curable compound, resulting in an improved elastic modulus. In the thermocompression bonding when transferring an electronic component to a mounting substrate, it exhibits excellent heat resistance capable of suppressing the occurrence of expansion, and is preferable in that it can prevent the decrease in the positional accuracy of the electronic component due to the linear expansion of the adhesive layer.

[0019] The tensile elastic modulus E’(200) at 200 °C after the active energy ray irradiation of the adhesive layer of the present invention is preferably 0.3 MPa or more. The configuration where the E’(200) is 0.3 MPa or more means that after the active energy ray irradiation, the adhesive layer of the present invention forms a crosslinked structure with an active energy ray curable compound, resulting in an improved elastic modulus. In the thermocompression bonding when transferring an electronic component to a mounting substrate, it exhibits excellent heat resistance capable of suppressing the occurrence of expansion and outgassing, and is suitable in that it can prevent the decrease in connection reliability due to the decrease in the positional accuracy of the electronic component.

[0020] The linear expansion coefficient α(260~270) at 260 to 270 °C after the active energy ray irradiation of the adhesive layer of the present invention is -5 preferably below 500×10 -5 / K. The configuration where the α(260~270) is below 500×10

[0021] The tensile modulus E'(260) of the adhesive layer of the present invention at 260°C after irradiation with active energy rays is preferably 0.05 MPa or higher. The configuration in which the tensile modulus E'(260) is 0.05 MPa or higher is preferable because, after irradiation with active energy rays, the elastic modulus of the adhesive layer of the present invention is improved by the formation of a crosslinked structure by the active energy ray curable compound. In particular, when transferring electronic components to a mounting substrate via bumps, even when thermocompression bonding is performed at high temperatures exceeding 250°C to improve connection reliability, it exhibits excellent heat resistance that can suppress the generation of expansion and outgassing, and can prevent a decrease in connection reliability due to a decrease in the positional accuracy of electronic components.

[0022] In the resin composition of the present invention, the active energy ray curable compound is preferably a polyfunctional monomer and / or a polyfunctional oligomer. The configuration in which the active energy ray curable compound of the present invention is a polyfunctional monomer and / or a polyfunctional oligomer is preferable because the elastic modulus of the adhesive layer is higher due to the formation of a crosslinked structure by multiple reactive functional groups, and it exhibits superior heat resistance that can suppress expansion and outgassing during thermocompression bonding when transferring electronic components to a mounting substrate.

[0023] In the resin composition of the present invention, it is preferable that the active energy ray-curable compound has three or more reactive functional groups. The configuration in which the active energy ray-curable compound has three or more reactive functional groups is preferable because the elastic modulus of the adhesive layer is further increased by the formation of a three-dimensional crosslinked structure by the three or more reactive functional groups, and it exhibits even better heat resistance that can suppress the generation of expansion and outgassing during thermocompression bonding when transferring electronic components to a mounting substrate.

[0024] In the resin composition of the present invention, the molecular weight of the active energy ray-curable compound is preferably less than 20,000. The configuration in which the molecular weight of the active energy ray-curable compound is less than 20,000 is preferable because it imparts flexibility to the adhesive layer of the present invention before irradiation with active energy rays, adjusts the G'(100k) to 60 MPa or less, and provides excellent shock absorption when the adhesive layer of the present invention is used as a shock absorption layer for a transfer substrate. Furthermore, if the active energy ray-curable compound of the present invention is a polymer (oligomer), the molecular weight shall include the weight-average molecular weight (Mw).

[0025] The thickness of the adhesive layer of the present invention is preferably 1 μm or more and 500 μm or less. The configuration in which the adhesive layer of the present invention is 1 μm or more is preferable in that it has excellent shock absorption due to collisions of electronic components. Furthermore, the configuration in which the adhesive layer of the present invention is 500 μm or less is preferable from the viewpoint of transferability when transferring the received electronic components to the mounting substrate.

[0026] The resin composition of the present invention is preferably an acrylic adhesive composition. The configuration in which the resin composition of the present invention is an acrylic adhesive composition is preferable in terms of ease of designing an adhesive to adjust the G'(100k) to 60 MPa or less, the ability to improve the heat resistance of the adhesive layer by forming a crosslinked structure with the active energy ray curable compound, transparency, tackiness, cost, etc.

[0027] The adhesive layer of the present invention may have another adhesive layer laminated on top of it. This configuration is preferable because the adhesive layer of the present invention can achieve both excellent shock absorption before irradiation with active energy rays and excellent heat resistance after irradiation with active energy rays, and furthermore, the laminated other adhesive layer can be bonded to a substrate constituting the transfer substrate, or a carrier substrate, thereby suppressing lifting from the transfer substrate.

[0028] The adhesive layer of the present invention (including cases where the aforementioned additional adhesive layer is laminated) may be further laminated with a substrate layer. The adhesive layer of the present invention is preferable in that it further has a substrate layer, as this improves stability and handling when receiving electronic components.

[0029] In the adhesive layer of the present invention, another adhesive layer may be laminated on the surface of the base layer where the adhesive layer is not laminated. By laminating another adhesive layer on the surface of the base layer where the adhesive layer is not laminated, for example, another adhesive layer can be fixed to the carrier substrate, which is preferable from the viewpoint of workability. The aforementioned substrate layer is preferably formed from a light-transmitting heat-resistant film, from the viewpoint of stability and handling when receiving electronic components, and from the viewpoint of heat resistance during thermocompression bonding when transferring electronic components to the mounting substrate.

[0030] A second aspect of the present invention provides an adhesive layer formed by the resin composition of the present invention. A third aspect of the present invention provides an adhesive sheet having the adhesive layer of the second aspect of the present invention. The adhesive layer of the second aspect of the present invention and the adhesive sheet of the third aspect of the present invention have an adhesive layer of the present invention that can achieve both excellent shock absorption before irradiation with active energy rays and excellent heat resistance after irradiation with active energy rays, and are suitable for receiving electronic components placed on a temporary fixing material. More specifically, they are suitable for receiving electronic components when placed on a temporary fixing material with a gap between them and the surface on which the electronic components are placed. [Effects of the Invention]

[0031] The adhesive layer formed from the resin composition of the present invention (the adhesive layer of the present invention) exhibits excellent shock absorption before irradiation with active energy rays, preventing defects such as damage, misalignment, and inversion when receiving electronic components. After irradiation with active energy rays, it exhibits excellent heat resistance, preventing a decrease in connection reliability caused by misalignment of electronic components due to expansion and outgassing during thermocompression bonding when transferring electronic components to a mounting substrate. Therefore, the resin composition of the present invention can be suitably used to form an adhesive layer that combines shock absorption and heat resistance, particularly for use in laser transfer, which directly transfers electronic components received on a transfer substrate onto a mounting substrate. [Brief explanation of the drawing]

[0032] [Figure 1] This is a schematic cross-sectional view showing one embodiment of an adhesive sheet having an adhesive layer according to the present invention. [Figure 2] This is a schematic cross-sectional view showing another embodiment of an adhesive sheet having an adhesive layer according to the present invention. [Figure 3] This is a schematic cross-sectional view showing another embodiment of an adhesive sheet having an adhesive layer according to the present invention. [Figure 4] This is a schematic cross-sectional view showing another embodiment of an adhesive sheet having an adhesive layer according to the present invention. [Figure 5] Figure 1 is a schematic cross-sectional view illustrating one embodiment of a method for fixing an adhesive sheet to a carrier substrate. [Figure 6] Figure 5 is a schematic cross-sectional view showing the first step in one embodiment of a method for processing electronic components using an adhesive sheet fixed to a carrier substrate. [Figure 7] Figure 5 is a schematic cross-sectional view showing the second to fourth steps in one embodiment of a method for processing electronic components using an adhesive sheet fixed to a carrier substrate. [Modes for carrying out the invention]

[0033] The resin composition of the present invention is used to form an adhesive layer (the adhesive layer of the present invention). The adhesive layer of the present invention is used in processing techniques for transferring small electronic components such as semiconductor chips and LED chips onto mounting substrates such as circuit boards, and is particularly suitable for use in the following processes. - The process of placing an adhesive layer (shock-absorbing layer) on the temporary fixing material, with a gap between it and the surface on which the electronic components are placed, and receiving the electronic components. The process of transferring electronic components received by the adhesive layer (shock-absorbing layer) to another carrier substrate, or directly to a mounting substrate. To reduce costs by minimizing the number of steps and to prevent a decrease in the positional accuracy of electronic components on the circuit board due to repeated transfers, a process is preferred in which electronic components are transferred directly from the transfer substrate to the mounting substrate without using another carrier substrate.

[0034] By using the adhesive layer of the present invention for transferring electronic components, it becomes possible to position multiple electronic components on the adhesive layer on an optical timescale, eliminating the need for individual pickup. Furthermore, the adhesive layer of the present invention has excellent shock absorption properties to mitigate the impact when receiving the electronic components before irradiation with active energy rays, and excellent heat resistance to prevent expansion due to heating and outgassing when transferring the electronic components onto the mounting substrate by thermocompression bonding after irradiation with active energy rays. Therefore, since electronic components transferred to the adhesive layer of the present invention can be directly transferred from the adhesive layer to the mounting substrate, the process of transferring to another carrier substrate before transferring to the mounting substrate can be omitted, reducing manufacturing costs. Moreover, it is possible to prevent a decrease in connection reliability due to a decrease in the positional accuracy of electronic components caused by repeating the transfer process twice.

[0035] The adhesive layer of the present invention is not particularly limited in form. For example, it may constitute a single-sided adhesive sheet where only one side is an adhesive surface, or a double-sided adhesive sheet where both sides are adhesive surfaces. Furthermore, when the adhesive layer of the present invention constitutes a double-sided adhesive sheet, the double-sided adhesive sheet may have a form in which both adhesive surfaces are provided by the adhesive layer of the present invention, or one adhesive surface may be provided by the adhesive layer of the present invention, and the other adhesive surface may be provided by an adhesive layer other than the adhesive layer of the present invention (which may be referred to as "another adhesive layer" in this specification).

[0036] The adhesive layer of the present invention may constitute a so-called "substrate-less type" adhesive sheet that does not have a substrate (substrate layer), or it may constitute an adhesive sheet that has a substrate. In this specification, a "substrate-less type" adhesive sheet may be referred to as a "substrate-less adhesive sheet," and an adhesive sheet that has a substrate may be referred to as a "substrate-attached adhesive sheet." Examples of the substrate-less adhesive sheet include a double-sided adhesive sheet consisting only of the adhesive layer of the present invention, and a double-sided adhesive sheet consisting of the adhesive layer of the present invention and another adhesive layer (an adhesive layer other than the adhesive layer of the present invention). Examples of the substrate-attached adhesive sheet include a single-sided adhesive sheet having the adhesive layer of the present invention on one side of the substrate, a double-sided adhesive sheet having the adhesive layer of the present invention on both sides of the substrate, and a double-sided adhesive sheet having the adhesive layer of the present invention on one side of the substrate and another adhesive layer on the other side. The "substrate (substrate layer)" above refers to the support, which is the part that receives electronic components together with the adhesive layer when using the adhesive layer of the present invention. The release liner that is peeled off when using the adhesive layer is not included in the above substrate. Furthermore, the term "adhesive sheet" shall include the meaning of "adhesive tape." That is, the adhesive sheet may be an adhesive tape having a tape-like form.

[0037] Preferably, the adhesive surface of the adhesive layer of the present invention is protected by a release liner. The release liner is laminated on at least one adhesive surface to protect the shock absorption properties of the adhesive layer of the present invention. Preferably, the release liner protects the adhesive surface for which the adhesive layer of the present invention receives electronic components, in which case it is preferable to peel off the adhesive layer of the present invention immediately before it is used to receive the electronic components.

[0038] Embodiments of the adhesive layer of the present invention will be described below with reference to the drawings, but the adhesive layer of the present invention is not limited to these embodiments. Figure 1 is a schematic cross-sectional view showing one embodiment of an adhesive sheet having an adhesive layer according to the present invention, where 1 is the adhesive sheet, 10 is the adhesive layer, and R1 and R2 are the release liners.

[0039] As shown in Figure 1, the adhesive sheet 1 has a laminated structure in which a release liner R1, an adhesive layer 10, and a release liner R2 are stacked in this order. The adhesive sheet 1 is used in processing techniques for mounting small electronic components such as semiconductor chips and LED chips onto mounting substrates such as circuit boards. In the adhesive sheet 1, the adhesive layer 10 is composed of the adhesive layer of the present invention and is suitably used to separate electronic components placed on a temporary fixing material and to receive the separated electronic components. The release liner R1 is peeled off from the adhesive layer 10 before use, and the exposed adhesive surface 10a receives the electronic components. The adhesive surface 10b that is exposed by peeling off the release liner R2 is bonded to a substrate constituting a transfer substrate, or a carrier substrate, etc. In the adhesive sheet 1, the adhesive layer 10 is composed of the adhesive layer of the present invention. Therefore, the adhesive layer 10 before irradiation with active energy rays has excellent shock absorption properties when receiving electronic components, and the adhesive layer 10 after irradiation with active energy rays exhibits excellent heat resistance when transferring electronic components onto the mounting substrate by thermocompression bonding.

[0040] Figure 2 is a schematic cross-sectional view showing another embodiment of an adhesive sheet having an adhesive layer according to the present invention, where 2 is the adhesive sheet, 20 and 21 are the adhesive layers, and R1 and R2 are the release liners.

[0041] As shown in Figure 2, the adhesive sheet 2 has a laminated structure in which a release liner R1, an adhesive layer 20, an adhesive layer 21, and a release liner R2 are stacked in this order. The adhesive sheet 2 is used in processing techniques for mounting small electronic components such as semiconductor chips and LED chips onto mounting substrates such as circuit boards. In the adhesive sheet 2, the adhesive layer 20 is composed of the adhesive layer of the present invention and is suitably used to separate electronic components placed on a temporary fixing material and to receive the separated electronic components. In the adhesive sheet 2, the adhesive layer 21, together with the adhesive layer 20, can adjust the shock absorption when receiving electronic components. The adhesive layer 21 may be composed of the adhesive layer of the present invention, or it may be composed of an adhesive layer other than the adhesive layer of the present invention. The release liner R1 is peeled off from the adhesive layer 20 before use, and the electronic components are received on the exposed adhesive surface 20a. The adhesive surface 21b that is exposed by peeling off the release liner R2 is bonded to a substrate constituting a transfer substrate, or a carrier substrate, etc. In the adhesive sheet 2, the adhesive layer 20 is composed of the adhesive layer of the present invention. Therefore, the adhesive layer 20 before irradiation with active energy rays has excellent shock absorption properties when receiving electronic components, and the adhesive layer 20 after irradiation with active energy rays exhibits excellent heat resistance when transferring electronic components onto the mounting substrate by thermocompression bonding.

[0042] Figure 3 is a schematic cross-sectional view showing another embodiment of an adhesive sheet having an adhesive layer according to the present invention, where 3 is the adhesive sheet, 30 is the adhesive layer, S1 is the substrate, and R1 is the release liner.

[0043] As shown in Figure 3, the adhesive sheet 3 has a laminated structure in which a release liner R1, an adhesive layer 30, and a base material S1 are stacked in this order. The adhesive sheet 3 is used in processing technology for mounting small electronic components such as semiconductor chips and LED chips onto mounting substrates such as circuit boards. In the adhesive sheet 3, the adhesive layer 30 is composed of the adhesive layer of the present invention and is suitably used to separate electronic components placed on a temporary fixing material and to receive the separated electronic components. In the adhesive sheet 3, the base material S1 improves the stability and handling when receiving electronic components. The release liner R1 is peeled off from the adhesive layer 30 before use and receives electronic components with its exposed adhesive surface 30a. In the adhesive sheet 3, since the adhesive layer 30 is composed of the adhesive layer of the present invention, the adhesive layer 30 before irradiation with active energy rays has excellent shock absorption when receiving electronic components, and the adhesive layer 30 after irradiation with active energy rays exhibits excellent heat resistance when transferring electronic components onto the mounting substrate by thermocompression bonding.

[0044] Figure 4 is a schematic cross-sectional view showing another embodiment of an adhesive sheet having an adhesive layer according to the present invention, where 4 is the adhesive sheet, 40 and 41 are the adhesive layers, S1 is the substrate, and R1 and R2 are the release liners.

