JP7746032B2 - Laminated Film - Google Patents

Description

The present invention relates to a laminated film.

In the manufacturing process of semiconductor devices, a semiconductor wafer is typically diced into individual pieces while temporarily fixed on a dicing tape. The individual semiconductor chips are then pushed from the dicing tape side of the backside of the wafer with a pin member, picked up with a suction tool called a collet, and mounted on a mounting substrate such as a circuit board (see, for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 2019-9203

However, advances in microfabrication technology have led to semiconductor chips becoming smaller and thinner, making them more susceptible to damage when picked up with a collet. Furthermore, as semiconductor devices continue to become smaller and more multi-layered, there is a demand for densely packed multi-layer mounting of numerous fine semiconductor chips on a mounting board, making the method of picking up chips with a collet and mounting them individually increasingly inefficient.

One possible method to eliminate such damage to semiconductor chips and inefficient mounting is to receive multiple electronic components that have been diced onto a double-sided adhesive film for transfer that is temporarily fixed to a carrier substrate, and then transfer these components all at once to the mounting substrate.

However, with this method, when using a laminate film in which both sides of the double-sided adhesive film for transfer are protected by separators, problems that reduce work efficiency can easily arise, such as mistakes in the peeling process of the surface protection film (separator) on the adhesive surface, the film lifting from the carrier substrate when peeling the surface protection film (separator) after being attached to the carrier substrate, difficulty in peeling the double-sided adhesive film for transfer from the carrier substrate when being recovered, and adhesive residue.

The present invention was made in consideration of the above problems, and its purpose is to provide a laminated film with excellent reworkability that prevents mistakes during the separator peeling process when temporarily fixing the film to a carrier substrate to receive semiconductor chips, etc., does not peel off from the carrier substrate when transferring semiconductor chips, etc. to a mounting substrate, and can be peeled off from the carrier substrate after transferring the semiconductor chips, etc. to the mounting substrate without leaving any adhesive residue or other contamination.

As a result of extensive research to achieve the above-mentioned objective, the inventors have discovered that a laminate film comprising a surface protective film (first separator), a first adhesive layer for temporarily fixing fine electronic components such as semiconductor chips, a base material, a second adhesive layer for temporarily fixing the components to a carrier substrate, and a surface protective film (second separator), in which the peel strength F(1) of the first separator to the first adhesive layer, the peel strength F(2) of the second separator to the second adhesive layer, the adhesive strength P(2) of the second adhesive layer to a glass plate, and the adhesive strength P'(2) of the second adhesive layer to the glass plate after being attached to the glass plate at 160°C for 5 minutes, satisfies specific relationships, can prevent the separator from being peeled off when attached to the carrier substrate to temporarily fix the electronic components, does not peel off from the carrier substrate when the electronic components are transferred to the mounting substrate, and can easily peel off when peeled off from the carrier substrate after the electronic components have been transferred to the mounting substrate, leaving little adhesive residue. The present invention was completed based on these findings.

That is, the present invention relates to a laminated film in which a first separator, a first pressure-sensitive adhesive layer, a substrate, a second pressure-sensitive adhesive layer, and a second separator are laminated in this order, wherein the first pressure-sensitive adhesive layer is a low-tack pressure-sensitive adhesive layer, and the second pressure-sensitive adhesive layer is a releasable pressure-sensitive adhesive layer, and the laminated film has a 180° peel strength F(1) (N/50 mm) of the first separator from the first pressure-sensitive adhesive layer measured under conditions of 23°C, 50% RH and a peel speed of 0.3 m/min, and a 180° peel strength F(2) (N/50 mm) of the second separator from the second pressure-sensitive adhesive layer measured under conditions of 23°C, 50% RH and a peel speed of 0.3 m/min, and a 180° peel strength F(3) (N/50 mm) of the second separator from the second pressure-sensitive adhesive layer measured under conditions of 23°C, 50% RH and a peel speed of 0.3 m/min, and a 180° peel strength F(4) (N/50 mm) of the second separator from the second pressure-sensitive adhesive layer measured under conditions of 23°C, 50% RH and a peel speed of 0.3 m/min, and a 180° peel strength F(5) (N/50 mm) of the second separator from the second pressure-sensitive adhesive layer measured under conditions of 23°C, 50% RH and a peel speed of 0.3 m/min. and a pulling speed of 0.3 m/min, and after 5 minutes have passed since the second pressure-sensitive adhesive layer was attached to the glass plate, the 180° peel adhesive strength P(2) (N/50 mm) of the second pressure-sensitive adhesive layer from a glass plate measured under conditions of 23°C, 50% R.H. and a pulling speed of 0.3 m/min, and the 180° peel adhesive strength P'(2) (N/50 mm) of the second pressure-sensitive adhesive layer from a glass plate measured under conditions of 23°C, 50% R.H. and a pulling speed of 0.3 m/min.
F(2)≦F(1)
P(2) ≧ F(1)
P'(2)/P(2)<1.20
P'(2)<1.00

The laminated film preferably further satisfies the following formula:
F(2)/F(1)<0.80
P(2)/F(1)>1.00

In the laminate film, it is preferable that the 90° trigger peel strength T(1) (N/50 mm) of the first pressure-sensitive adhesive layer from the first separator, measured under conditions of 23°C, 50% RH and a pulling speed of 0.3 m/min, the 90° trigger peel strength T(2) (N/50 mm) of the second pressure-sensitive adhesive layer from the second separator, measured under conditions of 23°C, 50% RH and a pulling speed of 0.3 m/min, and the adhesive strength P(2) satisfy the relationship of the following formula:
T(1)/T(2)>1.05
P(2)/T(1)<1.00

The laminated film of the present invention eliminates errors in the separator peeling process when temporarily fixing it to a carrier substrate to receive semiconductor chips, etc., and does not peel off from the carrier substrate when transferring semiconductor chips, etc. to a mounting substrate. Furthermore, after transferring semiconductor chips, etc. to the mounting substrate, the film can be peeled off from the carrier substrate without leaving any adhesive residue or other contamination, resulting in excellent reworkability and improving work efficiency in the semiconductor device manufacturing process.

1 is a cross-sectional view showing an embodiment of a laminated film of the present invention. 2 is a cross-sectional view showing an embodiment of a first step in a method for mounting an electronic component on a mounting substrate using the laminate film shown in FIG. 1. FIG. 2 is a cross-sectional view showing an embodiment of a second step in a method for mounting an electronic component onto a mounting substrate using the laminate film shown in FIG. 1. FIG. 1A to 1C are cross-sectional views showing a process from temporarily fixing a laminated film of the present invention to a carrier substrate to peeling it off.

[Laminated film]
The laminate film of the present invention has a laminate structure in which a first separator, a first pressure-sensitive adhesive layer, a substrate, a second pressure-sensitive adhesive layer, and a second separator are laminated in this order. That is, the laminate film of the present invention has a laminate structure in which the adhesive surfaces (adhesive surfaces of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer) of a double-sided pressure-sensitive adhesive film for transfer composed of the first pressure-sensitive adhesive layer, the substrate, and the second pressure-sensitive adhesive layer are protected by the first separator and the second separator.

The first pressure-sensitive adhesive layer comprises a low-tack pressure-sensitive adhesive layer, and the second pressure-sensitive adhesive layer comprises a releasable pressure-sensitive adhesive layer, and the 180° peel force F(1) (N/50 mm) of the first separator from the first pressure-sensitive adhesive layer measured under conditions of 23°C, 50% RH and a peel speed of 0.3 m/min, the 180° peel force F(2) (N/50 mm) of the second separator from the second pressure-sensitive adhesive layer measured under conditions of 23°C, 50% RH and a peel speed of 0.3 m/min, the 180° peel adhesion P(2) (N/50 mm) of the second pressure-sensitive adhesive layer to a glass plate measured under conditions of 23°C, 50% RH and a pulling speed of 0.3 m/min, and the second pressure-sensitive adhesive layer is attached to a glass plate and measured at 23°C, 50% RH and a pulling speed of 0.3 m/min, and the second pressure-sensitive adhesive layer is attached to a glass plate and measured at 23°C, 50% RH and a pulling speed of 0.3 m/min. H. and a 180° peel adhesive strength P′(2) (N/50 mm) of the second pressure-sensitive adhesive layer from a glass plate, measured under conditions of a pulling speed of 0.3 m/min, satisfies the relationship of the following formula:
F(2)≦F(1)
P(2) ≧ F(1)
P'(2)/P(2)<1.20
P'(2)<1.00

One embodiment of the laminate film of the present invention will be described below with reference to the drawings, but the laminate film of the present invention is not limited to this embodiment.

Figure 4 is a cross-sectional schematic diagram showing the process from temporarily fixing the laminate film of the present invention to a carrier substrate to peeling it off.

In Figure 4(a), the second separator 120 is peeled off from the adhesive layer 12 of the laminated film 1, which is adsorbed onto an adsorption stage (not shown). At this time, no lift occurs at the interface between the first separator 110 and the first adhesive layer 11. The adhesive surface of the second adhesive layer 12 is then bonded to a carrier substrate 22 (not shown).

In Figure 4(b), the first separator 110 is peeled off from the adhesive layer 11. At this time, no lifting occurs at the interface of the second adhesive layer 22.

In Figure 4(c), a double-sided adhesive sheet temporarily fixed to a carrier substrate 22 by a second adhesive layer 12 is used to perform a process in which the first adhesive layer 11 receives the diced electronic component 21 shown in Figure 2, and a process in which the electronic component 21 received by the first adhesive layer 11 shown in Figure 3 is transferred to a mounting substrate 30.

In Figure 4(d), the second adhesive layer 12 is peeled off from the carrier substrate 22 (not shown). The second adhesive layer 12 exhibits excellent reworkability, meaning that it can be peeled off without leaving any residue or other contamination, allowing the carrier substrate 22 to be easily reused.

In the laminate film of the present invention, by satisfying F(2)≦F(1), peeling of the first separator from the first pressure-sensitive adhesive layer can be made less likely to occur when the second separator is peeled from the second pressure-sensitive adhesive layer.

Here, F(2)/F(1) (the ratio of F(2) to F(1)) is 1.00 or less (F(2)/F(1)≦1.00), preferably 0.90 or less (F(2)/F(1)≦0.90), more preferably less than 0.80 (F(2)/F(1)<0.80), and even more preferably less than 0.50 (F(2)/F(1)<0.50). Furthermore, F(2)/F(1) is not particularly limited, but is preferably 0.10 or more (F(2)/F(1)≧0.10).

From the viewpoint of workability when peeling off the first separator and the balance with the adhesive strength P(2) of the adhesive 2 to the carrier substrate, F(1) is preferably less than 0.50 N/50 mm (F(1) < 0.50), more preferably 0.40 N/50 mm or less (F(1) ≦ 0.40), and even more preferably 0.35 N/50 mm or less (F(1) ≦ 0.35). Furthermore, from the viewpoint of separator lift during transfer sheet processing and transport, F(1) is preferably 0.04 N/50 mm or more (F(1) ≧ 0.04), more preferably 0.05 N/50 mm or more (F(1) ≧ 0.05, and even more preferably 0.06 N/50 mm or more (F(1) ≦ 0.06).

