CN117642476A

CN117642476A - Pressure-sensitive adhesive sheet

Info

Publication number: CN117642476A
Application number: CN202280049379.8A
Authority: CN
Inventors: 由藤拓三; 加藤和通; 中尾航大
Original assignee: Nitto Denko Corp
Current assignee: Nitto Denko Corp
Priority date: 2021-07-13
Filing date: 2022-06-30
Publication date: 2024-03-01
Also published as: KR20240032112A; DE112022002949T5; TW202338049A; WO2023286619A1; JPWO2023286619A1

Abstract

The invention provides an adhesive sheet, which has good balance and combines the inhibition of residual glue during peeling and good following property to the surface shape of an adherend. The invention provides an adhesive sheet, which comprises a base material and an adhesive layer arranged on at least one side of the base material. The pressure-sensitive adhesive sheet has a surface of the pressure-sensitive adhesive layer having an indentation hardness H1 of 0.10MPa or more and 0.50MPa or less, and has an indentation hardness H2 of 0.001MPa or more and 0.090MPa or less, as measured at a position at a distance of 4 [ mu ] m from the base material to the surface side of the pressure-sensitive adhesive layer in a cross section of the pressure-sensitive adhesive sheet.

Description

Pressure-sensitive adhesive sheet

Technical Field

The present invention relates to an adhesive sheet. The present application claims priority based on japanese patent application No. 2021-115926 filed on day 2021, 7 and 13, the entire contents of which are incorporated herein by reference.

Background

In the manufacture of a semiconductor device including a semiconductor chip, the semiconductor chip may be sealed with a resin to prevent damage to the semiconductor chip, expansion of metal wiring, and the like. In the resin sealing step, the resin sealing of the semiconductor chip may be performed above the adhesive sheet from the viewpoint of workability and the like. For example, a plurality of semiconductor chips are arranged on an adhesive layer of an adhesive sheet as a temporary fixing material, and the semiconductor chips are sealed on the adhesive layer at one time. Thereafter, in a specific subsequent step, the adhesive sheet is peeled from the structure containing the sealing resin and the semiconductor chip.

Prior art literature

Patent literature

Patent document 1: japanese patent application laid-open No. 2001-308116

Patent document 2: japanese patent application laid-open No. 2001-313350

Disclosure of Invention

Problems to be solved by the invention

In the pressure-sensitive adhesive sheet used in the above-described step, it is required that, when the pressure-sensitive adhesive sheet is peeled from a structure containing a sealing resin and a semiconductor chip, no residual glue (adhesive residue) is generated on the structure. In order to suppress the residual glue, the adhesive layer on which the semiconductor chip is disposed in the adhesive sheet is generally formed of an adhesive having a very high elastic modulus. However, there may be a level difference on the surface of the semiconductor chip due to a metal wiring or the like formed in advance, and as a result, if the adhesive layer is made to have a high elastic modulus, the adhesive cannot sufficiently adhere to the level difference on the surface of the chip, and a problem that the sealing resin intrudes into the interface between the chip and the adhesive may occur.

The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide an adhesive sheet which combines, with good balance, suppression of residual glue at the time of peeling and good followability to the surface shape of an adherend.

Solution for solving the problem

The pressure-sensitive adhesive sheet provided by this specification includes a base material and a pressure-sensitive adhesive layer disposed on at least one side of the base material. In the pressure-sensitive adhesive sheet, the indentation hardness H1 of the surface of the pressure-sensitive adhesive layer is 0.10MPa or more and 0.50MPa or less, and the indentation hardness H2 measured at a position at a distance of 4 [ mu ] m from the base material to the surface side of the pressure-sensitive adhesive layer in the cross section of the pressure-sensitive adhesive sheet is 0.001MPa or more and 0.090MPa or less, in indentation hardness measurement using a nanoindenter. The indentation hardness H1 measured by using the surface of the pressure-sensitive adhesive layer as a measurement position (hereinafter, also referred to as "measurement position a") is 0.10MPa or more, whereby the residual glue at the time of peeling can be suppressed. In addition, the following property to the surface shape of the adherend can be improved by setting the indentation hardness H2 measured at a position (hereinafter, also referred to as "measurement position B") inside the measurement position a (substrate side), specifically, at a position where the distance from the substrate to the surface side of the pressure-sensitive adhesive layer is 4 μm in the cross section of the pressure-sensitive adhesive sheet to 0.090MPa or less. Therefore, the pressure-sensitive adhesive sheet having the indentation hardness H1, H2 in the above range can achieve both the suppression of the residual adhesive at the time of peeling and the good follow-up property to the surface shape of the adherend with good balance.

In some embodiments, the ratio (H2/H1) of the indentation hardness H2[ MPa ] to the indentation hardness H1[ MPa ] is 0.002 to 0.90. The pressure-sensitive adhesive sheet having the indentation hardness H2 at the measurement position B (inside) of 0.90 times or less the indentation hardness H1 at the measurement position a (surface) can suitably achieve both the suppression of the residual glue and the surface shape following property.

In some embodiments, in the stringiness evaluation using a nanoindenter, the stringiness D1 of the surface of the adhesive layer is 50nm to 500 nm. The stringiness D1 at the surface of the adhesive layer (measurement position A) of 500nm or less is advantageous from the viewpoint of inhibiting the residual adhesive. In the stringiness evaluation, the stringiness D2 measured at a position (measurement position B) having a distance of 4 μm from the base material to the surface side of the pressure-sensitive adhesive layer in the cross section of the pressure-sensitive adhesive sheet is preferably 150nm to 1000 nm. The pressure-sensitive adhesive layer having stringiness D2 in the above range can easily achieve good surface shape following property.

In some embodiments, the ratio (D2/D1) of the stringiness D2 nm to the stringiness D1 nm is 0.3 to 20.0. An adhesive sheet having a ratio (D2/D1) in the above range is easy to suitably achieve both of inhibition of the residual adhesive and surface shape following property.

In some embodiments, the difference (T1-T0; hereinafter also referred to as "thickness variation") between the thickness T1[ mu ] m of the adhesive layer and the initial thickness T0[ mu ] m of the adhesive layer after dropping 4-T-butylphenyl glycidyl ether onto the surface of the adhesive layer and leaving it for 1 minute is 20 [ mu ] m or less. An adhesive sheet having an adhesive layer with a small thickness variation is preferable because it is less likely to cause a step (standing off) between the semiconductor chip and the sealing resin in a use mode in which a step of disposing the semiconductor chip on the adhesive layer and sealing the semiconductor chip with the resin is performed, for example.