[0045] As shown in Figure 4, the adhesive sheet 4 has a laminated structure in which a release liner R1, an adhesive layer 40, a base material S1, an adhesive layer 41, and a release liner R2 are stacked in this order. The adhesive sheet 4 is used in processing technology for mounting small electronic components such as semiconductor chips and LED chips onto mounting substrates such as circuit boards. In the adhesive sheet 4, the adhesive layer 40 is composed of the adhesive layer of the present invention and is suitably used to separate electronic components placed on a temporary fixing material and to receive the separated electronic components. In the adhesive sheet 4, the base material S1 improves the stability and handling when receiving electronic components. In the adhesive sheet 4, the adhesive layer 41, together with the adhesive layer 40, can adjust the shock absorption when receiving electronic components. The adhesive layer 41 may be composed of the adhesive layer of the present invention, or it may be composed of an adhesive layer other than the adhesive layer of the present invention. The release liner R1 is peeled off from the adhesive layer 40 before use and receives electronic components with its exposed adhesive surface 40a. The adhesive surface 41b exposed by peeling off the release liner R2 is bonded to a substrate constituting the transfer substrate, or a carrier substrate, etc. Since the adhesive layer 40 in the adhesive sheet 4 is composed of the adhesive layer of the present invention, the adhesive layer 40 before irradiation with active energy rays has excellent shock absorption when receiving electronic components, and the adhesive layer 40 after irradiation with active energy rays exhibits excellent heat resistance when transferring electronic components onto the mounting substrate by thermocompression bonding. The following explains each component.

[0046] (The adhesive layer of the present invention) The adhesive layer of the present invention has a storage modulus G'(100k) of 60 MPa or less at 100 kHz and 25°C. In the laser transfer process, the transfer of electronic components is completed on an optical timescale, making the shock absorption characteristics of the adhesive on this timescale crucial. Specifically, the optical timescale is correlated with the frequency at which the laser light is swept, for example, 100 kHz. Converted to a timescale, this is approximately 10 microseconds, and the adhesive needs to respond to shocks on this timescale by deforming.

[0047] In the adhesive layer of the present invention, the configuration in which G'(100k) is 60 MPa or less is preferable in that it realizes excellent shock absorption of the adhesive layer on an optical time scale and provides excellent transferability when the adhesive layer of the present invention is used as a shock absorption layer for a transfer substrate. In terms of achieving even better shock absorption of the adhesive layer on an optical time scale, G'(100k) is more preferably 30 MPa or less, even more preferably 15 MPa or less, and may also be 10 MPa or less. Furthermore, from the viewpoint of preventing misalignment of received electronic components, G'(100k) is preferably 0.03 MPa or more, more preferably 0.05 MPa or more, and even more preferably 0.1 MPa or more.

[0048] In the adhesive layer of the present invention, it is preferable that tanδ(100k) at 100kHz and 25℃ is 1 or greater. tanδ (loss coefficient) is one of the indicators of viscoelasticity, expressed as the ratio of the loss modulus (G") to the storage modulus (G') (G'' / G'). A high tanδ indicates high viscosity and easy plastic deformation, while a low tanδ indicates high elasticity. The configuration in the adhesive layer of the present invention, where tanδ(100k) is 1 or greater, is preferable in that it achieves excellent shock absorption of the adhesive layer on an optical time scale and imparts excellent transferability when the adhesive layer of the present invention is used as a shock absorption layer for a transfer substrate. In terms of achieving even better shock absorption of the adhesive layer on an optical time scale, tanδ(100k) is preferably 1.1 or greater, and more preferably 1.2 or greater. Furthermore, from the viewpoint of preventing misalignment of received electronic components, tanδ(100k) is preferably 3 or less, and may be 2 or less.

[0049] In the adhesive layer of the present invention, G'(100k) and tanδ(100k) represent the storage modulus and loss coefficient of the adhesive layer before irradiation with active energy rays. In this specification, "irradiation with active energy rays" means "ultraviolet irradiation" in the examples described below, unless otherwise specified, and specifically refers to 8280 mJ / cm². 2This is ultraviolet irradiation.

[0050] Specifically, G'(100k) and tanδ(100k) are measured by the dynamic viscoelasticity measurement described in the examples below, and can be adjusted by the type and composition (monomer composition) of the resin composition constituting the adhesive layer of the present invention (the resin composition of the present invention), the type and amount of the active energy ray curable compound described below, the type and amount of the crosslinking agent, etc.

[0051] Gel fraction G of the adhesive layer of the present invention before irradiation with active energy rays 0 Gel fraction G after active energy ray irradiation (%) 1 (%) ratio (G 1 / G 0 ) is preferably 1.1 or higher. 1 / G 0 A configuration in which is 1.1 or higher is preferable because, before irradiation with active energy rays, the adhesive layer of the present invention exhibits excellent shock absorption, and after irradiation with active energy rays, the elastic modulus of the adhesive layer of the present invention is improved by the formation of a crosslinked structure due to the reaction of the active energy ray curable compound, and it exhibits excellent heat resistance that can suppress expansion and outgassing even during thermocompression bonding when transferring electronic components to a mounting substrate. In terms of achieving a higher level of both shock absorption before irradiation with active energy rays and heat resistance after irradiation with active energy rays, the above G 1 / G 0 The ratio of G is more preferably 1.15 or higher, even more preferably 1.2 or higher, and may be 1.3 or higher. 1 / G 0 The upper limit is not particularly limited, and a higher value is preferable, but considering the effect on the characteristics before irradiation with active energy rays (e.g., displacement of electronic components), it may be 10,000 or less, 1,000 or less, or 100 or less.

[0052] Gel fraction G of the adhesive layer of the present invention before irradiation with active energy rays 0(%) is preferably 85% or less, and more preferably 80% or less, in order to achieve excellent shock absorption of the adhesive layer and to impart excellent transferability when the adhesive layer of the present invention is used as a shock absorption layer for a transfer substrate. Furthermore, from the viewpoint of preventing misalignment of the received electronic components, the above G 0 The percentage (%) is preferably 10% or more, and may be 20% or more.

[0053] Gel fraction G of the adhesive layer of the present invention after irradiation with active energy rays 1 Gel fraction G 1 The upper limit of (%) is preferable as it is higher, and is not particularly limited, but may be less than 100%, for example.

[0054] The above gel fraction G 0 , G 1 , and their ratio G 1 / G 0 Specifically, this is measured by the gel fraction measurement described in the examples below, and can be adjusted by the type and composition (monomer composition) of the resin composition (resin composition of the present invention) constituting the adhesive layer of the present invention, the type and amount of the active energy ray curable compound described below, the type and amount of the crosslinking agent, etc.

[0055] The coefficient of linear expansion α(200-210°C) of the adhesive layer of the present invention at 200-210°C after irradiation with active energy rays is 500 × 10⁻⁶ -5 It is preferable that the value of α(200~210) is 500 × 10 -5The configuration of α(200~210) being less than or equal to 250 × 10⁻¹⁰ is preferable because, after irradiation with active energy rays, the elastic modulus of the adhesive layer of the present invention is improved by the formation of a crosslinked structure by the active energy ray curable compound, exhibiting excellent heat resistance that can suppress the occurrence of expansion during thermocompression bonding when transferring electronic components to a mounting substrate, and preventing a decrease in the positional accuracy of electronic components due to the linear expansion of the adhesive layer. From the viewpoint of exhibiting even better heat resistance and preventing a decrease in the positional accuracy of electronic components due to the linear expansion of the adhesive layer at a higher level, the above α(200~210) is 250 × 10⁻¹⁰. -5 / K or less is more preferable, 150×10 -5 A value of / K or less is even more preferable. The lower limit of α(200~210) is not particularly limited, and a lower value is preferable, but 1 × 10 -5 It may be / K or higher.

[0056] The coefficient of linear expansion α(260-270) of the adhesive layer of the present invention at 260-270°C after irradiation with active energy rays is 500 × 10⁻⁶ -5 It is preferable that the value of α(260~270) is 500 × 10 -5 The configuration of α(260~270) being less than or equal to 350 × 10⁻¹⁰ is preferable because, after irradiation with active energy rays, the elastic modulus of the adhesive layer of the present invention is improved by the formation of a crosslinked structure by the active energy ray curable compound, and in particular, when thermocompressing at high temperatures exceeding 250°C to improve connection reliability when transferring electronic components to a mounting substrate via bumps, it exhibits excellent heat resistance that can suppress the occurrence of expansion, and can prevent a decrease in the positional accuracy of electronic components due to the linear expansion of the adhesive layer. From the viewpoint of exhibiting even better heat resistance at high temperatures and being able to prevent a decrease in the positional accuracy of bumps of electronic components due to the linear expansion of the adhesive layer at a higher level, the above α(260~270) is 350 × 10⁻¹⁰. -5 / K or less is more preferable, 200 × 10 -5 A value of / K or less is even more preferable. The lower limit of α(260~270) is not particularly limited, and a lower value is preferable, but 1 × 10 -5 It may be / K or higher.

[0057] The above values ​​α(200~210) and α(260~270) are measured in accordance with JIS K 7197, specifically by measuring the coefficient of linear expansion as described in the examples below, and can be adjusted by the type and composition (monomer composition) of the resin composition constituting the adhesive layer of the present invention (the resin composition of the present invention), the type and amount of the active energy ray-curable compound described below, the type and amount of the crosslinking agent, the thickness of the adhesive layer, etc.

[0058] The tensile modulus E'(200) of the adhesive layer of the present invention at 200°C after irradiation with active energy rays is preferably 0.3 MPa or higher. The configuration in which E'(200) is 0.3 MPa or higher is preferable because, after irradiation with active energy rays, the elastic modulus of the adhesive layer of the present invention is improved by the formation of a crosslinked structure by the active energy ray curable compound, exhibiting excellent heat resistance that can suppress expansion and outgassing during thermocompression bonding when transferring electronic components to a mounting substrate, and preventing a decrease in connection reliability due to a decrease in the positional accuracy of electronic components. From the viewpoint of exhibiting even better heat resistance and preventing a decrease in the positional accuracy of electronic components due to expansion of the adhesive layer and outgassing at a higher level, E'(200) is more preferably 0.5 MPa or higher, and even more preferably 0.9 MPa or higher. There is no particular upper limit to E'(200), and a higher value is preferable, but it may be, for example, 1000 MPa or less in order to prevent misalignment of the adherend (workpiece) even at high temperatures and to have appropriate adhesiveness.

[0059] The tensile modulus E'(260) of the adhesive layer of the present invention at 260°C after irradiation with active energy rays is preferably 0.05 MPa or higher. The configuration in which the tensile modulus E'(260) is 0.05 MPa or higher is preferable because, after irradiation with active energy rays, the elastic modulus of the adhesive layer of the present invention is improved by the formation of a crosslinked structure by the active energy ray curable compound. In particular, when transferring electronic components to a mounting substrate via bumps, even when thermocompression bonding is performed at high temperatures exceeding 250°C to improve connection reliability, it exhibits excellent heat resistance that can suppress the generation of expansion and outgassing, and can prevent a decrease in connection reliability due to a decrease in the positional accuracy of electronic components. From the viewpoint of exhibiting even better heat resistance at high temperatures and being able to prevent a decrease in the positional accuracy of bumps of electronic components due to expansion of the adhesive layer and outgassing at a higher level, the above E'(260) is more preferably 0.1 MPa or higher, and even more preferably 0.5 MPa or higher. The upper limit of E'(260) is not particularly limited, and a higher value is preferable. However, it may be, for example, 1000 MPa or less, in order to prevent displacement of the adherend (workpiece) even at high temperatures and to have appropriate adhesiveness.

[0060] Specifically, E'(200) and E'(260) above are measured by the tensile elasticity test measurement described in the examples below, and can be adjusted by the type and composition (monomer composition) of the resin composition (resin composition of the present invention) constituting the adhesive layer of the present invention, the type and amount of the active energy ray curable compound described below, the type and amount of the crosslinking agent, the thickness of the adhesive layer, etc.

[0061] The ratio of the sinking depth to the thickness of the adhesive layer of the present invention, as determined by thermomechanical analysis (TMA) under the following conditions before irradiation with active energy rays (sinking depth / thickness × 100), is preferably 5% or more. ·Thermomechanical analysis (TMA) Probe diameter: 1.0 mm Mode: Hands on Mode Indentation load: 0.05N Measurement ambient temperature: -40℃ Press-down load time: 20 minutes

[0062] On an optical timescale, the adhesive properties in the 100kHz frequency range correspond to the adhesive properties in the -40°C low-temperature range according to the temperature-time conversion law. Therefore, a larger deformation when a load is applied to the adhesive in this temperature range indicates superior shock absorption characteristics. For example, the above ratio (sinking depth / thickness × 100) when a load is applied to the adhesive layer at -40°C using thermomechanical analysis (TMA) can be used as an indicator of shock absorption characteristics. A configuration in which the above ratio (sinking depth / thickness × 100) in thermomechanical analysis (TMA) at -40°C is 5% or more is preferable because it can sufficiently absorb the impact caused by collisions of electronic components and receive the electronic components without damage or displacement. From the viewpoint of sufficiently absorbing the impact caused by collisions of electronic components, the above ratio is more preferably 10% or more, even more preferably 30% or more, and particularly preferably 50% or more. From the viewpoint of the transferability of the received electronic components to the mounting substrate, the above ratio is preferably 95% or less, and may be 90% or less.

[0063] The above ratio (sinking depth / thickness × 100) is specifically measured by the method described in the examples below, and can be adjusted by the type and composition (monomer composition) of the resin composition constituting the adhesive layer of the present invention (the resin composition of the present invention), the type and amount of the active energy ray curable compound described below, the type and amount of the crosslinking agent, the thickness of the adhesive layer, etc.

[0064] Temperature at which the adhesive layer of the present invention loses 5% of its weight after irradiation with active energy rays (T d5 ) is preferably 340°C or higher. d5The configuration in which the temperature is 340°C or higher is preferable because, after irradiation with active energy rays, the elastic modulus of the adhesive layer of the present invention is improved by the formation of a crosslinked structure by the active energy ray curable compound, exhibiting excellent heat resistance that can suppress outgassing during thermocompression bonding when transferring electronic components to a mounting substrate, and preventing a decrease in the positional accuracy of electronic components due to outgassing of the adhesive layer. From the viewpoint of exhibiting even better heat resistance and preventing a decrease in the positional accuracy of electronic components due to outgassing of the adhesive layer at a higher level, the above T d5 The temperature is more preferably 345°C or higher, and even more preferably 350°C or higher. d5 The upper limit is not particularly limited; a higher temperature is preferable, but it may be 500°C or less.

[0065] Temperature (T) of 5% weight loss of the adhesive layer of the present invention after irradiation with the above energy rays d5 Specifically, this is measured by the method described in the examples below, and can be adjusted by the type and composition (monomer composition) of the resin composition (resin composition of the present invention) constituting the adhesive layer of the present invention, the type and amount of the active energy ray curable compound described below, the type and amount of the crosslinking agent, the thickness of the adhesive layer, etc.

[0066] The thickness of the adhesive layer of the present invention is preferably 1 μm or more and 500 μm or less. The configuration in which the adhesive layer of the present invention is 1 μm or more is preferred in that it has excellent shock absorption due to collisions of electronic components. From the viewpoint of shock absorption due to collisions of electronic components, the thickness of the adhesive layer of the present invention is preferably 5 μm or more, and may be 10 μm or more, 20 μm or more, or 30 μm or more. The configuration in which the adhesive layer of the present invention is 500 μm or less is preferred from the viewpoint of transferability when transferring electronic components to a mounting substrate, and may be 400 μm or less, or 300 μm or less. Note that if the adhesive layer of the present invention is a laminated structure with another adhesive layer, the thickness of the adhesive layer is the thickness of the entire laminated structure.

[0067] When the adhesive layer of the present invention has a laminated structure with another adhesive layer, the thickness of the adhesive layer of the present invention without the other adhesive layer is preferably 1 μm or more and 450 μm or less. The configuration in which the adhesive layer of the present invention has a thickness of 1 μm or more is preferred in terms of excellent shock absorption due to collisions with electronic components, 2 μm or more is preferred, and 5 μm or more is more preferred. Furthermore, the configuration in which the adhesive layer of the present invention has a thickness of 450 μm or less is preferred from the viewpoint of transferability when transferring to a mounting substrate for electronic components, and may be 350 μm or less, or 250 μm or less.

[0068] The probe tack value of the adhesive layer of the present invention before irradiation with active energy rays at room temperature is 7 N / cm². 2 More than 42N / cm 2 The following is preferable: The probe tack value is 10 N / cm 2 The above configuration is preferable because it can sufficiently absorb the impact caused by collisions with the adhesive layer of electronic components, and can suppress displacement and inversion of electronic components due to bouncing during collisions. In terms of suppressing displacement and inversion of electronic components, the above probe tack value is 9 N / cm 2 The above is preferable, and 11 N / cm 2 Above or above, or 13 N / cm² 2 The above values ​​may also be acceptable. Furthermore, the probe tack value may be 42 N / cm². 2 The following configuration is preferred from the viewpoint of preventing adhesive from sticking to the received electronic components and leaving adhesive residue: 40 N / cm 2 The following, or 35 N / cm² 2 The following is also acceptable.