From the viewpoint of workability when peeling the second separator and the balance with the first separator peeling force F(1), F(2) is preferably less than 0.20 N/50 mm (F(2) < 0.20), more preferably 0.15 N/50 mm or less (F(2) ≦ 0.15 N), and even more preferably 0.10 N/50 mm or less (F(2) ≦ 0.10). Furthermore, from the viewpoint of separator lift during transfer sheet processing and transport, F(2) is preferably 0.01 N/50 mm or more (F(1) ≧ 0.01), more preferably 0.02 N/50 mm or more (F(2) ≧ 0.02), and even more preferably 0.04 N/50 mm or more (F(2) ≧ 0.04).

In the laminate film of the present invention, by satisfying P(2)≧F(1), peeling of the second pressure-sensitive adhesive layer from the carrier substrate can be made less likely to occur when the first separator is peeled from the first pressure-sensitive adhesive layer.

Here, P(2)/F(1) (the ratio of P(2) to F(1)) is 1.00 or greater (P(2)/F(1)≧1.00), preferably greater than 1.00 (F(2)/F(1)>1.00), and more preferably 1.20 or greater (F(2)/F(1)≧1.20). Furthermore, P(2)/F(1) is not particularly limited, but is preferably 4.50 or less (F(2)/F(1)≦4.50), for example.

From the viewpoint of improving reworkability, that is, peeling from the carrier substrate without leaving any adhesive residue or other contamination, P(2) is preferably less than 1.10 N/50 mm (P(2)<1.10), more preferably 1.00 N/50 mm or less (P(2)≦1.00), and even more preferably 0.90 N/50 mm or less (P(2)≦0.90). Furthermore, from the viewpoint of adhesion of the carrier substrate to the second adhesive layer, P(2) is preferably 0.10 N/50 mm or more (P(2)≧0.10), more preferably 0.20 N/50 mm or more (P(2)≧0.20), and even more preferably 0.30 N/50 mm or more (P(2)≦0.30).

By satisfying the above relationships for F(1), F(2), and P(2), errors are less likely to occur during the separator peeling process when attaching the double-sided adhesive film for transfer to the carrier substrate.

In the second adhesive layer according to the present invention, P'(2)/P(2) (the ratio of P'(2) to P(2)) is less than 1.20 (P'(2)/P(2)<1.20), preferably 1.0 or less (P'(2)/P(2)≦1.0), and more preferably 0.8 or less (P'(2)/P(2)≦0.8), from the viewpoint of preventing an increase in the adhesive strength of the second adhesive layer to the carrier substrate even during thermocompression bonding when transferring and mounting electronic components to the mounting substrate, and achieving good peeling and excellent reworkability. Furthermore, P'(2)/P(2) is not particularly limited, but is preferably 0.01 or more (F(2)/F(1)≧0.01), and more preferably 0.03 or more (F(2)/F(1)≧0.03).

In the second adhesive layer according to the present invention, P'(2) is less than 1.00 N/50 mm (P'(2)<1.00), preferably 0.6 N/50 mm or less (P'(2)≦0.6), and more preferably 0.4 N/50 mm or less (P'(2)≦0.4), from the viewpoint of ensuring that the double-sided adhesive film for transfer can be easily peeled from the carrier substrate without leaving any adhesive residue and that reworkability is excellent. Furthermore, P'(2) is not particularly limited, but is preferably 0.01 N/50 mm or more (P'(2)≧0.01), and more preferably 0.02 N/50 mm or more (P'(2)≧0.02).

By satisfying the above relationship between P(2) and P'(2), the double-sided adhesive film for transfer is less likely to peel off from the carrier substrate when transferring a semiconductor chip or the like to a mounting substrate, and the double-sided adhesive film for transfer is more likely to peel off from the carrier substrate after transferring a semiconductor chip or the like to a mounting substrate, making it less likely that adhesive residue will remain.

In the laminate film of the present invention, it is preferable that the 90° trigger peel strength T(1) (N/50 mm) of the first pressure-sensitive adhesive layer from the first separator, measured under conditions of 23°C, 50% RH and a pulling speed of 0.3 m/min, the 90° trigger peel strength T(2) (N/50 mm) of the second pressure-sensitive adhesive layer from the second separator, measured under conditions of 23°C, 50% RH and a pulling speed of 0.3 m/min, and the adhesive strength P(2) satisfy the relationship of the following formula:
T(1)/T(2)>1.05
P(2)/T(1)<1.90

The initial peel force T(1) refers to the maximum peel force (maximum stress) recorded at the beginning of peeling when peeling the first separator from the first adhesive layer, and the initial peel force T(2) refers to the maximum peel force (maximum stress) recorded at the beginning of peeling when peeling the second separator from the second adhesive layer.

In the laminate film of the present invention, T(1)/T(2) (the ratio of T(1) to T(2)) is preferably greater than 1.05 (T(1)/T(2) > 1.05), more preferably 1.10 or greater (T(1)/T(2) ≧ 1.10), and even more preferably 1.15 or greater (T(1)/T(2) ≧ 1.15), from the viewpoint of making it more difficult for the first separator to peel from the first pressure-sensitive adhesive layer when the second separator is peeled from the second pressure-sensitive adhesive layer. Furthermore, T(1)/T(2) is not particularly limited, but is preferably, for example, 3.50 or less (T(1)/T(2) ≦ 3.50).

In the laminate film of the present invention, P(2)/T(1) (the ratio of P(2) to T(1)) is preferably less than 1.90 (P(2)/T(1)<1.90), more preferably 1.50 or less (P(2)/T(1)≦1.50), even more preferably less than 1.00 (P(2)/T(1)<1.00), and particularly preferably 0.90 or less (P(2)/T(1)≦0.90). Furthermore, P(2)/T(1) is not particularly limited, but is preferably 0.20 or more (P(2)/T(1)≧0.20), and more preferably 0.40 or more (P(2)/T(1)≧0.40).

T(1) is preferably 0.10 N/50 mm or greater (T(1)≧0.10), more preferably 0.15 N/50 mm or greater (T(1)≧0.15), and even more preferably 0.20 N/50 mm or greater (T(1)≧0.20). Furthermore, T(1) is not particularly limited, but is preferably 1.00/50 mm or less (T(1)≦0.1.00), more preferably 0.85/50 mm or less (T(1)≦0.85), and even more preferably 0.70/50 mm or less (PT(1)≦0.70).

T(2) is preferably 0.50 N/50 mm or less (T(2)≦0.50), more preferably 0.45 N/50 mm or less (T(2)≦0.45), and even more preferably 0.40 N/50 mm or less (T(2)≦0.40). T(1) is not particularly limited, but is preferably 0.10 N/50 mm or more (T(2)≧0.10), and more preferably 0.15 N/50 mm or more (T(2)≧0.15).

By satisfying the above relationships for T(1), T(2), and P(2), it becomes even less likely that errors will occur during the separator peeling process when attaching the double-sided adhesive film for transfer to the carrier substrate.

As described above, by optimizing the overall configuration for peel force and adhesive force so that the above relationships are satisfied for F(1), F(2), P(2), P'(2), T(1), and T(2), it is possible to improve work efficiency in the semiconductor device manufacturing process.

The above F(1), F(2), P(2), P'(2), T(1), and T(2) can be adjusted by adjusting the adhesive strength by the type and composition of the adhesives constituting the first and second adhesive layers, the degree of crosslinking, etc., forming a WBL (Weak Boundary Layer) by incorporating a light release agent or plasticizer, the thickness of the first and second separators, the constituent materials, release treatment, etc.

<First adhesive layer>
In the double-sided adhesive film for transfer according to the present invention, the first adhesive layer is an adhesive layer for receiving and holding an electronic component and is composed of a low-tack adhesive layer. The configuration in which the first adhesive layer is composed of a low-tack adhesive layer is advantageous in that it reduces the force applied to the electronic component during reception and suppresses damage to the electronic component. Furthermore, when the first adhesive layer receives an electronic component in a non-contact manner, for example, the electronic component is peeled off from the dicing tape by pushing it with a pin member and then dropped onto the first adhesive layer. However, the dropped electronic component may bounce when received by the first adhesive layer, preventing it from being received accurately. If this occurs, the positional accuracy of the electronic product may be reduced, resulting in poor contact. The configuration in which the first adhesive layer is composed of a low-tack adhesive layer is also advantageous in that when the first adhesive layer receives an electronic component in a non-contact manner, the electronic component is easily caught by the first adhesive layer without bouncing, allowing it to be received with high positional accuracy. Furthermore, this is also preferable in that when the electronic component received by the double-sided pressure-sensitive adhesive film for transfer is mounted on a mounting substrate, the electronic component can be easily peeled off from the first pressure-sensitive adhesive layer.

The first adhesive layer can be made into a low-tack adhesive layer by adjusting the type, composition, and degree of crosslinking of the adhesive that makes it up, or by forming a weak boundary layer (WBL) by incorporating a light release agent or plasticizer.

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

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

In the laminate film of the present invention, the ratio (E'1b/E'1a) of the storage modulus (E'1b) of the first pressure-sensitive adhesive layer measured by AFM-DMA at a frequency of 1 Hz and 25°C to the storage modulus (E'1a) of the first pressure-sensitive adhesive layer measured by AFM-DMA at a frequency of 1 Hz and 25°C is preferably greater than 1.00. This configuration is preferable in that it provides a good balance between the adhesion of electronic components to the first pressure-sensitive adhesive layer, positional accuracy, and transferability to the mounting substrate. From the perspective of a balance between the adhesion of electronic components, positional accuracy, and transferability to the mounting substrate, E'1b/E'1a is preferably 1.05 or greater, and more preferably 1.10 or greater. There is no particular upper limit to E'1b/E'1a, but from the perspective of the above-mentioned balance, it is preferably 3.00 or less.

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

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

In the laminate film of the present invention, the tack strength of the first pressure-sensitive adhesive layer against a stainless steel plate (diameter 5 mm) is preferably 10 to 250 gf/Φ5mm SUS. A configuration in which the tack strength is 10 gf/Φ5mm SUS or more is preferred from the standpoint of adhesion and positional accuracy of electronic components to the first pressure-sensitive adhesive layer, with 20 gf/Φ5mm SUS or more being more preferred. On the other hand, a configuration in which the tack strength is 250 gf/Φ5mm SUS or less is preferred from the standpoint of transferability of electronic components to mounting substrates, with 200 gf/Φ5mm SUS or less being more preferred.

The tack strength of the first adhesive layer against a stainless steel plate (5 mm diameter) can be adjusted by the type and composition of the adhesive that makes it up, the degree of crosslinking, and additives such as fatty acid esters and fluorine-based surfactants.

In the laminate film of the present invention, the surface strength of the first pressure-sensitive adhesive layer is preferably -500 to -100 μN. A surface strength of -500 μN or more is preferred from the standpoint of adhesion and positional accuracy of electronic components to the first pressure-sensitive adhesive layer, with -400 μN or more being more preferred. On the other hand, a surface strength of -100 μN or less is preferred from the standpoint of transferability of electronic components to mounting substrates, with -150 μN or less being more preferred.

The surface strength of the first adhesive layer can be adjusted by the type and composition of the adhesive that makes it up, the degree of crosslinking, and additives such as fatty acid esters and fluorine-based surfactants.