In some embodiments, the penetration probe is submerged from the surface of the pressure-sensitive adhesive layer by a thermal mechanical analyzer (Thermomechanical Analyzer; TMA) at a temperature of 23 ℃ under a pressure load of 0.01N for 60 minutes, and the penetration probe is submerged from the surface of the pressure-sensitive adhesive layer by a time of 3.50 μm to 20.0 μm. According to the adhesive sheet having the sagging amount in the above-described range, for example, in a use mode of performing a step of disposing a semiconductor chip on the adhesive layer and sealing the semiconductor chip with a resin, the following property of the surface shape of the semiconductor chip and the suppression of the embedding of the semiconductor chip into the adhesive sheet can be simultaneously achieved with good balance.

In some embodiments of the adhesive sheet disclosed herein, the adhesive layer has a thickness of 5 μm or more and 110 μm or less. The pressure-sensitive adhesive layer having the above thickness can suitably exhibit the effect of having the measurement position a and the measurement position B different from each other.

In some embodiments, the substrate is a substrate film made of a resin material having a glass transition temperature (Tg) of 25 ℃ or higher. In a use mode of the adhesive sheet having the above-described configuration in which the adhesive layer is provided on the base film, for example, in a step of disposing the semiconductor chip on the adhesive layer of the adhesive sheet and sealing the semiconductor chip with a resin, even if heating is performed in this step, the embedding of the semiconductor chip into the adhesive sheet can be suppressed, and a step (stand off) between the semiconductor chip and the sealing resin can be suppressed.

Some embodiments have an adhesive force of 0.05N/20mm or more and 1.00N/20mm or less to a polyethylene terephthalate (PET) film. If the amount is within this range, it is preferable to fix the adherend (for example, semiconductor chip) and to suppress the load applied to the adherend when the pressure-sensitive adhesive sheet is peeled off.

In some embodiments, the adhesive layer has an anchoring force of 4.00N/20mm or more to the substrate measured at 23 ℃ after heating the adhesive sheet at 150 ℃ for 1 hour. In a use mode of the adhesive sheet exhibiting the above-mentioned anchoring force, for example, in a step of disposing a semiconductor chip on an adhesive layer of the adhesive sheet and sealing the semiconductor chip with a resin, the adhesive sheet is preferably used because the adhesive sheet can suppress the residual adhesive in a subsequent peeling step even if heated in the step.

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

In some embodiments, the acrylic polymer has an SP value of 18.0 to 20.0. By forming the adhesive surface with an acrylic adhesive containing an acrylic polymer having an SP value in the above range as a base polymer, the indentation hardness H1 in the above range can be easily achieved, and, for example, in a use mode in which a step of disposing a semiconductor chip on the adhesive surface and sealing the semiconductor chip with a resin is performed, it is easy to suppress the adhesive force to the sealing resin from becoming too high.

In some embodiments of the adhesive sheet disclosed herein, the adhesive layer includes: a layer a constituting a surface of the pressure-sensitive adhesive layer, and a layer B disposed between the layer a and the base material and adjacent to the base material. The pressure-sensitive adhesive sheet disclosed herein can be preferably implemented so as to have a pressure-sensitive adhesive layer having a structure including an a layer (surface layer) and a B layer (primer layer).

The thickness L1 of the layer A is preferably 1 μm or more and 10 μm or less, for example. The layer a having such a thickness can easily and suitably suppress the residual glue and can favorably exhibit the following property of the surface shape.

The thickness L2 of the B layer is preferably, for example, 4 μm or more and 100 μm or less. The B layer having such a thickness can easily and suitably suppress the residual glue and can suitably satisfy the following property of the surface shape.

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

In some embodiments, T of the S component obtained by pulse NMR of the A layer ₂ Relaxation time (T) _2s ) T of S component obtained by pulse NMR of the B layer of 45 musec or less ₂ Relaxation time (T) _2s ) Longer than 45 musec. According to the method having a characteristic of satisfying the above relaxation time (T _2s ) The adhesive sheet of the adhesive layers A and B of (C) is easy to suitably achieve both of the suppression of the transfer of components between the adhesive layer and the sealing resin and the surface shape following property.

In some embodiments, the layer a is crosslinked by an epoxy-based crosslinking agent, and the layer B is crosslinked by an isocyanate-based crosslinking agent. The pressure-sensitive adhesive sheet disclosed herein can be preferably implemented so as to have a pressure-sensitive adhesive layer having such a configuration.

In some embodiments of the adhesive sheet disclosed herein, the adhesive sheet includes the base material, the adhesive layer (1 st adhesive layer) disposed on one side of the base material, and the 2 nd adhesive layer disposed on the opposite side of the base material from the adhesive layer. The pressure-sensitive adhesive sheet having such a structure can be fixed to an appropriate carrier by using the 2 nd pressure-sensitive adhesive layer, and the resin sealing step on the 1 st pressure-sensitive adhesive layer is performed in this state, so that the usability is good.

In some embodiments, at least the surface of the 2 nd adhesive layer is composed of an adhesive containing thermally expandable microspheres. The pressure-sensitive adhesive sheet of this embodiment is preferable because the heat-expandable microspheres are expanded by heating at an appropriate timing as needed, and the bonding between the 2 nd pressure-sensitive adhesive layer and the adherend can be easily released.

The invention claimed in the present application may be embodied by appropriately combining the elements described in the present specification.

Drawings

Fig. 1 is a cross-sectional view schematically showing the structure of an adhesive sheet according to an embodiment.

Fig. 2 (i) to (iv) are explanatory views showing an example of a semiconductor chip resin sealing process using the adhesive sheet shown in fig. 1.

Fig. 3 is a cross-sectional view schematically showing the structure of an adhesive sheet according to another embodiment.

Fig. 4 is a cross-sectional view schematically showing the structure of an adhesive sheet according to another embodiment.

Fig. 5 is a schematic diagram for explaining definition of stringiness.

Detailed Description

Hereinafter, preferred embodiments of the present invention will be described. Matters necessary for the practice of the present invention other than those specifically mentioned in the present specification can be understood by those skilled in the art based on the teachings of the present specification regarding the practice of the present invention and technical knowledge at the time of application. The present invention can be implemented based on the disclosure of the present specification and common technical knowledge in the field.