[0069] The above probe tack value is measured using a probe tack measuring instrument (for example, RHESCA's "TACKINESS Model TAC-II"), and can be adjusted by the type and composition (monomer composition) of the resin composition constituting the adhesive layer of the present invention (the resin composition of the present invention), the type and amount of the active energy ray curable compound described below, the type and amount of the crosslinking agent, the thickness of the adhesive layer, etc.

[0070] The adhesive strength of the adhesive layer of the present invention to stainless steel at room temperature after irradiation with active energy rays is preferably 0.01 N / 20 mm or more and 4.2 N / 20 mm or less. The configuration in which the adhesive strength of the adhesive layer to stainless steel at room temperature after irradiation with active energy rays is 0.01 N / 20 mm or more is preferred in that it suppresses and holds the positional displacement of the received electronic components when transporting them to the next process, and the adhesive strength is more preferably 0.03 N / 20 mm or more, and may be 0.05 N / 20 mm or more. The configuration in which the adhesive strength of the adhesive layer to stainless steel at room temperature after irradiation with active energy rays is 4.2 N / 20 mm or less is preferred in that it

[0071] The adhesive strength of the adhesive layer of the present invention to stainless steel at room temperature after irradiation with active energy rays is more preferably 1 N / 20 mm or less. The configuration in which the adhesive strength of the adhesive layer to stainless steel at room temperature after irradiation with active energy rays is 1 N / 20 mm or less is preferred from the viewpoint of improving the transferability of received electronic components to the mounting substrate and suppressing adhesive residue of electronic components, and may be 0.75 N / 20 mm or less, or 0.5 N / 20 mm or less. Alternatively, the adhesive strength of the adhesive layer to stainless steel at room temperature after irradiation with active energy rays may be 0.001 N / 20 mm or more, or 0.005 N / 20 mm or more.

[0072] The adhesive strength of the adhesive layer of the present invention to stainless steel at room temperature before irradiation with active energy rays is preferably 0.01 N / 20 mm or more. The configuration in which the adhesive strength of the adhesive layer before irradiation with active energy rays is 0.01 N / 20 mm or more is preferable in that it can suppress displacement and inversion of electronic components due to bouncing during collisions. In terms of suppressing displacement and inversion of electronic components, the adhesive strength of the adhesive layer before irradiation with active energy rays is more preferably 0.02 N / 20 mm or more, and may be 0.03 N / 20 mm or more. The upper limit of the adhesive strength of the adhesive layer before irradiation with active energy rays is not particularly limited, but may be 20 N / 20 mm or less, 18 N / 20 mm or less, or 15 N / 20 mm or less.

[0073] The above adhesive strength is measured, for example, in accordance with JIS Z 0237, and can be adjusted by the type and composition (monomer composition) of the resin composition (resin composition of the present invention) constituting the adhesive layer of the present invention, the type and amount of the active energy ray curable compound described below, the type and amount of the crosslinking agent, the thickness of the adhesive layer, etc.

[0074] In the adhesive layer of the present invention before irradiation with active energy rays, the impact absorption rate (%) in the ball-dropping test described below is preferably 10% or more, more preferably 15% or more, and may be 20% or more, 25% or more, 30% or more, 35% or more, or 40% or more.

[0075] Furthermore, in the ball-dropping test described later, the ratio of the depth of the adhesive layer to the thickness of the adhesive layer before irradiation with active energy rays (depth of adhesive layer sinking after the ball-dropping test / thickness × 100) is preferably 7% or more, more preferably 10% or more, and may be 15% or more, 20% or more, 25% or more, or 30% or more.

[0076] A configuration in which the aforementioned ratio (sinking depth / thickness × 100) is 7% or more is preferable because the adhesive layer of the present invention exhibits excellent shock absorption before irradiation with active energy rays, preventing problems such as damage, bouncing and displacement, or inversion when receiving electronic components. Furthermore, from the viewpoint of transferability of electronic components to the mounting substrate, the aforementioned ratio (sinking depth / thickness × 100) is preferably 95% or less, more preferably 90% or less.

[0077] The ball drop test can be performed using the following method. First, the entire surface of the adhesive sheet (30mm wide x 30mm long) opposite the adhesive layer on the evaluation surface is attached to a SUS plate (5mm thick) using double-sided adhesive tape and a 2kg hand roller. Using a ball-dropping tester, a 1g iron ball is dropped from a height of 1m onto the adhesive layer surface of the evaluation sample obtained as described above. The depth to which the iron ball penetrates the adhesive layer surface is measured using a confocal laser microscope. Next, the penetration depth (μm) is divided by the thickness of the adhesive sheet (μm) to determine the ratio of the penetration depth of the adhesive to the thickness of the adhesive (penetration depth of the adhesive after the ball-dropping test / thickness × 100). Furthermore, the impact load F when an impact is applied under the above conditions is measured using the ball-dropping test machine, and the impact absorption rate (%) is calculated using the following formula. Shock absorption rate (%) = {(F0-F1) / F0} × 100 (In the above formula, F0 is the impact load when the iron ball strikes only the SUS plate without the adhesive sheet attached, and F1 is the impact load when the iron ball strikes the adhesive sheet of a structure consisting of a SUS plate and an adhesive sheet.)

[0078] The impact absorption force in the iron ball drop test, and the ratio (sinking depth / thickness × 100), can be adjusted by the type and composition (monomer composition) of the resin composition constituting the adhesive layer of the present invention, the type and amount of the active energy ray curable compound described below, the type and amount of the crosslinking agent, the thickness of the adhesive layer, and so on.

[0079] (The resin composition of the present invention) The resin composition (adhesive composition) constituting the adhesive layer of the present invention is not particularly limited, but examples include acrylic adhesives, rubber adhesives, vinyl alkyl ether adhesives, silicone adhesives, polyester adhesives, polyamide adhesives, urethane adhesives, fluorine adhesives, and epoxy adhesives. As the resin composition constituting the adhesive layer, acrylic adhesives and silicone adhesives are preferred, and among these, acrylic adhesives are preferred in terms of the ease of designing an adhesive to adjust the G'(100k) to 60MPa or less, transparency, tackiness, and cost of the adhesive layer of the present invention. In other words, the adhesive layer of the present invention is preferably an acrylic adhesive layer composed of an acrylic adhesive composition. The above adhesives can be used alone or in combination of two or more types.

[0080] The above acrylic adhesive composition contains an acrylic polymer as a base polymer. The above acrylic polymer is a polymer that contains an acrylic monomer (a monomer having a (meth)acryloyl group in the molecule) as a monomer component constituting the polymer. Preferably, the above acrylic polymer is a polymer that contains an alkyl (meth)acrylate as a monomer component constituting the polymer. The acrylic polymer can be used alone or in combination of two or more types.

[0081] The adhesive composition forming the adhesive layer of the present invention may be in any form. For example, the adhesive composition may be an emulsion type, a solvent type (solution type), an active energy ray curing type, a hot melt type, etc. Among these, solvent type and active energy ray curing type adhesive compositions are preferred from the viewpoint of productivity and ease of obtaining an adhesive layer with excellent optical properties and appearance. In particular, active energy ray curing type adhesive compositions are preferred from the viewpoint of absorbing the impact caused by collisions of electronic components before irradiation with active energy rays and suppressing displacement and inversion of electronic components, and from the viewpoint of exhibiting excellent heat resistance that can suppress expansion due to heating and outgassing during thermocompression bonding when transferring electronic components to the mounting substrate after irradiation with active energy rays.

[0082] In other words, the adhesive layer of the present invention is an acrylic adhesive layer containing an acrylic polymer as a base polymer, and is preferably formed by an active energy ray curable acrylic adhesive composition.

[0083] Examples of the active energy rays mentioned above include ionizing radiation such as alpha rays, beta rays, gamma rays, neutron rays, and electron beams, as well as ultraviolet rays, with ultraviolet rays being particularly preferred. In other words, the active energy ray curing type adhesive composition is preferably an ultraviolet-curing type adhesive composition.

[0084] Examples of adhesive compositions for forming the above-mentioned acrylic adhesive layer (acrylic adhesive compositions) include acrylic adhesive compositions comprising an acrylic polymer as an essential component, or acrylic adhesive compositions comprising a mixture of monomers constituting the acrylic polymer (sometimes referred to as a "monomer mixture") or a partially polymer thereof as an essential component. An example of the former is a so-called solvent-type acrylic adhesive composition. An example of the latter is a so-called active energy ray-curable acrylic adhesive composition. The above-mentioned "monomer mixture" means a mixture containing monomer components that constitute the polymer. The above-mentioned "partially polymerized product" may also be referred to as a "prepolymer," and means a composition in which one or more monomer components of the above-mentioned monomer mixture are partially polymerized.

[0085] The above acrylic polymer is a polymer composed (formed) using acrylic monomers as essential monomer components. Preferably, the above acrylic polymer is a polymer composed (formed) using alkyl (meth)acrylate as an essential monomer component. That is, it is preferable that the above acrylic polymer contains alkyl (meth)acrylate as a constituent unit. In this specification, "(meth)acrylic" means "acrylic" and / or "methacrylic" (either one or both of "acrylic" and "methacrylic"), and the same applies to other terms. The above acrylic polymer is composed of one or more monomer components.

[0086] Examples of the above acrylic adhesives include acrylic adhesives that use an acrylic polymer (homopolymer or copolymer) as a base polymer, in which one or more alkyl (meth)acrylate esters are used as monomer components. Specific examples of alkyl (meth)acrylate esters include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, and (meth) Examples of C1-20 alkyl esters of (meth)acrylate include nonyl acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate. Among these, alkyl esters of (meth)acrylate having a linear or branched alkyl group with 2 to 18 carbon atoms are preferably used. In the acrylic polymer, the content ratio of the constituent units of alkyl (meth)acrylate is preferably 70 to 100 parts by weight, more preferably 75 to 99.9 parts by weight, and even more preferably 80 to 99.9 parts by weight, per 100 parts by weight of the acrylic polymer.

[0087] The above acrylic polymer may, if necessary, contain constituent units derived from other monomers copolymerizable with the above alkyl (meth)acrylate, for purposes such as modifying cohesive strength, heat resistance, crosslinkability, and improving the dimensional stability of the adhesive layer. Examples of such monomers include the following monomers. Carboxylate-containing monomers: for example, ethylenically unsaturated monocarboxylic acids such as acrylic acid (AA), methacrylic acid (MAA), and crotonic acid; ethylenically unsaturated dicarboxylic acids such as maleic acid, itaconic acid, and citraconic acid, and their anhydrides (maleic anhydride, itaconic anhydride, etc.); Hydroxyl group-containing monomers: for example, hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 2-hydroxybutyl (meth)acrylate; unsaturated alcohols such as vinyl alcohol and allyl alcohol; ether compounds such as 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, and diethylene glycol monovinyl ether; Amino group-containing monomers: for example, aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, t-butylaminoethyl (meth)acrylate; Epoxy group-containing monomers: for example, glycidyl (meth)acrylate, methylglycidyl (meth)acrylate, allyl glycidyl ether; Cyano group-containing monomers: e.g., acrylonitrile, methacrylonitrile; Keto group-containing monomers: for example, diacetone (meth)acrylamide, diacetone (meth)acrylate, vinyl methyl ketone, vinyl ethyl ketone, allyl acetate, vinyl acetate; Monomers having a nitrogen atom-containing ring: for example, N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N-vinylmorpholine, N-vinylcaprolactam, N-(meth)acryloylmorpholine; Monomers containing alkoxysilyl groups: for example, 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane; Isocyanate group-containing monomers: (meth)acryloyl isocyanate, 2-(meth)acryloyloxyethyl isocyanate, m-isopropenyl-α,α-dimethylbenzyl isocyanate. These monomers may be used individually or in combination of two or more.

[0088] In one embodiment, the acrylic polymer preferably contains structural units derived from carboxyl group-containing monomers. The content of structural units derived from carboxyl group-containing monomers in the acrylic polymer is preferably 1 to 20 parts by weight, more preferably 2 to 15 parts by weight, and even more preferably 3 to 10 parts by weight, per 100 parts by weight of the acrylic polymer. In one embodiment, the acrylic polymer containing structural units derived from carboxyl group-containing monomers is preferably used in combination with an epoxy crosslinking agent described later. When an acrylic polymer containing structural units derived from carboxyl group-containing monomers is used in combination with an epoxy crosslinking agent, an adhesive layer with excellent heat resistance and dimensional stability at high temperatures can be formed. Furthermore, the combined use of the acrylic polymer and the epoxy crosslinking agent is also advantageous in that an adhesive layer with less expansion and outgassing can be formed during thermocompression bonding when transferring electronic components to a mounting substrate. These effects become more pronounced when the content of structural units derived from carboxyl group-containing monomers is within the above range.

[0089] In one embodiment, the acrylic polymer preferably contains structural units derived from hydroxyl group-containing monomers. The content of structural units derived from hydroxyl group-containing monomers in the acrylic polymer is preferably 0.01 to 10 parts by weight, more preferably 0.05 to 8 parts by weight, and even more preferably 0.1 to 5 parts by weight, per 100 parts by weight of the acrylic polymer. In one embodiment, the acrylic polymer containing structural units derived from hydroxyl group-containing monomers is preferably used in combination with an isocyanate-based crosslinking agent described later. Using an acrylic polymer containing structural units derived from hydroxyl group-containing monomers in combination with an isocyanate-based crosslinking agent is preferable because it can form an adhesive layer with excellent heat resistance and dimensional stability at high temperatures, and it can also suppress expansion and outgassing during thermocompression bonding when transferring electronic components to a mounting substrate. These effects become more pronounced when the content of structural units derived from hydroxyl group-containing monomers is within the above range.

[0090] Furthermore, other monomers copolymerizable with alkyl (meth)acrylates include, for example, polyfunctional monomers. Examples of these polyfunctional monomers include hexanediol di(meth)acrylate, butanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, allyl(meth)acrylate, vinyl(meth)acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, and urethane acrylate. Polyfunctional monomers can be used individually or in combination of two or more.

[0091] When the above-mentioned acrylic polymer contains the above-mentioned polyfunctional monomer as a monomer component constituting the polymer, the proportion of the above-mentioned polyfunctional monomer in the total monomer components (100% by weight) constituting the above-mentioned acrylic polymer is not particularly limited, but is preferably 5% by weight or less (for example, greater than 0% by weight and 5% by weight or less), more preferably 3% by weight or less (for example, greater than 0% by weight and 3% by weight or less), and particularly preferably 1% by weight or less (for example, greater than 0% by weight and 1% by weight or less).

[0092] While not particularly limited, the above-mentioned acrylic polymer preferably contains a monomer with a low glass transition temperature (Tg) when forming a homopolymer (hereinafter sometimes referred to as "low-Tg monomer") as a monomer component constituting the polymer. Using a low-Tg monomer as the monomer component is preferable from the viewpoint that the adhesive containing the acrylic polymer becomes softer, thereby controlling the above-mentioned properties of the adhesive layer of the present invention (especially shock absorption), absorbing the impact caused by collisions of electronic components, and suppressing displacement or inversion of electronic components.

[0093] The glass transition temperature when forming the homopolymer of the low-Tg monomer described above is not particularly limited, but is, for example, 0°C or lower, preferably -10°C or lower, and more preferably -20°C or lower. Having the Tg of the low-Tg monomer within this range improves the shock absorption properties of the adhesive layer.

[0094] The low-Tg monomers mentioned above may be the monomers exemplified as monomers included in the monomer components constituting the acrylic polymer, or they may be other monomers. In particular, it is preferable that the monomer components constituting the acrylic polymer include monomers exemplified as monomer components constituting the acrylic polymer, and that are low-Tg monomers. The low-Tg monomers may be one type or two or more types.

[0095] The low Tg monomers mentioned above are not particularly limited, but examples include 2-ethylhexyl acrylate (EHA, homopolymer Tg: -70°C), butyl acrylate (BA, homopolymer Tg: -55°C), ethyl acrylate (EA, homopolymer Tg: -24°C), lauryl methacrylate (LMA, homopolymer Tg: -65°C), lauryl acrylate (LA, homopolymer Tg: -23°C), and isononyl acrylate (iNAA, homopolymer Tg: -58°C), with 2-ethylhexyl acrylate, butyl acrylate, and lauryl methacrylate being preferred.