In the double-sided adhesive film for transfer according to the present invention, the thickness of the first adhesive layer is not particularly limited, but is preferably 1 μm or more, and more preferably 3 μm or more. A thickness of at least a certain level is preferred, as it makes it easier for the first adhesive layer to receive electronic components with precision. Furthermore, the upper limit of the thickness of the first adhesive layer is not particularly limited, but is preferably 100 μm, and more preferably 75 μm. A thickness of at most a certain level is preferred, as it makes it easier for electronic components to be transferred to a mounting substrate with precision.

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

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

The adhesive constituting the first adhesive layer is not particularly limited, but examples include silicone-based adhesives, urethane-based adhesives, acrylic-based adhesives, rubber-based adhesives, polyester-based adhesives, polyamide-based adhesives, epoxy-based adhesives, vinyl alkyl ether-based adhesives, and fluorine-based adhesives. Among these, from the standpoint of being able to hold electronic components with good positional accuracy without damaging them and further enabling good transferability to the mounting substrate, silicone-based adhesives, urethane-based adhesives, and acrylic-based adhesives are preferred, as they are easy to control to have low adhesion, with silicone-based adhesives and urethane-based adhesives being more preferred, and silicone-based adhesives being even more preferred.

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

The above-mentioned addition-type silicone-based pressure-sensitive adhesives are generally pressure-sensitive adhesives that produce a silicone-based polymer by subjecting an organopolysiloxane that has an alkenyl group, such as a vinyl group, on the silicon atom and an organopolysiloxane that has a hydrosilyl group to an addition reaction (hydrosilylation reaction) using a platinum compound catalyst, such as chloroplatinic acid. Peroxide-curing silicone-based pressure-sensitive adhesives are generally pressure-sensitive adhesives that produce a silicone-based polymer by curing (crosslinking) an organopolysiloxane with peroxide. Condensation-type silicone-based pressure-sensitive adhesives are generally pressure-sensitive adhesives that produce a silicone-based polymer by a dehydration or dealcoholization reaction between polyorganosiloxanes that have hydrolyzable silyl groups, such as silanol groups or alkoxysilyl groups, at the terminals.

Examples of silicone-based adhesives include silicone-based adhesive compositions containing silicone rubber and silicone resin, which are easy to control to have low adhesion.

The silicone rubber is not particularly limited as long as it contains a silicone-based rubber component. For example, organopolysiloxanes whose main structural units are dimethylsiloxane, methylphenylsiloxane, etc. can be used. Depending on the type of reaction, silicone rubbers containing alkenyl groups bonded to silicon atoms (alkenyl-group-containing organopolysiloxanes; addition reaction types), silicone rubbers containing at least methyl groups (peroxide-curing types), and silicone rubbers containing silanol groups or hydrolyzable alkoxysilyl groups at the terminals (condensation types) can be used. The weight-average molecular weight of the organopolysiloxane in the silicone rubber is typically 150,000 or higher, preferably 280,000 to 1,000,000, with 500,000 to 900,000 being particularly suitable.

The silicone resin is not particularly limited as long as it is a silicone resin used in silicone-based pressure-sensitive adhesives, and examples thereof include silicone resins made of organopolysiloxanes made of (co)polymers having at least one unit selected from M units made of the structural unit " _{R3Si1 / 2} ", Q units made of the structural unit "SiO2 _{", T units made of the structural unit "RSiO3/2 "} , and D units made of the structural unit "R2SiO". In the structural units, R represents a hydrocarbon group or a hydroxyl group. Examples of the hydrocarbon group include aliphatic hydrocarbon groups (e.g., alkyl groups such as methyl and ethyl), alicyclic hydrocarbon groups (e.g., cycloalkyl groups such as cyclohexyl), and aromatic hydrocarbon groups (e.g., aryl groups such as phenyl and naphthyl). The ratio (ratio) of the M units to at least one unit selected from Q units, T units, and D units is preferably, for example, a former/latter (molar ratio) of 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 undergoing a crosslinking reaction. MQ resins composed of M units and Q units are preferred as silicone resins. The weight-average molecular weight of the organopolysiloxane in the silicone resin is typically 1,000 or more, preferably 1,000 to 20,000, and particularly preferably 1,500 to 10,000.

There are no particular restrictions on the blend ratio of silicone rubber to silicone resin, but because it is easier to control the adhesiveness to low levels, it is preferable that the silicone resin be 100 to 220 parts by weight (particularly 120 to 180 parts by weight) per 100 parts by weight of silicone rubber.

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

Furthermore, silicone-based pressure-sensitive adhesive compositions containing silicone rubber and silicone resin typically contain a crosslinking agent to form a crosslinked structure, which makes it easier to control the adhesiveness to low levels. There are no particular restrictions on such crosslinking agents, but siloxane-based crosslinking agents (silicone-based crosslinking agents) and peroxide-based crosslinking agents are suitable. Crosslinking agents can be used alone or in combination of two or more.

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 polyorganohydrogensiloxanes, the silicon atoms to which hydrogen atoms are bonded may have various organic groups bonded in addition to the hydrogen atoms. Examples of such organic groups include alkyl groups such as methyl and ethyl groups; aryl groups such as phenyl groups; and halogenated alkyl groups. However, from the standpoint of synthesis and handling, methyl groups are preferred. Furthermore, the skeletal structure of the polyorganohydrogensiloxane may be linear, branched, or cyclic, although linear structures are preferred.

Examples of the peroxide-based crosslinking agent that can be used include diacyl peroxides, alkyl peroxy esters, peroxydicarbonates, monoperoxycarbonates, peroxyketals, dialkyl peroxides, hydroperoxides, and ketone peroxides. More specific examples include benzoyl peroxide, t-butyl peroxybenzoate, dicumyl peroxide, t-butylcumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di-t-butylperoxyhexane, 2,4-dichloro-benzoyl peroxide, di-t-butylperoxy-diisopropylbenzene, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, and 2,5-dimethyl-2,5-di-t-butylperoxyhexyne-3.

Addition-type silicone-based adhesives are commercially available under the trade names "KR-3700," "KR-3701," "X-40-3237-1," "X-40-3240," "X-40-3291-1," and "X-40-3306" (all manufactured by Shin-Etsu Chemical Co., Ltd.). Peroxide-curing silicone-based adhesives are commercially available under the trade names "KR-100," "KR-101-10," and "KR-130" (all manufactured by Shin-Etsu Chemical Co., Ltd.).

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

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

Any suitable polyol having two or more hydroxyl groups can be used as the polyol. Examples of such polyols include polyols (diols) having two hydroxyl groups, polyols (triols) having three hydroxyl groups, polyols (tetraols) having four hydroxyl groups, polyols (pentaols) having five hydroxyl groups, and polyols (hexaols) having six hydroxyl groups. Polyols can be used alone or in combination of two or more.

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

Examples of the polyols include polyester polyols, polyether polyols, polycaprolactone polyols, polycarbonate polyols, and castor oil-based polyols.

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

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

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

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

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

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

The castor oil-based polyol may be, for example, a castor oil-based polyol obtained by reacting a castor oil fatty acid with the polyol component. Specifically, for example, a castor oil-based polyol obtained by reacting a castor oil fatty acid with polypropylene glycol may be used.

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

Examples of the polyfunctional isocyanate compounds include aliphatic polyisocyanates, alicyclic polyisocyanates, and aromatic polyisocyanate compounds.

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

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

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

Among these, aliphatic polyisocyanates and their modified products are preferred. Compared to other isocyanate-based crosslinking agents, aliphatic polyisocyanates and their modified products have a more flexible crosslinked structure, making it easier to control the adhesiveness to low levels. Of aliphatic polyisocyanates and their modified products, hexamethylene diisocyanate and its modified products are particularly preferred.

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

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

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

Furthermore, as a urethane-based adhesive, a urethane-based adhesive composition containing a urethane prepolymer is also preferred, as it is easy to control the adhesiveness to low levels.

Examples of urethane-based pressure-sensitive adhesive compositions containing urethane prepolymers include pressure-sensitive adhesive compositions containing polyurethane polyol as the urethane prepolymer and a polyfunctional isocyanate compound. Urethane prepolymers can be used alone or in combination of two or more types. Polyfunctional isocyanate compounds can be used alone or in combination of two or more types.

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

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

Polyester polyols with molecular weights ranging from low to high can be used. The number average molecular weight of the polyester polyol is preferably 500 to 5,000. If the number average molecular weight is less than 500, the reactivity may be high and gelation may occur easily. If the number average molecular weight exceeds 5,000, the reactivity may decrease and the cohesive strength of the polyurethane polyol itself may become weak. The amount of polyester polyol used is preferably 10 to 90 mol % of the polyols that make up the polyurethane polyol.

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

Polyether polyols with molecular weights ranging from low to high can be used. The number average molecular weight of the polyether polyol is preferably 1,000 to 5,000. If the number average molecular weight is less than 1,000, the reactivity may be high and gelation may occur easily. If the number average molecular weight exceeds 5,000, the reactivity may decrease and the cohesive strength of the polyurethane polyol itself may become weak. The amount of polyether polyol used is preferably 20 to 80 mol % of the polyols that make up the polyurethane polyol.

If necessary, polyether polyols can be partially replaced with glycols such as ethylene glycol, 1,4-butanediol, neopentyl glycol, butylethylpentanediol, glycerin, trimethylolpropane, and pentaerythritol, or polyamines such as ethylenediamine, N-aminoethylethanolamine, isophoronediamine, and xylylenediamine.

As the polyether polyol, only a bifunctional polyether polyol may be used, or a polyether polyol having a number-average molecular weight of 1000 to 5000 and at least three hydroxyl groups per molecule may be used in part or in whole. Using a polyether polyol having an average molecular weight of 1000 to 5000 and at least three hydroxyl groups per molecule in part or in whole can achieve a good balance between adhesive strength and removability. If such a polyether polyol has a number-average molecular weight of less than 1000, it may become highly reactive and prone to gelation. If such a polyether polyol has a number-average molecular weight of more than 5000, it may become less reactive and the cohesive strength of the polyurethane polyol itself may become weaker. The number-average molecular weight of such a polyether polyol is more preferably 2500 to 3500.

Any suitable organic polyisocyanate compound can be used as the organic polyisocyanate compound. Examples of such organic polyisocyanate compounds include aromatic polyisocyanates, aliphatic polyisocyanates, araliphatic polyisocyanates, and alicyclic polyisocyanates.

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

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

Examples of aromatic aliphatic polyisocyanates include ω,ω'-diisocyanate-1,3-dimethylbenzene, ω,ω'-diisocyanate-1,4-dimethylbenzene, ω,ω'-diisocyanate-1,4-diethylbenzene, 1,4-tetramethylxylylene diisocyanate, and 1,3-tetramethylxylylene diisocyanate.

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

Organic polyisocyanate compounds that can be used in combination include trimethylolpropane adducts, biuret compounds reacted with water, and trimers having an isocyanurate ring.

Any suitable catalyst can be used to obtain polyurethane polyol. Examples of such catalysts include tertiary amine compounds and organometallic compounds.

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

Examples of organometallic compounds include tin-based compounds and non-tin-based compounds.

