KR20240032112A - adhesive sheet - Google Patents

Abstract

An adhesive sheet is provided that achieves both suppression of adhesive residue during peeling and good followability to the surface shape of the adherend in a balanced manner. An adhesive sheet is provided including a base material and an adhesive layer disposed on at least one side of the base material. The adhesive sheet has an indentation hardness H1 of the surface of the adhesive layer of 0.10 MPa or more and 0.50 MPa or less, and an indentation hardness measured at a distance of 4 μm from the substrate to the surface of the adhesive layer on the cross section of the adhesive sheet. H2 is 0.001 MPa or more and 0.090 MPa or less.

Description

adhesive sheet

The present invention relates to an adhesive sheet. This application claims priority based on Japanese Patent Application No. 2021-115926 filed on July 13, 2021, the entire content of which is incorporated herein by reference.

In the manufacture of semiconductor components including semiconductor chips, the semiconductor chip may be resin-sealed in order to prevent scratches on the semiconductor chip, expand metal wiring, etc. In the resin encapsulation process, the semiconductor chip is sometimes resin encapsulated on an adhesive sheet from the viewpoint of workability and the like. For example, a plurality of semiconductor chips are placed on an adhesive layer of an adhesive sheet as a temporary fixing material, and the semiconductor chips are collectively sealed on the adhesive layer. Thereafter, in a predetermined post-process, the adhesive sheet is peeled from the structure containing the sealing resin and the semiconductor chip.

Japanese Patent Application Publication No. 2001-308116 Japanese Patent Application Publication No. 2001-313350

In the adhesive sheet used in the above process, it is required that no adhesive residue (residual adhesive) is generated on the structure when peeling the adhesive sheet from the structure containing the sealing resin and the semiconductor chip. In order to suppress the adhesive residue, the adhesive layer on which the semiconductor chip is disposed in the adhesive sheet is generally formed of an adhesive with a very high elastic modulus. However, there may be steps on the surface of the semiconductor chip due to pre-formed metal wiring, etc., so if the adhesive layer has a high elastic modulus, the adhesive does not adhere sufficiently to the steps on the chip surface, and a sealing resin is applied at the interface between the chip and the adhesive. Problems with intrusion become more likely to occur.

The present invention was created in consideration of the above situation, and its purpose is to provide a pressure-sensitive adhesive sheet that achieves both suppression of adhesive residue during peeling and good followability to the surface shape of the adherend in a balanced manner.

The adhesive sheet provided by this specification includes a base material and an adhesive layer disposed on at least one side of the base material. The adhesive sheet has an indentation hardness H1 of the surface of the adhesive layer of 0.10 MPa or more and 0.50 MPa or less in the measurement of indentation hardness using a nanoindenter, and furthermore, in a cross section of the adhesive sheet, the adhesive layer is separated from the base material in a cross section of the adhesive sheet. The indentation hardness H2 measured at a distance of 4 μm toward the surface is 0.001 MPa or more and 0.090 MPa or less. When the indentation hardness H1 measured using the surface of the adhesive layer as the measurement position (hereinafter also referred to as “measurement position A”) is 0.10 MPa or more, adhesive residue during peeling can be suppressed. In addition, the measurement is made inside (substrate side) of the measurement position A, specifically at a position of 4 μm from the substrate to the surface of the pressure-sensitive adhesive layer on the cross-section of the pressure-sensitive adhesive sheet (hereinafter also referred to as “measurement position B”). When the indentation hardness H2 is 0.090 MPa or less, followability to the surface shape of the adherend can be improved. Therefore, the pressure-sensitive adhesive sheet having the indentation hardness H1 and H2 in the above range can achieve both suppression of adhesive residue during peeling and good followability to the surface shape of the adherend in a balanced manner.

In some embodiments, the ratio (H2/H1) of the indentation hardness H2 [MPa] to the indentation hardness H1 [MPa] is 0.002 or more and 0.90 or less. According to an adhesive sheet in which the indentation hardness H2 at measurement position B (inside) is 0.90 times or less than the indentation hardness H1 at measurement position A (surface), adhesive residue suppression and surface shape followability can be preferably achieved at both times.

In some embodiments, in the evaluation of stringiness using a nanoindenter, the stringiness D1 of the surface of the adhesive layer is 50 nm or more and 500 nm or less. It is advantageous from the viewpoint of suppressing adhesive residue that the threadability D1 on the surface of the adhesive layer (measurement position A) is 500 nm or less. In the above-mentioned stringiness evaluation, the stringiness D2 measured at a position (measurement position B) at a distance of 4 μm from the substrate to the surface side of the pressure-sensitive adhesive layer on the cross-section of the pressure-sensitive adhesive sheet is preferably 150 nm or more and 1000 nm or less. . According to the adhesive layer whose threadability D2 is in the above range, it is easy to realize good surface shape followability.

In some embodiments, the ratio (D2/D1) of the stringiness D2 [nm] to the stringiness D1 [nm] is 0.3 or more and 20.0 or less. According to the pressure-sensitive adhesive sheet with the ratio (D2/D1) in the above range, it is easy to achieve both suppression of adhesive residue and surface shape followability preferably.

In some embodiments, the difference between the initial thickness T0 [μm] of the pressure-sensitive adhesive layer and the thickness T1 [μm] of the pressure-sensitive adhesive layer after dropping 4-t-butylphenylglycidyl ether on the surface of the pressure-sensitive adhesive layer and allowing it to stand for 1 minute ( T1-T0 (hereinafter also referred to as “thickness change amount”) is 20 μm or less. A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer with a small change in thickness may, for example, be used to perform a process of placing a semiconductor chip on the pressure-sensitive adhesive layer and sealing the semiconductor chip with a resin, so that there is a step between the semiconductor chip and the sealing resin. This is desirable because it is difficult to generate (stand-off).

For some types of adhesive sheets, the needle penetration from the surface of the adhesive layer is measured using a thermomechanical analyzer (TMA) under the conditions of an environmental temperature of 23°C, an indentation load of 0.01N, and an indentation load time of 60 minutes. The penetration amount of the probe is 3.50 ㎛ or more and 20.0 ㎛ or less. According to the adhesive sheet having the penetration amount in the above range, for example, in a usage mode of placing a semiconductor chip on the adhesive layer and performing a process of sealing the semiconductor chip with a resin, the following features include: Suppression of embedding in the adhesive sheet of the semiconductor chip can be achieved in a balanced manner.

In some embodiments of the adhesive sheet disclosed herein, the thickness of the adhesive layer is 5 μm or more and 110 μm or less. According to the adhesive layer of the above thickness, the effect of varying the characteristics at measurement position A and measurement position B can be preferably exhibited.

In some embodiments, the substrate is a substrate film made of a resin material with a glass transition temperature (Tg) of 25°C or higher. The pressure-sensitive adhesive sheet having the above-mentioned pressure-sensitive adhesive layer on such a base film may be used, for example, in a use mode in which a semiconductor chip is placed on the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet and a process of sealing the semiconductor chip with a resin is performed during the process. Even when heated, embedding of the semiconductor chip in the adhesive sheet can be suppressed, and the level difference (stand-off) between the semiconductor chip and the sealing resin can be suppressed.

Some types of adhesive sheets have an adhesive force to a polyethylene terephthalate (PET) film of 0.05 N/20 mm or more and 1.00 N/20 mm or less. Within this range, the adherend (for example, a semiconductor chip) can be preferably fixed, and the load applied to the adherend when peeling off the adhesive sheet can be suppressed.

In some embodiments, the anchoring force of the adhesive layer to the substrate measured at 23°C after heating the adhesive sheet at 150°C for 1 hour is 4.00 N/20 mm or more. The adhesive sheet exhibiting the anchoring force may be peeled off even if heated during the process, for example, in an aspect of use in which a semiconductor chip is placed on the adhesive layer of the adhesive sheet and a process of sealing the semiconductor chip with a resin is performed. This is desirable because adhesive residue can be suppressed during the process.

In some embodiments, the adhesive constituting at least the surface of the adhesive layer is an acrylic adhesive that uses an acrylic polymer as a base polymer. The technology disclosed herein can be preferably implemented in the form of an adhesive sheet having at least a surface (adhesive surface) of an adhesive layer made of an acrylic adhesive.

In some embodiments, the SP value of the acrylic polymer is 18.0 to 20.0. By constructing the adhesive surface with an acrylic adhesive that uses an acrylic polymer with an SP value in the above range as the base polymer, it is easy to realize an indentation hardness H1 in the above range. Additionally, for example, by placing a semiconductor chip on the adhesive surface, the semiconductor Even in a usage mode in which a process of sealing a chip with a resin is performed, it is easy to suppress excessively high adhesion to the sealing resin.

In some embodiments of the pressure-sensitive adhesive sheet disclosed herein, the pressure-sensitive adhesive layer includes a layer A constituting the surface of the pressure-sensitive adhesive layer, and a layer B disposed between the layer A and the substrate and adjacent to the substrate. The pressure-sensitive adhesive sheet disclosed herein can preferably be implemented in an aspect provided with a pressure-sensitive adhesive layer having a structure including an A layer (surface layer) and a B layer (undercoat layer).

The thickness L1 of the layer A is preferably, for example, 1 μm or more and 10 μm or less. With a layer A of this thickness, it is easy to achieve both adhesive residue suppression and surface shape followability preferably.

The thickness L2 of the layer B is preferably, for example, 4 μm or more and 100 μm or less. With a B layer of this thickness, it is easy to achieve both adhesive residue suppression and surface shape followability preferably.

The ratio (L2/L1) of the thickness L2 [μm] of the layer B to the thickness L1 [μm] of the layer A is preferably 1.0 to 100.0.

In some embodiments, the T ₂ relaxation time (T _2s ) of the S component by pulsed NMR of the A layer is less than or equal to 45 μsec, and the T ₂ relaxation time (T _2s ) of the S component by pulse NMR of the B layer is greater than 45 μsec. long. According to the pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer including the A layer and the B layer that satisfies the above relaxation time (T _2s ), it is easy to achieve both suppression of component migration between the pressure-sensitive adhesive layer and the sealing resin and desirable surface shape followability.

In some embodiments, the A layer is crosslinked with an epoxy-based crosslinking agent, and the B layer is crosslinked with an isocyanate-based crosslinking agent. The pressure-sensitive adhesive sheet disclosed herein can be suitably implemented in an aspect provided with a pressure-sensitive adhesive layer having such a structure.

In some embodiments of the adhesive sheet disclosed herein, the adhesive sheet includes the substrate, the adhesive layer (first adhesive layer) disposed on one side of the substrate, and the adhesive layer disposed on the opposite side of the substrate. and a second adhesive layer. The pressure-sensitive adhesive sheet of this configuration has good usability because, for example, the second pressure-sensitive adhesive layer can be used to fix it on a suitable carrier, and then the resin sealing process on the first pressure-sensitive adhesive layer can be performed in that state.

In some embodiments, at least the surface of the second adhesive layer is made of an adhesive containing heat-expandable microspheres. This type of pressure-sensitive adhesive sheet is preferable because the bond between the second pressure-sensitive adhesive layer and the adherend can be easily released by heating at an appropriate timing to expand the heat-expandable microspheres as needed.

In addition, appropriate combinations of the elements described in this specification may also be included in the scope of the invention for which patent protection is sought by this patent application.

1 is a cross-sectional view schematically showing the structure of an adhesive sheet according to an embodiment.
Figures 2 (i) to (iv) are explanatory diagrams showing an example of a semiconductor chip resin sealing process performed using the adhesive sheet shown in Figure 1.
Figure 3 is a cross-sectional view schematically showing the configuration of an adhesive sheet according to another embodiment.
Figure 4 is a cross-sectional view schematically showing the configuration of an adhesive sheet according to another embodiment.
Figure 5 is a schematic diagram to explain the definition of regularity.

Hereinafter, preferred embodiments of the present invention will be described. Matters other than those specifically mentioned in this specification and matters necessary for practicing the present invention can be understood by those skilled in the art based on the teachings for implementing the invention described in this specification and the technical common sense at the time of filing the application. The present invention can be implemented based on the content disclosed in this specification and common technical knowledge in the field.

In addition, in the drawings below, members and parts that exert the same function may be described with the same reference numerals, and overlapping descriptions may be omitted or simplified. In addition, the embodiments described in the drawings are modeled to clearly explain the present invention, and do not necessarily accurately represent the size or scale of the actually provided product.

In this specification, the “base polymer” of the adhesive refers to the main component of the rubber-like polymer contained in the adhesive, and other than this, it is not interpreted in any limited way. The rubber-like polymer refers to a polymer that exhibits rubbery elasticity in a temperature range around room temperature. In addition, in this specification, the "main component" refers to a component contained in excess of 50% by weight, unless otherwise specified.

In addition, in this specification, “acrylic polymer” refers to a polymer containing a monomer unit derived from a monomer having at least one (meth)acryloyl group in one molecule as a monomer unit constituting the polymer. Hereinafter, a monomer having at least one (meth)acryloyl group in one molecule is also referred to as an “acrylic monomer.” Therefore, the acrylic polymer in this specification is defined as a polymer containing a monomer unit derived from an acrylic monomer. A typical example of an acrylic polymer is a polymer in which the proportion of acrylic monomers out of all monomers used in the synthesis of the acrylic polymer is more than 50% by weight (preferably more than 70% by weight, for example, more than 90% by weight). . Hereinafter, the monomer used in polymer synthesis is also referred to as the monomer component constituting the polymer.

In addition, in this specification, “(meth)acryloyl” is meant to comprehensively refer to acryloyl and methacryloyl. Likewise, “(meth)acrylate” refers comprehensively to acrylate and methacrylate, and “(meth)acrylic” refers to acrylic and methacrylic, respectively. Therefore, the concept of acrylic monomer as used herein may include both a monomer having an acryloyl group (acrylic monomer) and a monomer having a methacryloyl group (methacrylic monomer).

<Overview of adhesive sheets>

The adhesive sheet disclosed herein can be suitably used as a temporary fixing material when resin sealing a semiconductor chip. More specifically, the adhesive sheet of the present invention arranges a semiconductor chip on the adhesive layer of the adhesive sheet, covers the semiconductor chip with a sealing resin (usually an epoxy resin), and cures the sealing resin to form the semiconductor chip. It can be used as a temporary fixing material for the semiconductor chip during resin sealing. After resin sealing the semiconductor chip, during certain post-processes (e.g., back side grinding of the sealing resin, pattern formation, bump formation, chipping (cutting)), the adhesive sheet includes the sealing resin and the semiconductor chip. It may be peeled off from the constructed structure. The epoxy equivalent weight of the sealing resin is, for example, 50 g/eq to 500 g/eq.