In the following drawings, members and portions that perform the same function may be denoted by the same reference numerals, and overlapping description may be omitted or simplified. The embodiments described in the drawings are schematically illustrated for the sake of clarity of explanation of the present invention, and do not necessarily accurately represent the dimensions or scale of the product actually provided.

In this specification, the "base polymer" of the adhesive means the main component of the rubbery polymer contained in the adhesive, and is not limited in any way except for this. The rubbery polymer is a polymer exhibiting rubber elasticity in a temperature range around room temperature. In this specification, unless otherwise specified, "main component" means a component contained in an amount exceeding 50% by weight.

In addition, in this specification, the "acrylic polymer" refers to a polymer containing a monomer unit derived from a monomer having at least 1 (meth) acryloyl group in 1 molecule as a monomer unit constituting the polymer. Hereinafter, a monomer having at least 1 (meth) acryloyl group in 1 molecule is also referred to as an "acrylic monomer". Thus, an acrylic polymer in this specification is defined as a polymer comprising monomer units derived from an acrylic monomer. Typical examples of the acrylic polymer include: the proportion of acrylic monomer in 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) of the polymer. Hereinafter, the monomer used for the synthesis of the polymer is also referred to as a monomer component constituting the polymer.

In this specification, "(meth) acryl" means an acryl group and a methacryl group. Similarly, "(meth) acrylate" is intended to mean both acrylate and methacrylate, and "(meth) acrylic acid" is intended to mean both acrylic acid and methacrylic acid. Therefore, the term "acrylic monomer" as used herein may include both a monomer having an acryl group (acrylic monomer) and a monomer having a methacryl group (methacrylic monomer).

< summary of adhesive sheet >

The adhesive sheet disclosed herein can be suitably used as a temporary fixing material when resin-sealing a semiconductor chip. More specifically, in the adhesive sheet of the present invention, when semiconductor chips are arranged on an adhesive layer of the adhesive sheet, the semiconductor chips are covered with a sealing resin (typically, an epoxy resin), and the semiconductor chips are resin-sealed by curing the sealing resin, the adhesive sheet of the present invention is useful as a temporary fixing material for the semiconductor chips. When a predetermined subsequent step (for example, back grinding of the sealing resin, patterning, bumping, and dicing (cutting) is performed after the sealing of the semiconductor chip with the resin), the adhesive sheet may be peeled from the structure including the sealing resin and the semiconductor chip. The epoxy equivalent of the sealing resin is, for example, 50g/eq to 500g/eq.

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

The adhesive sheet 100 can be used for resin sealing of a semiconductor chip as shown in fig. 2, for example. First, a plurality of semiconductor chips 1 are bonded to an adhesive layer (1 st adhesive layer) of the adhesive sheet 100 (step (i)). Next, the semiconductor chip 1 is covered with the prepreg 2 'of the sealing resin (step (ii)), and the semiconductor chip 1 is sealed with the sealing resin 2 by curing the prepreg 2' (step (iii)). The above-mentioned prepreg 2' can be formed, for example, using a composition comprising a naphthalene type 2-functional epoxy resin (epoxy equivalent: 144). Thereafter, when a predetermined subsequent step is performed, the pressure-sensitive 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 is such that the indentation hardness H1 at the measurement site a is 0.10MPa or more, thereby making it less likely that the structural body 50 will have adhesive residues in the step (iv) shown in fig. 2. In addition, since the indentation hardness H2 in the adhesive layer, specifically at the measurement position B, is 0.09MPa or less, the adhesive layer can satisfactorily follow the surface shape of the adherend (for example, a level difference due to a metal wiring or the like possibly present on the adhesive layer side surface of the semiconductor chip 1), and 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 from occurring.

Fig. 3 is a schematic cross-sectional view showing another embodiment of the pressure-sensitive adhesive sheet disclosed herein. In the pressure-sensitive adhesive sheet 200, the pressure-sensitive adhesive layer 20 in the pressure-sensitive adhesive sheet 100 shown in fig. 1 includes an a layer 22 constituting a surface (pressure-sensitive adhesive surface) of the pressure-sensitive adhesive layer 20, and a B layer 24 disposed between the a layer 22 and the substrate 10 and adjacent to the substrate 10. According to the adhesive layer 20 having such a structure, the indentation hardness H1 at the measurement position a and the indentation hardness H2 at the measurement position B can be easily adjusted to appropriate ranges, respectively. The pressure-sensitive adhesive sheet disclosed herein can be preferably implemented such 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.

Fig. 4 is a schematic cross-sectional view showing another embodiment of the pressure-sensitive adhesive sheet disclosed herein. The pressure-sensitive adhesive sheet 300 further includes the 2 nd pressure-sensitive adhesive layer 30 on the back surface side (opposite side to the pressure-sensitive adhesive layer 20) of the base material 10. Specifically, the pressure-sensitive adhesive sheet 300 includes, in order, the pressure-sensitive adhesive layer 20, the base material 10, and the 2 nd pressure-sensitive adhesive layer 30. By providing the 2 nd pressure-sensitive adhesive layer 30, the 2 nd pressure-sensitive adhesive layer 30 side can be bonded to the carrier when the carrier is resin-sealed, and the pressure-sensitive adhesive sheet 300 can be easily fixed to the carrier.

In some embodiments, at least the surface of the 2 nd adhesive layer is comprised of an adhesive comprising thermally expandable microspheres. Such an adhesive layer containing thermally expandable microspheres can expand the thermally expandable microspheres by heating to a predetermined temperature or higher, thereby generating irregularities on the surface of the adhesive layer and reducing or eliminating the adhesive force. By constituting at least the surface of the 2 nd adhesive layer with an adhesive containing thermally expandable microspheres, a desired adhesion can be exhibited when the adhesive sheet is fixed (for example, fixed to a carrier) via the 2 nd adhesive layer, and the adhesion can be reduced or eliminated by heating when the adhesive sheet is peeled (for example, peeled from the carrier), thereby exhibiting a good peelability. An elastic intermediate layer (which may be an adhesive layer) containing no thermally expandable microspheres or a small content of thermally expandable microspheres may be disposed between the adhesive layer containing thermally expandable microspheres and the substrate.