[0096] When the above acrylic polymer contains the low-Tg monomer as a monomer component constituting the polymer, the proportion of the low-Tg monomer in the total monomer components (100% by weight) constituting the acrylic polymer is not particularly limited, but is preferably 40% by weight or more, and may be 60% by weight or more, or 80% by weight or more. The upper limit of the proportion of low-Tg monomer is also not particularly limited, but may be 99% by weight or less, or 98% by weight or less. When the proportion of low-Tg monomer is within the above range, it is preferable from the viewpoint of controlling the above properties (especially shock absorption), absorbing the shock caused by collisions of electronic components, and suppressing displacement or inversion of electronic components. If the monomer components constituting the polymer contain two or more types of low-Tg monomers, the above "proportion of low-Tg monomers" is the sum of the proportions of the two or more types of low-Tg monomers.

[0097] The content of the base polymer (particularly acrylic polymer) in the adhesive layer of the present invention is not particularly limited, but is preferably 10% by weight or more (e.g., 10-100% by weight) based on 100% by weight of the total weight of the adhesive layer of the present invention, more preferably 15% by weight or more (e.g., 15-100% by weight), and even more preferably 20% by weight or more (e.g., 20-100% by weight).

[0098] The base polymer, such as the acrylic polymer described above, contained in the adhesive composition of the present invention is obtained by polymerizing monomer components. The polymerization method is not particularly limited, but examples include solution polymerization, emulsion polymerization, bulk polymerization, and polymerization by active energy ray irradiation (active energy ray polymerization). Among these, solution polymerization and active energy ray polymerization are preferred from the viewpoint of transparency of the adhesive layer and cost, and active energy ray polymerization is more preferred.

[0099] Furthermore, various common solvents may be used in the polymerization of the above monomer components. Examples of such solvents include esters such as ethyl acetate and n-butyl acetate; aromatic hydrocarbons such as toluene and benzene; aliphatic hydrocarbons such as n-hexane and n-heptane; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; and organic solvents such as ketones such as methyl ethyl ketone and methyl isobutyl ketone. The solvents can be used individually or in combination of two or more.

[0100] When polymerizing the above monomer components, polymerization initiators such as thermal polymerization initiators and photopolymerization initiators (photoinitiators) may be used depending on the type of polymerization reaction. Polymerization initiators can be used alone or in combination of two or more types.

[0101] The above-mentioned thermal polymerization initiators are not particularly limited, but examples include azo polymerization initiators, peroxide polymerization initiators (e.g., dibenzoyl peroxide, tert-butyl permaleate, etc.), and redox polymerization initiators. Among these, peroxide polymerization initiators are preferred. Examples of the above-mentioned azo polymerization initiators include 2,2'-azobisisobutyronitrile (hereinafter sometimes referred to as "AIBN"), 2,2'-azobis-2-methylbutyronitrile (hereinafter sometimes referred to as "AMBN"), 2,2'-azobis(2-methylpropionic acid)dimethyl, and 4,4'-azobis-4-cyanovaleric acid. The thermal polymerization initiators can be used alone or in combination of two or more.

[0102] The amount of the above-mentioned thermal polymerization initiator used is not particularly limited, but for example, it is preferably 0.05 parts by weight or more, more preferably 0.1 parts by weight or more, and more preferably 0.5 parts by weight or less, and more preferably 0.3 parts by weight or less, based on 100 parts by weight of the total monomer components constituting the acrylic polymer.

[0103] The above-mentioned photopolymerization initiators are not particularly limited, but examples include benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α-ketol-based photopolymerization initiators, aromatic sulfonyl chloride-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, ketal-based photopolymerization initiators, and thioxanthone-based photopolymerization initiators. Other examples include acylphosphine oxide-based photopolymerization initiators and titanocene-based photopolymerization initiators. Examples of the above-mentioned benzoin ether-based photopolymerization initiators include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethane-1-one, and anisole methyl ether. Examples of the above acetophenone-based photopolymerization initiators include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenyl ketone, 4-phenoxydichloroacetophenone, and 4-(t-butyl)dichloroacetophenone. Examples of the above α-ketol-based photopolymerization initiators include 2-methyl-2-hydroxypropiophenone and 1-[4-(2-hydroxyethyl)phenyl]-2-methylpropan-1-one. Examples of the above aromatic sulfonyl chloride-based photopolymerization initiators include 2-naphthalenesulfonyl chloride. Examples of the above photoactive oxime-based photopolymerization initiators include 1-phenyl-1,1-propanedione-2-(O-ethoxycarbonyl)-oxime. Examples of the above benzoin-based photopolymerization initiators include benzoin. Examples of the above benzyl-based photopolymerization initiators include benzyl. Examples of the benzophenone-based photopolymerization initiators include benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, and α-hydroxycyclohexylphenyl ketone. Examples of the ketal-based photopolymerization initiators include benzyldimethyl ketal.Examples of the thioxanthone-based photopolymerization initiators include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, and dodecylthioxanthone. Examples of the acylphosphine oxide-based photopolymerization initiators include 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide. Examples of the titanocene-based photopolymerization initiators include bis(η. 5 Examples include -2,4-cyclopentadiene-1-yl)-bis(2,6-difluoro-3-(1H-pyrrole-1-yl)-phenyl)titanium. The photopolymerization initiator can be used alone or in combination of two or more.

[0104] When the above-mentioned photopolymerization initiator is used during the polymerization of the above-mentioned acrylic polymer, the amount of the photopolymerization initiator used is not particularly limited, but for example, it is preferably 0.01 parts by weight or more, more preferably 0.1 parts by weight or more, and preferably 3 parts by weight or less, and more preferably 1.5 parts by weight or less, per 100 parts by weight of the total monomer components constituting the above-mentioned acrylic polymer.

[0105] The resin composition (adhesive composition) of the present invention contains an active energy ray-curable compound. The configuration of the resin composition of the present invention, which contains an active energy ray-curable compound, is preferable because, before irradiation with active energy rays, the adhesive layer of the present invention exhibits excellent shock absorption properties, and after irradiation with active energy rays, the elastic modulus of the adhesive layer of the present invention is improved by the formation of a crosslinked structure due to the reaction of the active energy ray-curable compound, thereby exhibiting excellent heat resistance that can suppress expansion and outgassing during thermocompression bonding when transferring electronic components to a mounting substrate.

[0106] In the resin composition of the present invention, the active energy ray curable compound is preferably a polyfunctional monomer and / or a polyfunctional oligomer. The configuration in which the active energy ray curable compound of the present invention is a polyfunctional monomer and / or a polyfunctional oligomer is preferable because the elastic modulus of the adhesive layer is higher due to the formation of a crosslinked structure by multiple reactive functional groups, and it exhibits superior heat resistance that can suppress expansion and outgassing during thermocompression bonding when transferring electronic components to a mounting substrate.

[0107] In the resin composition of the present invention, the active energy ray-curable compound preferably has three or more reactive functional groups. The configuration in which the active energy ray-curable compound has three or more reactive functional groups is preferable because the elastic modulus of the adhesive layer is further increased by the formation of a three-dimensional crosslinked structure by the three or more reactive functional groups, and it exhibits even better heat resistance, which can suppress the generation of expansion and outgassing during thermocompression bonding when transferring electronic components to a mounting substrate. From the viewpoint of exhibiting even better heat resistance, the number of reactive functional groups is more preferably four or more, even more preferably five or more, and may be six or more, seven or more, eight or more, nine or more, or ten or more.

[0108] In the resin composition of the present invention, the molecular weight of the active energy ray-curable compound is preferably less than 20,000. The configuration in which the molecular weight of the active energy ray-curable compound is less than 20,000 is preferable because it imparts flexibility to the adhesive layer of the present invention before irradiation with active energy rays, adjusts the G'(100k) to 60 MPa or less, and provides excellent shock absorption when the adhesive layer of the present invention is used as a shock absorption layer for a transfer substrate. From the viewpoint of achieving even better shock absorption of the adhesive layer of the present invention before irradiation with active energy rays, the molecular weight of the active energy ray-curable compound of the present invention is more preferably 10,000 or less, even more preferably 3,000 or less, and may be 1,500 or less. The molecular weight of the active energy ray-curable compound of the present invention is not particularly limited, but is preferably 100 or more, and may be 200 or more. Furthermore, if the active energy ray-curable compound of the present invention is a polymer (oligomer), the molecular weight shall include the weight-average molecular weight (Mw).

[0109] The softening point of the active energy ray-curable compound of the present invention is not particularly limited, but is more preferably -28°C or lower, and even more preferably -34°C or lower, in that it enables better shock absorption when the adhesive layer of the present invention is used as a shock absorption layer for a transfer substrate before irradiation with active energy rays. The melting point of the active energy ray-curable compound of the present invention is not particularly limited, but is preferably -140°C or higher, and may be -120°C or higher. The aforementioned "softening point" is the temperature at which a material such as glass or resin begins to deform as its temperature rises, and is specifically measured by the method described in the examples below. Furthermore, if a low softening point compound is contained in the adhesive layer, the softening point can also be measured by extracting the compound using an organic solvent that dissolves it (for example, a polar solvent such as THF (tetrahydrofuran)), and then allowing the polar solvent to evaporate completely to prepare an evaluation sample.

[0110] The softening point of the active energy ray curable compound of the present invention can be measured, for example, by the following method. Approximately 5.0 mg of the compound sample is placed in a Φ4.0 mm aluminum pan to obtain a sheet of the evaluation sample. If the compound sample is diluted with an organic solvent, the evaluation sample is prepared by allowing it to evaporate completely at a temperature above the boiling point of the organic solvent. The evaluation sample sheet obtained above is set in a TMA Q400 (manufactured by TA-instrument Co., Ltd.), and using a Φ3.0 mm probe, the thickness reduction of the evaluation sample sheet is measured while heating under the following conditions: nitrogen gas flow rate: 50.0 ml / min, indentation load: 0.01 N, measurement ambient temperature range: -75℃ to 40℃, heating rate: 3℃ / min, in needle insertion mode. From the obtained data, the temperature at which the thickness reduction is 10% is extracted and defined as the softening point (10% heat distortion temperature).

[0111] As the aforementioned polyfunctional monomer, polyfunctional (meth)acrylate monomers with a molecular weight of less than 1000 are preferred. Examples of polyfunctional (meth)acrylate monomers include trifunctional monomers such as trimethylolpropane tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, propionic acid-modified dipentaerythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propylene oxide-modified trimethylolpropane tri(meth)acrylate, and tris(acryloyloxyethyl) isocyanurate; tetrafunctional monomers such as diglycerin tetra(meth)acrylate and pentaerythritol tetra(meth)acrylate; pentafunctional monomers such as propionic acid-modified dipentaerythritol penta(meth)acrylate; and hexafunctional monomers such as dipentaerythritol hexa(meth)acrylate and caprolactone-modified dipentaerythritol hexa(meth)acrylate. These may be used individually or in combination of two or more types.

[0112] Examples of the polyfunctional oligomers include polyester acrylate, epoxy acrylate, urethane acrylate, polyether acrylate, polybutadiene acrylate, and silicone acrylate oligomers. These may be used individually or in combination of two or more.

[0113] The weight-average molecular weight (Mw) of the polyfunctional oligomer is preferably less than 20,000, more preferably 10,000 or less, even more preferably 3,000 or less, or 1,500 or less, from the viewpoint of achieving better shock absorption of the adhesive layer of the present invention before irradiation with active energy rays. Furthermore, the weight-average molecular weight (Mw) of the polyfunctional oligomer is preferably 100 or more, and may be 200 or more.

[0114] When the resin composition of the present invention contains an active energy ray-curable compound, the amount thereof is not particularly limited, but in order for the adhesive layer of the present invention to exhibit excellent shock absorption before irradiation with active energy rays and excellent heat resistance after irradiation with active energy rays, it is preferably 10 parts by weight or more, more preferably 20 parts by weight or more, even more preferably 30 parts by weight or more, and also preferably 1000 parts by weight or less, and more preferably 500 parts by weight or less, per 100 parts by weight of the total monomer components constituting the acrylic polymer.

[0115] The resin composition (adhesive composition) of the present invention preferably contains a crosslinking agent. The resin composition of the present invention is preferable because it contains a crosslinking agent, which allows for the formation of an appropriate crosslinked structure in the adhesive layer, providing excellent processability and suppressing misalignment when receiving electronic components. It is also advantageous because it has excellent heat resistance, and when thermocompressing electronic components to a mounting substrate, it can form an adhesive layer with less expansion and outgassing. The crosslinking agent can be used alone or in combination of two or more types.

[0116] The above-mentioned crosslinking agents are not particularly limited, but examples include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, melamine-based crosslinking agents, peroxide-based crosslinking agents, urea-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, carbodiimide-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, and amine-based crosslinking agents. Among these, isocyanate-based crosslinking agents and epoxy-based crosslinking agents are preferred, and epoxy-based crosslinking agents are more preferred.

[0117] Examples of the above-mentioned isocyanate-based crosslinking agents (polyfunctional isocyanate compounds) include lower aliphatic polyisocyanates such as 1,2-ethylene diisocyanate, 1,4-butylene diisocyanate, and 1,6-hexamethylene diisocyanate; alicyclic polyisocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, and hydrogenated xylene diisocyanate; and aromatic polyisocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and xylylene diisocyanate. In addition, commercially available isocyanate-based crosslinking agents include, for example, trimethylolpropane / tolylene diisocyanate adduct (product name "Coronate L", manufactured by Nippon Polyurethane Industry Co., Ltd.), trimethylolpropane / hexamethylene diisocyanate adduct (product name "Coronate HL", manufactured by Nippon Polyurethane Industry Co., Ltd.), trimethylolpropane / xylylene diisocyanate adduct (product name "Takenate D-110N", manufactured by Mitsui Chemicals, Inc.), and toluene diisocyanate adduct (product name "Takenate D-101A", manufactured by Mitsui Chemicals, Inc.).

[0118] Examples of the epoxy crosslinking agents (polyfunctional epoxy compounds) mentioned above include N,N,N',N'-tetraglycidyl-m-xylenediline, 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 epoxy crosslinking agents include diglycidyl ethers, glycerol polyglycidyl ethers, pentaerythritol polyglycidyl ethers, polyglycerol polyglycidyl ethers, sorbitan polyglycidyl ethers, trimethylolpropane polyglycidyl ethers, diglycidyl adipate esters, diglycidyl o-phthalate esters, triglycidyl-tris(2-hydroxyethyl) isocyanurate, resorcinol diglycidyl ethers, bisphenol-S-diglycidyl ethers, and epoxy resins having two or more epoxy groups in their molecules. In addition, commercially available epoxy crosslinking agents such as the trade name "Tetrad C" (manufactured by Mitsubishi Gas Chemical Company, Inc.) can also be used.

[0119] When the acrylic adhesive composition contains a crosslinking agent, the amount of the crosslinking agent used is not particularly limited. However, from the viewpoint of forming an appropriate crosslinked structure in the adhesive layer, adjusting the G'(100k) to 60 MPa or less, and preventing misalignment of electronic components when the adhesive layer of the present invention is used as an impact absorption layer for a transfer substrate, and from the viewpoint of forming an adhesive layer with excellent heat resistance and less expansion and outgassing during thermocompression bonding when transferring electronic components to a mounting substrate, the amount of the crosslinking agent is preferably 0.5 parts by weight or more, more preferably 1.0 part by weight or more, and even more preferably 1.5 parts by weight or more, per 100 parts by weight of the base polymer. Furthermore, from the viewpoint of obtaining appropriate flexibility in the adhesive layer and improving adhesive strength, the upper limit of the amount used is preferably 10 parts by weight or less, and more preferably 5 parts by weight or less, per 100 parts by weight of the base polymer.

[0120] The acrylic adhesive composition of the present invention is not particularly limited, but 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, a crosslinking accelerator refers to a catalyst that increases the rate of the crosslinking reaction by the crosslinking agent. Examples of such crosslinking accelerators include tin (Sn)-containing compounds such as dioctyl tin dilaurate, dibutyl tin dilaurate, dibutyl tin diacetate, dibutyl tin diacetylacetonate, tetra-n-butyl tin, and trimethyl tin 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 sub-monomer and an isocyanate-based crosslinking agent is used as the crosslinking agent. The amount of crosslinking accelerator contained in the above 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) per 100 parts by mass of the acrylic polymer.

[0121] The adhesive layer of the present invention may be an adhesive layer whose adhesive strength can be intentionally reduced by external forces (adhesive strength reduction type adhesive layer), or it may be an adhesive layer whose adhesive strength is hardly or not reduced at all by external forces (adhesive strength non-reduction type adhesive layer), and can be appropriately selected depending on the method and conditions for mounting electronic components.