1 is a schematic cross-sectional view showing one embodiment of the adhesive sheet disclosed herein. The adhesive sheet 100 includes a substrate 10 and an adhesive layer (first adhesive layer) 20 disposed on one side of the substrate 10. This adhesive sheet 100 has an indentation hardness H1 of 0.10 MPa or more on the surface of the adhesive layer (first adhesive layer) 20, that is, measurement position A (arrow A in Fig. 1), and the adhesive sheet 100 ), the indentation hardness H2 measured at a distance of 4 μm from the substrate 10 to the surface side of the adhesive layer 20 (measurement position B indicated by arrow B in FIG. 1) is 0.09 MPa or less.

The adhesive sheet 100 can be used for resin sealing of a semiconductor chip, for example, as shown in FIG. 2. First, a plurality of semiconductor chips 1 are adhered onto the adhesive layer (first adhesive layer) of the adhesive sheet 100 (step (i)). Next, the semiconductor chip 1 is covered with a semi-cured product 2' of the sealing resin (step (ii)), and this semi-cured product 2' is cured to seal the semiconductor chip 1 with the sealing resin 2. (Process (iii)). The semi-cured product 2' can be formed, for example, using a composition containing a naphthalene-type bifunctional epoxy resin (epoxy equivalent weight: 144). Thereafter, during a predetermined post-process, the adhesive sheet 100 is peeled from the structure 50 containing the semiconductor chip 1 and the sealing resin 2 (step (iv)).

The pressure-sensitive adhesive sheet disclosed herein has an indentation hardness H1 of 0.10 MPa or more at the measurement position A, so that adhesive residue is unlikely to be generated on the structure 50 in step (iv) shown in FIG. 2. In addition, the indentation hardness H2 inside the adhesive layer, specifically at the measurement position B, is 0.09 MPa or less, so that the adhesive layer is aligned with the surface shape of the adherend (for example, on the adhesive layer side surface of the semiconductor chip 1). It is possible to follow satisfactorily the steps (steps that may exist due to metal wiring, etc.) that may exist, and the occurrence of a problem (mold flash) in which the sealing resin 2 intrudes into the interface between the adhesive sheet and the semiconductor chip 1 can be prevented.

Figure 3 is a schematic cross-sectional view showing another embodiment of the adhesive sheet disclosed herein. In the adhesive sheet 200, the adhesive layer 20 in the adhesive sheet 100 shown in FIG. 1 consists of a layer A 22 constituting the surface (adhesive surface) of the adhesive layer 20, and a layer A. It includes a B layer 24 disposed between 22 and the substrate 10 and adjacent to the substrate 10. According to the adhesive layer 20 of this structure, it is easy to adjust the indentation hardness H1 at measurement position A and the indentation hardness H2 at measurement position B to appropriate ranges, respectively. The pressure-sensitive adhesive sheet disclosed herein can be preferably implemented in such a manner that the pressure-sensitive adhesive layer 20 including the A layer 22 and the B layer 24 is provided on at least one side of the substrate 10.

Figure 4 is a schematic cross-sectional view showing another embodiment of the adhesive sheet disclosed herein. The adhesive sheet 300 further includes a second adhesive layer 30 on the back side of the substrate 10 (the side opposite to the adhesive layer 20). That is, the adhesive sheet 300 includes an adhesive layer 20, a base material 10, and a second adhesive layer 30 in this order. By providing the second adhesive layer 30, the adhesive sheet 300 can be easily fixed to the carrier by adhering the second adhesive layer 30 side to the carrier when resin sealing is performed on the carrier.

In some embodiments, at least the surface of the second adhesive layer is made of an adhesive containing heat-expandable microspheres. When the pressure-sensitive adhesive layer containing such heat-expandable microspheres is heated above a predetermined temperature, the heat-expandable microspheres expand, thereby generating irregularities on the surface of the pressure-sensitive adhesive layer, and the adhesive force can be reduced or lost. By configuring at least the surface of the second adhesive layer with an adhesive containing heat-expandable microspheres, the necessary adhesiveness is exhibited when fixing the adhesive sheet through the second adhesive layer (for example, fixing it to a carrier), When peeling off the adhesive sheet (for example, peeling from the carrier), good peelability is achieved by lowering or disappearing the adhesive force by heating. An elastic intermediate layer (which may be an adhesive layer) that does not contain thermally expandable microspheres or has a low content thereof may be disposed between the adhesive layer containing thermally expandable microspheres and the substrate.

(Indentation hardness)

The press-fit hardness H1 of the adhesive sheet disclosed herein is suitably 0.10 MPa or more (for example, more than 0.10 MPa) from the viewpoint of suppressing adhesive residue, and is preferably 0.12 MPa or more. In some embodiments, the indentation hardness H1 may be 0.15 MPa or more, 0.18 MPa or more, or 0.20 MPa or more. The adhesive layer with a high indentation hardness H1 is generally used to prevent steps (stands) that may occur at the boundary between the semiconductor chip and the sealing resin in a usage mode in which a semiconductor chip is placed on the adhesive layer and a process of sealing the semiconductor chip with a resin is performed. It also tends to be advantageous from the perspective of suppressing off). Additionally, the indentation hardness H1 is suitably 0.50 MPa or less, and is preferably 0.40 MPa or less. From the viewpoint of adhesion to the surface of the adherend and facilitating the development of appropriate tack on the surface of the adhesive layer, in some embodiments, the indentation hardness H1 may be, for example, 0.30 MPa or less, 0.28 MPa or less, or 0.25 MPa or less. It may be less than MPa, less than 0.23 MPa, or less than 0.21 MPa.

The press-fit hardness H2 of the adhesive sheet disclosed herein is suitably lower than the press-fit hardness H1, and is preferably 0.090 MPa or less from the viewpoint of improving followability to the surface shape of the adherend. From the viewpoint of obtaining higher followability, in some embodiments, the indentation hardness H2 may be 0.080 MPa or less, 0.060 MPa or less, or 0.050 MPa or less. The lower limit of the indentation hardness H2 is not particularly limited and may be, for example, 0.001 MPa or more. From the viewpoint of preventing cohesive failure inside the adhesive layer, in some embodiments, the indentation hardness H2 is suitably 0.005 MPa or more, preferably 0.010 MPa or more, may be 0.030 MPa or more, may be 0.040 MPa or more, and may be 0.050 MPa or more. It may be more than MPa, and it may be more than 0.060 MPa.

The ratio (H2/H1) of the indentation hardness H2 [MPa] to the indentation hardness H1 [MPa], for example, is suitably 0.90 or less, preferably 0.70 or less, may be 0.50 or less, and may be 0.40 or less, It may be less than 0.30. Additionally, the ratio (H2/H1) is suitably, for example, 0.002 or more, preferably 0.005 or more, and more preferably 0.01 or more. According to the pressure-sensitive adhesive sheet in which the ratio (H2/H1) is in this range, it is easy to achieve both adhesive residue suppression and surface shape followability in a balanced manner.

(Yasaseong)

In the adhesive sheet disclosed herein, the range of threadability D1 at measurement position A is not particularly limited and may be, for example, 800 nm or less. In some embodiments, from the viewpoint of improving adhesive residue prevention, the threadability D1 is suitably 500 nm or less, preferably 300 nm or less, may be 250 nm or less, may be 200 nm or less, and may be 150 nm or less. do. In addition, from the viewpoint of exhibiting appropriate tack on the surface of the adhesive layer and, for example, facilitating placement of a semiconductor chip on the surface of the adhesive layer, the threadness D1 is preferably 50 nm or more, and may be 80 nm or more. , may be 100 nm or more, and may be 120 nm or more.

In the adhesive sheet disclosed herein, the range of the linearity D2 at the measurement position B is not particularly limited, and may be, for example, 100 nm or more, and from the viewpoint of improving followability to the surface shape of the adherend, it is 150 nm. It is preferable that it is ㎚ or more, and it is more preferable that it is 200 ㎚ or more. In some embodiments, the threadability D2 may be 300 nm or more, 400 nm or more, or 500 nm or more. In addition, the threadability D2 may be, for example, 2500 nm or less, and from the viewpoint of preventing cohesive failure inside the adhesive layer, it is preferably 1500 nm or less, more preferably 1000 nm or less, and may be 800 nm or less, and may be 600 nm or less. It may be less than ㎚.

The ratio (D2/D1) of the stringiness D2 [nm] to the stringiness D1 [nm] may be, for example, 0.3 or more, 0.5 or more, or 1.0 or more. In some embodiments, the ratio (D2/D1) is preferably greater than 1.0 (eg, 1.2 or greater), may be 2.5 or greater, may be 3.5 or greater, or may be 5.0 or greater. In addition, the ratio (D2/D1) is suitably, for example, 20.0 or less, advantageously 15.0 or less, preferably 10.0 or less, may be 8.0 or less, 7.0 or less, and may be 6.0 or less. According to an adhesive sheet in which the ratio (D2/D1) is within the range defined by the combination of the upper and lower limits described above, it is easy to achieve both adhesive residue suppression and surface shape followability in a balanced manner.

The indentation hardness H1, H2 and the straightness D1 and D2 are determined by using a nanoindenter to press the indenter vertically from the surface of the sample to a predetermined depth at a predetermined measurement position, and then perform the operation of pulling out. The transition of the load applied to the indenter (vertical axis) is obtained from the load (indentation)-unloading (pulling) curve obtained by plotting the displacement of the indenter (horizontal axis) with respect to the surface of the sample. Here, in the measurement of indentation hardness H1 and threadability D1, the surface of the adhesive layer is used as the measurement position (measurement position A). In the measurement of indentation hardness H2 and threadability D2, the measurement position (measurement position B) is set at a distance of 4 μm from the base material to the surface of the adhesive layer on the cross section of the adhesive sheet.

Indentation hardness [MPa] is obtained by dividing the maximum load (Pmax) [μN] of the load curve when the indenter is indented to a predetermined depth by the contact projection area (A) of the indenter, that is, the following equation: Indentation hardness [MPa] ]=Pmax/A. The indentation hardness can be within the above range by appropriately selecting the structure of the adhesive layer or the composition of the adhesive constituting the adhesive layer (e.g., composition of base polymer, degree of crosslinking, type of crosslinking agent, etc.).

As schematically shown in FIG. 5, the linearity [nm] is defined as the amount of displacement when the unloading curve is on the negative displacement side and zero load is determined. The threadability can be within the above range by appropriately selecting the composition of the adhesive constituting the adhesive layer (for example, the composition of the base polymer, the degree of crosslinking, the type of crosslinking agent, etc.).

Indentation hardness and threadability are specifically measured under the following conditions using a nanoindenter manufactured by Hysitron, product name "Triboindenter TI-950" or its equivalent.

[Measuring conditions]

Indenter used: Berkovich (triangular pyramid) type diamond indenter

Measurement method: single indentation measurement

Measurement temperature: room temperature (25℃)

Indentation depth setting: 800 nm at measuring position A,

1000 nm at measuring position B

Indentation speed: 200㎚/sec

Drawing speed: 200 nm/sec

(swellability)

In some embodiments of the adhesive sheet disclosed herein, the initial thickness T0 [㎛] of the adhesive layer (first adhesive layer) and 4-t-butylphenylglycidyl ether (TBPGE) are dropped on the surface of the adhesive layer. Therefore, the difference in thickness T1 [μm] of the adhesive layer after standing for 1 minute (T1-T0), that is, the amount of thickness change is 20 μm or less. A pressure-sensitive adhesive sheet including a pressure-sensitive adhesive layer with a small change in thickness due to swelling in TBPGE suppresses migration of components between the pressure-sensitive adhesive layer and the sealing resin, for example, in a usage mode of performing resin sealing of a semiconductor chip on the pressure-sensitive adhesive layer. This tends to occur, and thereby the level difference (stand-off) between the semiconductor chip and the sealing resin can be suppressed. From this viewpoint, in some embodiments, the thickness change amount is preferably 15 μm or less, and more preferably 10 μm or less. The closer the thickness change amount is to 0 (zero) μm, the more preferable it is, and may be 0 μm. In some embodiments, from a practical viewpoint such as balance with other characteristics or cost, the thickness change amount may be, for example, 0.1 μm or more, 0.5 μm or more, 1 μm or more, 2 μm or more, or 3 μm or more. It may be ㎛ or more.

In some embodiments of the adhesive sheet disclosed herein, the rate of change in thickness of the adhesive layer after dropping TBPGE on the surface of the adhesive layer of the adhesive sheet and allowing it to stand for 1 minute is preferably 160% or less, and more preferably 150%. % or less. A pressure-sensitive adhesive sheet provided with a pressure-sensitive adhesive layer in which the rate of change in thickness due to swelling in TBPGE is suppressed, for example, in a usage mode of performing resin sealing of a semiconductor chip on the pressure-sensitive adhesive layer, there is no transition of components between the pressure-sensitive adhesive layer and the sealing resin. It tends to be suppressed, and standoff can thereby be suppressed. From this point of view, in some embodiments, the thickness change rate may be, for example, 120% or less, 100% or less, 80% or less, or 60% or less. The smaller the thickness change rate, the more preferable it is, and its lower limit is not particularly limited. In some embodiments, from a practical viewpoint such as balance with other characteristics or cost, the thickness change rate may be, for example, 5% or more, 10% or more, or 20% or more.

The thickness change amount is determined by dropping a predetermined amount of TBPGE (0.02 g using a syringe with a diameter of 22 mm) on the surface of the adhesive layer and leaving it for 1 minute in an environment of 23°C and 50% RH, and measuring the TBPGE remaining on the surface of the adhesive layer. It is obtained by the equation T1-T0 from the thickness T1 of the adhesive layer at the location where TBPGE was dropped after wiping and the thickness (initial thickness) T0 of the adhesive layer at the location before dropping TBPGE. The thickness change rate is obtained from T0 and T1 using the formula (T1-T0)/T0. The thickness change amount and thickness change rate are within the above range, for example, by appropriately selecting the composition of the base polymer (e.g., acrylic polymer) of the A layer constituting at least the surface of the adhesive layer, the degree of crosslinking, the type of crosslinking agent, etc. You can do this. For example, at least 30% by weight (more preferably at least 40% by weight) of the monomer component constituting the acrylic polymer has an alkyl group with a large number of carbon atoms (for example, 4 or more, preferably 8 or more) at the ester terminal. By using an alkyl (meth)acrylate, it is possible to form an adhesive layer with a small amount of change in thickness and/or a small rate of change in thickness.