(indentation hardness)

The indentation hardness H1 of the pressure-sensitive adhesive sheet disclosed herein is preferably 0.10MPa or more (for example, more than 0.10 MPa), and more preferably 0.12MPa or more, from the viewpoint of inhibition of the residual glue. In some embodiments, the indentation hardness H1 may be 0.15MPa or more, 0.18MPa or more, or 0.20MPa or more. In general, in a use method of a step of disposing a semiconductor chip on the adhesive layer and sealing the semiconductor chip with a resin, an adhesive layer having a high indentation hardness H1 is advantageous in terms of suppressing a level difference (standing off) that may occur at a boundary between the semiconductor chip and a sealing resin. The indentation hardness H1 is preferably 0.50MPa or less, more preferably 0.40MPa or less. In some embodiments, the indentation hardness H1 may be, for example, 0.30MPa or less, 0.28MPa or less, 0.25MPa or less, 0.23MPa or less, or 0.21MPa or less, from the viewpoint of easy expression of adhesion to the surface of the adherend or moderate tackiness in the surface of the adhesive layer.

The indentation hardness H2 of the pressure-sensitive adhesive sheet disclosed herein is preferably lower than the indentation hardness H1, and is preferably 0.090MPa or less from the viewpoint of improving the following property with respect to the surface shape of the adherend. In some embodiments, the indentation hardness H2 may be 0.080MPa or less, 0.060MPa or less, or 0.050MPa or less from the viewpoint of obtaining higher followability. The lower limit of the indentation hardness H2 may be, for example, 0.001MPa or more, and is not particularly limited. In some embodiments, the indentation hardness H2 is preferably 0.005MPa or more, more preferably 0.010MPa or more, and may be 0.030MPa or more, or 0.040MPa or more, or 0.050MPa or more, or 0.060MPa or more, in view of preventing cohesive failure in the adhesive layer.

The ratio (H2/H1) of the indentation hardness H2[ MPa ] to the indentation hardness H1[ MPa ] is, for example, preferably 0.90 or less, more preferably 0.70 or less, and may be 0.50 or less, or may be 0.40 or less, or may be 0.30 or less. The ratio (H2/H1) is preferably, for example, 0.002 or more, more preferably 0.005 or more, and still more preferably 0.01 or more. An adhesive sheet having the above ratio (H2/H1) in such a range is easy to achieve both of inhibition of the residual adhesive and surface shape following property with good balance.

(wiredrawing property)

In the pressure-sensitive adhesive sheet disclosed herein, the range of stringiness D1 at the measurement position A may be, for example, 800nm or less, and is not particularly limited. In some embodiments, from the viewpoint of improving the anti-blocking property, the stringiness D1 is preferably 500nm or less, more preferably 300nm or less, and may be 250nm or less, or 200nm or less, or 150nm or less. Further, from the viewpoint of exhibiting moderate tackiness on the surface of the pressure-sensitive adhesive layer, for example, it is easy to dispose a semiconductor chip on the surface of the pressure-sensitive adhesive layer, and the stringiness D1 is preferably 50nm or more, or may be 80nm or more, or may be 100nm or more, or may be 120nm or more.

In the pressure-sensitive adhesive sheet disclosed herein, the range of stringiness D2 at the measurement position B may be, for example, 100nm or more, and is not particularly limited, and in view of improving the following property to the surface shape of the adherend, the stringiness D2 is preferably 150nm or more, more preferably 200nm or more. In some embodiments, the stringiness D2 may be 300nm or more, 400nm or more, or 500nm or more. The stringiness D2 may be 2500nm or less, for example, and is preferably 1500nm or less, more preferably 1000nm or less, 800nm or less, or 600nm or less, from the viewpoint of preventing cohesive failure in the adhesive layer.

The ratio (D2/D1) of the stringiness D2 nm to the stringiness D1 nm may be, for example, 0.3 or more, or 0.5 or more, or 1.0 or more. In some embodiments, the ratio (D2/D1) is preferably more than 1.0 (e.g., 1.2 or more), and may be 2.5 or more, 3.5 or more, or 5.0 or more. The ratio (D2/D1) is, for example, preferably 20.0 or less, more preferably 15.0 or less, and preferably 10.0 or less, or 8.0 or less, or 7.0 or less, or 6.0 or less. An adhesive sheet having a ratio (D2/D1) within a range defined by a combination of any of the above upper and lower limits is easy to achieve both inhibition of residual glue and surface shape following property with good balance.

The indentation hardness H1, H2 and the stringiness D1, D2 were obtained by performing an operation of vertically pressing a indenter from the surface of a sample to a predetermined depth at a predetermined measurement position using a nanoindenter and then pulling out the indenter, and drawing a transition of a load (vertical axis) applied to the indenter at this time with respect to a displacement (horizontal axis) of the indenter with the surface of the sample as a reference, and obtaining a load (press-in) -unload (pull-out) curve obtained by the above. In the measurement of the indentation hardness H1 and the stringiness D1, the surface of the adhesive layer was set as the measurement position (measurement position a). In the measurement of the indentation hardness H2 and the stringiness D2, a position in the cross section of the pressure-sensitive adhesive sheet, at which the distance from the base material to the surface side of the pressure-sensitive adhesive layer was 4 μm, was set as a measurement position (measurement position B).

Regarding the indentation hardness [ MPa ], the maximum load (Pmax) [ μn ] of the load curve when the indenter is pressed to a predetermined depth can be divided by the contact projected area (a) of the indenter, that is, the following formula: indentation hardness [ MPa ] =pmax/a. The indentation hardness may be set to the above range by appropriately selecting the structure of the adhesive layer or the composition of the adhesive constituting the adhesive layer (for example, the composition of the base polymer, the degree of crosslinking, the kind of crosslinking agent, and the like).

Stringiness [ nm ] can be defined as: as schematically shown in fig. 5, the unloading curve has a displacement amount at which the negative displacement side becomes zero load. The stringiness can be set in 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 kind of crosslinking agent, and the like).

Specifically, indentation hardness and stringiness can be measured under the following conditions using a nanoindenter manufactured by Hysicron corporation, the product name "Triboindeter TI-950" or an equivalent thereof.

[ measurement conditions ]

Using a pressure head: berkovich diamond indenter

The measuring method comprises the following steps: single press-in assay

Measuring temperature: room temperature (25 ℃ C.)