[0122] When the adhesive layer of the present invention is a type of adhesive layer whose adhesive strength can be reduced, it becomes possible to use the adhesive layer of the present invention in a state where it exhibits relatively high adhesive strength and a state where it exhibits relatively low adhesive strength. For example, in the process in which the adhesive layer of the present invention receives (transfers) electronic components, by utilizing the state in which the adhesive layer of the present invention exhibits relatively high adhesive strength, the impact caused by collisions with the adhesive layer by electronic components can be sufficiently absorbed, and displacement or inversion due to the bouncing of electronic components during collisions can be suppressed. On the other hand, in the subsequent process of transferring the received electronic components to the mounting substrate, by reducing the adhesive strength of the adhesive layer of the present invention, it is possible to improve transferability (transferability) and suppress adhesive residue on electronic components.

[0123] Examples of adhesives that can form such a tack-reducing adhesive layer include radiation-curable adhesives and heat-foaming adhesives, with radiation-curable adhesives being preferred in terms of ease of handling. In other words, the adhesive layer of the present invention is preferably formed from a radiation-curable adhesive. One type of adhesive may be used to form the tack-reducing adhesive layer, or two or more types of adhesives may be used.

[0124] As the above-mentioned radiation-curable adhesive, for example, an adhesive that hardens upon irradiation with electron beams, ultraviolet rays, alpha rays, beta rays, gamma rays, or X-rays can be used, and an adhesive that hardens upon irradiation with ultraviolet rays (ultraviolet-curable adhesive) can be used in particular preference.

[0125] The above-mentioned radiation-curable adhesives also include intrinsically charged radiation-curable adhesives containing a base polymer having radiation-polymerizable functional groups such as carbon-carbon double bonds in the polymer side chains, polymer main chain, or polymer main chain ends. Using such intrinsically charged radiation-curable adhesives tends to suppress unintended changes in adhesive properties over time caused by the movement of low molecular weight components within the formed adhesive layer.

[0126] As the base polymer contained in the above-mentioned intrinsically charged radiation-curable adhesive, an acrylic polymer is preferred. As a method for introducing a radiation-polymerizable carbon-carbon double bond into an acrylic polymer, for example, an acrylic polymer is obtained by polymerizing (copolymerizing) a raw material monomer containing a monomer component having a first functional group, and then a compound having a second functional group that can react with the first functional group and a radiation-polymerizable carbon-carbon double bond is subjected to a condensation or addition reaction with the acrylic polymer while maintaining the radiation polymerizability of the carbon-carbon double bond.

[0127] Examples of combinations of the first functional group and the second functional group include carboxyl group and epoxy group, epoxy group and carboxyl group, carboxyl group and aziridyl group, aziridyl group and carboxyl group, hydroxyl group and isocyanate group, and isocyanate group and hydroxyl group. Among these, from the viewpoint of ease of reaction tracking, combinations of hydroxyl group and isocyanate group, and combinations of isocyanate group and hydroxyl group are preferred. In particular, producing polymers having highly reactive isocyanate groups is technically difficult, while from the viewpoint of ease of production and acquisition of acrylic polymers having hydroxyl groups, a combination in which the first functional group is a hydroxyl group and the second functional group is an isocyanate group is preferred. Examples of compounds having an isocyanate group and a radioactively polymerizable carbon-carbon double bond, i.e., radioactively polymerizable unsaturated functional group-containing isocyanate compounds, include methacryloyl isocyanate, 2-methacryloyloxyethyl isocyanate, and m-isopropenyl-α,α-dimethylbenzyl isocyanate. Furthermore, examples of acrylic polymers having hydroxyl groups include those containing the above-mentioned hydroxyl group-containing monomers, as well as constituent units derived from ether compounds such as 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, and diethylene glycol monovinyl ether.

[0128] When using the above-mentioned radiation-polymerizable unsaturated functional group-containing isocyanate compound, the content of the above-mentioned radiation-polymerizable unsaturated functional group-containing isocyanate compound in the radiation-curable adhesive forming the adhesive layer of the present invention is, for example, 5 to 100 parts by mass, preferably 7 to 50 parts by mass, per 100 parts by mass of the base polymer.

[0129] The above radiation-curable adhesive preferably contains a photopolymerization initiator. Examples of the above 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 above α-ketol compounds include 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone, α-hydroxy-α,α'-dimethylacetophenone, 2-methyl-2-hydroxypropiophenone, 1-hydroxycyclohexylphenyl ketone, and 2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methylpropan-1-one. Examples of the above acetophenone compounds include methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, and 2-methyl-1-[4-(methylthio)-phenyl]-2-morpholinopropane-1. Examples of the above benzoin ether compounds include benzoin ethyl ether, benzoin isopropyl ether, and anisoin methyl ether. Examples of the above ketal compounds include benzyldimethyl ketal. Examples of the above aromatic sulfonyl chloride compounds include 2-naphthalenesulfonyl chloride. Examples of the above photoactive oxime compounds include 1-phenyl-1,2-propanedione-2-(O-ethoxycarbonyl)oxime. Examples of the above benzophenone compounds include benzophenone, benzoylbenzoic acid, and 3,3'-dimethyl-4-methoxybenzophenone. Examples of the thioxanthone compounds mentioned above include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, and 2,4-diisopropylthioxanthone.The amount of 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.

[0130] The above-mentioned heat-foaming adhesive is an adhesive containing components (foaming agents, thermally expandable microspheres, etc.) that foam or expand upon heating. Examples of the foaming agents include various inorganic and organic foaming agents. Examples of the inorganic foaming agents include ammonium carbonate, ammonium bicarbonate, sodium bicarbonate, ammonium nitrite, sodium borohydride, and azides. Examples of the above-mentioned organic blowing agents include salt fluoride alkanes such as trichloromonofluoromethane and dichloromonofluoromethane; azo compounds such as azobisisobutyronitrile, azodicarbonamide, and barium azodicarboxylate; hydrazine compounds such as p-toluenesulfonyl hydrazide, diphenylsulfon-3,3'-disulfonyl hydrazide, 4,4'-oxybis(benzenesulfonyl hydrazide), and allylbis(sulfonyl hydrazide); semicarbazide compounds such as p-toluenesulfonyl semicarbazide and 4,4'-oxybis(benzenesulfonyl semicarbazide); 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'-dinitrosotelephthalamide. Examples of the above-mentioned thermally expandable microspheres include microspheres in which a substance that readily gasifies and expands upon heating is enclosed within the shell. Examples of substances that readily gasifies and expand upon heating include isobutane, propane, and pentane. Thermally expandable microspheres can be produced by enclosing a substance that readily gasifies and expands upon heating within a shell-forming material using methods such as coacervation or interfacial polymerization. As the shell-forming material, substances that exhibit thermal fusion or substances that can rupture due to the thermal expansion of the enclosed material can be used. Examples of such substances include vinylidene chloride-acrylonitrile copolymer, polyvinyl alcohol, polyvinyl butyral, polymethyl methacrylate, polyacrylonitrile, polyvinylidene chloride, and polysulfone.

[0131] Examples of the non-reducing adhesive layer include a pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer includes an adhesive layer formed from a radiation-curable adhesive (as described above) that has been pre-cured by radiation while maintaining a certain level of adhesion. One type of adhesive may be used to form the non-reducing adhesive layer, or two or more types of adhesives may be used. Furthermore, the entire adhesive layer of the present invention may be a non-reducing adhesive layer, or only a portion of it may be a non-reducing adhesive layer. For example, if the adhesive layer of the present invention has a single-layer structure, the entire adhesive layer may be a non-reducing adhesive layer, or a specific portion of the adhesive layer may be a non-reducing adhesive layer while other portions are adhesive layers capable of reducing adhesion. Also, if the adhesive layer of the present invention has a laminated structure, all adhesive layers in the laminated structure may be non-reducing adhesive layers, or some adhesive layers in the laminated structure may be non-reducing adhesive layers.

[0132] An adhesive layer formed from a radiation-curable adhesive (a radiation-curable adhesive layer that has not been irradiated) and then cured in advance by radiation (a radiation-irradiated radiation-curable adhesive layer) exhibits tackiness due to the polymer components it contains, even if its tackiness is reduced by radiation, and is capable of exhibiting the minimum tackiness required for the adhesive layer of the present invention. When using a radiation-irradiated radiation-curable adhesive layer, the entire adhesive layer of the present invention may be a radiation-irradiated radiation-curable adhesive layer in the direction of surface expansion of the adhesive layer of the present invention, or a part of the adhesive layer of the present invention may be a radiation-irradiated radiation-curable adhesive layer and the other part may be a radiation-curable adhesive layer that has not been irradiated. In this specification, "radiation-curable adhesive layer" refers to an adhesive layer formed from a radiation-curable adhesive, and includes both a radiation-curable unirradiated radiation-curable adhesive layer and a radiation-cured radiation-curable adhesive layer that has been cured by radiation.

[0133] As the adhesive forming the pressure-sensitive adhesive layer described above, known or conventional pressure-sensitive adhesives can be used, and acrylic adhesives with an acrylic polymer as the base polymer are preferably used. When the adhesive layer of the present invention contains an acrylic polymer as a pressure-sensitive adhesive, it is preferable that the acrylic polymer is a polymer that contains (meth)acrylic acid ester-derived constituent units as the most abundant constituent units by mass. As the acrylic polymer described above, for example, an acrylic polymer described as an acrylic polymer that can be included in the additive-type radiation-curable adhesive described above can be used.

[0134] The silicone adhesive described above is not particularly limited, and known or conventional silicone adhesives can be used, such as addition-type silicone adhesives, peroxide-curing type silicone adhesives, and condensation-type silicone adhesives. The silicone adhesive may be one-component or two-component. The silicone adhesive can be used alone or in combination of two or more types.

[0135] The aforementioned addition-type silicone adhesives are adhesives that produce a silicone polymer by an 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. Peroxide-curing type silicone adhesives are adhesives that produce a silicone polymer by curing (crosslinking) an organopolysiloxane with a peroxide. Furthermore, condensation-type silicone adhesives are adhesives that produce a silicone polymer by a dehydration or dealcoholization reaction between polyorganosiloxanes having hydrolyzable silyl groups such as silanol groups or alkoxysilyl groups at their ends.

[0136] As a silicone-based adhesive, one example is a silicone-based adhesive composition containing silicone rubber and silicone resin, which offers a high level of control over the balance between low tackiness and low adhesiveness, the shock absorption of the adhesive layer on an optical time scale, and excellent heat resistance that suppresses expansion and outgassing during thermocompression bonding when transferring electronic components to a mounting substrate. This allows for both excellent shock absorption and heat resistance when the adhesive layer of the present invention is used as a shock absorption layer for a transfer substrate.

[0137] The silicone rubber is not particularly limited as long as it is a silicone-based rubber component, but for example, organopolysiloxanes mainly composed of dimethylsiloxane, methylphenylsiloxane, etc. can be used. Depending on the type of reaction, silicone rubber having alkenyl groups bonded to silicon atoms (alkenyl group-containing organopolysiloxane; in the case of addition reaction), silicone rubber having at least methyl groups (in the case of peroxide curing), and silicone rubber having silanol groups or hydrolyzable alkoxysilyl groups at the ends (in the case of condensation) can be used. The weight-average molecular weight of organopolysiloxane in silicone rubber is usually 150,000 or more, but is preferably 280,000 to 1,000,000, and particularly preferably 500,000 to 900,000.

[0138] Furthermore, the silicone resin is not particularly limited as long as it is a silicone-based resin used in silicone-based adhesives, for example, the constituent unit "R3Si 1 / 2 The M unit consists of the constituent unit "SiO2", the Q unit consists of the constituent unit "RSiO2", and the constituent unit "RSiO 3 / 2Examples include silicone resins made of organopolysiloxanes composed of a (co)polymer having at least one unit selected from T units consisting of "" and D units consisting of the constituent unit "R2SiO". In the constituent unit, R represents a hydrocarbon group or a hydroxyl group. Examples of the hydrocarbon group include aliphatic hydrocarbon groups (alkyl groups such as methyl and ethyl groups), alicyclic hydrocarbon groups (cycloalkyl groups such as cyclohexyl groups), and aromatic hydrocarbon groups (aryl groups such as phenyl and naphthyl groups). The ratio of the M unit to at least one unit selected from the Q, T, and D units is preferably about 0.3 / 1 to 1.5 / 1 (preferably 0.5 / 1 to 1.3 / 1). Various functional groups such as vinyl groups may be introduced into the organopolysiloxane in such silicone resins as needed. The introduced functional groups may be functional groups capable of crosslinking reactions. As the silicone resin, MQ resin consisting of M units and Q units is preferred. The weight-average molecular weight of the organopolysiloxane in the silicone resin is usually 1000 or more, but is preferably 1000 to 20000, and particularly preferably 1500 to 10000.

[0139] While there are no particular restrictions on the mixing ratio of silicone rubber to silicone resin, it is preferable, for example, that the ratio of silicone resin is 100 to 220 parts by weight (particularly 120 to 180 parts by weight) per 100 parts by weight of silicone rubber, as this makes it easier to control low tackiness and low adhesiveness.

[0140] In a silicone-based adhesive composition containing silicone rubber and silicone resin, the silicone rubber and silicone resin may simply be in a mixed state, or they may react with each other to form condensates (especially partial condensates), crosslinked products, addition reaction products, etc.

[0141] As addition-type silicone adhesives, for example, the following are commercially available: product names "SD4580", "SD4584", "SD4585", "SD4587L", "SD4560", "SD4570", "SD4600FC", "SD4593", and "SE1700" (all manufactured by Dow Toray Industries, Inc.); and product 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.). Furthermore, peroxide-curing silicone adhesives such as "KR-100," "KR-101-10," and "KR-130" (all manufactured by Shin-Etsu Chemical Co., Ltd.) are commercially available.

[0142] A silicone-based adhesive composition containing silicone rubber and silicone resin is preferable because it allows for easy control of low tackiness and low adhesiveness, provides excellent shock absorption of the adhesive layer on an optical time scale, and offers superior heat resistance that suppresses expansion and outgassing during thermocompression bonding when transferring electronic components to a mounting substrate. This allows for both excellent shock absorption and heat resistance when using the adhesive layer of the present invention as a shock absorption layer for a transfer substrate. In addition to the shock absorption of the silicone-based adhesive, crosslinking the silicone rubber and silicone resin in the silicone-based adhesive layer provides excellent heat resistance that suppresses expansion and outgassing during thermocompression bonding when transferring electronic components to a mounting substrate, thus providing excellent heat resistance when using the adhesive layer of the present invention as a shock absorption layer for a transfer substrate. While there are no particular limitations on the crosslinking agent, siloxane-based crosslinking agents (silicone-based crosslinking agents) and peroxide-based crosslinking agents can be suitably used. Among these, siloxane-based crosslinking agents are preferred. Crosslinking agents can be used individually or in combination of two or more types.

[0143] 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 a polyorganohydrogensiloxane, various organic groups other than hydrogen atoms may be bonded to the silicon atoms to which the hydrogen atoms are bonded. Examples of such organic groups include alkyl groups such as methyl groups and ethyl groups; aryl groups such as phenyl groups; and alkyl halides, but from the viewpoint of synthesis and handling, methyl groups are preferred. Furthermore, the skeletal structure of the polyorganohydrogensiloxane may be linear, branched, or cyclic, but a linear structure is preferred.

[0144] Examples of peroxide-based crosslinking agents include diacyl peroxide, alkyl peroxyester, peroxydicarbonate, monoperoxycarbonate, peroxyketal, dialkyl peroxide, hydroperoxide, and ketone peroxide. More specifically, examples include benzoyl peroxide, t-butyl peroxybenzoate, dicumyl peroxide, t-butylcumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di-t-butyl peroxyhexane, 2,4-dichlorobenzoyl peroxide, di-t-butyl peroxydiisopropylbenzene, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, and 2,5-dimethyl-2,5-di-t-butyl peroxyhexyn-3.

[0145] Examples of siloxane-based crosslinking agents that are commercially available include the trade names "BY24-741" and "SE1700Catalyst" (both manufactured by Dow Toray Industries, Inc.); and "X-92-122" (both manufactured by Shin-Etsu Chemical Co., Ltd.).