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

Non-tin compounds include, for example, titanium compounds such as dibutyltitanium dichloride, tetrabutyltitanium, and butoxytitanium trichloride; lead compounds such as lead oleate, lead 2-ethylhexanoate, lead benzoate, and lead naphthenate; iron compounds such as iron 2-ethylhexanoate and iron acetylacetonate; cobalt compounds such as cobalt benzoate and cobalt 2-ethylhexanoate; zinc compounds such as zinc naphthenate and zinc 2-ethylhexanoate; and zirconium compounds such as zirconium naphthenate.

When using a catalyst to produce polyurethane polyol, in systems containing two types of polyols, polyester polyol and polyether polyol, differences in reactivity can easily lead to problems such as gelation and cloudy reaction solutions when using a single catalyst. Therefore, using two types of catalysts to produce polyurethane polyol makes it easier to control the reaction rate, catalyst selectivity, and other factors, thereby solving these problems. Examples of such combinations of two catalysts include tertiary amine/organometallic, tin/non-tin, and tin/tin. Tin/tin combinations are preferred, and a combination of dibutyltin dilaurate and tin 2-ethylhexanoate is even more preferred. The weight ratio of tin 2-ethylhexanoate/dibutyltin dilaurate is preferably less than 1, and more preferably 0.2 to 0.6. A ratio of 1 or more can lead to gelation due to the balance of catalytic activity.

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

When a catalyst is used to obtain polyurethane polyol, the reaction temperature is preferably below 100°C, and more preferably between 85°C and 95°C. Temperatures above 100°C may make it difficult to control the reaction rate and crosslinking structure, making it difficult to obtain polyurethane polyol with the desired molecular weight.

When obtaining polyurethane polyol, it is not necessary to use a catalyst. In that case, the reaction temperature is preferably 100°C or higher, and more preferably 110°C or higher. Furthermore, when obtaining polyurethane polyol without a catalyst, it is preferable to carry out the reaction for 3 hours or more.

Methods for obtaining polyurethane polyol include, for example, 1) charging polyester polyol, polyether polyol, catalyst, and organic polyisocyanate into a volumetric flask, and 2) charging polyester polyol, polyether polyol, and catalyst into a flask and adding the organic polyisocyanate dropwise. Method 2) is preferred for obtaining polyurethane polyol in terms of reaction control.

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

The polyfunctional isocyanate compounds mentioned above can be used.

Any appropriate manufacturing method can be used to produce a polyurethane composition obtained from a composition containing a urethane prepolymer, as long as it is a method for producing a polyurethane resin composition using a so-called "urethane prepolymer" as a raw material.

(acrylic adhesive)
The acrylic pressure-sensitive adhesive is not particularly limited, and any known or commonly used acrylic pressure-sensitive adhesive can be used. For example, an acrylic pressure-sensitive adhesive composition containing an acrylic polymer as a base polymer can be used, as this can be easily controlled to have low adhesion.

The acrylic polymer is a polymer containing structural units derived from acrylic monomers (monomer components having a (meth)acryloyl group in the molecule) as structural units of the polymer. The acrylic polymer is preferably a polymer containing structural units derived from (meth)acrylic acid esters in the largest proportion by mass. Acrylic polymers can be used alone or in combinations of two or more. In this specification, "(meth)acrylic" refers to "acrylic" and/or "methacrylic" (either one or both of "acrylic" and "methacrylic"), and similar terms apply to other polymers.

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

The above hydrocarbon group-containing (meth)acrylic esters can be used alone or in combination of two or more. Because the basic properties of the hydrocarbon group-containing (meth)acrylic ester, such as adhesion, are appropriately exhibited in the first adhesive layer and low adhesion can be easily controlled, the proportion of the hydrocarbon group-containing (meth)acrylic ester in all monomer components used to form the acrylic polymer is preferably 40% by mass or more, and more preferably 60% by mass or more.

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

The acrylic polymer may contain structural units derived from a polyfunctional monomer copolymerizable with the monomer components forming the acrylic polymer to form a crosslinked structure within the polymer backbone. Examples of polyfunctional monomers include monomers containing a (meth)acryloyl group and other reactive functional groups within the molecule, such as hexanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, epoxy (meth)acrylate (e.g., polyglycidyl (meth)acrylate), polyester (meth)acrylate, and urethane (meth)acrylate. The polyfunctional monomers may be used alone or in combination. In order to ensure that the basic properties of the hydrocarbon group-containing (meth)acrylic acid ester, such as adhesion, are properly exhibited in the first adhesive layer and to facilitate control of low adhesion, the proportion of the above-mentioned polyfunctional monomer in all monomer components used to form the acrylic polymer is preferably 40% by mass or less, and more preferably 30% by mass or less.

Acrylic polymers are obtained by polymerizing one or more monomer components, including acrylic monomers. Polymerization methods include solution polymerization, emulsion polymerization, bulk polymerization, and suspension polymerization.

The mass-average molecular weight of the acrylic polymer is preferably 100,000 or more, and more preferably 200,000 to 3,000,000. When the mass-average molecular weight is 100,000 or more, the amount of low-molecular-weight substances in the adhesive layer tends to be low, which can further reduce contamination of electronic components, etc.

The acrylic pressure-sensitive adhesive composition forming the first pressure-sensitive adhesive layer may contain a crosslinking agent. For example, by crosslinking the acrylic polymer, it is possible to further reduce low-molecular-weight substances in the first pressure-sensitive adhesive layer. Furthermore, by increasing the weight-average molecular weight of the acrylic polymer, it is possible to control the adhesiveness to be low. Examples of the crosslinking agent include polyisocyanate compounds, epoxy compounds, polyol compounds (such as polyphenol compounds), aziridine compounds, and melamine compounds, with isocyanate-based crosslinking agents and/or epoxy-based crosslinking agents being preferred. When a crosslinking agent is used, the amount used is preferably approximately 10 parts by weight or less, more preferably 0.1 to 10 parts by weight, per 100 parts by weight of the acrylic polymer.

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

Examples of epoxy crosslinking agents (multifunctional epoxy compounds) include N,N,N',N'-tetraglycidyl-m-xylenediamine, 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 suitable crosslinking agents include glycerol polyglycidyl ether, glycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitan polyglycidyl ether, trimethylolpropane polyglycidyl ether, adipic acid diglycidyl ester, o-phthalic acid diglycidyl ester, triglycidyl tris(2-hydroxyethyl)isocyanurate, resorcinol diglycidyl ether, and bisphenol-S-diglycidyl ether. Examples of suitable crosslinking agents include epoxy resins having two or more epoxy groups in the molecule. An example of a commercially available epoxy crosslinking agent is "Tetrad C" manufactured by Mitsubishi Gas Chemical Company, Inc.

The adhesive composition constituting the first adhesive layer preferably contains a light release agent. By including a light release agent, a WBL (Weak Boundary Layer) is formed on the surface of the first adhesive layer, making it easier to control low adhesion.

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

The silicone-based release agent is not particularly limited, but examples include heat-curable silicone-based release agents and ionizing radiation-curable silicone-based release agents. Silicone-based release agents may be either solvent-free, meaning they contain no solvent, or solvent-based, meaning they are dissolved or dispersed in an organic solvent. Silicone-based release agents can be used alone or in combination of two or more types.

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

The above-mentioned thermal addition reaction curable silicone release agent is not particularly limited, but preferred examples include release agents containing a polysiloxane having a hydrogen atom (H) bonded to a silicon atom (Si) in the molecule (Si-H group-containing polysiloxane) and a polysiloxane containing a functional group (Si-H group-reactive functional group) in the molecule that is reactive with Si-H bonds (covalent bonds between Si and H) (Si-H group-reactive polysiloxane). This release agent cures through crosslinking caused by an addition reaction between the Si-H group and the Si-H group-reactive functional group.

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

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

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

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

The ionizing radiation-curable silicone-based release agent is not particularly limited, but a preferred example is a UV-curable silicone-based release agent that cures through a crosslinking reaction upon exposure to ultraviolet (UV) light.

The above-mentioned UV-curable silicone-based release agent is a release agent that cures through a chemical reaction such as cationic polymerization, radical polymerization, radical addition polymerization, or hydrosilylation reaction upon UV irradiation. Of the above-mentioned UV-curable silicone-based release agents, UV-curable silicone-based release agents that cure through cationic polymerization are particularly preferred.

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

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

When the first adhesive layer in the double-sided adhesive film for transfer according to the present invention contains a silicone-based adhesive, the content of the silicone-based release agent is not particularly limited, but is preferably 0.5 parts by weight or more and 100 parts by weight or less per 100 parts by weight of the silicone-based polymer base polymer. A content of 0.5 parts by weight or more makes it easier to achieve the effect of easily controlling the adhesiveness of the first adhesive layer to be low, and is more preferably 1 part by weight or more, and even more preferably 3 parts by weight or more. Furthermore, a content of 100 parts by weight or less makes it easier to prevent the problem of insufficient adhesiveness resulting in difficulty in receiving electronic components, and is more preferably 30 parts by weight or less, and even more preferably 25 parts by weight or less.

By using the above fluorosurfactants as light release agents, the low surface free energy of the fluorine moieties can be used to achieve a light release effect.

The fluorosurfactant is not particularly limited, but examples include fluorooligomers, perfluorobutanesulfonates, perfluoroalkyl group-containing carboxylates, hexafluoropentane trimer derivative-containing sulfonates, hexafluoropentane trimer derivative-containing carboxylates, hexafluoropentane trimer derivative-containing quaternary ammonium salts, hexafluoropentane trimer derivative-containing betaines, and hexafluoropentane trimer derivative-containing polyoxyethylene ethers, with fluorooligomers being preferred. The fluorosurfactants can be used alone or in combination of two or more.

Specific examples of the above-mentioned fluorine-based surfactants include, for example, commercially available products under the trade names "Megafac F(1)14" and "Megafac F-410" (both manufactured by DIC Corporation), "Surflon S-211," "Surflon S-221," "Surflon S-231," "Surflon S-232," "Surflon S-233," "Surflon S-241," "Surflon S-242," "Surflon S-243," and "Surflon S-420" (all manufactured by AGC Seimi Chemical Co., Ltd.), and products under the trade names "Ftergent 100," "Ftergent 100C," "Ftergent 110," "Ftergent 150," "Ftergent 150CH," "Ftergent 300," and "Ftergent 420." Examples of suitable compounds include Ftergent 310, Ftergent 320, Ftergent 400SW, Ftergent 251, Ftergent 212M, Ftergent 215M, Ftergent 250, Ftergent 209F, Ftergent 222F, Ftergent 245F, Ftergent 208G, Ftergent 218GL, Ftergent 240G, Ftergent 212P, Ftergent 220P, Ftergent 228P, Ftergent FTX-218, and Ftergent DFX-18 (all manufactured by Neos Corporation). These compounds can be used alone or in combination of two or more.