Setting the pressing depth: at the measurement position A was 800nm,

1000nm at measurement position B

Press-in speed: 200 nm/sec

Extraction speed: 200 nm/sec

(swelling Property)

In some embodiments of the adhesive sheet disclosed herein, 4-T-butylphenyl glycidyl ether (TBPGE) is added dropwise to the surface of the adhesive layer and left to stand for 1 minute, whereby the difference (T1-T0) between the thickness T1[ mu ] of the adhesive layer and the initial thickness T0[ mu ] of the adhesive layer (1 st adhesive layer), that is, the thickness variation is 20 [ mu ] m or less. Regarding an adhesive sheet having an adhesive layer with a small amount of thickness variation due to swelling of TBPGE, for example, in a use system in which resin sealing of a semiconductor chip is performed on the adhesive layer, component transfer between the adhesive layer and the sealing resin tends to be suppressed, whereby a level difference (standing off) between the semiconductor chip and the sealing resin can be suppressed. From this viewpoint, in some embodiments, the thickness variation is preferably 15 μm or less, and more preferably 10 μm or less. The thickness variation is preferably 0 μm as the thickness variation approaches 0 (zero). In some embodiments, the thickness variation may be, for example, 0.1 μm or more, or 0.5 μm or more, or 1 μm or more, or 2 μm or more, or 3 μm or more, from the practical standpoint, such as balance with other characteristics and cost.

In some modes of the adhesive sheet disclosed herein, the thickness change rate of the adhesive layer after the TBPGE is dropped onto the adhesive layer surface of the adhesive sheet and left for 1 minute is preferably 160% or less, more preferably 150% or less. In the case of an adhesive sheet having an adhesive layer in which the rate of change in thickness due to swelling of TBPGE is suppressed, for example, in a use system in which resin sealing of a semiconductor chip is performed on the adhesive layer, the transfer of components between the adhesive layer and the sealing resin tends to be suppressed, and thus the level difference can be suppressed. From this viewpoint, in some embodiments, the thickness change rate may be 120% or less, 100% or less, 80% or less, or 60% or less, for example. The lower limit of the thickness change rate is not particularly limited as the thickness change rate is smaller. In some embodiments, the thickness change rate may be, for example, 5% or more, 10% or more, or 20% or more from the practical standpoint, such as balance with other characteristics and cost.

The thickness variation was determined as follows: a predetermined amount (0.02 g using a 22mm diameter syringe) of TBPGE was dropped onto the surface of the adhesive layer, and the adhesive layer was left to stand in an environment of 23 ℃ 50% rh for 1 minute, and the thickness T1 of the adhesive layer at the portion where TBPGE was dropped after the TBPGE remaining on the surface of the adhesive layer was erased and the thickness (initial thickness) T0 of the adhesive layer at the portion before TBPGE was dropped were obtained by the formula of T1 to T0. The thickness change rate can be obtained from the above-mentioned T0 and T1 by the formula (T1-T0)/T0. The thickness variation and the thickness variation rate can be set in the above ranges by appropriately selecting, for example, the composition of the base polymer (for example, acrylic polymer) of the a layer constituting at least the surface of the pressure-sensitive adhesive layer, the degree of crosslinking, the kind of crosslinking agent, and the like. For example, by setting 30 wt% or more (more preferably 40 wt% or more) of the monomer components constituting the acrylic polymer as an alkyl (meth) acrylate having an alkyl group having a relatively large number of carbons (for example, 4 or more, preferably 8 or more) at the ester end, an adhesive layer having a small thickness variation and/or thickness variation rate can be formed.

(TMA sinking amount)

In some aspects of the adhesive sheets disclosed herein, the adhesive sheet may have a sag of about 20.0 μm or less (e.g., about 1.00 μm or more and 20.0 μm or less) in an environment at 23 ℃ obtained using TMA. Here, "the amount of sagging in an environment of 23 ℃ obtained by using TMA for the adhesive sheet" (hereinafter, also referred to as "TMA sagging") means the amount of sagging after 60 minutes by bringing the probe into contact with the adhesive layer (1 st adhesive layer) using a thermo-mechanical analyzer (Thermomechanical Analyzer; TMA). The measurement conditions for TMA subsidence were set as follows: and (3) probe: needle (cylindrical, front diameter 1mm Φ), nitrogen flow: 50.0ml/min, press-in load: 0.01N. As the thermal mechanical analysis device, the product name "TMA Q400" manufactured by TA instruments, inc., or an equivalent thereof may be used.

In the case where the pressure-sensitive adhesive sheet has a pressure-sensitive adhesive layer on only one side of the substrate (that is, in the case where the following 2 nd pressure-sensitive adhesive layer is not provided), the above measurement is performed after providing a standard pressure-sensitive adhesive layer on the side of the substrate opposite to the pressure-sensitive adhesive layer (1 st pressure-sensitive adhesive layer). The standard adhesive layer is the following adhesive layer: an adhesive layer having a thickness of 45 μm was formed by mixing 100 parts by weight of an acrylic polymer (monomer component consisting of Ethyl Acrylate (EA)/2-ethylhexyl acrylate (2 EHA)/Methyl Methacrylate (MMA)/2-hydroxyethyl acrylate (HEA) =30/70/5/5 (weight ratio)), 10 parts by weight of a tackifier (trade name "mightyiace G125" manufactured by Yasuhara Chemical company), 2 parts by weight of an isocyanate-based crosslinking agent (trade name "Coronate L" manufactured by easter company), 30 parts by weight of thermally expandable microspheres (trade name "Matsumoto Microsphere F-190D" manufactured by pine oil company), and toluene.

In some embodiments, the TMA sink amount is preferably 15.0 μm or less, more preferably 10.0 μm or less, and may be 9.00 μm or less, or may be 6.00 μm or less. In a use mode of the adhesive sheet in which TMA sagging is small, for example, in a step of disposing a semiconductor chip on the adhesive layer and sealing the semiconductor chip with a resin, embedding of the semiconductor chip into the adhesive sheet due to a force applied to the semiconductor chip at the time of resin sealing (for example, in step (ii) and step (iii) of fig. 2) tends to be smaller. By reducing the above-described embedding, a level difference (standing off) between the semiconductor chip and the sealing resin due to the embedding can be reduced in the structure including the chip and the sealing resin. The reduction of the level difference is also preferable from the viewpoint of improving the adhesive residue resistance when the pressure-sensitive adhesive sheet is peeled from the structure.