[0146] When a silicone-based adhesive composition contains a crosslinking agent, the amount of the crosslinking agent used is not particularly limited, but from the viewpoint of controlling low tackiness and low adhesiveness to suppress detachment and displacement of electronic components during transport, and from the viewpoint of achieving both excellent shock absorption and heat resistance, it is preferably 0.5 parts by weight or more, more preferably 0.7 parts by weight or more, and even more preferably 1 part by weight or more, per 100 parts by weight of the base polymer. Furthermore, the upper limit of the amount used is preferably 10 parts by weight or less, and more preferably 5 parts by weight or less, per 100 parts by weight of the base polymer, from the viewpoint of obtaining appropriate flexibility in the adhesive layer and improving adhesive strength.

[0147] The addition-type silicone adhesive composition preferably contains a curing catalyst such as a platinum catalyst. Examples of commercially available platinum catalysts include "CAT-PL-50T" (manufactured by Shin-Etsu Chemical Co., Ltd.), "DOWSIL NC-25 Catalyst," or "DOWSIL SRX212 Catalyst" (both manufactured by Dow-Toray Industries, Inc.). From the viewpoint of balancing the adhesive layer's ability to accept electronic components, positional accuracy, transferability to the mounting substrate, and tack strength, the curing catalyst content is preferably about 0.1 to 10 parts by weight per 100 parts by weight of the silicone polymer (including silicone rubber, silicone resin, etc.) used as the base polymer.

[0148] The resin composition of the present invention may optionally further contain additives such as tackifying resins (rosin derivatives, polyterpene resins, petroleum resins, oil-soluble phenols, etc.), antioxidants, fillers, colorants (pigments, dyes, etc.), UV absorbers, antioxidants, chain transfer agents, plasticizers, softeners, surfactants, and antistatic agents, to the extent that they do not impair the effects of the present invention. Such additives can be used individually or in combination of two or more.

[0149] The method for producing the adhesive layer (particularly the acrylic adhesive layer) of the present invention is not particularly limited, but examples include applying the resin composition onto a substrate or release liner and drying and curing the resulting adhesive composition layer, or applying the resin composition onto a substrate or release liner and curing the resulting adhesive composition layer by irradiating it with active energy rays. Furthermore, if necessary, it may be further heated and dried.

[0150] Examples of the active energy rays mentioned above include ionizing radiation such as alpha rays, beta rays, gamma rays, neutron rays, and electron beams, as well as ultraviolet rays, with ultraviolet rays being particularly preferred. Furthermore, there are no particular limitations on the irradiation energy, irradiation time, or irradiation method of the active energy rays.

[0151] The above resin compositions can be prepared by known or conventional methods. For example, a solvent-type acrylic adhesive composition can be prepared by mixing an additive (e.g., an ultraviolet absorber) as needed with a solution containing the above acrylic polymer. For example, an active energy ray-curable acrylic adhesive composition can be prepared by mixing an additive (e.g., an ultraviolet absorber) as needed with a mixture of the above acrylic monomers or a partial polymer thereof.

[0152] Furthermore, known coating methods may be used for applying (coating) the above resin composition. For example, coaters such as gravure roll coaters, reverse roll coaters, kiss roll coaters, dip roll coaters, bar coaters, knife coaters, spray coaters, comma coaters, and direct coaters may be used.

[0153] In particular, when forming an adhesive layer with an active energy ray-curable adhesive composition, it is preferable that the active energy ray-curable adhesive composition contains a photopolymerization initiator. Furthermore, if the active energy ray-curable adhesive composition contains an ultraviolet absorber, it is preferable that it contains at least a photopolymerization initiator having absorption properties over a wide wavelength range. For example, it is preferable to contain at least a photopolymerization initiator that has absorption properties not only for ultraviolet light but also for visible light. This is because there is a concern that curing by active energy rays may be inhibited by the action of the ultraviolet absorber, and if a photopolymerization initiator having absorption properties over a wide wavelength range is included, it becomes easier to obtain high photocurability in the adhesive composition.

[0154] (Removable liner) The adhesive surface of the adhesive layer of the present invention and / or another adhesive layer may be protected by a release liner until use. When the adhesive layer of the present invention constitutes a double-sided adhesive sheet, each adhesive surface may be protected by two release liners, or it may be protected in a roll-like form (winding body) by a single release liner with both sides being release surfaces. The release liner is used as a protective material for the shock absorption and adhesiveness of the adhesive layer and is peeled off when used. Furthermore, when the adhesive layer of the present invention constitutes a substrate-less adhesive sheet, the release liner also plays a role as a support for the adhesive layer.

[0155] The above-mentioned release liner can be conventional release paper or the like, and is not particularly limited, but examples include a substrate having a release layer. Examples of substrates having a release layer include plastic films and paper that have been surface-treated with release agents such as silicone-based, long-chain alkyl-based, and fluorine-based agents.

[0156] Silicone-based release agents include known silicone-based release agents such as addition reaction type, condensation reaction type, cationic polymerization type, and radical polymerization type. Examples of commercially available addition reaction type silicone-based release agents include KS-776A, KS-847T, KS-779H, KS-837, KS-778, KS-830 (manufactured by Shin-Etsu Chemical Co., Ltd.), SRX-211, SRX-345, SRX-357, SD7333, SD7220, SD7223, LTC-300B, LTC-350G, and LTC-310 (manufactured by Dow Toray Industries, Inc.). Examples of commercially available condensation reaction type products include SRX-290 and SYLOFF-23 (manufactured by Dow Toray Industries, Inc.). Examples of commercially available cationic polymerization type products include TPR-6501, TPR-6500, UV9300, VU9315, UV9430 (manufactured by Momentive Performance Materials), and X62-7622 (manufactured by Shin-Etsu Chemical Co., Ltd.). Examples of commercially available radical polymerization type products include X62-7205 (manufactured by Shin-Etsu Chemical Co., Ltd.). Furthermore, silicone resin (R3SiO) can be added to these release agents to adjust their release performance. 1 / 2 Units and SiO 4 / 2 Silicon resin (composed of units), silica, ethylcellulose, etc. may also be added.

[0157] Examples of long-chain alkyl group release agents include known long-chain alkyl-based release agents such as long-chain alkyl group-containing amino alkyd resins, long-chain alkyl group-containing acrylic resins, and long-chain aliphatic pendant-type resins (reaction products of at least one active hydrogen-containing polymer selected from the group of compounds consisting of polyvinyl alcohol, ethylene / vinyl alcohol copolymers, polyethyleneimine, and hydroxyl group-containing cellulose derivatives, and long-chain alkyl group-containing isocyanates). Release agents may be those that undergo a curing reaction by adding a curing agent and an ultraviolet initiator, or release agents that solidify by volatilizing a solvent.

[0158] As for the "long-chain alkyl group," alkyl groups with 8 to 30 carbon atoms are preferred, but groups with 10 or more carbon atoms, 12 or more carbon atoms, 18 or less carbon atoms, 24 or less carbon atoms are also acceptable, and linear alkyl groups are preferred among them. Specific examples include one or more alkyl groups selected from decyl group, undecyl group, lauryl group, dodecyl group, tridecyl group, myristyl group, tetradecyl group, pentadecyl group, cetyl group, palmityl group, hexadecyl group, heptadecyl group, stearyl group, octadecyl group, nonadecyl group, icosyl group, docosyl group, etc.

[0159] Examples of commercially available long-chain alkyl-based stripping agents include Asio Industries Ltd.'s Asioresin® RA-30, Ipposha Oil & Fat Industry Co., Ltd.'s P-Royl® 1010, P-Royl 1010S, P-Royl 1050, P-Royl HT, Chukyo Oil & Fat Co., Ltd.'s Rezem N-137, Kao Corporation's Exepearl® PS-MA, and Hitachi Chemical Co., Ltd.'s Tesfine® 303.

[0160] Examples of fluorine-based release agents include perfluoroalkyl group-containing vinyl ether polymers and coating agents in which fluororesins such as tetrafluoroethylene and trifluoroethylene are dispersed in a binder resin.

[0161] The release agent may contain, if necessary, an antistatic agent, a silane coupling agent, a lubricant, etc. Forming a release agent layer on the surface of plastic film or paper can be done by known methods. Specifically, known coating methods such as gravure coating, Meyer bar coating, and air knife coating can be used. The thickness of the release liner is not particularly limited and can be appropriately selected from the range of 5 to 100 μm.

[0162] (Another adhesive layer) The adhesive layer of the present invention may constitute an adhesive sheet laminated with another adhesive layer. That is, the adhesive layer of the present invention may constitute a substrate-less double-sided adhesive sheet having a two-layer adhesive structure. By having the adhesive layer of the present invention constitute a substrate-less double-sided adhesive sheet having a two-layer adhesive structure, for example, the adhesive layer of the present invention can control shock absorption together with another adhesive layer. Furthermore, the other adhesive layer can be fixed to another substrate (carrier substrate), which is preferable from the viewpoint of workability.

[0163] The aforementioned other adhesive layer may be composed of the same adhesive as the adhesive layer of the present invention, or it may be composed of a different adhesive. For example, it is preferable that it be an adhesive layer with reduced adhesive strength, such as a radiation-curable adhesive or a heat-foaming adhesive. This is preferable from the viewpoint of easy reuse of the carrier substrate and excellent reworkability, as it allows for the transfer of electronic components with high adhesion between the other adhesive layer and the carrier substrate, and subsequently reduces the adhesive strength of the other adhesive layer by radiation irradiation or heating, allowing for easy peeling from the carrier substrate.

[0164] The thickness of the other adhesive layer is not particularly limited, but is preferably 1 μm or more, and more preferably 3 μm or more. A thickness above a certain level makes it easier to control shock absorption and easier to stably fix to the carrier substrate, which is preferable. Furthermore, the upper limit of the thickness of the other adhesive layer is not particularly limited, but is preferably 450 μm or less, and more preferably 300 μm or less. A thickness below a certain level makes it easier to peel from the carrier substrate, improving reworkability, which is preferable.

[0165] (base material) The adhesive layer of the present invention (including a two-layer structure with another adhesive layer) may constitute an adhesive sheet on which a substrate layer is laminated. That is, the adhesive layer of the present invention (including a two-layer structure with another adhesive layer) may constitute an adhesive sheet with a substrate. It is preferable that the adhesive layer of the present invention constitutes an adhesive sheet with a substrate, as the substrate functions as a support, improving stability and handling when receiving electronic components.

[0166] The above-mentioned substrate is not particularly limited, but for example, a plastic film can be suitably used. As the constituent material of the plastic substrate, a thermoplastic resin is preferred from the viewpoint of stability and handling when receiving electronic components. Examples of thermoplastic resins include polyolefins, polyesters, polyurethanes, polycarbonates, polyether ether ketones, polyimides, polyetherimides, polyamides, fully aromatic polyamides, polyvinyl chloride, polyvinylidene chloride, polyphenyl sulfide, aramids, fluororesins, cellulose resins, and silicone resins, with polyester films being preferred. Examples of polyolefins include low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene, ultra-low-density polyethylene, random copolymer polypropylene, block copolymer polypropylene, homopolypropylene, polybutene, polymethylpentene, ethylene-vinyl acetate copolymer, ionomer resin, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic acid ester copolymer, ethylene-butene copolymer, and ethylene-hexene copolymer. Examples of polyesters include polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate. The base material is preferably made of a light-transmitting heat-resistant film, such as a polyester film, from the viewpoint of stability and handling when receiving electronic components, and heat resistance during thermocompression bonding when transferring electronic components to the mounting board. The base material may consist of one type of material or two or more types of materials. The base material may have a single-layer structure or a multi-layer structure. Furthermore, if the base material is made of a plastic film, it may be an unoriented film, a uniaxially oriented film, or a biaxially oriented film. The release liner that is peeled off during use is not included in the "base material".

[0167] The thickness of the above-mentioned substrate is not particularly limited, but from the viewpoint of ensuring strength for functioning as a support, for example, it is preferably 10 μm or more, more preferably 30 μm or more. Furthermore, from the viewpoint of achieving appropriate flexibility, the thickness of the substrate is preferably 200 μm or less, more preferably 180 μm or less. The above-mentioned substrate may be in the form of a single layer or a multi-layer structure. In addition, the surface of the above-mentioned substrate may be appropriately subjected to known and conventional surface treatments, such as physical treatments such as corona discharge treatment or plasma treatment, or chemical treatments such as undercoating, in order to improve adhesion with the adhesive layer of the present invention.

[0168] When the adhesive layer of the present invention (including a two-layer structure with another adhesive layer) constitutes an adhesive sheet with a substrate, the other adhesive layer may be laminated on the side of the substrate layer where the adhesive layer is not laminated. That is, the adhesive layer of the present invention (including a two-layer structure with another adhesive layer) may constitute a double-sided adhesive sheet with a substrate. By having the adhesive layer of the present invention (including a two-layer structure with another adhesive layer) constitute a double-sided adhesive sheet with a substrate, the substrate functions as a support, improving stability and handling when receiving electronic components, and the other adhesive layer can be fixed to another substrate (carrier substrate), which is preferable from the viewpoint of workability.

[0169] (Method of manufacturing adhesive sheets) The method for producing the adhesive sheet having the adhesive layer of the present invention (which may be referred to as "the adhesive sheet of the present invention" in this specification) varies depending on the composition of the resin composition (adhesive composition) of the present invention, and is not particularly limited, and known forming methods can be used, but examples include the following methods (1) to (4). (1) A method for manufacturing an adhesive sheet by applying (coating) the above resin composition onto a substrate to form a composition layer, and curing the composition layer (for example, by heat curing or curing by irradiation with active energy rays such as ultraviolet light) to form an adhesive layer. (2) A method for producing an adhesive sheet by applying the above resin composition onto a release liner to form a composition layer, curing the composition layer (for example, by heat curing or curing by irradiation with active energy rays such as ultraviolet light) to form an adhesive layer, and then transferring the adhesive layer onto a substrate. (3) A method for producing an adhesive sheet by applying the above resin composition onto a substrate, drying it to form an adhesive layer. (4) A method for producing an adhesive sheet by applying the above resin composition onto a release liner, drying it to form an adhesive layer, and then transferring the adhesive layer onto a substrate.

[0170] In the above (1) to (4), the preferred method for forming the film is one in which the film is dried to form an adhesive layer, as this offers excellent productivity.

[0171] As a method for applying (coating) the above resin composition onto a predetermined surface, known coating methods can be employed and are not particularly limited, but examples include roll coating, kiss roll coating, gravure coating, reverse coating, roll brushing, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, lip coating, and extrusion coating methods using a die coater.

[0172] The thickness (total thickness) of the adhesive sheet of the present invention is not particularly limited, but is preferably 1 μm or more, more preferably 2 μm or more, and even more preferably 3 μm or more. A thickness above a certain level is preferable because it facilitates the accurate transfer of electronic components to the adhesive layer of the present invention. Furthermore, the upper limit of the thickness (total thickness) of the adhesive sheet of the present invention is not particularly limited, but is preferably 500 μm or less, and more preferably 300 μm or less. A thickness below a certain level is preferable because it facilitates the accurate transfer of electronic components to the mounting substrate. Note that the thickness of the adhesive sheet of the present invention does not include the thickness of the release liner.

[0173] (Methods for processing electronic components) The adhesive sheet of the present invention is used in methods for processing electronic components (processing applications for electronic components). More specifically, the adhesive sheet of the present invention is preferably used to receive electronic components placed on a temporary fixing material (substrate or adhesive sheet) with the adhesive layer of the present invention. Because the adhesive sheet of the present invention has the adhesive layer of the present invention, before irradiation with active energy rays, it can sufficiently absorb the impact caused by collisions with the adhesive layer of electronic components, etc., and can suppress displacement or inversion caused by the bouncing of electronic components during collisions. Furthermore, because the adhesive sheet of the present invention has the adhesive layer of the present invention, after irradiation with active energy rays, it has excellent heat resistance that can suppress expansion and outgassing during thermocompression bonding when transferring electronic components to a mounting substrate.

[0174] The adhesive sheet of the present invention is preferably fixed to a carrier substrate when used in the electronic component processing method of the present invention. By fixing the adhesive sheet of the present invention to the carrier substrate, the transfer and transport of electronic components can be performed stably. The carrier substrate can be a glass plate or the above-mentioned plastic film, and a glass plate is preferred from the viewpoint of stability.

[0175] An embodiment of the method for fixing the adhesive sheet of the present invention to a carrier substrate will be described below with reference to the drawings, but the method for fixing the adhesive sheet of the present invention to a carrier substrate is not limited to this embodiment. Figure 5 is a schematic cross-sectional view showing one embodiment of the method for fixing the adhesive sheet of the present invention to a carrier substrate using the adhesive sheet 1 shown in Figure 1.