The weight-average molecular weight (Mw) of the fluorine-based oligomer is preferably 3,500 or more, more preferably 5,000 or more, even more preferably 10,000 or more, and particularly preferably 20,000 or more. When the weight-average molecular weight of the fluorine-based oligomer is 3,500 or more, it is easier to control the adhesiveness to low levels. Furthermore, a weight-average molecular weight of 20,000 or more is preferable because it can suppress foaming during blending of the adhesive (composition) and results in excellent appearance after application of the adhesive. The upper limit of the weight-average molecular weight (Mw) of the fluorine-based oligomer is preferably 200,000, more preferably 100,000. Setting the upper limit to 200,000 makes it easier for the fluorine-based oligomer to be unevenly distributed on the surface, making it easier to exhibit an easy release effect, which is preferable.

Furthermore, examples of the above-mentioned fluorine-based oligomers include commercially available products under the trade names "Megafac F (2) 51," "Megafac F (2) 53," "Megafac F (2) 81," "Megafac F-410," "Megafac F-430," "Megafac F-444," "Megafac F-477," "Megafac F-510," "Megafac F-511," "Megafac F-551," "Megafac F-552," "Megafac F-553," "Megafac F-554," "Megafac F-555," "Megafac F-556," "Megafac F-557," "Megafac F-558," "Megafac F-559," "Megafac F-560," "Megafac F-561," and "Megafac F-562." Examples of such compounds include "Megafac F-562," "Megafac F-563," "Megafac F-565," "Megafac F-568," "Megafac F-569," "Megafac F-570," "Megafac F-571," and "Megafac F-572" (all manufactured by DIC Corporation), trade names "Surflon S-611," "Surflon S-651," and "Surflon S-386" (all manufactured by AGC Seimi Chemical Co., Ltd.), and trade names "Ftergent 610FM," "Ftergent 710FL," "Ftergent 710FM," "Ftergent 710FS," "Ftergent 730FL," and "Ftergent 730LM" (all manufactured by Neos Corporation). These compounds can be used alone or in combination of two or more.

When the first adhesive layer of the double-sided adhesive film for transfer according to the present invention contains a fluorochemical surfactant, the content of the fluorochemical surfactant is not particularly limited, but is preferably 0.01 to 5 parts by weight per 100 parts by weight of the silicone polymer base polymer. A content of 0.01 parts by weight or more makes it easier to achieve the effect of easily controlling the adhesiveness of the first adhesive layer to be low, and is more preferably 0.05 parts by weight or more, and even more preferably 0.1 parts by weight or more. Furthermore, a content of 5 parts by weight or less makes it easier to prevent the problem of insufficient adhesiveness resulting in difficulty in receiving electronic components, and from the viewpoint of preventing a decrease in transparency, is more preferably 3 parts by weight or less, and even more preferably 2 parts by weight or less.

By including a fatty acid ester in the adhesive composition that constitutes the first adhesive layer, the first adhesive layer can be expected to have low adhesion and wettability to electronic components.

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

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

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

The adhesive composition constituting the first adhesive layer preferably contains an anti-deterioration agent such as an antioxidant or an ultraviolet absorber. The inclusion of an anti-deterioration agent can suppress deterioration such as discoloration of the double-sided adhesive film for transfer according to the present invention during storage, and can also improve processability, such as making the double-sided adhesive film for transfer easier to cut.

The UV absorber is not particularly limited, but examples include triazine-based UV absorbers, benzotriazole-based UV absorbers, benzophenone-based UV absorbers, oxybenzophenone-based UV absorbers, salicylic acid ester-based UV absorbers, and cyanoacrylate-based UV absorbers. These can be used alone or in combination of two or more. Among these, triazine-based UV absorbers and benzotriazole-based UV absorbers are preferred. At least one UV absorber selected from the group consisting of triazine-based UV absorbers having two or less hydroxyl groups per molecule and benzotriazole-based UV absorbers having one benzotriazole skeleton per molecule is preferred because it has good solubility in the monomers used to form the acrylic pressure-sensitive adhesive composition and has high UV absorption capacity at wavelengths around 380 nm.

Specific examples of triazine-based ultraviolet absorbers having two or less hydroxyl groups per molecule include 2,4-bis-[{4-(4-ethylhexyloxy)-4-hydroxy}-phenyl]-6-(4-methoxyphenyl)-1,3,5-triazine (trade name "Tinosorb S", manufactured by BASF), 2,4-bis[2-hydroxy-4-butoxyphenyl]-6-(2,4-dibutoxyphenyl)-1,3,5-triazine (trade name "TINUVIN 460", manufactured by BASF), 2-(4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl)-5-hydroxyphenyl and [(C ₁₀ -C ₁₆ (mainly C ₁₂ -C ₁₃ 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine and (2-ethylhexyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine]-5-[3-(dodecyloxy)-2-hydroxypropoxy]phenol (trade name "TINUVIN 400", manufactured by BASF), 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine and (2-ethylhexyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine), Examples of suitable esters include 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[(hexyl)oxy]-glycidic acid esters (trade name "TINUVIN 405", manufactured by BASF), 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[(hexyl)oxy]-phenol (trade name "TINUVIN 1577", manufactured by BASF), 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[2-(2-ethylhexanoyloxy)ethoxy]-phenol (trade name "ADK STAB LA46", manufactured by ADEKA), and 2-(2-hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine (trade name "TINUVIN 479", manufactured by BASF).

Furthermore, examples of benzotriazole-based ultraviolet absorbers having one benzotriazole skeleton per molecule include 2-(2H-benzotriazol-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol (trade name "TINUVIN 928", manufactured by BASF), 2-(2-hydroxy-5-tert-butylphenyl)-2H-benzotriazole (trade name "TINUVIN PS", manufactured by BASF), benzenepropanoic acid and 3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)-4-hydroxy(C _7-9 side chain and linear alkyl) ester compound (trade name "TINUVIN 384-2", manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (trade name "TINUVIN 900", manufactured by BASF), 2-(2H-benzotriazol-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol (trade name "TINUVIN 928", manufactured by BASF), reaction product of methyl-3-(3-(2H-benzotriazol-2-yl)-5-t-butyl-4-hydroxyphenyl)propionate/polyethylene glycol 300 (trade name "TINUVIN 1130", manufactured by BASF), 2-(2H-benzotriazol-2-yl)-p-cresol (trade name "TINUVIN P", manufactured by BASF), 2(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (trade name "TINUVIN 234", manufactured by BASF), 2-[5-chloro(2H)-benzotriazol-2-yl]-4-methyl-6-(tert-butyl)phenol (trade name "TINUVIN 326", manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (trade name "TINUVIN 328", manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol (trade name "TIN methyl 3-(3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl)propionate and polyethylene glycol 300 (trade name "TINUVIN 213", manufactured by BASF), 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol (trade name "TINUVIN 571", manufactured by BASF), and 2-[2-hydroxy-3-(3,4,5,6-tetrahydrophthalimido-methyl)-5-methylphenyl]benzotriazole (trade name "Sumisorb 250", manufactured by Sumitomo Chemical Co., Ltd.).

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

Furthermore, examples of the salicylate ester-based UV absorbers (salicylate ester-based compounds) include phenyl-2-acryloyloxybenzoate, phenyl-2-acryloyloxy-3-methylbenzoate, phenyl-2-acryloyloxy-4-methylbenzoate, phenyl-2-acryloyloxy-5-methylbenzoate, phenyl-2-acryloyloxy-3-methoxybenzoate, phenyl-2-hydroxybenzoate, phenyl-2-hydroxy-3-methylbenzoate, phenyl-2-hydroxy-4-methylbenzoate, phenyl-2-hydroxy-5-methylbenzoate, phenyl-2-hydroxy-3-methoxybenzoate, and 2,4-di-tert-butylphenyl-3,5-di-tert-butyl-4-hydroxybenzoate (trade name "TINUVIN 120", manufactured by BASF).

Examples of the cyanoacrylate-based ultraviolet absorbers (cyanoacrylate-based compounds) include alkyl-2-cyanoacrylate, cycloalkyl-2-cyanoacrylate, alkoxyalkyl-2-cyanoacrylate, alkenyl-2-cyanoacrylate, and alkynyl-2-cyanoacrylate.

The maximum absorption wavelength in the absorption spectrum of the above-mentioned ultraviolet absorber is preferably in the wavelength range of 300 to 400 nm, and more preferably in the wavelength range of 320 to 380 nm.

The antioxidant may be, for example, a phenol-based, phosphorus-based, sulfur-based, or amine-based antioxidant, and at least one selected from these may be used. Among these, phenol-based antioxidants are preferred, and hindered phenol-based antioxidants are particularly preferred.

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

The above-mentioned anti-deterioration agents can be used alone or in combination of two or more. From the viewpoints of suppressing deterioration such as discoloration during storage and the processability of the double-sided adhesive film for transfer, the content of the anti-deterioration agent contained in the adhesive composition is, for example, preferably 0.01 to 10 parts by weight, more preferably 0.03 to 5 parts by weight, and even more preferably 0.1 to 3 parts by weight, per 100 parts by weight of the above-mentioned first adhesive composition.

The adhesive composition constituting the first adhesive layer may contain any appropriate other components as long as the effects of the present invention are not impaired. Examples of such other components include tackifiers, inorganic fillers, organic fillers, metal powders, pigments, foil-like materials, softeners, plasticizers, conductive agents, surface lubricants, leveling agents, heat stabilizers, polymerization inhibitors, lubricants, and solvents.

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

The second adhesive layer can be made into a releasable adhesive layer by adjusting the adhesiveness through the type, composition, and degree of crosslinking of the adhesive, or by lowering the adhesive strength through physical stimuli such as heat or electromagnetic waves such as ultraviolet rays.

The adhesive strength of the second adhesive layer can be adjusted by adjusting the type, composition, and degree of crosslinking of the adhesive that makes it up, or by forming a weak boundary layer (WBL) by incorporating a light release agent or plasticizer.

In the double-sided adhesive film for transfer according to the present invention, the thickness of the second adhesive layer is not particularly limited, but is preferably 1 μm or more, and more preferably 3 μm or more. A thickness of at least a certain level is preferred, as it makes it easier for the second adhesive layer to be stably fixed to the carrier substrate. Furthermore, the upper limit of the thickness of the second adhesive layer is not particularly limited, but is preferably 30 μm, and more preferably 20 μm. A thickness of less than a certain level is preferred, as it makes it easier for the second adhesive layer to be peeled from the carrier substrate, improving reworkability.

The adhesive constituting the second adhesive layer is not particularly limited, but examples include the silicone-based adhesives, urethane-based adhesives, acrylic-based adhesives, rubber-based adhesives, polyester-based adhesives, polyamide-based adhesives, epoxy-based adhesives, vinyl alkyl ether-based adhesives, and fluorine-based adhesives used in the first adhesive layer. Among these, from the viewpoints of peeling from the carrier substrate without leaving any adhesive residue or other contamination and improving reworkability, silicone-based adhesives, urethane-based adhesives, and acrylic-based adhesives are preferred, with urethane-based adhesives and acrylic-based adhesives being more preferred, and acrylic-based adhesives being even more preferred.