In some embodiments, the TMA sagging amount may be, for example, 1.50 μm or more, preferably 2.00 μm or more, more preferably 2.50 μm or more, more preferably 3.00 μm or more, or more preferably 3.50 μm or more, from the viewpoint of improving the following property with respect to the surface shape of the adherend (for example, a level difference that may be present on the surface of the semiconductor chip). In the adhesive sheet exhibiting such TMA sagging amount, both the following property of the surface shape of the semiconductor chip and the suppression of the embedding of the semiconductor chip into the adhesive sheet can be suitably achieved.

The TMA sagging amount can be set in the above range by appropriately selecting, for example, the structure (thickness, layer structure, etc.) of the adhesive layer, the composition or degree of crosslinking of the base polymer (for example, acrylic polymer) of the adhesive constituting the adhesive layer, the kind of crosslinking agent, the kind of substrate, and the like.

In some embodiments of the pressure-sensitive adhesive sheet disclosed herein, the amount of sagging in an environment of 145 ℃ obtained by using TMA (hereinafter, may also be referred to as "high temperature TMA sagging amount") of the pressure-sensitive adhesive sheet is preferably 2.00 μm or more and 60 μm or less, and may be, for example, 3.00 μm or more and 50 μm or less, or may be 4.00 μm or more and 40 μm or less. The adhesive sheet having the high temperature TMA sagging amount in the above range can be suitably prevented from being embedded in the adhesive sheet even when subjected to a high temperature environment (for example, a heat treatment environment during resin sealing). The high temperature TMA deposition was measured in the same manner as the TMA deposition in the above 23 ℃ environment except that the measurement atmosphere temperature was 145 ℃.

(Probe tack value)

In some embodiments of the adhesive sheet disclosed herein, the probe tack value measured in the surface of the above-mentioned adhesive layer (1 st adhesive layer) is preferably 50N/5 mm. Phi. Or more, more preferably 75N/5 mm. Phi. Or more, and still more preferably 100N/5 mm. Phi. Or more. The probe tack value falling within such a range is preferable from the viewpoint of preventing positional displacement of an adherend (e.g., a semiconductor chip) disposed on the adhesive layer. Probe tack values the area and texture of the probe area at 23 ℃ and 50% rh using a commercially available probe tack tester: 5mm phi SUS (stainless steel), probe descent speed: 30mm/min, seal load: 100gf, seal retention time: 1 second, test speed: the measurement was performed under the condition of 30 mm/min.

(adhesion to PET)

The adhesive force of the adhesive sheet disclosed herein to the polyethylene terephthalate film (adhesive force to PET) may be, for example, 5.00N/20mm or less, 3.00N/20mm or less, or 2.00N/20mm or less, and is not particularly limited. In some embodiments, the adhesion to PET is preferably 1.00N/20mm or less, more preferably 0.05N/20mm or less, from the viewpoint of preventing damage to the adherend due to the load when peeling the adhesive sheet. In some embodiments, the adhesive strength of the adhesive sheet to PET is preferably 0.03N/20mm or more, more preferably 0.05N/20mm or more, still more preferably 0.10N/20mm or more, still more preferably 0.15N/20mm or more, from the viewpoint of securing an adherend (for example, a semiconductor chip) preferably.

The adhesion to PET is an adhesion measured by bonding (bonding condition: 1 round trip by a 2kg roller) a PET film (thickness: 25 μm) as an adherend to an adhesive layer (1 st adhesive layer) of an adhesive sheet having a width of 20mm and a length of 140mm, leaving the sheet at an ambient temperature of 23℃for 30 minutes, and then performing a tensile test (peeling angle of 180 degrees, tensile speed of 300 mm/min).

(tensile elastic modulus)

In some embodiments, the 1 st adhesive layer preferably has a tensile elastic modulus at 25℃of less than 100MPa, more preferably from 0.1MPa to 50MPa, and still more preferably from 0.1MPa to 10MPa. When the amount is within this range, it is easy to obtain an adhesive sheet in which the 1 st adhesive layer exhibits an appropriate adhesive force. The tensile elastic modulus may be according to jis k7161:2008, measurement is performed.

< adhesive layer (1 st adhesive layer) >)

In the pressure-sensitive adhesive sheet disclosed herein, any suitable pressure-sensitive adhesive may be used as the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer (1 st pressure-sensitive adhesive layer) disposed on at least one side of the substrate, as long as the effects of the present invention can be obtained. The pressure-sensitive adhesive layer may contain, for example, 1 or 2 or more types of pressure-sensitive adhesives selected from known various pressure-sensitive adhesives such as acrylic pressure-sensitive adhesives, rubber-based adhesives (natural rubber-based, synthetic rubber-based, and mixtures of these), silicone pressure-sensitive adhesives, polyester pressure-sensitive adhesives, urethane pressure-sensitive adhesives, polyether pressure-sensitive adhesives, polyamide pressure-sensitive adhesives, and fluorine pressure-sensitive adhesives. In the adhesive layer containing 2 or more adhesives, these adhesives may be 2 or more types selected from adhesives of the same system (for example, acrylic adhesives), or 1 or 2 or more types may be selected from adhesives of 2 or more types of different systems (for example, acrylic adhesives and polyester adhesives). In the above-mentioned adhesive layer containing 2 or more adhesives, these adhesives may be uniformly mixed, may be disposed (for example, laminated) at different positions in the thickness direction, may be disposed (for example, separately coated) at different positions in the planar direction, may be disposed by combining these, or may be disposed in the middle of these.

The thickness of the 1 st adhesive layer is preferably 5 μm or more. When the thickness of the 1 st pressure-sensitive adhesive layer is 5 μm or more, good conformability to the surface shape of the adherend is easily exhibited. The upper limit of the thickness of the 1 st pressure-sensitive adhesive layer is not particularly limited, and may be, for example, 200 μm or less or 150 μm or less. In some embodiments, the 1 st adhesive layer preferably has a thickness of 110 μm or less, more preferably 60 μm or less, and still more preferably 20 μm or less, from the viewpoint of preventing the adhesive residue caused by cohesive failure of the adhesive layer, or from the viewpoint of suppressing the embedding of the semiconductor chip into the adhesive sheet in a use mode in which the resin sealing step of the semiconductor chip is performed on the adhesive layer.