[0176] In this embodiment of the method for fixing the adhesive sheet of the present invention to a carrier substrate, the release liner R2 of the adhesive sheet 1 is peeled off to expose the adhesive surface 10b (see Figures 5(a) and (b)), the carrier substrate S2 is attached to the exposed adhesive surface 10b (see Figure 5(c)), and then the release liner R1 of the adhesive sheet 1 is peeled off to expose the adhesive surface 10a (see Figures 5(d) and (e)).

[0177] In Figure 5(a), the release liner R2 is peeled off from the adhesive layer 10 of the adhesive sheet 1 that has been adsorbed onto the adsorption stage (not shown), exposing the adhesive surface 10b of the adhesive layer 10.

[0178] The peeling force of the release liner R2 on the adhesive surface 10b is controlled to be smaller than the peeling force of the release liner R1 on the adhesive surface 10a, from the viewpoint of preventing so-called "separation." Here, "separation" refers to the phenomenon in this embodiment where the release liner R1 also peels off when the release liner R2 is peeled off. The peeling force of the release liner R2 on the adhesive surface 10b is not particularly limited as long as it is smaller than the peeling force of the release liner R1 on the adhesive surface 10a, but from the viewpoint of efficiently preventing "separation," it is sufficient to set it to about 1 / 3 to 1 / 2 of the peeling force of the release liner R1 on the adhesive surface 10a. Figure 5(b) shows the state in which the release liner R2 has been completely peeled off and the entire surface of the adhesive surface 10b is exposed. Next, in Figure 5(c), the carrier substrate S2 is attached to the exposed adhesive surface 10b.

[0179] In Figure 5(d), the release liner R1 is peeled off from the adhesive layer 10 to expose the adhesive surface 10a. Figure 5(e) shows the state in which the release liner R1 has been completely peeled off and the entire adhesive surface 10a is exposed, and in this state it is subjected to the electronic component processing method of the present invention.

[0180] When the adhesive sheet of the present invention is used for processing the above-mentioned electronic components, it is preferable that the surface of the temporary fixing material on which the electronic components are placed and the adhesive surface of the adhesive layer of the adhesive sheet of the present invention face each other, with a gap between them. This configuration is preferable because it allows control of the positional relationship between the temporary fixing material and the adhesive sheet of the present invention, and allows the electronic components to be placed at a desired position on the adhesive sheet.

[0181] The present invention relates to a method for processing electronic components, which includes a step (first step) of receiving an electronic component placed on a temporary fixing material with the adhesive surface of the adhesive layer of the adhesive sheet of the present invention. In the method for processing electronic components of the present invention, the adhesive sheet of the present invention can sufficiently absorb the impact caused by collisions with the adhesive layer of electronic components, and can suppress displacement or inversion of electronic components due to bouncing during collisions.

[0182] In the method for processing electronic components of the present invention, it is preferable that the surface on which the electronic components are placed on the temporary fixing material and the adhesive surface of the adhesive layer of the adhesive sheet of the present invention are facing each other, with a gap between them. This configuration is preferable because it allows control of the positional relationship between the temporary fixing material and the adhesive sheet of the present invention, and allows the electronic components to be placed at a desired position on the adhesive sheet.

[0183] The method for processing electronic components of the present invention preferably further includes the steps of: placing the electronic components on the adhesive sheet onto a mounting substrate (second step); thermocompressing the electronic components onto the mounting substrate (third step); and peeling the electronic components from the adhesive surface of the adhesive layer of the adhesive sheet (fourth step). By including the second, third, and fourth steps, the method for processing electronic components of the present invention can efficiently transfer the electronic components onto the mounting substrate.

[0184] Embodiments of the electronic component processing method of the present invention will be described below with reference to the drawings, but the electronic component processing method of the present invention is not limited to these embodiments. Figure 6 is a schematic cross-sectional view showing the first step in one embodiment of the electronic component processing method of the present invention using an adhesive sheet (see Figure 5(e)) fixed to a carrier substrate shown in Figure 5.

[0185] In this embodiment, the first step of the electronic component processing method of the present invention is to separate the electronic component 51 (see Figure 6(a)) placed on the temporary fixing material 50 and receive it on the adhesive surface 10a of the adhesive layer 10 fixed to the carrier substrate S2 (see Figures 6(b) and (c)).

[0186] In Figure 6(a), multiple electronic components 51 are arranged on one side of the temporary fixing material 50 via bumps 52. The bumps 52 are protruding electrodes provided on one side of the electronic components 51 and are connected to an electronic circuit provided on a mounting base as described later. The material constituting the temporary fixing material 50 is not particularly limited and includes the plastic film and glass substrate mentioned above. The temporary fixing material 50 may also be an adhesive sheet, in which case the electronic components 51 may be arranged on the adhesive surface of the adhesive sheet via bumps 52. It is preferable that the temporary fixing material 50 be made of a radiopaque material.

[0187] The method for arranging the electronic component 51 on one side of the temporary fixing material 50 is not particularly limited, and one example is to arrange the electronic component 51 via the adhesive strength reduction type adhesive layer described above. In this case, the temporary fixing state can be released by irradiating or heating the adhesive strength reduction type adhesive layer. In this embodiment, the electronic component 51 is arranged on the temporary fixing material 50 via the radiation-curable adhesive layer (not shown) described above.

[0188] In this embodiment, a plurality of electronic components 51 are arranged on one side of the temporary fixing material 50 via bumps 52. In this embodiment, the size of the electronic components 51 is, for example, 1 μm 2 ~250,000 μm 2 Therefore, according to the electronic component processing method of the present invention, such small electronic components can be efficiently transferred.

[0189] In this embodiment, the temporary fixing material 50 is positioned with the surface on which the electronic component 51 is placed facing downwards, and the adhesive surface 10a of the adhesive layer 10 fixed to the carrier substrate S2 is positioned facing upwards. The surface on which the electronic component 51 is temporarily fixed to the temporary fixing material 50 and the adhesive surface 10a of the adhesive layer 10 are positioned opposite each other with a gap d between them. By providing a gap d, the positional relationship between the temporary fixing material 50 and the adhesive layer 10 can be controlled, and the electronic component 51 can be placed at a desired position on the adhesive layer 10. The spacing of the gap d is not particularly limited, but for example, it is about 1 to 1000 μm.

[0190] In this embodiment, the temporary fixing state of the electronic component 51 is released by irradiating the electronic component 51 with laser light L from the side of the temporary fixing material 50, thereby separating the electronic component 51 from the temporary fixing material 50. More specifically, when the laser light L is irradiated onto the portion of the temporary fixing material 50 in contact with the electronic component 51 via the bump 52, the adhesive force decreases, and the electronic component 51 is separated by peeling it off the temporary fixing material 50. The laser light L may be irradiated onto multiple electronic components 51 individually, onto some of them, onto all of the electronic components 51 at once, or by sweeping. In this embodiment, the laser light L is irradiated onto some of the multiple electronic components 51.

[0191] In Figure 6(b), the electronic component 51 separated from the temporary fixing material 50 falls toward the adhesive layer 10, and the side of the electronic component 51 without the bump 52 is received by the adhesive surface 10a. The adhesive layer 10 is composed of the adhesive layer of the present invention and exhibits excellent shock absorption, so it can absorb the impact caused by collisions with electronic components to prevent damage and suppress displacement or inversion of electronic components.

[0192] In Figures 6(c) and 6(d), another electronic component 51 placed on the temporary fixing material 50 is irradiated with laser light L to separate and drop it, and then received (transferred) onto the adhesive surface 10a of the adhesive layer 10. In this embodiment, the laser light L is irradiated onto the electronic component 51 adjacent to the electronic component 51 that was irradiated with laser light L in Figure 6(a).

[0193] In Figures 6(c) and 6(d), the positional relationship between the temporary fixing material 50 and the adhesive layer 10 may be the same as in Figure 6(b), or it may be shifted. In this embodiment, the temporary fixing material 50 is shifted by a predetermined distance to the right in Figure 6 relative to the adhesive layer 10, and then the laser light L is irradiated. This makes it possible to control the placement of the electronic components 51 in the adhesive layer 10 at a desired pitch.

[0194] Figure 6(e) shows the state in which all electronic components 51 have been received by the adhesive layer 10 by repeating the steps shown in Figures 6(c) and (d). In this embodiment, the electronic components 51 are arranged with a desired pitch.

[0195] Figure 7 is a schematic cross-sectional view showing the second to fourth steps in one embodiment of the electronic component processing method of the present invention using an adhesive sheet fixed to the carrier substrate shown in Figure 5.

[0196] As shown in Figure 7(a), electronic components 51 arranged on an adhesive layer 10 fixed to a carrier substrate S2 are placed opposite and spaced apart from the mounting substrate 60. In this embodiment, by directly transferring the electronic components from the transfer substrate to the mounting substrate, the process of transferring them to another carrier substrate before transferring them to the mounting substrate can be omitted, thereby reducing manufacturing costs. Furthermore, it is possible to prevent a decrease in connection reliability due to a decrease in the positional accuracy of the electronic components caused by repeating the transfer process twice.

[0197] In Figure 7(a), the electronic component 51 in the state shown in Figure 6(e) is inverted, with the bump 52 facing downwards, and positioned facing the surface 61 of the mounting substrate 60. A circuit surface (not shown) is formed on the surface 61 of the mounting substrate 60 facing the electronic component 51, and the bump 52 on the electronic component 51 is positioned facing the circuit so as to connect to it.

[0198] Next, as shown in Figure 7(b), by bringing the surface 61 of the mounting substrate 60 and the electronic components 51 arranged on the adhesive surface 10a of the adhesive layer 10 into close proximity, and bringing the bumps 52 on the electronic components 51 into contact with the surface 61, the electronic components 51 can be positioned on the surface 61 of the mounting substrate 60, and the electronic circuits formed on the surface 61 can be connected to the bumps 52.

[0199] Next, as shown in Figure 7(c), the adhesive layer 10 is irradiated with active energy rays U from the carrier substrate S2 side. Irradiation with active energy rays U causes the active energy ray-curable compound contained in the adhesive layer 10 to react and form a crosslinked structure, improving the elastic modulus and resulting in excellent heat resistance that suppresses thermal expansion and outgassing. 11 is the adhesive layer whose heat resistance has been improved by irradiation with active energy rays U. In addition, the adhesive strength of the adhesive layer 11 decreases, and the electronic component 51 becomes detachable. The active energy rays U may be irradiated onto all of the adhesive layer 10, or, if necessary, only some of the adhesive layer 10 may be irradiated with a mask or the like. In this embodiment, all of the adhesive layer 10 is irradiated with active energy rays U. In another embodiment, the adhesive layer 10 may be irradiated with active energy rays U before the electronic component 51 is brought into contact with the mounting substrate 60 (Figure 7(a)) (not shown).

[0200] Examples of the active energy rays U mentioned above include ionizing radiation such as alpha rays, beta rays, gamma rays, neutron rays, and electron beams, as well as ultraviolet rays, with ultraviolet rays being particularly preferred. The conditions for ultraviolet irradiation are not particularly limited, but specifically, 8280 mJ / cm² is preferred. 2 UV irradiation is preferred.

[0201] Next, as shown in Figure 7(d), the thermocompression heads 70 and 71 are brought into contact with the carrier substrate S2 and the mounting substrate, respectively, and pressed while being heated (thermocompression bonding process). Ultrasonic vibration may be applied during the thermocompression bonding process. This thermocompression bonding process causes the bump 52 to plastically deform, improving the reliability of the connection to the electronic circuit on the mounting substrate. The heating temperature of the thermocompression heads 70 and 71 is preferably controlled to be the same to prevent displacement of the mounting position due to the effects of thermal expansion and contraction. Typically, this temperature is 150°C or higher, and from the viewpoint of improving connection reliability, 250 to 400°C is preferred.

[0202] The adhesive layer 11, whose heat resistance has been improved by irradiation with active energy ray U, exhibits suppressed expansion and outgassing even during heating in the thermocompression bonding process, thereby suppressing a decrease in connection reliability due to misalignment of the electronic components 51.

[0203] Next, as shown in Figure 7(e), by separating the adhesive layer 11 from the mounting substrate 60, the electronic component 51 can be peeled off the adhesive layer 11 and simultaneously transferred to the surface 61 of the mounting substrate 60. Because the adhesive strength of the adhesive layer 11 is reduced by irradiation with active energy ray U, the electronic component 51 can be easily peeled off, transferred to the surface 61 of the mounting substrate 60, and placed. The electronic component 51 is transferred and placed on the surface 61 while maintaining the placement pattern of the electronic component 51 on the adhesive layer 10.

[0204] The adhesive layer 11 from which the electronic component 51 has been detached has improved storage modulus due to irradiation with active energy rays U, giving it elastic properties and allowing it to be peeled off from the carrier substrate S2 without leaving any adhesive residue. Therefore, it is also preferable because the carrier substrate S2 can be recovered without requiring thorough cleaning.

[0205] In Figures 5-7, the same electronic component processing method can be carried out using adhesive sheets 2-4 shown in Figures 2-4 instead of adhesive sheet 1. In the case of adhesive sheet 3, the base material S1 can be fixed to the carrier substrate S2 via double-sided adhesive tape or the like.

[0206] The electronic components to be mounted on the substrate are not particularly limited, but they can be suitably used for fine, thin semiconductor chips and LED chips. [Examples]

[0207] The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way by these examples.

[0208] [Manufacturing Example 1] Manufacturing of Acrylic Polymer A To toluene, 50 parts by weight of ethyl acrylate, 50 parts by weight of butyl acrylate, 5 parts by weight of acrylic acid, 0.1 parts by weight of 2-hydroxyethyl acrylate, 0.3 parts by weight of trimethylolpropane triacrylate as a polyfunctional monomer, and 0.1 parts by weight of benzoyl peroxide as a polymerization initiator were added. Then, a polymerization reaction was carried out at 60°C under a nitrogen gas stream to obtain a toluene solution of an acrylic copolymer (acrylic polymer A).

[0209] [Manufacturing Example 2] Manufacturing of Acrylic Polymer B To toluene, 100 parts by weight of 2-ethylhexyl acrylate, 2 parts by weight of acrylic acid, 0.01 parts by weight of trimethylolpropane triacrylate as a polyfunctional monomer, and 0.2 parts by weight of benzoyl peroxide as a polymerization initiator were added. The polymerization reaction was then carried out at 60°C under a nitrogen gas stream to obtain a toluene solution of an acrylic copolymer (acrylic polymer B).

[0210] [Manufacturing Example 3] Manufacturing of Acrylic Polymer C To ethyl acetate, 30 parts by weight of 2-ethylhexyl acrylate, 70 parts by weight of methyl acrylate, 10 parts by weight of acrylic acid, and 0.2 parts by weight of benzoyl peroxide as a polymerization initiator were added. The polymerization reaction was then carried out at 60°C under a nitrogen gas stream to obtain an ethyl acetate solution of an acrylic copolymer (acrylic polymer C).

[0211] [Manufacturing Example 4] Manufacturing of Acrylic Polymer D To toluene, 30 parts by weight of 2-ethylhexyl acrylate, 70 parts by weight of ethyl acrylate, 5 parts by weight of methyl methacrylate, 4 parts by weight of 2-hydroxyethyl acrylate, and 0.2 parts by weight of benzoyl peroxide as a polymerization initiator were added. The polymerization reaction was then carried out at 60°C under a nitrogen gas stream to obtain an acrylic copolymer (acrylic polymer D) toluene solution.

[0212] [Example 1] (Preparation of adhesive) To an acrylic polymer solution A containing 100 parts by weight of acrylic polymer A, 50 parts by weight of a polyfunctional monomer (Toagosei Co., Ltd., trade name "Arronix M-321", propylene oxide modified trimethylolpropane tri(meth)acrylate, number of functional groups: 3, molecular weight: 644, softening point: -59℃) as an active energy ray curable compound, 3 parts by weight of a crosslinking agent (Mitsubishi Gas Chemical Company, Inc., trade name "Tetrad C", 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane), and an α-hydroxyketone photopolymerization initiator (BASF Japan, trade name "Irgacure 127", molecular weight: 340.4, extinction coefficient at wavelength 365 nm: 1.07 × 10⁻⁶) are added. 2 An adhesive was obtained by adding 0.5 parts by weight (ml / g·cm). (Adhesive sheet) An adhesive layer was formed by applying the above adhesive to the release surface of release liner 1 (manufactured by Fujiko Co., Ltd., product name "PET-75-SCA1", thickness: 75 μm) so that the thickness after solvent evaporation (drying) was 50 μm. The adhesive surface of the obtained adhesive layer was protected with release liner 2 (manufactured by Toray Industries, Inc., product name "Therapyel MDA", thickness: 38 μm) to obtain an adhesive sheet consisting of (release liner 1 / adhesive layer / release liner 2).