(TMA intrusion amount)

In some embodiments of the adhesive sheet disclosed herein, the penetration amount in a 23°C environment using TMA of the adhesive sheet may be approximately 20.0 μm or less (e.g., approximately 1.00 μm or more and 20.0 μm or less). Here, the “invasion amount under a 23°C environment using TMA of the adhesive sheet” (hereinafter also referred to as the “TMA penetration amount”) refers to the amount of penetration into the adhesive layer (the first layer) using a thermomechanical analyzer (TMA). This refers to the amount of penetration after 60 minutes of contacting the probe with the adhesive layer. The measurement conditions for the TMA penetration amount are probe: needle penetration (cylindrical, tip diameter 1 mmΦ), nitrogen gas flow rate: 50.0 ml/min, and indentation load: 0.01 N. As a thermomechanical analysis device, the product name "TMA Q400" manufactured by TA instruments, or an equivalent product thereof, can be used.

In addition, when the adhesive sheet has an adhesive layer only on one side of the substrate (i.e., does not have a second adhesive layer described later), a standard adhesive layer is applied on the side opposite to the adhesive layer (first adhesive layer) of the substrate. After preparation, the measurements are made. The standard adhesive layer is an acrylic polymer (ethyl acrylate (EA)/2-ethylhexyl acrylate (2EHA)/methyl methacrylate (MMA)/2-hydroxyethyl acrylate (HEA) = 30/70/5/5 ( 100 parts by weight of an acrylic polymer composed of monomer components (weight ratio: 450,000 weight average molecular weight), 10 parts by weight of a tackifier (manufactured by Yasuhara Chemical, brand name "Mighty Ace G125"), and an isocyanate-based crosslinking agent (manufactured by Tosoh Corporation) Using an adhesive composition obtained by mixing 2 parts by weight of manufactured product, brand name “Coronate L”), 30 parts by weight of heat-expandable microballoon (manufactured by Matsumoto Yushi Seiyaku Co., Ltd., brand name “Matsumoto Micro Spare F-190D”), and toluene. This is the formed adhesive layer with a thickness of 45 μm.

In some embodiments, the TMA penetration amount is preferably 15.0 μm or less, more preferably 10.0 μm or less, may be 9.00 μm or less, and may be 6.00 μm or less. The adhesive sheet with a smaller TMA penetration amount is, for example, used at the time of resin sealing (e.g., in FIG. 2 In steps (ii) and (iii)), the embedding of the semiconductor chip into the adhesive sheet due to the force applied to the semiconductor chip tends to become smaller. By reducing the embedding, in the structure including the chip and the sealing resin, the level difference (stand-off) between the semiconductor chip and the sealing resin resulting from the embedding can be reduced. Reducing the level difference is also desirable from the viewpoint of improving the adhesive residue prevention ability when peeling the adhesive sheet from the structure.

In some embodiments, from the viewpoint of improving followability to the surface shape of the adherend (e.g., steps that may exist on the surface of a semiconductor chip), the amount of TMA penetration may be, for example, 1.50 μm or more, and may be 2.00 μm or more. It is suitable to be ㎛ or more, and may be 2.50 ㎛ or more, 3.00 ㎛ or more, or 3.50 ㎛ or more. In a pressure-sensitive adhesive sheet showing such a TMA penetration amount, it is possible to achieve both the ability to follow the surface shape of the semiconductor chip and the suppression of embedding of the semiconductor chip into the pressure-sensitive adhesive sheet.

The amount of TMA penetration depends, for example, on the structure of the adhesive layer (thickness, layer composition, etc.), the composition and degree of crosslinking of the base polymer (e.g., acrylic polymer) of the adhesive constituting the adhesive layer, the type of crosslinking agent, and the substrate. The above range can be achieved by appropriately selecting the type, etc.

In some embodiments of the adhesive sheet disclosed herein, the penetration amount (hereinafter also referred to as “high temperature TMA penetration amount”) in a 145°C environment using TMA of the adhesive sheet is suitably 2.00 μm or more and 60 μm or less, For example, it may be 3.00 μm or more and 50 μm or less, and may be 4.00 μm or more and 40 μm or less. The pressure-sensitive adhesive sheet with the high-temperature TMA penetration amount within the above range can suitably suppress embedding of the semiconductor chip into the pressure-sensitive adhesive sheet even when subjected to a high-temperature environment (for example, a heat treatment environment during resin sealing). The amount of high-temperature TMA penetration is measured in the same manner as the amount of TMA penetration in the 23°C environment described above, except that the measurement ambient temperature is 145°C.

(probe tag value)

In some embodiments of the adhesive sheet disclosed herein, the probe tack value measured on the surface of the adhesive layer (first adhesive layer) is preferably 50 N/5 mmϕ or more, and more preferably 75 N/5. It is mmϕ or more, and more preferably 100N/5mmϕ or more. It is preferable that the probe tack value is within this range from the viewpoint of preventing misalignment of the adherend (eg, semiconductor chip) placed on the adhesive layer. The probe tack value was calculated using a commercially available probe tack tester in an environment of 23°C and 50% RH, probe area area and material: 5 mm ϕ SUS (stainless steel), probe lowering speed: 30 mm/min, close contact. It can be measured under the conditions of load: 100gf, adhesion holding time: 1 second, and test speed: 30mm/min.

(vs. PET adhesion)

The adhesive strength (vs. PET adhesive strength) of the adhesive sheet disclosed herein to the polyethylene terephthalate film is not particularly limited, and may be, for example, 5.00 N/20 mm or less, 3.00 N/20 mm or less, or 2.00 N/20 mm or less. It may be 20 mm or less. In some embodiments, from the viewpoint of preventing damage to the adherend due to the load when peeling off the adhesive sheet, the adhesive force to PET is preferably 1.00 N/20 mm or less, and more preferably 0.05 N/20 mm or less. In addition, in some embodiments, the adhesive strength of the adhesive sheet to PET is suitably 0.03 N/20 mm or more, and 0.05 N/20 mm or more, from the viewpoint of suitably fixing the adherend (e.g., semiconductor chip). It is preferable and may be 0.10N/20mm or more, and may be 0.15N/20mm or more.

The adhesion to PET was measured by bonding a PET film (thickness 25 μm) as an adherend to the adhesive layer (first adhesive layer) of an adhesive sheet with a width of 20 mm and a length of 140 mm (bonding conditions: 1 round trip of a 2 kg roller), 23 This refers to the adhesive force measured by performing a tensile test (peel angle 180 degrees, tensile speed 300 mm/min) after leaving it for 30 minutes at an environmental temperature of ℃.

(tensile modulus)

In some embodiments, the tensile modulus of elasticity at 25°C of the first adhesive layer is preferably less than 100 MPa, more preferably 0.1 MPa to 50 MPa, and even more preferably 0.1 MPa to 10 MPa. Within this range, it is easy to obtain a pressure-sensitive adhesive sheet in which the first pressure-sensitive adhesive layer exhibits appropriate adhesive strength. In addition, the tensile modulus of elasticity can be measured according to JIS K7161: 2008.

<Adhesive layer (first adhesive layer)>

In the adhesive sheet disclosed herein, as the adhesive constituting the adhesive layer (first adhesive layer) disposed on at least one side of the substrate, any suitable adhesive can be used as long as the effect of the present invention is obtained. The adhesive layer may be, for example, an acrylic adhesive, a rubber-based adhesive (natural rubber-based, synthetic rubber-based, a mixture thereof, etc.), a silicone-based adhesive, a polyester-based adhesive, a urethane-based adhesive, a polyether-based adhesive, a polyamide-based adhesive, and a fluorine-based adhesive. It may contain one or two or more types of adhesives selected from various known adhesives such as the like. In the adhesive layer containing two or more types of adhesives, these adhesives may be two or more types selected from the same type of adhesives (e.g., acrylic adhesives), or two or more types of adhesives of different types (e.g., acrylic adhesives). and polyester-based adhesive) may be selected from one or two or more of the following. In the adhesive layer containing the above two or more types of adhesives, these adhesives may be uniformly mixed with each other, may be arranged at different positions in the thickness direction (for example, stacked), or may be arranged at different positions in the planar direction. (For example, separate application) may be used, or a combination of these may be used, or an intermediate arrangement thereof may be used.

The thickness of the first adhesive layer is preferably 5 μm or more. If the thickness of the first adhesive layer is 5 μm or more, good followability to the surface shape of the adherend is likely to be exhibited. The upper limit of the thickness of the first adhesive layer is not particularly limited, and may be, for example, 200 μm or less, or 150 μm or less. In some embodiments, from the viewpoint of prevention of adhesive residue due to cohesive failure of the adhesive layer, suppression of embedding of the semiconductor chip in the adhesive sheet in a usage mode of performing a resin sealing process of the semiconductor chip on the adhesive layer, etc. The thickness of the first adhesive layer is suitably 110 μm or less, preferably 60 μm or less, and more preferably 20 μm or less.

<Floor A>

The adhesive layer (first adhesive layer) typically includes a layer A that constitutes at least the surface of the adhesive layer. In some embodiments, the adhesive layer may have a single-layer structure consisting of the A layer. In this case, the layer A is formed by directly bonding the opposite side of the surface to one surface of the base material. In some other embodiments, the adhesive layer may have a configuration in which another adhesive layer different from the A layer (for example, a B layer described later) is interposed between the A layer and one surface of the substrate. In this embodiment, the difference between the adhesive constituting the layer A and the adhesive constituting the other adhesive layers is, for example, a difference in the base polymer (for example, a difference in the composition of the monomer component constituting the base polymer). , differences in weight average molecular weight, differences in polymer chain structure, etc.), differences in crosslinking agents (e.g., differences in type and amount used), differences in tackifying resin (e.g., presence or absence of inclusion, content, difference in tackifying resin) There may be 1 or 2 or more, such as differences in type, etc.), presence or absence of other additives, differences in content, type, etc.

In some preferred embodiments, the adhesive constituting the layer A is an acrylic adhesive using an acrylic polymer as a base polymer. By configuring at least the surface of the first adhesive layer with an acrylic adhesive, the effects of the invention disclosed herein can be preferably exhibited.

(Acrylic polymer)

The acrylic polymer, which is the base polymer of the acrylic adhesive, preferably contains alkyl (meth)acrylate as the main monomer and, if necessary, is a polymer of monomer components that may further contain a secondary monomer copolymerizable with the main monomer. . Here, the main monomer refers to the main component in the monomer component constituting the acrylic polymer, that is, a component contained in excess of 50% by weight of the monomer component.

As the alkyl (meth)acrylate, for example, a compound represented by the following formula (A) can be preferably used.

Here, R ¹ in the formula (A) is a hydrogen atom or a methyl group. In addition, R ² is a chain alkyl group having 1 to 20 carbon atoms (hereinafter, such a range of carbon atoms may be indicated as “C _1-20 ”). From the viewpoint of ease of adjustment of adhesive properties, etc., alkyl (meth)acrylates in which R ² is a C _1-18 chain alkyl group are preferable, and alkyl (meth)acrylates in which R ² is a C _1-12 chain alkyl group are more preferable. desirable.

Specific examples of the alkyl (meth)acrylate include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, ( s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, (meth)acrylate ) Isooctyl acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, (meth)acrylic acid Tridecyl, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, eico (meth)acrylate (meth)acrylic acid C _1-20 alkyl esters such as thread. Among them, (meth)acrylic acid alkyl esters having a straight or branched alkyl group of C _4-20 (more preferably C _6-20 , more preferably C _8-18 ) (for example, (meth) It is preferable to use 2-ethylhexyl acrylate).

In some embodiments, 30% by weight or more of the monomer component constituting the acrylic polymer is a compound in which R ² in the above formula (A) has 4 or more carbon atoms (preferably 8 or more. Also, preferably 18 or less, for example) It is an alkyl (meth)acrylate with a structure of 12 or less) straight-chain or branched alkyl groups. By using such alkyl (meth)acrylate, component migration between the adhesive layer and sealing resin can be preferably suppressed. The content of the alkyl (meth)acrylate in the monomer component used in the synthesis of acrylic polymer is preferably 40% by weight or more, and in some embodiments, may be 50% by weight or more, and may be 70% by weight or more. The content of the alkyl (meth)acrylate in the monomer component is preferably 99.5% by weight or less, and is preferably 99% by weight or less from the viewpoint of making it easy to adjust the indentation hardness H1 at the measurement position A to a desirable range. It may be 98% by weight or less, and may be 97% by weight or less.

A secondary monomer that is copolymerizable with alkyl (meth)acrylate, the main monomer, can help introduce crosslinking points into the acrylic polymer or increase cohesion or heat resistance of the acrylic polymer. The secondary monomer may also be helpful in controlling the indentation hardness H1. As secondary monomers, for example, the following functional group-containing monomers can be used individually or in combination of two or more types. For example, the following functional group-containing monomers can be used individually or in combination of two or more types.

Carboxyl group-containing monomers such as acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid;

Acid anhydride monomers such as maleic anhydride and itaconic anhydride;

Hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, hydroxyhexyl (meth)acrylate, hydroxyoctyl (meth)acrylate, hydroxydecyl (meth)acrylate, (meth)acrylate ) Hydroxy group-containing monomers such as hydroxylauryl acrylate and (4-hydroxymethylcyclohexyl)methyl methacrylate;

(N) such as (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-butyl(meth)acrylamide, N-methylol(meth)acrylamide, N-methylolpropane(meth)acrylamide, etc. -Substituted) amide-based monomer;

N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole , monomers having a nitrogen atom-containing ring such as N-vinylimidazole, N-vinyloxazole, N-vinylmorpholine, N-vinylcaprolactam, and N-(meth)acryloylmorpholine;

Amino group-containing monomers such as aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, and t-butylaminoethyl (meth)acrylate;

Acrylic monomers containing epoxy groups such as glycidyl (meth)acrylate;

Cyano group-containing monomers such as acrylonitrile and methacrylonitrile;

Sulfonic acid groups such as styrenesulfonic acid, allylsulfonic acid, 2-(meth)acrylamide-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid. Containing monomers;

Maleimide monomers such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, and N-phenylmaleimide;

N-methyl itaconimide, N-ethyl itaconimide, N-butyl itaconimide, N-octyl itaconimide, N-2-ethylhexyl itaconimide, N-cyclohexyl itaconimide Itaconimide-based monomers such as mead and N-lauryl itaconimide;

N-(meth)acryloyloxymethylene succinimide, N-(meth)acryloyl-6-oxyhexamethylene succinimide, N-(meth)acryloyl-8-oxyoctamethylene succinimide, etc. succinimide monomer;

3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyl dimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxy Monomers containing alkoxysilyl groups such as silane.