< A layer >)

Typically, the adhesive layer (1 st adhesive layer) includes an a layer constituting at least a surface of the adhesive layer. In some embodiments, the adhesive layer may have a single-layer structure formed of the a layer. In this case, the a layer may be formed by directly bonding the opposite side of the surface to the surface of the substrate on one side. In another embodiment, the adhesive layer may be formed by sandwiching another adhesive layer (for example, the layer B described below) different from the layer a between the layer a and the one-side surface of the base material. In this embodiment, the difference between the adhesive constituting the layer a and the adhesive constituting the other adhesive layer may be, for example, 1 or 2 or more types of differences in the base polymer (for example, differences in the composition of the monomer components constituting the base polymer, differences in the weight average molecular weight, differences in the structure of the polymer chain, etc.), differences in the crosslinking agent (for example, differences in the type or amount of use), differences in the tackifying resin (for example, differences in the content, the type of tackifying resin, etc.), the presence or absence of other additives, differences in the content, the type, etc. of other additives, and the like.

In some preferred embodiments, the adhesive constituting the layer a is an acrylic adhesive containing an acrylic polymer as a base polymer. The effect of the invention disclosed herein can be suitably exhibited by constituting at least the surface of the 1 st pressure-sensitive adhesive layer with an acrylic pressure-sensitive adhesive.

(acrylic Polymer)

The acrylic polymer as the base polymer of the acrylic adhesive is preferably a polymer containing an alkyl (meth) acrylate as a main monomer and optionally further containing a monomer component of a secondary monomer copolymerizable with the main monomer. The main monomer herein refers to a main component among monomer components constituting the acrylic polymer, that is, a component contained in an amount exceeding 50% by weight in the monomer components.

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

CH ₂ ＝C(R ¹ )COOR ² (A)

Here, R in the above formula (A) ¹ 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 the number of carbon atoms may be referred to as "C") _1-20 "). R is preferable from the viewpoint of easiness in adjusting adhesive properties and the like ² Is C _1-18 Alkyl (meth) acrylates of chain alkyl groups of (2), more preferably R ² Is C _1-12 Alkyl (meth) acrylates of chain alkyl groups of (a) are described.

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, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate(C) acrylic acid such as hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl (meth) acrylate, eicosyl (meth) acrylate, and the like _1-20 Alkyl esters. Of these, those having C are preferably used _4-20 (more preferably C _6-20 Further preferably C _8-18 ) Alkyl (meth) acrylates of linear or branched alkyl groups (e.g., 2-ethylhexyl (meth) acrylate).

In some embodiments, 30% by weight or more of the monomer components constituting the acrylic polymer is R in the above formula (A) ² Alkyl (meth) acrylate having a structure of a linear or branched alkyl group having 4 or more carbon atoms (preferably 8 or more, and more preferably 18 or less, for example 12 or less). By using the alkyl (meth) acrylate, the transfer of components between the adhesive layer and the sealing resin can be preferably suppressed. The content of the alkyl (meth) acrylate in the monomer component used for the synthesis of the acrylic polymer is preferably 40% by weight or more, and in some embodiments, may be 50% by weight or more, or 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, more preferably 99% by weight or less, and may be 98% by weight or less, or 97% by weight or less, from the viewpoint of easily adjusting the indentation hardness H1 at the measurement position a to a suitable range.

The secondary monomer having copolymerizability with the alkyl (meth) acrylate as the main monomer can contribute to introducing crosslinking points into the acrylic polymer or to improving the cohesive force or heat resistance of the acrylic polymer. The secondary monomer may also help to adjust the indentation hardness H1. As the auxiliary monomer, for example, 1 kind or 2 or more kinds of functional group-containing monomers shown below may be used alone or in combination. For example, 1 kind or 2 or more kinds of functional group-containing monomers shown below may be used singly or in combination.

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

anhydride monomers such as maleic anhydride and itaconic anhydride;

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

(N-substituted) amide monomers such as (meth) acrylamide, N-dimethyl (meth) acrylamide, N-butyl (meth) acrylamide, N-methylol (meth) acrylamide, and N-methylol propane (meth) acrylamide;

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

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

Epoxy group-containing acrylic monomers such as glycidyl (meth) acrylate;

cyano group-containing monomers such as acrylonitrile and methacrylonitrile;

sulfonic acid group-containing monomers such as styrene sulfonic acid, allyl sulfonic acid, 2- (meth) acrylamide-2-methylpropanesulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate, and (meth) acryloxynaphthalene sulfonic acid;

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

an itaconimide monomer such as N-methyl itaconimide, N-ethyl itaconimide, N-butyl itaconimide, N-octyl itaconimide, N-2-ethylhexyl itaconimide, N-cyclohexyl itaconimide and N-month Gui Jiyi itaconimide;

succinimide-based monomers such as N- (meth) acryloyloxymethylene succinimide, N- (meth) acryloyl-6-oxyhexamethylene succinimide, and N- (meth) acryloyl-8-oxyoctamethylene succinimide;

alkoxysilyl group-containing monomers such as 3- (meth) acryloxypropyl trimethoxysilane, 3- (meth) acryloxypropyl triethoxysilane, 3- (meth) acryloxypropyl methyldimethoxysilane, and 3- (meth) acryloxypropyl methyldiethoxysilane.

The monomer component may contain, as a secondary monomer, a copolymerizable monomer other than the functional group-containing monomer exemplified above for the purpose of improving cohesive force and the like. Examples of the other copolymerizable monomer 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, isobornyl (meth) acrylate, and the like; aromatic ring-containing (meth) acrylates such as aryl (meth) acrylates (e.g., phenyl (meth) acrylate), aryloxyalkyl (meth) acrylates (e.g., phenoxyethyl (meth) acrylate), and arylalkyl (meth) acrylates (e.g., benzyl (meth) acrylate); olefin 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 monomers such as polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, methoxyethylene glycol (meth) acrylate, and methoxypolypropylene glycol (meth) acrylate;

And heterocyclic ring-containing monomers such as tetrahydrofurfuryl (meth) acrylate, fluoro (meth) acrylate, and silicone (meth) acrylate.

The monomer component may contain a polyfunctional monomer as the other copolymerizable monomer for the purpose of crosslinking or the like. Non-limiting examples of such polyfunctional monomers may include: polyfunctional monomers such as hexanediol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, polyfunctional epoxy acrylate, polyfunctional polyester acrylate, polyfunctional urethane acrylate, and the like; etc. The polyfunctional monomer may be used alone or in combination of 2 or more.