[0213] [Example 2] An adhesive sheet consisting of (release liner 1 / adhesive layer / release liner 2) was obtained in the same manner as in Example 1, except that the amount of polyfunctional monomer blended was 100 parts by weight.

[0214] [Example 3] An adhesive sheet consisting of (release liner 1 / adhesive layer / release liner 2) was obtained in the same manner as in Example 1, except that the amount of polyfunctional monomer blended was 150 parts by weight.

[0215] [Example 4] An adhesive sheet consisting of (release liner 1 / adhesive layer / release liner 2) was obtained in the same manner as in Example 1, except that the amount of polyfunctional monomer was 100 parts by weight and the amount of crosslinking agent was 5 parts by weight.

[0216] [Example 5] An adhesive sheet consisting of (release liner 1 / adhesive layer / release liner 2) was obtained in the same manner as in Example 1, except that 100 parts by weight of a polyfunctional oligomer (manufactured by Mitsubishi Chemical Corporation, trade name "Shiko UV-1700B", urethane acrylate, number of functional groups: 10, weight-average molecular weight (Mw): 2000, softening point: -26℃) was added as the active energy ray curable compound, instead of the polyfunctional monomer.

[0217] [Example 6] (Preparation of adhesive) To an acrylic polymer solution B containing 100 parts by weight of acrylic polymer B, 30 parts by weight of a polyfunctional monomer (Toagosei Co., Ltd., trade name "Arronix M-321", propylene oxide modified trimethylolpropane tri(meth)acrylate, number of functional groups: 3, molecular weight: 644, softening point: -59℃) as an active energy ray curable compound, 2 parts by weight of a crosslinking agent (Mitsubishi Gas Chemical Company, Inc., trade name "Tetrad C", 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane), and an α-hydroxyketone photopolymerization initiator (BASF Japan, trade name "Irgacure 127", molecular weight: 340.4, extinction coefficient at wavelength 365 nm: 1.07 × 10⁻⁶) are added. 2 Adding 3 parts by weight (ml / g·cm) obtained an adhesive. (Adhesive sheet) An adhesive sheet consisting of (release liner 1 / adhesive layer / release liner 2) was obtained in the same manner as in Example 1, except that the above-mentioned adhesive was used.

[0218] [Comparative Example 1] (Preparation of adhesive) To an acrylic polymer solution C containing 100 parts by weight of acrylic polymer C, 0.1 parts by weight of a crosslinking agent (manufactured by Mitsubishi Gas Chemical Company, trade name "Tetrad C", 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane) was added to obtain an adhesive. (Adhesive sheet) An adhesive sheet consisting of (release liner 1 / adhesive layer / release liner 2) was obtained in the same manner as in Example 1, except that the above-mentioned adhesive was used.

[0219] [Comparative Example 2] (Preparation of adhesive) To an acrylic polymer solution D containing 100 parts by weight of acrylic polymer D, 1 part by weight of a crosslinking agent (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate L", trimethylolpropane / tolylene diisocyanate adduct) was added to obtain an adhesive. (Adhesive sheet) An adhesive sheet consisting of (release liner 1 / adhesive layer / release liner 2) was obtained in the same manner as in Example 1, except that the above-mentioned adhesive was used.

[0220] <Rating> The adhesive sheets obtained in the examples and comparative examples were evaluated as follows. The results are shown in Table 1.

[0221] (1) Measurement of the softening point (10% heat distortion temperature) Approximately 5.0 mg of the compound sample was placed in a Φ4.0 mm aluminum pan to obtain a sheet of the evaluation sample. If the compound sample was diluted with an organic solvent, the evaluation sample was prepared by thoroughly evaporating the organic solvent at a temperature above its boiling point. The evaluation sample sheets obtained above were placed in a TMA Q400 (manufactured by TA-instrument Co., Ltd.), and the thickness reduction of the evaluation sample sheets was measured while heating them using a Φ3.0 mm probe in needle insertion mode under the following conditions: nitrogen gas flow rate: 50.0 ml / min, indentation load: 0.01 N, measurement ambient temperature range: -75℃ to 40℃, and heating rate: 3℃ / min. From the obtained data, the temperature at which the thickness reduction reached 10% was extracted and defined as the softening point (10% heat distortion temperature).

[0222] (2) Storage modulus (G'(100k)) and loss factor (tanδ(100k)) at a frequency of 100kHz and 25℃ before irradiation with active energy rays. The adhesive layers of the adhesive sheets obtained in the examples and comparative examples were laminated to a thickness of 1.0 mm or more, punched out to a size of Φ8 mm using a jig, and set on the probe of ARES-G2 (TA instruments). Measurements were taken at 5°C intervals from -45°C to 30°C at a strain of 0.05% and a frequency from 0.1 Hz to 10 Hz. Subsequently, using the analysis tool built into the analyzer, the measurement data was swept based on the WLF formula with a reference temperature of 25°C, and master curves were synthesized to obtain frequency dependence data of the storage modulus and tanδ. From the obtained data, the values ​​of the storage modulus (G'(100k)) and loss coefficient (tanδ(100k)) at 100 kHz were extracted.

[0223] (3) Coefficient of linear expansion after irradiation with active energy rays Using the "TMA Q400" (manufactured by TA-instrument), the coefficient of linear expansion of the adhesive layer at 200-210°C and 260-270°C was measured in tensile mode under the conditions of nitrogen gas flow rate: 50.0 ml / min and applied load: 0.0196 N. Specifically, the measurement was performed using the method described below. Using the same adhesive as that used in each example and comparative example, an adhesive layer with a thickness of 50 μm was formed, and this adhesive layer was laminated to obtain a sample with a thickness of 200 μm. This sample, with release liners attached to both sides, was subjected to 8280 mJ / cm². 2 After irradiating the sample with ultraviolet light once from each side, it was punched out to a size of 4 mm x 30 mm, and the adhesive layer, with the release liner removed, was set on the "TMA Q400" probe with an 8 mm gap between the layers. The dimensional change of the sample was measured while heating it from 20°C to 300°C at a heating rate of 10°C / min. From the obtained data, the slope of the dimensional change at 200~210°C and 260~270°C was calculated to obtain the value of the coefficient of linear expansion.

[0224] (4) Tensile modulus after irradiation with active energy rays The tensile modulus E' was measured using a dynamic viscoelasticity analyzer (TA Instrument Co., Ltd., product name "RSA-3") at a measurement frequency of 1 Hz, strain of 0.05%, and 25°C. Specifically, adhesive sheets without a substrate and with a thickness of 50 μm were prepared using the adhesives obtained in the examples and comparative examples, and these adhesive sheets were laminated to a thickness of 200 μm or more. With release liners attached to both sides of the sample, the measurement was 8280 mJ / cm². 2 After irradiating the adhesive layer with ultraviolet light once from each side and removing the release liner, a 10 mm wide sample was prepared. The distance between the chucks was 20 mm, and measurements were taken at a heating rate of 5 °C / min from 0 °C to 300 °C. From the obtained data, the tensile modulus E' values ​​at 200 °C and 260 °C were extracted.

[0225] (5) Gel fraction Approximately 0.5 g of the adhesive layer was accurately weighed and used as a sample (weight W1). This sample was wrapped in a porous polytetrafluoroethylene membrane (manufactured by Nitto Denko Corporation, product name "Nitoflon NTF1122", average pore size: 0.2 μm, porosity 75%, thickness 85 μm, weight W2) in a drawstring shape, and the opening was tied with thread (weight W3). This package was immersed in 50 mL of toluene and kept at room temperature (25°C) for 7 days to elute only the sol component in the adhesive layer to the outside of the membrane. Then the package was removed, the toluene adhering to the outer surface was wiped off, and the package was dried at 130°C for 2 hours, and the weight of the package (W4) was measured. The gel fraction was then determined by substituting each value into the following formula. Gel fraction (%) = [(W4 - W2 - W3) / W1] × 100 The gel fraction G0 was measured using the gel fraction measurement method described above, with the adhesive layer not irradiated with ultraviolet light. On the other hand, the gel fraction G1 was measured at 8280 mJ / cm² with release liners attached to both sides of the adhesive layer. 2 The gel fraction of the adhesive layer, obtained by removing the release liner after irradiation with ultraviolet light, was measured using the gel fraction measurement method described above.

[0226] (6) Receptivity before irradiation with active energy rays (sinking depth in a -40°C environment using TMA) Using a TMA Q400 (manufactured by TA Instruments), with a Φ1.0 mm probe, in the needle penetration mode, at a nitrogen gas flow rate of 50.0 ml / min, a pushing load of 0.05 N, a measurement ambient temperature of -40 °C, and a pushing load time of 20 min, the penetration depth of the adhesive layer exposed by peeling off the release liner was measured. The measurement was carried out with N = 5, and the average value of N = 3 excluding the maximum and minimum values among these measurement values was taken as the penetration depth of the sample. The ratio of the penetration depth to the initial thickness of the adhesive layer (penetration depth / thickness × 100) was calculated and evaluated according to the following criteria. 〇 (Good acceptability) ··· Penetration depth / thickness × 100 is 30% or more △ (Acceptability is practically problem-free) ··· Penetration depth / thickness × 100 is 5% or more and less than 30% × (Poor acceptability) ··· Penetration depth / thickness × 100 is less than 5%

[0227] (6) Heat resistance (5% weight loss temperature) after active energy ray irradiation Using a differential thermal analyzer (manufactured by TA Instruments, trade name "Discovery TGA"), under the conditions of a heating rate of 10 °C / min, a N2 atmosphere, and a gas flow rate of 25 ml / min, the temperature at which the weight of the adhesive layer decreased by 5% was measured. Specifically, it was measured by the following method. With release liners attached to both sides of the adhesive layer, after irradiating ultraviolet rays of 8280 mJ / cm 2 about 0.01 g of the adhesive layer sample from which the release liner had been removed was set in the "Discovery TGA". The weight loss of the adhesive sheet was measured while heating from 20 °C to 500 °C at a heating rate of 10 °C / min. From the obtained data, the temperature at which the weight loss reached 5% was extracted. 〇 (Good heat resistance) ··· 5% weight loss temperature is 340 °C or higher × (Poor heat resistance) ··· 5% weight loss temperature is less than 340 °C

[0228]

Table 1

[0229] The variations of the invention described above are appended below. [Appendix 1] A resin composition for forming an adhesive layer, wherein the storage elastic modulus G'(100k) of the adhesive layer at 100 kHz and 25°C is 60 MPa or less, and the resin composition contains an active energy ray-curable compound. [Appendix 2] The resin composition according to Appendix 1, wherein the adhesive layer is used in the following steps. · A step of disposing the adhesive layer with a gap provided so as to face the surface on which the electronic component is disposed on the temporary fixing material, and receiving the electronic component · A step of transferring the electronic component received by the adhesive layer to another carrier substrate or directly to the mounting substrate [Appendix 3] The ratio (G 0 / G 1 ) of the gel fraction G 1 after active energy ray irradiation to the gel fraction G 0 before active energy ray irradiation of the adhesive layer is 1.1 or more, and the resin composition according to Appendix 1 or 2. [Appendix 4] The resin composition according to any one of Appendices 1 to 3, wherein the linear expansion coefficient α(200 - 210) of the adhesive layer at 200 - 210°C after active energy ray irradiation is 500×10 -5 / K or less. [Appendix 5] The resin composition according to any one of Appendices 1 to 4, wherein the tensile elastic modulus E'(200) of the adhesive layer at 200°C after active energy ray irradiation is 0.3 MPa or more. [Appendix 6] The resin composition according to any one of Appendices 1 to 5, wherein the linear expansion coefficient α(260 - 270) of the adhesive layer at 260 - 270°C after active energy ray irradiation is 500×10 -5 / K or less. [Appendix 7] The resin composition according to any one of Appendices 1 to 6, wherein the tensile elastic modulus E'(260) of the adhesive layer at 260°C after active energy ray irradiation is 0.05 MPa or more. [Note 8] The resin composition according to any one of Notes 1 to 7, wherein the active energy ray curable compound is a polyfunctional monomer and / or a polyfunctional oligomer. [Note 9] The resin composition according to any one of Notes 1 to 8, wherein the active energy ray curable compound has three or more reactive functional groups. [Note 10] The resin composition according to any one of Notes 1 to 9, wherein the molecular weight of the active energy ray curable compound is less than 20,000. [Note 11] The resin composition according to any one of Notes 1 to 10, wherein the thickness of the adhesive layer is 1 μm or more and 500 μm or less. [Note 12] An acrylic adhesive composition, the resin composition described in any one of Notes 1 to 11. [Note 13] The resin composition according to any one of Notes 1 to 12, wherein the adhesive layer is further laminated with another adhesive layer. [Note 14] The resin composition according to any one of Notes 1 to 13, wherein the adhesive layer is further laminated with a substrate layer. [Note 15] The resin composition according to Note 14, wherein another adhesive layer is laminated on the surface of the base layer where the adhesive layer is not laminated. [Note 16] The resin composition according to Note 14 or 15, wherein the base layer is formed from a light-transmitting heat-resistant film. [Note 17] An adhesive layer formed by the resin composition described in any one of Notes 1 to 16. [Note 18] An adhesive sheet having the adhesive layer described in Note 17. [Explanation of Symbols]

[0230] 1 Adhesive sheet 10 Adhesive layer R1, R2 peel-off liner 2 Adhesive sheets 20, 21 Adhesive layer 3 Adhesive sheet 30 Adhesive layer S1 base material 4 Adhesive sheets 40, 41 Adhesive layer S2 Carrier board 50 Temporary fixing material (substrate or adhesive sheet) 51 Electronic Components 52 Bumps (protruding electrodes) 11. Adhesive layer (after irradiation with active energy rays) 60 mounted circuit boards 70, 71 Heat press heads

Claims

1. A resin composition for forming an adhesive layer, The storage modulus G'(100k) of the adhesive layer at 100 kHz and 25°C is 60 MPa or less. It contains an active energy ray curing compound, It contains an acrylic polymer, and the acrylic polymer contains constituent units derived from a polyfunctional monomer. The adhesive layer is a resin composition used in the following steps. - The process of placing the adhesive layer on the temporary fixing material with a gap between it and the surface on which the electronic components are placed, and receiving the electronic components. - A step of transferring the electronic components received on the adhesive layer to another carrier substrate, or directly to a mounting substrate.

2. Gel fraction G of the adhesive layer before irradiation with active energy rays ０ Gel fraction G after irradiation with active energy rays (percentage) １ (Ratio of %) (G １ / G ０ The resin composition according to claim 1, wherein the ratio is 1.1 or higher.

3. The coefficient of linear expansion α (200-210°C) of the adhesive layer at 200-210°C after irradiation with active energy rays is 500 × 10⁻⁶ －５ The resin composition according to claim 1 or 2, wherein the K level is less than or equal to / K.

4. The resin composition according to any one of claims 1 to 3, wherein the tensile modulus E'(200) of the adhesive layer at 200°C after irradiation with active energy rays is 0.3 MPa or more.

5. The coefficient of linear expansion α (260-270) of the adhesive layer at 260-270°C after irradiation with active energy rays is 500 × 10⁻⁶. －５ A resin composition according to any one of claims 1 to 4, wherein the temperature is less than or equal to / K.

6. The resin composition according to any one of claims 1 to 5, wherein the tensile modulus E'(260) of the adhesive layer at 260°C after irradiation with active energy rays is 0.05 MPa or more.

7. The resin composition according to any one of claims 1 to 6, wherein the active energy ray curable compound is a polyfunctional monomer and / or a polyfunctional oligomer.

8. The resin composition according to any one of claims 1 to 7, wherein the active energy ray curable compound has three or more reactive functional groups.

9. The resin composition according to any one of claims 1 to 8, wherein the molecular weight of the active energy ray curable compound is less than 20,000.

10. The resin composition according to any one of claims 1 to 9, wherein the thickness of the adhesive layer is 1 μm or more and 500 μm or less.

11. The resin composition according to any one of claims 1 to 10, wherein the adhesive layer is further laminated with another adhesive layer.

12. The resin composition according to any one of claims 1 to 11, wherein the adhesive layer is further laminated with a substrate layer.

13. The resin composition according to claim 12, wherein another adhesive layer is laminated on the surface of the base layer where the adhesive layer is not laminated.

14. The resin composition according to claim 12 or 13, wherein the substrate layer is formed from a light-transmitting heat-resistant film.

15. An adhesive layer formed by the resin composition according to any one of claims 1 to 14.

16. An adhesive sheet having the adhesive layer described in claim 15.

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