The monomer component may contain copolymerizable monomers other than the functional group-containing monomers exemplified above as secondary monomers for purposes such as improving cohesion. Examples of such other copolymerizable monomers include vinyl ester monomers such as vinyl acetate, vinyl propionate, and vinyl laurate; Aromatic vinyl compounds such as styrene, substituted styrene (α-methylstyrene, etc.), and vinyl toluene; Cycloalkyl (meth)acrylates such as cyclohexyl (meth)acrylate, cyclopentyl (meth)acrylate, and isobornyl (meth)acrylate; Aryl (meth)acrylate (e.g. phenyl (meth)acrylate), aryloxyalkyl (meth)acrylate (e.g. phenoxyethyl (meth)acrylate), arylalkyl (meth)acrylate (e.g. For example, aromatic ring-containing (meth)acrylates such as benzyl (meth)acrylate); Olefin-based monomers such as ethylene, propylene, isoprene, butadiene, and isobutylene; Chlorine-containing monomers such as vinyl chloride and vinylidene chloride; Isocyanate group-containing monomers such as 2-(meth)acryloyloxyethyl isocyanate; Alkoxy group-containing monomers such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate; Vinyl ether monomers such as methyl vinyl ether and ethyl vinyl ether; Glycol-based monomers such as polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, methoxyethylene glycol (meth)acrylate, and methoxypolypropylene glycol (meth)acrylate;

In addition, heterocycle-containing monomers such as tetrahydrofurfuryl (meth)acrylate, fluorine (meth)acrylate, and silicone (meth)acrylate can be mentioned.

The monomer component, as the other copolymerizable monomers described above, may contain a polyfunctional monomer for the purpose of crosslinking or the like. Non-limiting examples of such multifunctional monomers include hexanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, and neopentyl glycol di(meth)acrylate. (meth)acrylate, pentaerythritol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, multifunctional epoxy Multifunctional monomers such as acrylate, multifunctional polyester acrylate, and multifunctional urethane acrylate may be included. Polyfunctional monomers can be used individually or in combination of two or more types.

In some preferred forms, the acrylic polymer is a monomer whose homopolymer glass transition temperature (Tg) is -5°C to 150°C (preferably 50°C to 150°C, more preferably 80°C to 120°C). It is preferable to include the derived structural unit a. By including this structural unit a, the molecular motion of the acrylic polymer is limited, and an A layer in which the T ₂ relaxation time of the S component by pulse NMR is suitably adjusted can be realized. In addition, since at least the surface of the first adhesive layer is composed of the layer A, a pressure-sensitive adhesive sheet excellent in low-temperature adhesiveness can be obtained. The content of the structural unit a is preferably 0.1% by weight to 20% by weight, more preferably 1% by weight to 10% by weight, and particularly preferably 1.5% by weight, based on the total structural units constituting the acrylic polymer. to 8% by weight, most preferably 3% to 6% by weight.

Monomers with a homopolymer Tg of -5°C to 150°C include, for example, 2-hydroxyethyl acrylate (Tg: -3°C), 2-hydroxyethyl methacrylate (Tg: 77°C), and acrylic acid ( Tg: 102℃), cyclohexyl methacrylate (Tg: 83℃), dicyclofentanyl acrylate (Tg: 120℃), dicyclofentanyl methacrylate (Tg: 175℃), isobornyl acrylate (Tg: 94℃) ), isobornyl methacrylate (Tg: 150℃), t-butyl methacrylate (Tg: 118℃), methyl methacrylate (Tg: 105℃), styrene (Tg: 80℃), acrylonitrile ( Tg: 97°C), N-acryloylmorpholine (Tg: 145°C), etc. As the glass transition temperature of homopolymers of monomers other than the above, the values described in known materials such as “Polymer Handbook” (3rd edition, John Wiley & Sons, Inc., 1989) shall be used. For monomers for which multiple types of values are described in the Polymer Handbook, the highest value is adopted. In cases where the Tg of the homopolymer is not described in known data, the value obtained by the measurement method described in Japanese Patent Application Laid-Open No. 2007-51271 is used.

These monomers can be used individually or in combination of two or more types. Among these, methyl methacrylate is preferable in order to increase transparency of the adhesive layer and increase visibility of the adherend during processing. Additionally, acrylic acid strongly adheres to the adherend due to intermolecular interactions, so it is preferable when strong adhesion is required. In addition, since 2-hydroxyethyl (meth)acrylate shows high reactivity with various crosslinking agents, it is suitable for forming an adhesive with a short T ₂ relaxation time, which will be described later.

In some preferred forms, the acrylic polymer contains structural units derived from a carboxyl group-containing monomer. The content of structural units derived from carboxyl group-containing monomers is preferably 0.1% by weight or more, more preferably 1% by weight or more, further preferably 2% by weight or more, based on the total structural units constituting the acrylic polymer. Preferably it is 15 weight% or less, more preferably 10 weight% or less, and even more preferably 7 weight% or less.

In some preferred forms, the acrylic polymer contains structural units derived from hydroxy group-containing monomers. The content of structural units derived from hydroxy group-containing monomers is preferably 0.01% by weight or more, more preferably 0.03% by weight or more, for example, 0.05% by weight or more, with respect to the total structural units constituting the acrylic polymer. Typically, it is 20% by weight or less, more preferably 10% by weight or less, for example, 7% by weight or less.

(SP value)

In some embodiments, the SP value of the base polymer (preferably an acrylic polymer) of the adhesive constituting layer A is suitably, for example, 10 or more and 30 or less, preferably 15 or more and 25 or less, and 18 or more and 20 or less. Particularly desirable. Within this range, migration of components between the adhesive layer/sealing resin can be preferably prevented. In addition, in this specification, the unit of the numerical value representing the SP value is all "(cal/cm3) ^1/2 ".

Here, the SP value is a value calculated from the basic structure of the compound using the method proposed by Fedors. Specifically, the SP value is calculated according to the following equation from the evaporation energy Δe (cal) of each atom or atomic group at 25°C and the molar volume Δv (cm3) of each atom or atomic group at the same temperature. .

SP value = (ΣΔe/ΣΔv) ^1/2

(Reference: Hideki Yamamoto, “SP Value Basics/Application and Calculation Method”, 4th printing, Information Organization Publishing Co., Ltd., published on April 3, 2006, pages 66 to 67).

When the polymer is a copolymer, the SP value is obtained by calculating the SP value of each homopolymer of each structural unit constituting the copolymer and multiplying each of these SP values by the mole fraction of each structural unit. It is calculated. In the above case, the analysis method of each structural unit (polymer composition analysis) involves appropriately collecting only the adhesive layer from the adhesive sheet and dissolving it in organic solvents such as dimethylformamide (DMF), acetone, methanol, and tetrahydrofuran (THF). The solvent-soluble portion obtained by immersion can be recovered and obtained by analytical methods such as gel filtration permeation chromatography (GPC), nuclear magnetic resonance spectroscopy (NMR), infrared spectroscopy (IR), and mass spectrometry.

(Cross-linking agent)

From the viewpoint of making it easy to achieve the above-described desirable indentation hardness H1, it is preferable that the base polymer of the A layer is crosslinked in the adhesive constituting the A layer. For example, by using a pressure-sensitive adhesive composition containing a base polymer and an appropriate cross-linking agent, it is possible to obtain a layer A composed of the pressure-sensitive adhesive in which the base polymer is cross-linked with the cross-linking agent.

The type of crosslinking agent is not particularly limited, and for example, isocyanate-based crosslinking agents, epoxy-based crosslinking agents, melamine-based crosslinking agents, peroxide-based crosslinking agents, urea-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, and carbodiyl crosslinking agents. It can be used by appropriately selecting from a mead-based crosslinking agent, an oxazoline-based crosslinking agent, an aziridine-based crosslinking agent, an amine-based crosslinking agent, etc. The crosslinking agent can be used individually or in combination of two or more types. Among these, preferred crosslinking agents include epoxy-based crosslinking agents and isocyanate-based crosslinking agents.

As an epoxy-based crosslinking agent, for example, N,N,N',N'-tetraglycidyl-m-xylenediamine, diglycidylaniline, 1,3-bis(N,N-glycidylaminomethyl) Cyclohexane (manufactured by Mitsubishi Gas Chemicals, brand name “Tetrad C”), 1,6-hexanediol diglycidyl ether (manufactured by Kyoesha Chemicals, brand name “Epolite 1600”), neopentyl glycol diglycy. Diyl ether (manufactured by Kyoesha Chemical, brand name “Epolite 1500NP”), ethylene glycol diglycidyl ether (manufactured by Kyoesha Chemical, brand name “Epolite 40E”), propylene glycol diglycidyl ether (manufactured by Kyoesha Chemical, brand name “Epolite 40E”) Esha Chemical Co., Ltd., brand name “Epolite 70P”), polyethylene glycol diglycidyl ether (Nippon Yushi Co., brand name “Epiol E-400”), polypropylene glycol diglycidyl ether (Nippon Yushi Co., Ltd., brand name) , brand name “Epiol P-200”), sorbitol polyglycidyl ether (manufactured by Nagase Chemtex, brand name “Denacol EX-611”), glycerol polyglycidyl ether (manufactured by Nagase Chemtex, brand name “Denacol EX-611”) "Chol EX-314"), pentaerythritol polyglycidyl ether, polyglycerol polyglycidyl ether (manufactured by Nagase Chemtex, brand name "Denacol EX-512"), sorbitan polyglycidyl ether, trimethylol Propane polyglycidyl ether, adipic acid diglycidyl ester, o-phthalic acid diglycidyl ester, triglycidyl-tris(2-hydroxyethyl)isocyanurate, resorcinol diglycidyl ether, bisphenol -S-diglycidyl ether, an epoxy resin having two or more epoxy groups in the molecule, etc. The amount of epoxy-based crosslinking agent used can be set to any appropriate amount depending on the desired properties. In some embodiments, the amount of the epoxy-based crosslinking agent used per 100 parts by weight of the base polymer may be, for example, 0.01 parts by weight or more and 50 parts by weight or less, preferably 0.6 parts by weight or more and 15 parts by weight or less, and more preferably It is 2 parts by weight or more and 13 parts by weight or less, and more preferably 3 parts by weight or more and 10 parts by weight or less.

Specific examples of the isocyanate-based crosslinking agent include lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; Alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate, and isophorone diisocyanate; Aromatic isocyanates such as 2,4-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and xylylene diisocyanate; Trimethylolpropane/tolylene diisocyanate trimer adduct (manufactured by Tosoh, brand name “Coronate L”), trimethylolpropane/hexamethylene diisocyanate trimer adduct (manufactured by Tosoh, brand name “Coronate HL”), hexamethylolpropane Isocyanate adducts, such as the isocyanurate form of methylene diisocyanate (manufactured by Tosoh Corporation, brand name "Coronate HX"), etc. are mentioned. The amount of isocyanate-based crosslinking agent used can be set to any appropriate amount depending on the desired adhesive strength. In some embodiments, the amount of the isocyanate-based crosslinking agent used per 100 parts by weight of the base polymer is typically 0.1 part by weight or more and 20 parts by weight or less, and preferably 1 part by weight or more and 10 parts by weight or less.

In some embodiments, as the crosslinking agent used in layer A, an epoxy-based crosslinking agent can be preferably employed. According to the A layer having a crosslinked structure in which the base polymer is crosslinked with an epoxy-based crosslinking agent, the preferred indentation hardness H1 disclosed herein can be suitably achieved. Additionally, an adhesive sheet that can appropriately reduce the level difference between the semiconductor chip and the sealing resin can be obtained. In addition, a pressure-sensitive adhesive layer with high cohesion can be formed, and misalignment of the adherend can be prevented more effectively.

In some embodiments, a cross-linking agent containing a nitrogen (N) atom can be preferably used as the cross-linking agent. A crosslinking agent containing an N atom is advantageous in that the catalytic action of the N atom promotes a crosslinking reaction (for example, a reaction with a carboxyl group in the base polymer) and tends to increase the gel fraction of the adhesive. Specific examples of the crosslinking agent containing an N atom include, in addition to the isocyanate crosslinking agent described above, an epoxy-based crosslinking agent containing an N atom (e.g., N,N,N',N'-tetraglycidyl-m-xylenediamine or epoxy-based crosslinking agents having a glycidylamino group, such as 1,3-bis(N,N-glycidylaminomethyl)cyclohexane. In some embodiments of using a cross-linking agent containing an N atom, the usage amount of the cross-linking agent is set so that the amount of nitrogen gas generated, as described later, is 0.06% by weight or more and 1.0% by weight or less (more preferably 0.06% by weight or more and 0.9% by weight or less). It is desirable. By using this amount, it is easy to obtain an adhesive sheet that preferably achieves both adhesive residue prevention and surface shape followability.

In some embodiments, a cross-linking agent (preferably a cross-linking agent that forms a cross-linked structure by reaction with a carboxyl group) relative to the amount of carboxyl groups possessed by the base polymer (e.g., an acrylic polymer). For example, an epoxy-based cross-linking agent, an isocyanate-based cross-linking agent, etc. ) The amount used is preferably 0.08 mole equivalent or more and 2 mole equivalent or less, and more preferably 0.1 mole equivalent or more and 1 mole equivalent or less. According to this usage amount, the desirable indentation hardness H1 disclosed herein can be accurately achieved. Additionally, by crosslinking the crosslinking agent in the above amount with carboxyl groups in the base polymer, a pressure-sensitive adhesive sheet with few residual carboxyl groups in the pressure-sensitive adhesive layer can be obtained.

(Other additives)

The adhesive constituting the A layer may contain appropriate additives other than the above as optional components as needed. Such additives include, for example, tackifiers, plasticizers (e.g., trimellitic acid ester plasticizers, pyromellitic acid ester plasticizers, etc.), pigments, dyes, fillers, anti-aging agents, conductive materials, antistatic agents, Examples include ultraviolet absorbers, light stabilizers, peeling regulators, softeners, surfactants, flame retardants, and antioxidants.

As the tackifier, any suitable tackifier can be used. As a tackifier, for example, a tackifier resin is used. Specific examples of the tackifying resin include rosin-based tackifying resins (e.g., unmodified rosin, modified rosin, rosin phenol-based resin, rosin ester-based resin, etc.), terpene-based tackifying resins (e.g., terpene-based resins) , terpene phenol resin, styrene-modified terpene resin, aromatic modified terpene resin, hydrogenated terpene resin), hydrocarbon tackifying resin (e.g., aliphatic hydrocarbon resin, aliphatic cyclic hydrocarbon resin, aromatic hydrocarbon resin) (e.g., styrene-based resin, xylene-based resin, etc.), aliphatic/aromatic-based petroleum resin, aliphatic/cycloaliphatic-based petroleum resin, hydrogenated hydrocarbon resin, coumarone-based resin, coumarone-indene-based resin, etc.), phenol-based tackifying resin (For example, alkylphenol-based resin, xylene formaldehyde-based resin, resol, novolak, etc.), ketone-based tackifying resin, polyamide-based tackifying resin, epoxy-based tackifying resin, elastomer-based tackifying resin, etc. You can. Among these, rosin-based tackifying resin, terpene-based tackifying resin, or hydrocarbon-based tackifying resin (styrene-based resin, etc.) are preferable. The tackifier can be used individually or in combination of two or more types.