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

When the second adhesive layer is an adhesive strength-reducible adhesive layer, it is possible to selectively switch between a state in which the second adhesive layer exhibits relatively high adhesive strength and a state in which it exhibits relatively low adhesive strength during the manufacturing process and use of the double-sided adhesive film for transfer according to the present invention. For example, during the process in which the first adhesive layer receives an electronic component during use of the double-sided adhesive film for transfer according to the present invention, it is possible to suppress or prevent the double-sided adhesive film for transfer from lifting off the carrier substrate by utilizing the state in which the second adhesive layer exhibits relatively high adhesive strength. On the other hand, during the subsequent process of peeling the double-sided adhesive film for transfer according to the present invention from the carrier substrate, it is possible to improve reworkability by reducing the adhesive strength of the second adhesive layer.

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

The radiation-curable adhesive may be, for example, an adhesive that cures when irradiated with electron beams, ultraviolet rays, alpha rays, beta rays, gamma rays, or X-rays, and it is particularly preferable to use an adhesive that cures when irradiated with ultraviolet rays (ultraviolet-curable adhesive).

Examples of the radiation-curable adhesive include additive-type radiation-curable adhesives that contain a base polymer such as an acrylic polymer and a radiation-polymerizable monomer or oligomer component that has a functional group such as a radiation-polymerizable carbon-carbon double bond.

The base polymer can be the same acrylic polymer as in the first pressure-sensitive adhesive layer. Because the basic properties of the hydrocarbon group-containing (meth)acrylic acid ester, such as adhesion, can be appropriately expressed in the second pressure-sensitive adhesive layer and adhesion and peelability can be easily controlled, the proportion of the hydrocarbon group-containing (meth)acrylic acid ester in all monomer components used to form the acrylic polymer is preferably 40% by mass or more, and more preferably 60% by mass or more.

The acrylic polymer may contain a hydroxy group-containing monomer. When the acrylic polymer in the second pressure-sensitive adhesive layer contains a hydroxy group-containing monomer, the second pressure-sensitive adhesive layer is more likely to have adequate cohesive strength. From the perspective of achieving adequate adhesiveness and cohesive strength in the second pressure-sensitive adhesive layer, the proportion of the hydroxy group-containing monomer in the acrylic polymer is, for example, 0.1 to 30% by mass, and preferably 0.5 to 20% by mass.

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

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

The acrylic pressure-sensitive adhesive composition forming the second pressure-sensitive adhesive layer may contain a crosslinking agent. For example, by crosslinking the acrylic polymer, it is possible to further reduce the amount of low-molecular-weight substances in the second pressure-sensitive adhesive layer. Furthermore, by increasing the weight-average molecular weight of the acrylic polymer, it is possible to control the adhesiveness and releasability to be low. Examples of the crosslinking agent include polyisocyanate compounds, epoxy compounds, polyol compounds (such as polyphenol compounds), aziridine compounds, and melamine compounds. Isocyanate-based crosslinking agents and/or epoxy-based crosslinking agents are preferred. When a crosslinking agent is used, the amount used is preferably about 10 parts by weight or less, more preferably 0.1 to 10 parts by weight, per 100 parts by weight of the acrylic polymer.

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

Examples of the radiation-polymerizable monomer component include urethane (meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and 1,4-butanediol di(meth)acrylate. Examples of the radiation-polymerizable oligomer component include various oligomers, such as urethane-based, polyether-based, polyester-based, polycarbonate-based, and polybutadiene-based oligomers, with those having a molecular weight of approximately 100 to 30,000 being preferred. The content of the radiation-curable monomer component and oligomer component in the radiation-curable adhesive that forms the second adhesive layer is, for example, 5 to 500 parts by weight, and preferably approximately 40 to 150 parts by weight, per 100 parts by weight of the base polymer. Additionally, additive-type radiation-curable adhesives such as those disclosed in JP-A-60-196956 may be used.

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

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

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

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

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

The non-reduced adhesive layer may be, for example, a pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer includes an adhesive layer formed from the radiation-curable adhesive described above for the reducible adhesive layer, which is cured by irradiation while maintaining a certain level of adhesive strength. The adhesives forming the non-reduced adhesive layer may be used alone or in combination of two or more. The second adhesive layer may be entirely or partially composed of a non-reduced adhesive layer. For example, when the second adhesive layer has a monolayer structure, the entire second adhesive layer may be a non-reduced adhesive layer, or a specific portion of the second adhesive layer may be a non-reduced adhesive layer and other portions may be reducible adhesive layers. When the second adhesive layer has a laminated structure, all adhesive layers in the laminated structure may be non-reduced adhesive layers, or only a portion of the adhesive layers in the laminated structure may be non-reduced adhesive layers.

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

The adhesive that forms the pressure-sensitive adhesive layer can be a known or commonly used pressure-sensitive adhesive, and an acrylic adhesive that uses an acrylic polymer as the base polymer is preferably used. When the second adhesive layer contains an acrylic polymer as the pressure-sensitive adhesive, the acrylic polymer is preferably a polymer that contains a structural unit derived from a (meth)acrylic acid ester as the structural unit that is most abundant by mass. For example, the acrylic polymer that can be used as the acrylic polymer is one of the acrylic polymers described above as being capable of being contained in the additive-type radiation-curable adhesive.

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

Examples of resins that may be used to form the plastic substrate include polyolefin resins such as low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene, very low-density polyethylene, random copolymer polypropylene, block copolymer polypropylene, homopolypropylene, polybutene, polymethylpentene, ethylene-vinyl acetate copolymer (EVA), ionomers, ethylene-(meth)acrylic acid copolymers, ethylene-(meth)acrylic acid ester (random, alternating) copolymers, ethylene-butene copolymers, and ethylene-hexene copolymers; polyurethanes; polyesters such as polyethylene terephthalate (PET), polyethylene naphthalate, and polybutylene terephthalate (PBT); polycarbonates; polyimides; polyether ether ketones; polyetherimides; polyamides such as aramids and wholly aromatic polyamides; polyphenyl sulfides; fluororesins; polyvinyl chloride; polyvinylidene chloride; cellulose resins; and silicone resins. When an electronic component received by the double-sided adhesive film for transfer according to the present invention is transferred and mounted on a mounting substrate by thermocompression bonding (e.g., at 150°C), the substrate exhibits good heat resistance, making it less susceptible to thermal expansion or contraction, and enabling accurate mounting. From this perspective, the substrate preferably contains a heat-resistant resin such as polyimide (PI), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyamide (PA), or polyether ether ketone (PEEK) as its main component, and more preferably contains polyimide as its main component. The main component of the substrate refers to the component that accounts for the largest mass percentage of the constituent components. The above resins can be used alone or in combination of two or more types. When the second adhesive layer is a radiation-curable adhesive layer as described above, the substrate is preferably radiation-transparent.

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

The surface of the substrate facing the first adhesive layer and/or second adhesive layer may be subjected to surface treatments, such as physical treatments such as corona discharge treatment, plasma treatment, sand matting, ozone exposure treatment, flame exposure treatment, high-voltage shock exposure treatment, and ionizing radiation treatment, chemical treatments such as chromate treatment, coating agents (primers), and adhesion-enhancing treatments such as silicone primer treatment, in order to enhance adhesion and retention with the adhesive layer. Furthermore, to impart antistatic properties, the substrate surface may be provided with a conductive vapor deposition layer containing a metal, alloy, or oxide thereof, or may be coated with a conductive polymer such as PEDOT-PSS. Surface treatments to enhance adhesion are preferably applied to the entire surface of the substrate facing the adhesive layer.

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

<Separator>
The surfaces of the pressure-sensitive adhesive layers (adhesive surfaces of the first and second pressure-sensitive adhesive layers) of the double-sided pressure-sensitive adhesive film for transfer according to the present invention are protected by a release liner (separator) until use. The separator is used as a protective material for the pressure-sensitive adhesive layers and is peeled off when the pressure-sensitive adhesive film is attached to an adherend.

Conventional release paper and the like can be used as the separator. Specific examples include substrates having a release layer formed on at least one surface using a release treatment agent, low-adhesion substrates made from fluorine-based polymers (e.g., polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, chlorofluoroethylene-vinylidene fluoride copolymer, etc.), and low-adhesion substrates made from non-polar polymers (e.g., olefin-based resins such as polyethylene and polypropylene).

As the separator, for example, a separator having a release layer formed on at least one surface of the separator substrate can be suitably used. Examples of such separator substrates include plastic substrate films (synthetic resin films) such as polyester films (polyethylene terephthalate film, etc.), olefin resin films (polyethylene film, polypropylene film, etc.), polyvinyl chloride film, polyimide film, polyamide film (nylon film), and rayon film; papers (high-quality paper, Japanese paper, kraft paper, glassine paper, synthetic paper, top-coated paper, etc.); and composites (2- to 3-layer composites) of these materials formed by lamination, co-extrusion, etc.

The release agent constituting the release layer is not particularly limited, but examples include silicone-based release agents, fluorine-based release agents, long-chain alkyl-based release agents, and fatty acid amide-based release agents, with silicone-based release agents being preferred. Release agents can be used alone or in combination of two or more. Because the first adhesive layer is composed of a low-tack adhesive layer, it is also possible to use a substrate that has not been treated with a release agent as the separator.

The thickness of the release layer for the first separator is preferably 10 to 2000 nm, more preferably 20 to 500 nm, even more preferably 30 to 150 nm, and particularly preferably 40 to 80 nm, so that F(1) and T(1) fall within the above-mentioned numerical ranges.

The thickness of the release layer for the second separator is preferably 10 to 2000 nm, more preferably 30 to 500 nm, even more preferably 50 to 250 nm, and particularly preferably 70 to 150 nm, so that F(2), P(2), P'(2), and T(2) are within the above-mentioned numerical ranges.

It is preferable that the thickness of the release layer for the first separator be less than the thickness of the release layer for the second separator.

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

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

The thickness of the first separator is preferably 1 to 150 μm, more preferably 5 to 100 μm, and even more preferably 10 to 80 μm, so that F(1) and T(1) fall within the above-mentioned numerical ranges.

The thickness of the second separator is preferably 10 to 150 μm, more preferably 15 to 100 μm, and even more preferably 20 to 80 μm, so that F(2), P(2), P'(2), and T(2) are within the above-mentioned numerical ranges.

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

As the curing method for (1) to (4) above, thermal curing is preferred because it is highly productive and can form a homogeneous adhesive layer with a smooth surface.

The method for applying (coating) the pressure-sensitive adhesive composition to a predetermined surface can be any known coating method, and includes, but is not limited to, 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 using a die coater, etc.

The thickness (total thickness) of the double-sided adhesive film for transfer according to the present invention is not particularly limited, but is preferably 10 μm or more, and more preferably 15 μm or more. A thickness of at least a certain level makes it easier for the first adhesive layer to receive electronic components with precision, which is preferable. Furthermore, the upper limit of the thickness (total thickness) of the double-sided adhesive film for transfer according to the present invention is not particularly limited, but is preferably 500 μm, and more preferably 300 μm. A thickness of at most a certain level makes it easier for electronic components to be transferred to a mounting substrate with precision, which is preferable.

The double-sided adhesive film for transfer according to the present invention is suitable for use in a method for mounting electronic components onto a mounting substrate. The method for mounting electronic components onto a mounting substrate using the double-sided adhesive film for transfer according to the present invention preferably includes the following steps:

The first adhesive layer of the double-sided adhesive film for transfer receives the diced electronic components (Step 1).