In some embodiments, a resin having a high softening point or glass transition temperature (Tg) is used as the tackifying resin. When a resin with a high softening point or glass transition temperature (Tg) is used, an adhesive layer that can exhibit high adhesiveness is formed even under a high temperature environment (for example, under a high temperature environment during processing during semiconductor chip sealing, etc.). can do. The softening point of the tackifier is preferably 100°C to 180°C, more preferably 110°C to 180°C, and still more preferably 120°C to 180°C. The glass transition temperature (Tg) of the tackifier is preferably 100°C to 180°C, more preferably 110°C to 180°C, and still more preferably 120°C to 180°C.

In some embodiments, as the tackifying resin, a low polar tackifying resin is used. Using a low-polarity tackifying resin is advantageous from the viewpoint of forming a pressure-sensitive adhesive layer with low affinity for the sealing material. Examples of low-polarity tackifying resins include aliphatic hydrocarbon resins, aliphatic cyclic hydrocarbon resins, aromatic hydrocarbon resins (e.g., styrene-based resins, xylene-based resins, etc.), and aliphatic/aromatic petroleum resins (C5/ (sometimes referred to as C9-based petroleum resin), aliphatic/alicyclic-based petroleum resin, and hydrocarbon-based tackifying resin per hydrogenated hydrocarbon resin. Among them, aliphatic/aromatic petroleum resins are preferable. This tackifying resin has low polarity and excellent compatibility with acrylic polymers, and can form a pressure-sensitive adhesive layer with excellent stability without phase separation over a wide temperature range.

The acid value of the tackifying resin is preferably 40 or less, more preferably 20 or less, and still more preferably 10 or less. Within this range, an adhesive layer with low affinity to the sealing material can be formed. The hydroxyl value of the tackifying resin is preferably 60 or less, more preferably 40 or less, and still more preferably 20 or less. Within this range, the affinity with the sealing material is low, and a pressure-sensitive adhesive layer suitable for suppressing component migration between the pressure-sensitive adhesive layer and the sealing resin can be formed.

The amount of the tackifier used may be, for example, 5 parts by weight or more and 100 parts by weight or less, and preferably 8 parts by weight or more and 50 parts by weight or less, based on 100 parts by weight of the base polymer. In some embodiments of the adhesive sheet disclosed herein, from the viewpoint of easy peelability from the adherend and suppression of adhesive residue, the mixing amount of the tackifier for 100 parts by weight of the base polymer of the adhesive constituting the A layer is 3 parts by weight. It is appropriate to set it to less than 1 part by weight or less than 0.5 part by weight, and it is preferable not to mix a tackifier (particularly a tackifier resin) with the adhesive constituting the A layer.

(T ₂ relaxation time)

In some embodiments of the adhesive sheet disclosed herein, the T ₂ relaxation time (T _{2 s} ) of the S component of the A layer by pulse NMR is preferably 45 μsec or less. According to the adhesive sheet in which the T ₂ relaxation time (T _2s ) of the A layer constituting at least the surface of the first adhesive layer is 45 μsec or less, for example, in a usage aspect of performing resin sealing of a semiconductor chip on the first adhesive layer, the adhesive The migration of components between the layer and the sealing resin can be suppressed, and the level difference between the semiconductor chip and the sealing resin can be preferably suppressed.

The relaxation time refers to the time taken for the excited atoms (group) to return to the ground state after irradiating an appropriate energy to excite the atoms to be measured in pulse NMR measurement. The excited state of atoms (groups) can be controlled depending on the amount and time of energy irradiation. In addition, it is known that there are various energy relaxation mechanisms for the excited atoms (group) to return to the ground state, and the relaxation time is determined depending on the relaxation mechanism (e.g., "Latest NMR for Chemists") , Dongin Chemical Co., Ltd. (1997)). The present inventors excited the ¹ H atom of an acrylic adhesive (substantially an acrylic polymer contained in the adhesive) under the following conditions, measured the subsequent relaxation behavior, and further analyzed the measured values. Among them, the adhesive layer It was found that the S component (T 2s ) of the T ₂ relaxation time is useful as information that can be used to know the molecular motion related to the degree of crosslinking of the base polymer (typically an acrylic _polymer ) contained in the adhesive that constitutes , it was found that the above effect can be obtained by specifying the S component (T _2s ) of the T ₂ relaxation time. The short T _2s indicates that the molecular movement related to the degree of crosslinking of the base polymer is limited, that is, the crosslinking progresses and the degree of freedom of movement of the polymer as a whole is reduced. In the adhesive in this state, the gap between the base polymers is small, and the migration of the adhesive layer components to the sealing resin and the migration of the low molecular weight components contained in the sealing resin to the adhesive layer tend to be suppressed. As a result, after the semiconductor chip is resin-sealed on the adhesive sheet, generation of steps between the semiconductor chip and the sealing resin is prevented when the adhesive sheet is peeled off.

The T ₂ relaxation time (T _{2 s} ) of the S component by pulse NMR of the A layer is preferably 40 μsec or less from the viewpoint of better suppressing the migration of the component from the sealing resin, and is 35 μsec or less (for example, 30 μsec or less). It is more desirable. The lower limit of T _2s of the A layer is not particularly limited and may be, for example, 5 μsec or more. From the viewpoint of making it easy to develop an appropriate tack on the surface of the adhesive layer, in some embodiments, T _2s of the A layer may be 10 μsec or more, 15 μsec or more, or 20 μsec or more. It is preferable that T _2s of the A layer is not too short from the viewpoint of improving the adhesion between the A layer and the layer adjacent to it (which may be a substrate, an adherend, a B layer, etc., which will be described later).

The T _2s of the A layer is obtained by obtaining a T ₂ relaxation curve measured by the solid echo method using about 100 mg of the adhesive constituting the A layer as a measurement sample, and fitting the T ₂ relaxation curve to the equation (1) below. You can. The T ₂ relaxation time (T _{2 s} ) of the S component by pulse NMR of the B layer, which will be described later, is also measured in the same manner.

M(t): Free induction damping

α: Proton ratio (%) of component with short relaxation time (S component)

T _2s : T ₂ relaxation time of S component (msec)

β: Proton ratio (%) of component with long relaxation time (L component)

T _2L : T ₂ relaxation time of L component (msec)

t: observation time (msec)

Wa: shape factor (=1)

The measurement conditions for the above measurement are as follows.

·90°pulse width: 2.1μsec

·Repetition time: 1sec

· Integration count: 32 times

·Measurement temperature: 30℃

(gel fraction)

The gel fraction of the adhesive constituting layer A is preferably 75% or more, more preferably 85% or more, and still more preferably 90% or more. Within this range, the molecular movement of the base polymer is preferably limited by crosslinking, and migration of components between the adhesive layer and the sealing resin can be suppressed. From the viewpoint of suppressing the migration of the components, the higher the gel fraction constituting the A layer, the more advantageous it is. In addition, in consideration of balance with other characteristics (e.g., appropriate tack and adhesiveness on the surface of the adhesive layer, followability to the surface shape of the adherend, etc.), in some embodiments, the adhesive constituting the A layer is used. The gel fraction may be, for example, 99.5% or less, or 99% or less. The gel fraction is obtained by immersing the adhesive collected from layer A in ethyl acetate for 7 days, drying it, and calculating (dry weight of the adhesive after immersion/weight of the adhesive before immersion) x 100.

(Nitrogen gas generation amount)

In some types of pressure-sensitive adhesive sheets, the amount of nitrogen gas generated when the pressure-sensitive adhesive constituting layer A is heat-treated is preferably 0.06% by weight to 0.06% by weight, assuming that the weight of the pressure-sensitive adhesive used in the heat treatment is 100% by weight. It is 1.0% by weight, more preferably 0.06% by weight to 0.9% by weight. If the amount of nitrogen gas generated is 0.06% by weight or more, the adhesive exhibits sufficient cohesive force, and by suppressing the migration of components between the adhesive layer and the sealing resin, there is a tendency for it to become difficult for a step to occur at the interface between the semiconductor chip and the sealing resin. . It is advantageous that the amount of nitrogen gas generated is 1.0% by weight or less from the viewpoint of suppressing misalignment of the adherend placed on the A layer.

The amount of nitrogen gas generated above is calculated by calculating the amount of nitrogen gas generated by heating 2 mg of the adhesive in question, placing it on a ceramic board, and weighing it with a microbalance under the conditions of 800°C for thermal decomposition/900°C for oxidation, as TN (trace amount). It is obtained by analyzing with a total nitrogen analysis (Nitrogen analysis) device. The conditions during measurement can be as follows.

·Carrier gas: O ₂ (300mL/min), Ar (300mL/min)

·Standard sample: pyridine/toluene solution

Detector: Reduced pressure chemiluminescence detector

·Range: High concentration

<B floor>

In some embodiments of the adhesive sheet disclosed herein, the first adhesive layer includes a layer A constituting at least the surface of the adhesive layer, and a layer B disposed between the layer A and the substrate and adjacent to the substrate. Includes. That is, the outer surface (surface on the adherend side) of the first adhesive layer is formed by layer A, and the inner surface (surface on the substrate side) of the first adhesive layer is formed by layer B. According to the first adhesive layer having such a structure, the properties (indentation hardness, e.g., indentation hardness, T ₂ relaxation time of the four-tone, S component, etc.) or their ratio can be easily adjusted.

As the adhesive constituting the B layer, any suitable adhesive can be used. The layer B is, for example, one or two types selected from various known adhesives such as acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, polyether adhesives, polyamide adhesives, and fluorine adhesives. It may contain more than one type of adhesive.

In some preferred embodiments, the adhesive constituting the layer B is an acrylic adhesive using an acrylic polymer as a base polymer. In an embodiment in which the A layer is comprised of an acrylic adhesive, it is particularly preferable to employ an acrylic adhesive as the adhesive constituting the B layer from the viewpoint of increasing the interlayer adhesion of the layers included in the first adhesive layer.

In an embodiment in which the adhesive constituting the B layer is an acrylic adhesive, the acrylic polymer that is the base polymer of the acrylic adhesive can be preferably selected from the same acrylic polymer as the base polymer of the A layer. The acrylic polymer that is the base polymer of the A layer and the acrylic polymer that is the base polymer of the B layer may be the same or different. In some embodiments, from the viewpoint of adhesion between the A layer and the B layer, the base polymer of the A layer and the B layer can be the same acrylic polymer. In this embodiment, the properties at measurement positions A and B are determined by selection of the presence, type, and amount of materials other than the base polymer (crosslinking agent, tackifier, etc.) used to form each layer. The ratio can be adjusted.

It is preferable that the base polymer of the B layer is crosslinked in the adhesive constituting the B layer. For example, by using a pressure-sensitive adhesive composition containing a base polymer and an appropriate cross-linking agent, it is possible to obtain a B layer composed of a pressure-sensitive adhesive in which the base polymer is cross-linked with the cross-linking agent. The type of crosslinking agent used in the B layer is not particularly limited, and can be preferably selected from those exemplified above as crosslinking agents that can be used in the A layer, for example. The cross-linking agent used in layer A and the cross-linking agent used in layer B may be the same type of cross-linking agent (for example, the same or different isocyanate-based cross-linking agent), or may be different cross-linking agents (for example, one is an epoxy-based cross-linking agent, the other is an epoxy-based cross-linking agent). An isocyanate-based crosslinking agent may also be used.

In some preferred forms, an epoxy-based crosslinking agent is used in layer A and an isocyanate-based crosslinking agent is used in layer B. In general, since a more flexible crosslinked structure tends to be formed using an isocyanate-based crosslinking agent compared to an epoxy-based crosslinking agent, according to the above embodiment, a first pressure-sensitive adhesive layer having an indentation hardness H2 smaller than an indentation hardness H1 can be preferably realized. .

When using an isocyanate-based crosslinking agent as a crosslinking agent for the B layer, the amount of the isocyanate-based crosslinking agent used relative to 100 parts by weight of the base polymer (for example, an acrylic polymer) of the B layer is not particularly limited, and can be adjusted appropriately to obtain the desired properties. You can. In some embodiments, the amount of the isocyanate-based crosslinking agent used per 100 parts by weight of the base polymer of the B layer is, for example, 0.1 part by weight or more and 20 parts by weight or less, preferably 1 part by weight or more and 10 parts by weight or less, and more preferably. It may be 1 part by weight or more and 7 parts by weight or less, 1 part by weight or more and 5 parts by weight or less, and 2 parts by weight or more and 5 parts by weight or less.

In order to advance the crosslinking reaction more effectively, a crosslinking catalyst may be used. Examples of the crosslinking catalyst include metal crosslinking catalysts such as tetra-n-butyl titanate, tetraisopropyl titanate, ferric nasem, butyltin oxide, and dioctyltin dilaurate. The amount of crosslinking catalyst used is not particularly limited. In some embodiments, in consideration of the balance between the speed of the crosslinking reaction rate and the length of pot life of the adhesive composition, the amount of the crosslinking catalyst used per 100 parts by weight of the base polymer is, for example, 0.0001 part by weight or more and 1 part by weight or less (preferably can be 0.001 parts by weight or more and 0.5 parts by weight or less). The crosslinking catalyst may be used in the A layer, or may be used in both the A layer and the B layer.

In some embodiments of the adhesive sheet disclosed herein, the T ₂ relaxation time (T _{2 s} ) of the S component by pulse NMR of the B layer constituting the first adhesive layer is the adherend disposed on the A layer of the adhesive layer. From the viewpoint of improving followability to the surface shape, it is preferable that the T _2s of the A layer is longer. The difference between T _2s of the A layer and T _2s of the B layer may be, for example, 5 μsec or more, preferably 10 μsec or more, more preferably 15 μsec or more, more preferably 20 μsec or more, 25 μsec or more, or 30 μsec or more. do. Additionally, from the viewpoint of preventing cohesive failure of the adhesive layer due to T _2s of the B layer being too long, the difference between T _2s of the A layer and T _2s of the B layer is suitably, for example, 70 μsec or less, and is preferably 60 μsec or less. It is more preferable that it is 50 μsec or less, and may be 40 μsec or less, or 35 μsec or less.