The second step is to transfer the electronic components received by the first adhesive layer to a mounting substrate.

Figure 2 is a schematic cross-sectional view showing one embodiment of the first step in a method for mounting electronic components on a mounting substrate using a double-sided adhesive film for transfer according to the present invention.

In Figure 2(a), the double-sided adhesive film for transfer 1 is attached to the carrier substrate 22 via the adhesive surface of the second adhesive layer 12. A marking pattern for arranging electronic components may be provided on the surface of the carrier substrate 22 that is attached to the second adhesive layer 12. Because the double-sided adhesive film for transfer 1 is highly transparent, the marking pattern provided on the carrier substrate 22 can be seen.

A plurality of electronic components 21, which have been diced into individual pieces, are attached to dicing tape 20 on the upper part of the adhesive surface of the first adhesive layer 11 of the double-sided adhesive film 1, and are arranged facing and spaced apart from the adhesive surface of the first adhesive layer 11.

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

The electronic components 21 can be received individually on the first adhesive layer 11, or multiple components can be received together. Figure 2(c) is a schematic cross-sectional view showing the state in which all of the electronic components 21 on the dicing tape 20 have been received on the adhesive surface of the first adhesive layer 11 of the double-sided adhesive film 1 for transfer.

Figure 3 is a schematic cross-sectional view showing the second step in the method for mounting electronic components on a mounting substrate using the double-sided adhesive film for transfer according to the present invention.

As shown in Figure 3(a), electronic components 21 are arranged on the adhesive surface of the first adhesive layer 11 of the double-sided adhesive film 1 for transfer, facing and spaced apart from the circuit surface 31 (circuit pattern not shown) of the mounting substrate 30. Next, as shown in Figure 4(b), the circuit surface 31 of the mounting substrate 30 and the electronic components 21 arranged on the adhesive surface of the first adhesive layer 11 of the double-sided adhesive film for transfer 1 are brought close together, so that the electronic components 21 and the circuit surface 31 of the mounting substrate 30 come into contact.

Transfer of the electronic component 21 to the circuit surface 31 of the mounting substrate 30 may be performed by thermocompression bonding (e.g., 150°C, 1 minute). The substrate 10, first adhesive layer 11, and/or second adhesive layer 12 that make up the double-sided adhesive film 1 for transfer have excellent heat resistance and are therefore less likely to expand, contract, or have their adhesive strength changed by thermocompression bonding, allowing for accurate transfer of the electronic component 21 to the circuit surface 31 of the mounting substrate 30.

Next, as shown in Figure 3(c), the double-sided adhesive film for transfer 1 and the mounting substrate 30 are separated, causing the electronic component 21 to peel from the first adhesive layer 11 and be transferred to the circuit surface 31 of the mounting substrate 30. Because the first adhesive layer 11 is composed of a low-tack adhesive layer, the electronic component 21 peels easily and can be efficiently mounted on the mounting substrate 30 without being damaged.

After the electronic component 21 has been mounted on the mounting substrate 30, the double-sided adhesive film 1 for transfer shown in Figure 3(c) may be peeled off from the carrier substrate 22 (not shown). Because the second adhesive layer 12 is composed of a peelable adhesive layer, it can be peeled off without leaving any adhesive residue, and its excellent reworkability allows the carrier substrate 22 to be easily reused.

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

The present invention will be explained in more detail below using examples, but the present invention is not limited to these examples in any way.

<Production Example 1> Production of Acrylic Copolymer (1) A four-neck flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser was charged with 95 parts by weight of butyl acrylate (manufactured by Nippon Shokubai Co., Ltd.), 5 parts by weight of acrylic acid (manufactured by Toagosei Co., Ltd.), 0.2 parts by weight of 2,2'-azobisisobutyronitrile (manufactured by Wako Pure Chemical Industries, Ltd.) as a polymerization initiator, and 156 parts by weight of ethyl acetate. Nitrogen gas was introduced while gently stirring, and a polymerization reaction was carried out for 10 hours while maintaining the liquid temperature in the flask at around 63°C, to prepare a solution of acrylic copolymer (1) (solid content: 40% by weight) having a weight-average molecular weight of 700,000.

<Production Example 2> Production of acrylic copolymer (2) A four-neck flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser was charged with 2.8 parts by weight of 80% acrylic acid (AA) (manufactured by Osaka Organic Chemical Industry Co., Ltd.), 44 parts by weight of 2-ethylhexyl acrylate (2EHA) (manufactured by Nippon Shokubai Co., Ltd.), 35.2 parts by weight of vinyl acetate (manufactured by Denka Co., Ltd.), and 20 parts by weight of toluene. Nitrogen gas was then introduced and stirred for 1 hour while gently stirring. Thereafter, 0.2 parts by weight of Nyper BW (manufactured by NOF Corporation) diluted with 96 parts by weight of toluene was added dropwise, and the liquid temperature in the flask was maintained at around 40 ° C. The liquid temperature in the flask was then raised to 60 ° C. and subjected to polymerization reaction for 8 hours, and then heated to 95 ° C. and stirred for 4 hours. A solution of acrylic copolymer (2) having a weight average molecular weight of 560,000 (solid content: 35 wt%) was prepared.

<Production Example 3> Production of Separator (1) 100 parts by weight of a silicone release agent (KS-847, manufactured by Shin-Etsu Chemical Co., Ltd.) and 3.0 parts by weight of a catalyst (CAT-PL-50T, manufactured by Shin-Etsu Chemical Co., Ltd.) were diluted with toluene to 1.0 wt % to obtain a silicone-based release treatment liquid. The obtained silicone-based release treatment liquid was applied to the surface of a substrate film (thickness 50 μm, product name "Diafoil T100-50S", manufactured by Mitsubishi Chemical Corporation) with a wire bar to form a release layer so that the thickness after drying was 50 nm. The film was then cured and dried under conditions of a drying temperature of 130°C and a drying time of 3 minutes (release treatment A), to produce a separator (1) consisting of a laminate of [release layer (thickness 50 nm, release treatment A)]/[substrate layer].

<Production Example 4> Production of Separator (2) A separator (2) consisting of a laminate of [release layer (thickness 100 nm, release treatment B)]/[substrate layer] was produced in the same manner as in Production Example 3, except that a substrate film (thickness 25 μm, product name "Diafoil T100-25", manufactured by Mitsubishi Chemical Corporation) was used and the release layer was applied so that the thickness after drying would be 100 nm. In addition, a separator to be used as a second separator was produced by arbitrarily changing the thickness of the substrate film as shown in Table 1.

<Production Example 5> Production of separator (3) A separator (3) composed of a laminate of [release layer (thickness 50 nm, release treatment C)]/[substrate layer] was produced in the same manner as in Production Example 3, except that the amount of catalyst (CAT-PL-50T, manufactured by Shin-Etsu Chemical Co., Ltd.) was changed to 1.0 part by weight.

Example 1
A silicone-based pressure-sensitive adhesive composition was prepared by adding 100 parts by weight of a silicone-based pressure-sensitive adhesive (addition reaction type silicone-based pressure-sensitive adhesive, product name "X-40-3306", manufactured by Shin-Etsu Chemical Co., Ltd.), 1.4 parts by weight of a platinum-based catalyst 1 (product name "CAT-PL-50T", manufactured by Shin-Etsu Chemical Co., Ltd.), and 5 parts by weight of a silicone-based release agent 1 (an addition reaction type silicone-based release agent whose main component is dimethylpolysiloxane, product name "KS-776A", manufactured by Shin-Etsu Chemical Co., Ltd.), diluting the mixture with toluene to a total solids content of 25% by weight, and mixing using a disper.

A silicone-based pressure-sensitive adhesive composition was applied to the silicone-primed surface of a substrate film (polyester film with one side treated with a silicone primer, thickness 75 μm, product name "Diafoil MRF#75", manufactured by Mitsubishi Plastics, Inc.) so that the adhesive thickness after drying would be 10 μm, and the composition was cured and dried at a drying temperature of 120°C for a drying time of 5 minutes. In this way, a film was obtained having a silicone-based pressure-sensitive adhesive layer on top of the silicone-primed layer of the substrate film.

The silicone-based pressure-sensitive adhesive layer was protected by bonding the release layer side of the separator (1) produced in Production Example 3 as the first separator, thereby obtaining a laminate (1) having a laminate structure of [first separator layer]/[silicone-based pressure-sensitive adhesive layer]/[base film layer].

Next, 6 parts by weight (solids equivalent) of TETRAD-C (manufactured by Mitsubishi Gas Chemical Co., Inc.) as a crosslinking agent was added to the solution of acrylic copolymer (1) obtained in Production Example 1 per 100 parts by weight of the solids content, and the mixture was diluted with ethyl acetate to a total solids content of 25% by weight. The acrylic pressure-sensitive adhesive composition (1) was stirred with a disperser and applied to the release layer side of the second separator (separator (2)) with a fountain roll to a thickness of 5 μm after drying, and then cured and dried at a drying temperature of 130°C for 30 seconds. In this way, an acrylic pressure-sensitive adhesive layer (1) was formed on the second separator.

Then, the substrate film side (the side not treated with silicone primer) of the laminate (1) obtained above was bonded to the surface of the acrylic pressure-sensitive adhesive layer (1), yielding a laminate film having a laminate structure of [first separator layer]/[silicone pressure-sensitive adhesive layer (first pressure-sensitive adhesive layer)]/[substrate film layer]/[acrylic pressure-sensitive adhesive (1) layer (second pressure-sensitive adhesive layer)]/[second separator layer].

Example 2
A laminated film was obtained in the same manner as in Example 1, except that the adhesive thickness of the silicone-based adhesive of the first adhesive layer after drying was 25 μm, and for the second separator, a separator in which the base film in separator (2) was changed to a base film (thickness 38 μm, product name “Diafoil T100C38”, manufactured by Mitsubishi Chemical Corporation) was used instead of separator (2).

Example 3
A laminated film was obtained in the same manner as in Example 1, except that the adhesive thickness of the silicone-based adhesive of the first adhesive layer after drying was 50 μm, and for the second separator, a separator in which the base film in separator (2) was changed to a base film (thickness 50 μm, product name “Diafoil T100-50S”, manufactured by Mitsubishi Chemical Corporation) was used instead of separator (2).

Example 4
A laminated film was obtained in the same manner as in Example 1, except that the adhesive thickness of the silicone-based adhesive of the first adhesive layer after drying was 75 μm, and for the second separator, a separator in which the base film in separator (2) was changed to a base film (thickness 75 μm, product name “Diafoil T100-75S”, manufactured by Mitsubishi Chemical Corporation) was used instead of separator (2).

Example 5
A laminated film was obtained in the same manner as in Example 1, except that the adhesive thickness of the silicone-based adhesive in the first adhesive layer after drying was 50 μm and separator (2) was used as the first separator.

Example 6
A laminated film was obtained in the same manner as in Example 5, except that the adhesive thickness of the silicone-based adhesive in the first adhesive layer after drying was set to 75 μm.

Example 7
A laminated film was obtained in the same manner as in Example 1, except that the adhesive thickness of the silicone-based pressure-sensitive adhesive in the first pressure-sensitive adhesive layer after drying was 25 μm, separator (3) was used as the first separator, and acrylic pressure-sensitive adhesive (2) was used instead of acrylic pressure-sensitive adhesive (1) for the first pressure-sensitive adhesive layer.

Example 8
A laminated film was obtained in the same manner as in Example 7, except that the adhesive thickness of the silicone-based adhesive in the first adhesive layer after drying was set to 50 μm.

Example 9
A laminated film was obtained in the same manner as in Example 7, except that the thickness of the silicone-based adhesive in the first adhesive layer after drying was 75 μm.

<Comparative Example 1>
A laminated film was obtained in the same manner as in Example 1, except that the separator (2) was used as the first separator.

<Comparative Example 2>
A laminated film was obtained in the same manner as in Example 2, except that the separator (2) was used as the first separator.

<Evaluation>
The double-sided pressure-sensitive adhesive films for transfer obtained in the examples and comparative examples were evaluated as follows. The results are shown in Table 2.

<Measurement of peel strength F(1) of first separator from first pressure-sensitive adhesive layer>
The double-sided adhesive transfer films of the Examples and Comparative Examples were cut into a width of 50 mm and a length of 100 mm to prepare evaluation samples.

The separator from the second pressure-sensitive adhesive layer was peeled off, and the surface of the second pressure-sensitive adhesive layer was attached to a glass plate (product name "S200423", manufactured by Matsunami Glass Industrial Co., Ltd.) at 23°C and 50% RH using a roller at 0.25 MPa and 0.3 m/min. The first separator was then peeled off from the first pressure-sensitive adhesive layer at a peel angle of 180 degrees and a peel speed of 0.3 m/min using a universal tensile tester (product name "TCM-1kNB", manufactured by Minebea Co., Ltd.), to measure the peel strength F(1).

<Measurement of Peel Force F(2) of Second Separator from Second Pressure-Sensitive Adhesive Layer>
The double-sided adhesive transfer films of the Examples and Comparative Examples were cut into a width of 50 mm and a length of 100 mm to prepare evaluation samples.

The separator from the first pressure-sensitive adhesive layer was peeled off, and the surface of the first pressure-sensitive adhesive layer was bonded to a glass plate (product name "S200423", manufactured by Matsunami Glass Industrial Co., Ltd.) at 23°C and 50% RH using a roller at 0.25 MPa and 0.3 m/min. The second separator was then peeled off from the second pressure-sensitive adhesive layer at a peel angle of 180 degrees and a peel speed of 0.3 m/min using a universal tensile tester (product name "TCM-1kNB", manufactured by Minebea Co., Ltd.), to measure the peel strength F(2).

<Measurement of peel adhesion strength P(2) of second adhesive layer from carrier substrate>
The double-sided transfer sheets of the examples and comparative examples were cut into a width of 50 mm and a length of 100 mm to prepare evaluation samples.

In an environment of 23°C and 50% RH, the surface of the second adhesive layer from which the separator of the evaluation sample had been peeled was attached to a glass plate (product name "S200423", manufactured by Matsunami Glass Industrial Co., Ltd.) using a roller at 0.25 MPa and 0.3 m/min. After curing for 30 minutes, the second adhesive layer was peeled from the glass plate using a universal tensile tester (product name "TCM-1kNB", manufactured by Minebea Co., Ltd.) at a peel angle of 180 degrees and a pulling speed of 0.3 m/min, to measure the peel adhesion strength P(2).

<Measurement of peel adhesive strength P'(2) of the second pressure-sensitive adhesive layer from a glass plate after 5 minutes at 160°C>
The double-sided adhesive transfer films of the Examples and Comparative Examples were cut into a width of 50 mm and a length of 100 mm to prepare evaluation samples.

In an environment of 23°C and 50% RH, the separator of the evaluation sample was peeled off and the surface of the second adhesive layer was attached to a glass plate (product name "S200423", manufactured by Matsunami Glass Industry Co., Ltd.) using a roller at 0.25 MPa and 0.3 m/min, and then cured for 30 minutes.

Then, the sample was heated in an air-circulating thermostatic oven at 160°C for 5 minutes, and then allowed to cool for 30 minutes in an environment of 23°C and 50% RH. The adhesive strength P'(2) was then measured by peeling the second adhesive layer from the glass plate at a peel angle of 180° and a pulling speed of 0.3 m/min using a universal tensile tester (product name "TCM-1kNB", manufactured by Minebea Co., Ltd.).

<Measurement of initial peel strength T(1) of first separator from first pressure-sensitive adhesive layer>
The double-sided adhesive transfer films of the Examples and Comparative Examples were cut into pieces 50 mm wide and 100 mm long using a push-cutting paper cutter to prepare evaluation samples.

The separator from the second adhesive layer was peeled off, and the surface of the second adhesive layer was bonded to a glass plate (product name "S200423", manufactured by Matsunami Glass Industry Co., Ltd.) at 23°C and 50% RH using a roller at 0.25 MPa and 0.3 m/min. Then, at 23°C and 50% RH, a rubber adhesive tape (product name "NO. 315", 19 mm wide, manufactured by Nitto Denko Corporation) was pressed onto the center of the back surface of the surface protection film in the width direction using a hand roller. Under the same conditions, the first separator was peeled from the first adhesive layer at a pulling speed of 0.3 m/min and a peel angle of 90 degrees, and the maximum stress applied at the start of peeling was recorded as the initial peel strength T(1) [N/50 mm].

<Measurement of initial peel strength T(2) of second separator from second pressure-sensitive adhesive layer>
The double-sided adhesive transfer films of the Examples and Comparative Examples were cut into pieces 50 mm wide and 100 mm long using a push-cutting paper cutter to prepare evaluation samples.

The separator from the second adhesive layer was peeled off, and the surface of the second adhesive layer was bonded to a glass plate (product name "S200423", manufactured by Matsunami Glass Industry Co., Ltd.) at 23°C and 50% RH using a roller at 0.25 MPa and 0.3 m/min. Then, under an environment of 23°C and 50% RH, a rubber-based adhesive tape (product name "NO. 315", 19 mm wide, manufactured by Nitto Denko Corporation) was pressed onto the center of the back surface of the surface protection film in the width direction using a hand roller. Under the same environment, the second separator was peeled from the second adhesive layer at a pulling speed of 0.3 m/min and a peel angle of 90 degrees, and the maximum stress applied at the start of peeling was recorded as the initial peel strength T(2) [N/50 mm].

<Evaluation of Peelability of First Separator>
The double-sided pressure-sensitive adhesive films for transfer of the Examples and Comparative Examples were cut into a width of 10 mm and a length of 10 mm to prepare evaluation samples.

The separator from the second adhesive layer was peeled off, and the surface of the second adhesive layer was bonded to a glass plate (product name "S200423", manufactured by Matsunami Glass Industry Co., Ltd.) at 23°C and 50% RH using a roller at 0.25 MPa and 0.3 m/min. The first separator was then peeled from the first adhesive layer at 23°C and 50% RH at a peel angle of 180 degrees and a peel speed of 0.3 m/min using acrylic adhesive tape (product name "NO. 31B", manufactured by Nitto Denko Corporation) that had been pressed with a hand roller against the right-angled corners of the evaluation sample. The peelability of the first separator was evaluated according to the following criteria.

(Evaluation criteria)
◯: The first separator peeled off without any lifting at the interface between the second pressure-sensitive adhesive layer and the glass plate. Δ: The first separator peeled off, but lifting occurred at the interface between the second pressure-sensitive adhesive layer and the glass plate. ×: The second pressure-sensitive adhesive layer peeled off from the glass plate before the first separator was peeled off.

<Evaluation of Peelability of Second Separator>
The double-sided pressure-sensitive adhesive films for transfer of the Examples and Comparative Examples were cut into a width of 10 mm and a length of 10 mm to prepare evaluation samples.

The evaluation sample was placed on a suction stage with the first separator side facing down and fixed by suction. Using acrylic adhesive tape (product name "NO. 31B", manufactured by Nitto Denko Corporation) pressed with a hand roller onto the right-angled corners of the fixed evaluation sample, the second separator was peeled from the second adhesive layer at a peel angle of 180 degrees and a peel speed of 0.3 m/min at 23°C and 50% RH, and the releasability of the second separator was evaluated according to the following criteria.

(Evaluation criteria)
◯: Peeling occurred without any lifting at the interface between the first pressure-sensitive adhesive layer and the first separator. Δ: Peeling occurred, but lifting occurred at the interface between the first pressure-sensitive adhesive layer and the first separator. ×: Peeling occurred between the first pressure-sensitive adhesive layer and the first separator before peeling.

<Glass reworkability>
After measuring the peel adhesive strength P'(2) of the second pressure-sensitive adhesive layer against the glass plate after 5 minutes at 160°C, the sample was visually observed and the reworkability was judged according to the following criteria.

(Evaluation criteria)
◎: No damage to the glass or contamination such as glue residue was observed on the glass plate. ◯: Almost no damage to the glass or contamination such as glue residue was observed on the glass plate. ×: Damage to the glass or contamination such as glue residue was observed on the glass plate.

REFERENCE SIGNS LIST 1 laminated film 10 substrate 11 first adhesive layer 12 second adhesive layer 110 first separator 120 second separator 20 dicing tape 21 electronic component 22 carrier substrate 23 pin member 30 mounting substrate 31 circuit surface

Claims (1)

a laminated film in which a first separator, a first pressure-sensitive adhesive layer, a substrate, a second pressure-sensitive adhesive layer, and a second separator are laminated in this order, the first pressure-sensitive adhesive layer being a low-tack pressure-sensitive adhesive layer, and the second pressure-sensitive adhesive layer being a releasable pressure-sensitive adhesive layer;
a 180° peel strength F(1) (N/50 mm) of the first separator from the first pressure-sensitive adhesive layer measured under conditions of 23°C, 50% R.H. and a peel speed of 0.3 m/min;
a 180° peel strength F(2) (N/50 mm) of the second separator from the second pressure-sensitive adhesive layer measured under conditions of 23°C, 50% R.H. and a peel speed of 0.3 m/min;
the 180° peel adhesive strength P(2) (N/50 mm) of the second pressure-sensitive adhesive layer from a glass plate measured under conditions of 23°C, 50% R.H. and a pulling speed of 0.3 m/min ;
The second pressure-sensitive adhesive layer is attached to a glass plate, and after 5 minutes at 160°C, the 180° peel adhesive strength P'(2) (N/50 mm ) of the second pressure-sensitive adhesive layer from the glass plate is measured under conditions of 23°C, 50% RH and a pulling speed of 0.3 m/min.
the 90° trigger peel strength T(1) (N/50 mm) of the first pressure-sensitive adhesive layer from the first separator, measured under conditions of 23°C, 50% R.H. and a pulling speed of 0.3 m/min; and
a 90° trigger peel strength T(2) (N/50 mm) of the second pressure-sensitive adhesive layer from the second separator, measured under conditions of 23°C, 50% R.H. and a pulling speed of 0.3 m/min, satisfies the relationship of the following formula:
F(2)/F(1)<0.80
P(2)/F(1)>1.00
P'(2)/P(2)<1.20
P'(2)<1.00
T(1)/T(2)>1.05
P(2)/T(1)<1.00