In some embodiments, the T _2s of the B layer is greater than the T _2s of the A layer and is suitably 30 μsec or more (e.g., 35 μsec or more, 40 μsec or more, or 45 μsec or more), which increases the followability to the surface shape of the adherend. From the viewpoint of exhibiting the effect preferably, it is preferable to be longer than 45 μsec, and may be 47 μsec or longer, or 50 μsec or longer. Furthermore, from the viewpoint of preventing cohesive failure of the B layer, T _2s of the B layer is suitably 80 μsec or less, preferably 70 μsec or less, may be 65 μsec or less, may be 60 μsec or less, and may be 57 μsec or less.

In some embodiments of a pressure-sensitive adhesive sheet including a pressure-sensitive adhesive layer comprising an A layer and a B layer, the thickness of the B layer may be, for example, 3 μm or more, and is preferably 4 μm or more, and the surface shape followability is maintained. From the viewpoint of enhancing the effect provided, it is preferable to be 5 ㎛ or more, may be 7 ㎛ or more, may be 10 ㎛ or more, and may be 15 ㎛ or more. The upper limit of the thickness of layer B is not particularly limited, and may be, for example, 300 μm or less, 250 μm or less, 150 μm or less, or 130 μm or less. From the viewpoint of suppressing embedding of the semiconductor chip in the adhesive sheet in the use mode of resin sealing the semiconductor chip on the adhesive layer, the thickness of the B layer is suitably 100 μm or less, preferably 90 μm or less, and 70 μm or less. It may be ㎛ or less, 50 ㎛ or less, 30 ㎛ or less, and 20 ㎛ or less.

In a pressure-sensitive adhesive sheet including a pressure-sensitive adhesive layer comprising an A layer and a B layer, the thickness of the A layer may be, for example, 1 μm or more and 20 μm or less. From the viewpoint of preferably exhibiting the effect of increasing surface shape followability due to the contribution of the B layer, in some embodiments, the thickness of the A layer is suitably 15 μm or less, preferably 10 μm or less, and may be 8 μm or less. It can be 6㎛ or less. In addition, from the viewpoint of preferably exerting the effect of suppressing the migration of components between the adhesive layer and the sealing resin due to the contribution of the A layer, in some embodiments, it is advantageous that the thickness of the A layer is 2 μm or more, 3 It is preferably ㎛ or more, and may be 4 ㎛ or more, or 5 ㎛ or more.

In the pressure-sensitive adhesive sheet provided with a pressure-sensitive adhesive layer composed of a layer A and a layer B, the ratio (L2/L1) of the thickness L2 [μm] of the layer B to the thickness L1 [μm] of the layer A is, in particular, It is not limited, and may be, for example, about 0.5 to 100.0. In some embodiments, from the viewpoint of making it easier to effectively exert the respective functions of the A layer and the B layer, the ratio (L2/L1) is suitably 0.5 or more, preferably 0.7 or more, may be 0.8 or more, and may be 0.9 or more. It may be more than 1.0. Also, from the same viewpoint, the ratio (L2/L1) is suitably 50.0 or less, preferably 30.0 or less, may be 20.0 or less, may be 15.0 or less, may be 10.0 or less, may be 5.0 or less, and may be 3.0 or less. Or it may be 2.0 or less.

<Description>

The base material of the adhesive sheet disclosed herein may be, for example, a resin sheet, non-woven fabric, paper, metal foil, woven fabric, rubber sheet, foam sheet, or a laminate thereof (in particular, a laminate containing a resin sheet). Resins constituting the resin sheet include, for example, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polyethylene (PE), polypropylene (PP), and ethylene-propylene copolymer. , ethylene-vinyl acetate copolymer (EVA), polyamide (nylon), wholly aromatic polyamide (aramid), polyimide (PI), polyvinyl chloride (PVC), polyphenylene sulfide (PPS), fluorine resin, poly Ether ether ketone (PEEK), etc. can be mentioned. Nonwoven fabrics include nonwoven fabrics made from natural fibers with heat resistance, such as nonwoven fabrics containing Manila hemp; Examples include synthetic resin nonwoven fabrics such as polypropylene resin nonwoven fabric, polyethylene resin nonwoven fabric, and ester resin nonwoven fabric. Examples of metal foil include copper foil, stainless steel foil, and aluminum foil. Examples of paper include Japanese paper and kraft paper.

In some embodiments, a resin sheet made of a resin having a glass transition temperature (Tg) of 25°C or higher (preferably 40°C or higher, more preferably 50°C or higher) is preferably used as a substrate. When such a resin sheet is used, the shape of the substrate is maintained even when heated during the sealing process, and embedding of the semiconductor chip in the adhesive sheet is prevented. As the resin constituting such a resin sheet, a polymer having an aromatic ring is preferable, and specific examples include polyethylene terephthalate (PET), polyimide, and polyethylene naphthalate, but are not limited to these.

The thickness of the substrate can be set to any appropriate thickness depending on desired strength or flexibility, purpose of use, etc. The thickness of the base material is preferably 1000 ㎛ or less, more preferably 25 ㎛ or more and 1000 ㎛ or less, further preferably 40 ㎛ or more and 500 ㎛ or less, particularly preferably 60 ㎛ or more and 300 ㎛ or less, and most preferably Preferably it is 80㎛ or more and 250㎛ or less. In one embodiment, a substrate with a thickness of 25 μm or more is used. A base material with such a thickness can easily maintain its shape even under pressure during the sealing process, and is suitable for preventing embedding in the adhesive sheet of a semiconductor chip.

In one embodiment, the thickness of the base material is 20% or more and 90% or less (preferably 20% or more and 89% or less, more preferably 20% or more and 88% or less) of the total thickness of the adhesive sheet. Within this range, embedding of the semiconductor chip into the adhesive sheet can be preferably prevented.

The above substrate may be surface treated. Examples of surface treatment include corona treatment, chromic acid treatment, ozone exposure, flame exposure, high-pressure electric shock exposure, ionizing radiation treatment, and coating treatment with a primer.

As the primer, an organic coating material may be used. Examples of the organic coating material include materials described in "Plastic Hard Coat Materials II" (published in 2004) by CMC Publishing. Preferably urethane-based polymers, more preferably polyacrylic urethane, polyester urethane, or precursors thereof are used. This is because it is easy to coat and apply to a base material, and a wide variety of products can be selected industrially, and can be obtained inexpensively. The urethane-based polymer is, for example, a polymer composed of a reaction mixture of an isocyanato monomer and an alcoholic hydroxyl group-containing monomer (for example, a hydroxyl group-containing acrylic compound or a hydroxyl group-containing ester compound). The organic coating material may contain optional additives such as chain extenders such as polyamines, anti-aging agents, and oxidation stabilizers. The thickness of the organic coating layer is not particularly limited, but is preferably about 0.1 μm to 10 μm, preferably about 0.1 μm to 5 μm, and more preferably about 0.5 μm to 5 μm.

<Second adhesive layer>

A pressure-sensitive adhesive sheet according to some embodiments includes the base material, the pressure-sensitive adhesive layer disposed on one side of the substrate, and the second pressure-sensitive adhesive layer disposed on the opposite side of the substrate from the pressure-sensitive adhesive layer. An adhesive sheet (double-sided adhesive sheet with a base material) of this configuration is, for example, a form in which the first adhesive layer is fixed on a suitable carrier (e.g., SUS plate, glass plate, etc.) using the second adhesive layer. Usability is good because the above resin sealing process can be performed. The second adhesive layer may be an adhesive layer composed of any suitable adhesive.

In some types of adhesive sheets, at least the surface of the second adhesive layer is made of an adhesive containing heat-expandable microspheres. This type of pressure-sensitive adhesive sheet is preferable because it can easily release the bond between the second pressure-sensitive adhesive layer and the adherend (e.g., the carrier) by heating at an appropriate timing to expand the heat-expandable microspheres as needed. .

The adhesive containing heat-expandable microspheres may be a curable adhesive (for example, an active energy ray-curable adhesive) or a pressure-sensitive adhesive. Examples of pressure-sensitive adhesives include acrylic adhesives and rubber-based adhesives. For details of the adhesive contained in the second adhesive layer, for example, the description in Japanese Patent Application Laid-Open No. 2018-009050 can be referred to. The entire disclosure of this publication is incorporated herein by reference.

As the heat-expandable microspheres, any appropriate heat-expandable microspheres can be used as long as they are microspheres that can expand or foam by heating. As the thermally expandable microspheres, for example, microspheres in which a material that easily expands by heating is encapsulated in an elastic shell can be used. Such heat-expandable microspheres can be produced by any suitable method, for example, coacervation method, interfacial polymerization method, etc.

Substances that easily expand by heating include, for example, halogens of propane, propylene, butene, n-butane, isobutane, isopentane, neopentane, n-pentane, n-hexane, isohexane, heptane, octane, petroleum ether, and methane. Low boiling point liquids such as cargo and tetraalkylsilane; and azodicarbonamide, which is gasified by thermal decomposition.

Examples of the material constituting the shell include nitrile monomers such as acrylonitrile, methacrylonitrile, α-chlor acrylonitrile, α-ethoxyacrylonitrile, and fumaronitrile; Carboxylic acid monomers such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, and citraconic acid; vinylidene chloride; Vinyl acetate; Methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, isobornyl (meth)acrylate, cyclo (meth)acrylic acid esters such as hexyl (meth)acrylate, benzyl (meth)acrylate, and β-carboxyethyl acrylate; Styrene monomers such as styrene, α-methylstyrene, and chlorostyrene; and polymers composed of amide monomers such as acrylamide, substituted acrylamide, methacrylamide, and substituted methacrylamide. The polymer comprised of these monomers may be a homopolymer or a copolymer. Examples of the copolymer include vinylidene chloride-methyl methacrylate-acrylonitrile copolymer, methyl methacrylate-acrylonitrile-methacrylonitrile copolymer, methyl methacrylate-acrylonitrile copolymer, Acrylonitrile-methacrylonitrile-itaconic acid copolymer, etc. are mentioned.

As the thermally expandable microspheres, an inorganic foaming agent or an organic foaming agent may be used. Examples of inorganic foaming agents include ammonium carbonate, ammonium bicarbonate, sodium bicarbonate, ammonium nitrite, sodium borohydroxide, and various azides. In addition, examples of organic blowing agents include chlorofluoroalkane compounds such as trichloromonofluoromethane and dichloromonofluoromethane; Azo compounds such as azobisisobutyronitrile, azodicarbonamide, and barium azodicarboxylate; Hydrazine-based 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-based compounds such as 5-morpholyl-1,2,3,4-thiatriazole; and N-nitroso-based compounds such as N,N'-dinitrosopentamethylenetetramine and N,N'-dimethyl-N,N'-dinitrosoterephthalamide.

The heat-expandable microspheres may be commercially available. Specific examples of commercially available thermally expandable microspheres include "Matsumoto Micro Spare" manufactured by Matsumoto Yushi Seiyaku Co., Ltd. (Grades: F-30, F-30D, F-36D, F-36LV, F-50, F-50D, F- 65, F-65D, FN-100SS, FN-100SSD, FN-180SS, FN-180SSD, F-190D, F-260D, F-2800D), brand name “Expansel” manufactured by Nippon Phillight Co., Ltd. (Grade: 053) -40, 031-40, 920-40, 909-80, 930-120), “Die Form” manufactured by Kureha Chemical Industry Co., Ltd. (Grade: H750, H850, H1100, S2320D, S2640D, M330, M430, M520) , “Advancell” manufactured by Sekisui Kagaku Kogyo Co., Ltd. (grades: EML101, EMH204, EHM301, EHM302, EHM303, EM304, EHM401, EM403, EM501), etc.

The particle diameter of the thermally expandable microspheres before heating is preferably 0.5 μm to 80 μm, more preferably 5 μm to 45 μm, further preferably 10 μm to 20 μm, and particularly preferably 10 μm to 15 μm. It is ㎛. Therefore, when looking at the average particle size of the thermally expandable microspheres before heating, the particle size is preferably 6 ㎛ to 45 ㎛, more preferably 15 ㎛ to 35 ㎛. The particle diameter and average particle diameter are values obtained by the particle size distribution measurement method in the laser scattering method.

The thickness of the adhesive layer made of an adhesive containing heat-expandable microspheres is not particularly limited, and can be, for example, 3 μm or more. From the viewpoint of suppressing the decrease in the smoothness of the adhesive surface due to the inclusion of heat-expandable microspheres, the thickness of the adhesive layer is generally appropriate to be 7 ㎛ or more, preferably more than 10 ㎛, may be more than 15 ㎛, or 25 ㎛. It may be greater than 35㎛. The upper limit of the thickness of the adhesive layer is not particularly limited, but is usually suitably 300 μm or less, and may be 200 μm or less, 150 μm or less, 100 μm or less, or 70 μm or less. The fact that the thickness of the adhesive layer is not too large can be advantageous from the viewpoint of avoiding cohesive failure of the adhesive layer due to expansion of the thermally expandable microspheres. In some embodiments, the thickness of the adhesive layer may be 60 μm or less, 50 μm or less, or 45 μm or less.

The thickness Ta of the adhesive layer is preferably larger than the average particle diameter D of the thermally expandable microspheres before heating. That is, it is preferable that Ta/D is greater than 1.0. From the viewpoint of the smoothness of the adhesive surface, in some embodiments, Ta/D is preferably 2.0 or more, may be 3.0 or more, and may be 4.0 or more. Furthermore, from the viewpoint of facilitating the peeling effect due to expansion of the heat-expandable microspheres, Ta/D is usually suitably 50 or less, preferably 20 or less, may be 15 or less, and may be 10 or less.

The thermally expandable microspheres preferably have an appropriate strength that does not rupture until the volume expansion rate is preferably 5 times or more, more preferably 7 times or more, and even more preferably 10 times or more. When using such heat-expandable microspheres, the adhesive force can be efficiently reduced by heat treatment.

The content ratio of the heat-expandable microspheres in the pressure-sensitive adhesive containing heat-expandable microspheres can be appropriately set depending on the desired adhesive strength reduction property, etc. The content ratio of heat-expandable microspheres is, for example, 1 part by weight to 150 parts by weight, preferably 10 parts by weight to 130 parts by weight, based on 100 parts by weight of the base polymer of the pressure-sensitive adhesive containing the heat-expandable microspheres. Preferably it is 20 parts by weight to 100 parts by weight.

When the adhesive constituting the surface of the second adhesive layer includes thermally expandable microspheres, the arithmetic mean roughness Ra of the surface of the second adhesive layer before the thermally expandable microspheres expand (i.e., before heating) is: Preferably it is 500 nm or less, more preferably 400 nm or less, and even more preferably 300 nm or less. Within this range, a pressure-sensitive adhesive sheet with excellent adhesion to the adherend on the second pressure-sensitive adhesive layer side can be obtained. In this way, the second adhesive layer having excellent surface smoothness is, for example, a pressure-sensitive adhesive layer formed by applying a pressure-sensitive adhesive composition containing heat-expandable microspheres to a release liner and drying it, with the thickness of the pressure-sensitive adhesive layer being in the above range, on a substrate. It can be obtained directly or by transferring it onto an intermediate layer (for example, an elastic intermediate layer) provided on the substrate.

When the second adhesive layer contains thermally expandable microspheres, the adhesive layer is composed of a base polymer having a dynamic storage modulus at 80°C in the range of 5 kPa to 1 MPa (more preferably 10 kPa to 0.8 MPa). It is preferable to include an adhesive. With such an adhesive layer, it is possible to form a pressure-sensitive adhesive sheet that has appropriate adhesiveness before heating and whose adhesive strength is prone to decrease by heating. Additionally, the dynamic storage modulus can be measured using a dynamic viscoelasticity measuring device (for example, product name “ARES” manufactured by Rheometrics) under measurement conditions of a frequency of 1 Hz and a temperature increase rate of 10°C/min.

<Method for manufacturing adhesive sheet>

The adhesive sheet of the present invention can be manufactured by any suitable method. The pressure-sensitive adhesive sheet of the present invention is, for example, a pressure-sensitive adhesive composition containing a pressure-sensitive adhesive composition (which may be a first pressure-sensitive adhesive layer, an A-layer or B-layer constituting the first pressure-sensitive adhesive layer, a second pressure-sensitive adhesive layer, etc.). A method of forming an adhesive layer by coating directly on or on an intermediate layer (e.g., B layer, elastic intermediate layer, etc.) provided on the substrate, or by applying the adhesive composition on any suitable peelable process material (e.g., release liner). It can be manufactured by forming a pressure-sensitive adhesive layer on the peelable process material, transferring the pressure-sensitive adhesive layer to a substrate or an intermediate layer on the substrate, or a combination thereof. The adhesive composition may be a solvent-based adhesive composition containing any suitable solvent.

When forming an adhesive layer containing heat-expandable microspheres, a composition containing heat-expandable microspheres, an adhesive, and any suitable solvent can be applied to a substrate to form the adhesive layer. Alternatively, after sprinkling heat-expandable microspheres on the adhesive coating layer, the heat-expandable microspheres may be embedded in the adhesive using a laminator or the like to form an adhesive layer containing the heat-expandable microspheres.

As a coating method for the adhesive and each composition, any suitable coating method can be adopted. For example, each layer can be formed by applying and then drying. Examples of the application method include a coating method using a multi-coater, die coater, gravure coater, applicator, etc. Drying methods include, for example, natural drying and heat drying. The heating temperature in the case of heat drying can be set to any appropriate temperature depending on the characteristics of the material to be dried.

Example

Below, several embodiments according to the invention are described, but it is not intended to limit the invention to what is shown in these embodiments. In addition, in the following description, “part” and “%” are based on weight unless otherwise specified.

<Evaluation method>

1. Indentation hardness

Using a nanoindenter, product name "Triboindenter TI-950" manufactured by Hysitron, the indentation hardness H1 and H2 were measured by the method described above.

2. Yesasung

Using a nanoindenter, product name "Triboindenter TI-950" manufactured by Hysitron, thread properties D1 and D2 were measured by the method described above.

3. Swelling test

Using a syringe (syringe diameter: 22 mm), 0.02 g of 4-t-butylphenylglycidyl ether (TBPGE) was dropped onto the surface of the first adhesive layer, and left to stand for 1 minute in an environment of 23°C and 50% RH. . After the TBPGE remaining on the surface of the adhesive layer is removed by sucking it into a vase, the thickness T1 [μm] of the adhesive layer at the location where the TBPGE was dropped is measured. From the thickness T0 [μm] of the pressure-sensitive adhesive layer at the relevant location before dropping TBPGE (initial thickness) and the thickness T1 [μm], the amount of change in thickness and the rate of change in thickness of the pressure-sensitive adhesive layer were calculated using the following equations.

Thickness change [㎛]=T1-T0

Thickness change rate [%]=((T1-T0)/T0)×100

4. TMA intrusion amount

Using a thermomechanical analysis device manufactured by TA Instruments, product name "TMA Q400", probe: needle penetration (cylindrical, tip diameter 1 mmΦ), nitrogen gas flow rate: 50.0 ml/min, indentation load: 0.01 N, measurement The amount of penetration from the surface of the first adhesive layer was measured under the conditions of atmospheric temperature: 23.0°C and press load time: 60 min. Measurements were performed on N = 5, and the average value of N = 3, which was obtained by subtracting the maximum and minimum values from these measured values, was taken as the TMA intrusion amount.

In addition, when the adhesive sheet has an adhesive layer (first adhesive layer) only on one side of the substrate and does not have a second adhesive layer on the opposite side (back side) of the substrate, for the adhesive sheet, the back side of the substrate For 100 parts of acrylic polymer of the standard adhesive layer (EA/2EHA/MMA/HEA=30/70/5/5 (weight ratio)) described above, 10 parts of tackifier, 2 parts of isocyanate crosslinker, and 30 parts of heat-expandable microspheres. After forming the pressure-sensitive adhesive layer (thickness: 45 μm), the amount of TMA penetration was measured.

5. Relaxation time

Approximately 100 mg of adhesive was collected by picking from the adhesive layer constituting layer A, and a T ₂ relaxation curve was obtained by pulse NMR measurement using this as a measurement sample. Fitting was performed using analysis software (TDNMR-A) using the above-mentioned equation (1), and the T ₂ relaxation time of the S component was obtained by analyzing the approximation to one component (α). In addition, all Wa was interpreted as 1. The shortest relaxation time calculated by the above analysis method was taken as the T ₂ relaxation time (T _{2 s} ) of the S component by pulse NMR of the A layer. Similarly, the T ₂ relaxation time (T _{2 s} ) of the S component was determined by pulse NMR of the B layer. In addition, the pulse NMR measurement was performed using a time domain NMR device manufactured by Bruker, device name "TD-NMR the minispec mq20", with a 90° pulse width of 2.1 μsec, repetition time of 1 second, integration count of 32, and measurement temperature of 30. It was performed by the solid echo method under conditions of ℃.

6. VS PET adhesion

The adhesive sheet was cut to a size of 20 mm in width and 140 mm in length, and the entire back side (the side opposite to the side on which the first adhesive layer was provided) was covered with double-sided adhesive tape (manufactured by Nitto Denko, product name “No. 531”). 」 was attached to a SUS304 plate using a 2 kg hand roller. Regarding the adhesive sheet configured to have a second adhesive layer on the back side of the base material, No. Instead of using 531 double-sided adhesive tape, the back side of the adhesive sheet was adhered to a SUS304 plate through the second adhesive layer.

In an environment of 23°C and 50% RH, a polyethylene terephthalate (PET) film (manufactured by Toray Corporation, product name “Lumirror S-10”) as an adherend is applied to the adhesive surface of the adhesive sheet whose back side is fixed to the SUS304 plate as described above. 」, thickness of 25 ㎛, width of 30 mm) were adhered by reciprocating a 2 kg roller once. After leaving it in the above-described environment for 30 minutes, the load when the PET film was peeled from the adhesive sheet was measured using a tensile tester under the conditions of a peeling angle of 180 degrees and a tensile speed of 300 mm/min. The average load was taken as the adhesive force of the adhesive sheet to PET. As the tensile tester, the product name "Autograph AG-120kN" manufactured by Shimadzu Seisakusho Co., Ltd. was used.

7. Anchoring force after heating

The adhesive sheet was cut to a size of 20 mm in width and 140 mm in length, and the entire back side (the side opposite to the side on which the first adhesive layer was provided) was covered with double-sided adhesive tape (manufactured by Nitto Denko, product name “No. 531”). 」 was attached to a SUS304 plate using a 2 kg hand roller. Regarding the adhesive sheet configured to have a second adhesive layer on the back side of the base material, No. Instead of using 531 double-sided adhesive tape, the adhesive sheet was adhered to a SUS304 plate through the second adhesive layer. This was kept in an environment of 150°C for 1 hour, and then left to stand in an environment of 23°C and 50% RH for 2 hours. Next, in an environment of 23°C and 50% RH, a notch with a depth from the surface of the first adhesive layer to the surface of the substrate was cut using a cutter knife, and a commercially available acrylic adhesive tape (manufactured by Nitto Denko, brand name: No. 315) was compressed by reciprocating a 2 kg roller and left to stand for 30 minutes. Thereafter, using the tensile tester, the load when peeling off the acrylic adhesive tape was measured under the conditions of a peeling angle of 180 degrees and a tensile speed of 50 mm/min, and the maximum load at that time was recorded as anchoring force after heating. did.

8. Great sealing resin adhesion

The adhesive sheet was cut to a size of 50 mm in width and 140 mm in length, and a template (opening size: rectangular shape with a width of 35 mm and a length of 90 mm, thickness: 564 μm) was bonded onto the first adhesive layer. A granular epoxy resin sealant (G730, manufactured by Sumitomo Bakelite) is sprayed into the mold so that the cured resin thickness is 0.3 mm, then a silicone-treated release liner is applied, and a “hydraulic molding machine” manufactured by Meisho Press is used. Using "NS-VPF-50", the sealing resin was sealed under the following conditions: temperature 145℃, molding time 600 seconds, pressurization condition 0.3MPa (square stage size with a side of 300mm), vacuum time 600 seconds, and vacuum degree -0.1MPa. was heat-molded on the first adhesive layer. This was heated at 150°C for 7 hours to cure the sealing resin, and then left to stand in an environment of 23°C and 50% RH for 2 hours. Then, the portion where the sealing resin and the first adhesive layer are in contact was formed into a width of 20 mm and a length of 88 mm. A sample for evaluation was produced by cutting it to size. After this evaluation sample was left in an environment of 23°C and 50% RH for 30 minutes, the adhesive sheet was peeled from the sealing resin using the above tensile tester under the conditions of a peeling angle of 180 degrees and a tensile speed of 300 mm/min. The load was measured, and the average load at that time was taken as the adhesive force of the adhesive sheet to the sealing resin.

9. Adhesive residue prevention

In the measurement of the sealing resin adhesive force, the presence or absence of adhesive residue on the sealing resin after peeling off the adhesive sheet was confirmed by visual observation. Based on the results, if adhesive residue is visible, the adhesive residue prevention property is rated as “P” (poor: poor adhesive residue prevention property), and if adhesive residue is not visible, the adhesive residue prevention property is rated as “G” (poor. Good: Adhesive residue prevention was judged to be good.

10. Mold flash evaluation

On the first adhesive surface of the adhesive sheet, a resin sealing process of a semiconductor chip (Si chip) was performed under the following conditions, and the performance of preventing penetration of the sealing resin (mold flash) into the interface between the chip and the sealing resin was evaluated. did.

Carrier: Carrier made of SUS (220㎜Φ)

Chip: Dummy chip with a step (dummy chip with a copper pad (pad target height 5.5 μm, mask: GNC-300 mm-G03-A-300S) on one side of a 7 mm × 7 mm × 400 μm thick silicon substrate. . Manufactured by Global Net Company)

Bonding device: FC3000W manufactured by Toray Engineering Co., Ltd.

Bonding conditions: pressing time 6 seconds, pressing pressure 10N, pressing temperature: 23℃

Sealing equipment: MS-150HP manufactured by Apik Yamada

Sealing resin: G730 manufactured by Sumitomo Bakelite Co., Ltd.

Preheating conditions: 130℃×30 seconds

Time from preheating to start of sealing: 1 hour

Sealing temperature: 145℃

Vacuum time: 5 seconds

Sealing time: 600 seconds

Clamping force: 3.6MPa

Sealing thickness: 600㎛

The sealing operation was performed in the following procedures.

1) The back side of the adhesive sheet was attached to a SUS carrier through an adhesive layer containing heat-expandable microspheres (attachment conditions: 23°C atmosphere, attachment cylinder pressure 0.1 MPa, attachment speed 0.5 m/min).

As the pressure-sensitive adhesive layer containing the heat-expandable microspheres, the second pressure-sensitive adhesive layer was used as is in a pressure-sensitive adhesive sheet having a configuration having a second pressure-sensitive adhesive layer containing heat-expandable microspheres on the back side of the substrate. For an adhesive sheet configured not to have a second adhesive layer on the back side of the substrate, a layer of the above-described standard adhesive layer (heat-expandable microspheres (manufactured by Matsumoto Yushi Seiyaku Co., Ltd., product name) per 100 parts of acrylic polymer) is applied to the back side of the substrate. A pressure-sensitive adhesive layer containing 30 parts (45 μm thick) of “Matsumoto Micro Spare F-190D”) was formed, and the back side of the pressure-sensitive adhesive sheet was fixed to a SUS carrier through the standard pressure-sensitive adhesive layer.

2) Using the bonding device, a total of 25 dummy chips with the above steps are placed on the first adhesive layer of the adhesive sheet fixed to the SUS carrier, along eight radial straight lines with a central angle of 45 degrees, from the center to the outer periphery. It was arranged so that the gap gradually widened accordingly. The orientation of the chip was such that the step surface (pad formation surface) of the chip faced the first adhesive layer.

3) The SUS carrier with a dummy chip having a step placed on the first adhesive layer of the adhesive sheet was preheated under predetermined conditions.

4) After preheating, the chip was left to stand in an environment of 23° C. and 50% RH for 1 hour, and then a predetermined sealing resin was evenly sprayed by hand on the dummy chip and sealed under the predetermined sealing equipment and sealing conditions.

5) The obtained laminate was heated at 150°C for 4 hours to cure the sealing resin.

6) The heat-cured laminate is left in an environment of 23°C and 50% RH for 5 days, and then heated on a hot plate to expand the heat-expandable microspheres in the adhesive layer that fixes the adhesive sheet to the SUS carrier, thereby forming the above-described lamination. The SUS carrier was separated from the sieve.

7) The adhesive sheet was peeled from the laminate after the SUS carrier was separated, and a structure consisting of a sealing resin and a dummy chip having a step was obtained.

Regarding the structure, the surface in contact with the first adhesive surface was observed with a laser confocal microscope (OLS-4000 manufactured by OLYMPUS) to confirm whether the sealing resin had penetrated onto the dummy chip having a step. When adhesive residues (adhesive residues) etc. were confirmed on the surface, the residues were removed using toluene and then observed. As a result, if penetration of the sealing resin was observed in any of the dummy chips, it was classified as “P” (Poor: insufficient mold flash prevention), and if invasion of the sealing resin was not visible in any of the dummy chips, it was classified as “G” (Good: Mold flash prevention was judged to be good).

11. Standoff evaluation

On the first adhesive surface of the adhesive sheet, the resin of the semiconductor chip (Si chip) was evaluated in the same manner as the mold flash evaluation described above except that a Si mirror chip (7 mm × 7 mm × 400 μm thick) was used as the semiconductor chip (Si chip). A sealing process was performed, and a structure consisting of a sealing resin and a Si mirror chip was obtained.

For this structure, the surface in contact with the first adhesive surface was observed with a laser confocal microscope (OLS-4000 manufactured by OLYMPUS), and the Si chip disposed in the center was examined to determine the Si chip and the Si chip on the surface. The height of the step (stand-off height) at the interface of the sealing resin was measured. When adhesive residues (adhesive residues) etc. were confirmed on the surface, measurements were performed after removing the residues using toluene. As a result, when the standoff height was less than 3.3㎛, it was judged as “G” (Good: standoff was well suppressed), and when it was 3.3㎛ or more, it was judged as “P” (Poor: standoff was insufficiently suppressed). .

<Example 1>

To a toluene solution containing 100 parts of Polymer P1 (2-ethylhexyl acrylate (2EHA)/acrylic acid (AA) = 95/5 (weight ratio), an acrylic polymer composed of monomer components, SP value 19.3), an epoxy-based crosslinking agent (Mitsubishi Gas) was added. 5 parts (trade name: "Tetrad C", manufactured by Kagaku Corporation) and toluene for dilution (total amount of 100 parts) were added and mixed to prepare adhesive composition 1a. This adhesive composition 1a was subjected to a peeling process on a release film R1 (manufactured by Toray Film Kako, brand name "Cerafil MDAR", thickness 38 ㎛) made of polyethylene terephthalate (PET) on one side of which was subjected to a release treatment with a silicone-based release treatment agent. By applying it to the surface and drying it, an adhesive layer 1A (thickness L1 = 10㎛) was formed on the release film R1.

Pressure-sensitive adhesive composition 1b was prepared in the same manner as preparation of adhesive composition 1a, except that 5 parts of the epoxy-based crosslinking agent were changed to 3 parts of isocyanate-based crosslinking agent (manufactured by Tosoh Corporation, brand name “Coronate L”). This adhesive composition 1b was applied to one side of a PET film (manufactured by Toray Corporation, brand name “Lumiror S10”, thickness 38 μm) as a substrate and dried to form an adhesive layer 1B (thickness L2 = 10 μm) on one side of the substrate. formed.

By bonding the adhesive surface of the adhesive layer 1A formed on the release film R1 to the adhesive surface of the adhesive layer 1B, a first adhesive layer consisting of the adhesive layer 1B and the adhesive layer 1A is disposed on one side of the substrate, forming an adhesive sheet (base material/ A pressure-sensitive adhesive sheet having the structure of pressure-sensitive adhesive layer 1B (layer B)/pressure-sensitive adhesive layer 1A (layer A) was obtained.

<Example 2>

An adhesive sheet having the structure of base material/adhesive layer 2B (layer B)/adhesive layer 2A (layer A) in the same manner as in Example 1 except that the amount of crosslinking agent used and the thickness of layer A and layer B were as shown in Table 1. got it

<Example 3>

In a toluene solution containing 100 parts of polymer P2 (an acrylic polymer composed of monomer components of n-butyl acrylate (BA)/ethyl acrylate (EA)/AA=50/50/5 (weight ratio), SP value 19.6), epoxy-based 5 parts of a crosslinking agent (manufactured by Mitsubishi Gas Chemical Company, brand name "Tetrad C") and toluene for dilution (total amount of 100 parts) were added and mixed to prepare adhesive composition 3a. This adhesive composition 3a was applied to the release treatment surface of the release film R1 and dried, thereby forming an adhesive layer 3A (thickness L1 = 5 μm) on the release film R1.

Pressure-sensitive adhesive composition 3b was prepared in the same manner as the preparation of adhesive composition 3a, except that 5 parts of the epoxy-based crosslinking agent were changed to 3 parts of the isocyanate-based crosslinking agent (manufactured by Tosoh Corporation, brand name “Coronate L”). This adhesive composition 3b was applied to one side of a PET film (manufactured by Toray Corporation, brand name "Lumirror S10", thickness 38 μm) as a substrate and dried, thereby forming an adhesive layer 3B (thickness L2 = 35 μm) on one side of the substrate. formed.

By bonding the adhesive surface of the adhesive layer 3A formed on the release film R1 to the adhesive surface of the adhesive layer 3B, a pressure-sensitive adhesive sheet having the structure of base material/adhesive layer 3B (layer B)/adhesive layer 3A (layer A) was obtained.

<Example 4>

In the same manner as in Example 3, except that the thicknesses of the A layer and B layer were as shown in Table 1, an adhesive sheet having the structure of base material/adhesive layer 4B (B layer)/adhesive layer 4A (A layer) was obtained.

<Example 5>

Polymer P3 (acrylic polymer composed of monomer components of EA/2EHA/methyl methacrylate (MMA)/2-hydroxyethyl acrylate (HEA)=30/70/5/4 (weight ratio). SP value 20.7) 100 parts A toluene solution containing 30 parts of heat-expandable microspheres (manufactured by Matsumoto Yushi Seiyaku Corporation, brand name "Matsumoto Micro Spare F-190D"), 1.4 parts of an isocyanate-based crosslinking agent (manufactured by Tosoh Corporation, brand name "Coronate L"), 10 parts of a tackifier (manufactured by Yasuhara Chemical, brand name "Mighty Ace G125") and toluene for dilution (total amount of 100 parts) were added and mixed to prepare adhesive composition 5c. This adhesive composition 5c was applied to the peeling treated surface of the peeling film R1 and dried, thereby forming an adhesive layer 5C (thickness of 45 μm) on the peeling film R1.

By bonding the adhesive surface of the adhesive layer 5C formed on the release film R1 to the back of the substrate of the adhesive sheet according to Example 4, adhesive layer 5C (second adhesive layer) / base material / adhesive layer 4B (layer B) / adhesive layer 4A A double-sided adhesive sheet having the structure (A layer) was obtained.

<Example 6>

To a toluene solution containing 100 parts of polymer P3, 1.5 parts of an isocyanate-based crosslinking agent (manufactured by Tosoh Corporation, brand name “Coronate L”), and 10 parts of a tackifier (manufactured by Yasuhara Chemical Company, brand name “Mighty Ace G125”) , toluene for dilution (a total amount of 100 parts) was added and mixed, and adhesive composition 6a was prepared. This adhesive composition 6c was applied to the peeling treated surface of the peeling film R1 and dried, thereby forming an adhesive layer 6A (thickness of 30 μm) on the peeling film R1.

To a toluene solution containing 100 parts of polymer P3, 1 part of an isocyanate-based crosslinking agent (manufactured by Tosoh Corporation, brand name "Coronate L") and toluene for dilution (total amount of 100 parts) were added and mixed, and adhesive composition 6b was prepared. It was prepared. This adhesive composition 6b was applied to one side of a PET film (manufactured by Toray Corporation, brand name "Lumiror S10", thickness 38 μm) as a substrate and dried, thereby forming an adhesive layer 6B (thickness L2 = 20 μm) on one side of the substrate. formed.

By bonding the adhesive surface of the adhesive layer 6A formed on the release film R1 to the adhesive surface of the adhesive layer 6B, a pressure-sensitive adhesive sheet having the structure of base material/adhesive layer 6B (layer B)/adhesive layer 6A (layer A) was obtained.

<Example 7>

Polymer P4 (an acrylic polymer composed of monomer components of 2EHA/acryloyl morpholine (ACMO)/HEA=75/25/22 (molar ratio)) is mixed with 11 moles of 2-isocyanatoethylmethane relative to 22 moles of HEA. A toluene solution containing 100 parts of acrylate (Karenz MOI: an acrylic polymer obtained by modifying Showa Denko), 5 parts of an isocyanate-based crosslinking agent (manufactured by Tosoh, brand name "Coronate L"), and a UV-curable oligomer. Add and mix 10 parts of photoinitiator (manufactured by Toa Gosei, brand name "Aronix M321"), 3 parts of photoinitiator (manufactured by IGM Resins, brand name "Omnirad 651"), and ethyl acetate for dilution to prepare adhesive composition 7a. did. This adhesive composition 7a was applied to the release treatment surface of release film R1 and dried to form an adhesive layer 7A (thickness L1 = 5 μm) on the release film R1.

To a toluene solution containing 100 parts of polymer P2, 1 part of an isocyanate-based crosslinking agent (manufactured by Tosoh Corporation, brand name “Coronate L”), 10 parts of UV-curable oligomer (manufactured by Toa Kosei Corporation, brand name “Aronix M321”), 3 parts of photoinitiator (manufactured by IGM Resins, brand name "Omnirad 651") and ethyl acetate for dilution were added and mixed to prepare adhesive composition 7b. This adhesive composition 7b was applied to one side of a PET film (manufactured by Toray Co., Ltd., brand name "Lumiror S10", thickness 38 μm) as a substrate and dried, thereby forming an adhesive layer 7B (thickness L2 = 150 μm) on one side of the substrate. formed.

By bonding the adhesive surface of the adhesive layer 7A formed on the release film R1 to the adhesive surface of the adhesive layer 7B, a pressure-sensitive adhesive sheet having the structure of base material/adhesive layer 7B (layer B)/adhesive layer 7A (layer A) was obtained.

The obtained adhesive sheet was evaluated by the method described above. The results are shown in Table 1. In addition, in the measurement of the anchoring force after heating, all peeling progressed at the interface between the acrylic adhesive tape and the adhesive surface of the measurement object, and no anchoring destruction was observed between the adhesive surface and the base material (PET film).

As shown in Table 1, the adhesive sheets of Examples 1 to 5 having an indentation hardness H1 of 0.10 MPa to 0.50 MPa and an indentation hardness H2 of 0.001 MPa to 0.090 MPa have good mold flash prevention properties and prevent adhesive residue. The quality was also good.

Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes to the specific examples illustrated above.

1: Semiconductor chip
2: Sealing resin
10: Base (base film)
20: Adhesive layer (first adhesive layer)
22: A floor
24: B floor
30: Second adhesive layer
100, 200, 300: Adhesive sheet
A: Measuring position A
B: Measuring position B

Claims (19)

An adhesive sheet comprising a base material and an adhesive layer disposed on at least one side of the base material,
In measuring the indentation hardness using a nanoindenter, the indentation hardness H1 of the surface of the adhesive layer is 0.10 MPa or more and 0.50 MPa or less, and the distance from the substrate to the surface of the adhesive layer in the cross section of the adhesive sheet is 4 μm. An adhesive sheet with an indentation hardness H2 measured at the location of 0.001 MPa or more and 0.090 MPa or less. According to paragraph 1,
An adhesive sheet wherein the ratio (H2/H1) of the press-fit hardness H2 [MPa] to the press-fit hardness H1 [MPa] is 0.002 or more and 0.90 or less. According to claim 1 or 2,
In the evaluation of the stringiness by a nanoindenter, the stringiness D1 of the surface of the pressure-sensitive adhesive layer is 50 nm or more and 500 nm or less, and the distance from the base material to the surface of the pressure-sensitive adhesive layer in the cross section of the pressure-sensitive adhesive sheet is 4 μm. An adhesive sheet whose threadability D2 measured at a position is 150 nm or more and 1000 nm or less. According to paragraph 3,
An adhesive sheet, wherein the ratio (D2/D1) of the threadiness D2 [nm] to the threadness D1 [nm] is 0.3 or more and 20.0 or less. According to any one of claims 1 to 4,
The difference between the thickness T1 [μm] of the pressure-sensitive adhesive layer after dropping 4-t-butylphenylglycidyl ether on the surface of the pressure-sensitive adhesive layer and allowing it to stand for 1 minute and the initial thickness T0 [μm] of the pressure-sensitive adhesive layer (T1 -T0) is 20㎛ or less, an adhesive sheet. According to any one of claims 1 to 5,
An adhesive sheet wherein the penetration amount of the needle penetration probe from the surface of the adhesive layer is 3.50 μm or more and 20.0 μm or less, measured using a thermomechanical analysis device under the conditions of a measurement environmental temperature of 23°C, an indentation load of 0.01 N, and an indentation load time of 60 minutes. According to any one of claims 1 to 6,
An adhesive sheet wherein the thickness of the adhesive layer is 5 μm or more and 110 μm or less. According to any one of claims 1 to 7,
An adhesive sheet wherein the substrate is a substrate film made of a resin material with a glass transition temperature of 25°C or higher. According to any one of claims 1 to 8,
An adhesive sheet having an adhesive force to a polyethylene terephthalate film of 0.05 N/20 mm or more and 1.00 N/20 mm or less. According to any one of claims 1 to 9,
An adhesive sheet in which the anchoring force of the adhesive layer to the substrate, measured at 23°C after heating the adhesive sheet at 150°C for 1 hour, is 4.00 N/20 mm or more. According to any one of claims 1 to 10,
An adhesive sheet wherein the adhesive constituting at least the surface of the adhesive layer is an acrylic adhesive using an acrylic polymer as a base polymer. According to clause 11,
An adhesive sheet wherein the SP value of the acrylic polymer is 18.0 to 20.0. According to any one of claims 1 to 12,
The pressure-sensitive adhesive layer includes a layer A constituting the surface of the pressure-sensitive adhesive layer, and a layer B disposed between the layer A and the substrate and adjacent to the substrate. According to clause 13,
An adhesive sheet wherein the thickness L1 of the layer A is 1 μm or more and 10 μm or less. According to claim 13 or 14,
An adhesive sheet wherein the thickness L2 of the B layer is 4 μm or more and 100 μm or less. According to any one of claims 13 to 15,
An adhesive sheet wherein the ratio (L2/L1) of the thickness L2 [μm] of the layer B to the thickness L1 [μm] of the layer A is 1.0 to 100.0. According to any one of claims 13 to 16,
An adhesive sheet wherein the T ₂ relaxation time (T _2s ) of the S component by pulse NMR of the A layer is 45 μsec or less, and the T ₂ relaxation time (T _2s ) of the S component by pulse NMR of the B layer is longer than 45 μsec. . According to any one of claims 13 to 17,
An adhesive sheet wherein the A layer is crosslinked with an epoxy-based crosslinking agent, and the B layer is crosslinked with an isocyanate-based crosslinking agent. According to any one of claims 1 to 18,
comprising the substrate, the adhesive layer disposed on one side of the substrate, and a second adhesive layer disposed on an opposite side of the substrate to the adhesive layer,
An adhesive sheet wherein at least the surface of the second adhesive layer is made of an adhesive containing thermally expandable microspheres.