In some preferred embodiments, the acrylic polymer preferably contains a constituent unit a derived from a monomer having a glass transition temperature (Tg) of-5℃to 150℃of a homopolymer (preferably 50℃to 150℃and more preferably 80℃to 120 ℃). By including such a constituent unit a, T of S component obtained by pulse NMR, in which molecular motion of the acrylic polymer is restricted, can be realized ₂ The relaxation time is preferably adjusted for the a layer. In addition, by forming at least the surface of the 1 st pressure-sensitive adhesive layer of the layer a, a pressure-sensitive adhesive sheet excellent in low-temperature adhesiveness can be obtained. The content of the constituent unit a is preferably 0.1 to 20% by weight, more preferably 1 to 10% by weight, particularly preferably 1.5 to 8% by weight, and most preferably 3 to 6% by weight, relative to the total constituent units constituting the acrylic polymer.

Examples of the monomer having a Tg of-5℃to 150℃as a homopolymer include: 2-hydroxyethyl acrylate (Tg: -3 ℃), 2-hydroxyethyl methacrylate (Tg: 77 ℃), acrylic acid (Tg: 102 ℃), cyclohexyl methacrylate (Tg: 83 ℃), dicyclopentanyl acrylate (Tg: 120 ℃), dicyclopentanyl 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 ℃) and N-acryloylmorpholine (Tg: 145 ℃), and the like. As the glass transition temperature of the homopolymer of the monomer other than the above, the values described in the publicly known materials such as "Polymer Handbook" (3 rd edition, john Wiley & Sons, inc., 1989) are used. The highest value was used for the monomer described in the Polymer Handbook. When the Tg of the homopolymer is not described in the known material, a value obtained by the measurement method described in Japanese patent application laid-open No. 2007-51271 is used.

These monomers may be used singly or in combination of 1 or more than 2. Among them, methyl methacrylate is preferable in terms of improving the visibility of an adherend during processing because it can improve the transparency of the adhesive layer. In addition, acrylic acid is preferable when strong adhesion is required because it strongly adheres to an adherend by intermolecular interaction. In addition, since 2-hydroxyethyl (meth) acrylate exhibits high reactivity with various crosslinking agents, it is suitable for forming T as described below ₂ Adhesives with shorter relaxation times.

In some preferred embodiments, the acrylic polymer contains constituent units derived from a carboxyl group-containing monomer. The content of the constituent unit derived from the carboxyl group-containing monomer is preferably 0.1% by weight or more, more preferably 1% by weight or more, still more preferably 2% by weight or more, and further preferably 15% by weight or less, more preferably 10% by weight or less, still more preferably 7% by weight or less, relative to the total constituent units constituting the acrylic polymer.

In some preferred embodiments, the acrylic polymer contains constituent units derived from a hydroxyl group-containing monomer. The content of the constituent unit derived from the hydroxyl group-containing monomer is preferably 0.01% by weight or more, more preferably 0.03% by weight or more, for example, 0.05% by weight or more, and further preferably 20% by weight or less, more preferably 10% by weight or less, for example, 7% by weight or less, relative to the total constituent units constituting the acrylic polymer.

(SP value)

In some embodiments, the SP value of the base polymer (preferably acrylic polymer) constituting the adhesive of the a layer is, for example, 10 or more and 30 or less, preferably 15 or more and 25 or less, and particularly preferably 18 or more and 20 or less. If the content is within this range, the transfer of components between the adhesive layer and the sealing resin can be preferably prevented. In the present specification, the units indicating the numerical value of the SP value are "(cal/cm) ³ ) ^1/2 ”。

Here, the SP value refers to a value calculated from the basic structure of the compound by the method proposed by Fedors. Specifically, the evaporation energy Δe (cal) of each atom or group at 25℃is equivalent to the molar volume Δv (cm) of each atom or group at the same temperature ³ ) The SP value is calculated according to the following equation.

SP value= (ΣΔe/ΣΔv) ^1/2

(reference: shanbu literature, "SP value base, application and calculation method", 4 th edition, published by Johokiko Co., ltd., release 4/2006, pages 66 to 67).

In the case where the polymer is a copolymer, the SP value thereof is calculated by: SP values of homopolymers constituting the constituent units of the copolymer are calculated, the SP values are multiplied by mole fractions of the constituent units, and the obtained values are summed up. In the above case, the analysis method of each constituent unit (composition analysis of the polymer) is performed as follows: the adhesive layer alone is suitably collected from the adhesive sheet, immersed in an organic solvent such as Dimethylformamide (DMF), acetone, methanol, tetrahydrofuran (THF), and the like, and the solvent-soluble fraction obtained is recovered, and obtained by Gel Permeation Chromatography (GPC), nuclear magnetic resonance spectroscopy (NMR), infrared spectroscopy (IR), and mass spectrometry.

(crosslinking agent)

In view of easy realization of the preferable indentation hardness H1, the base polymer of the a layer is preferably crosslinked in the binder constituting the a layer. For example, by using an adhesive composition containing a base polymer and an appropriate crosslinking agent, an a layer composed of an adhesive in which the base polymer is crosslinked by the crosslinking agent can be obtained.

The type of the crosslinking agent is not particularly limited, and may be appropriately selected from isocyanate-based crosslinking agents, epoxy-based crosslinking agents, melamine-based crosslinking agents, peroxide-based crosslinking agents, urea-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, carbodiimide-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, amine-based crosslinking agents, and the like, for example. The crosslinking agent may be used alone or in combination of 2 or more. Among them, preferable crosslinking agents include: epoxy-based crosslinking agents and isocyanate-based crosslinking agents.

Examples of the epoxy-based crosslinking agent include: n, N, N ', N' -tetraglycidyl m-xylylenediamine, diglycidyl aniline, 1, 3-bis (N, N-glycidylaminomethyl) cyclohexane (manufactured by Mitsubishi gas chemical corporation under the trade name "tetra C"), 1, 6-hexanediol diglycidyl ether (manufactured by Kyowa chemical corporation under the trade name "Epoligo 1600"), neopentyl glycol diglycidyl ether (manufactured by Kyowa chemical corporation under the trade name "Epoligo 1500 NP"), ethylene glycol diglycidyl ether (manufactured by Kyowa chemical corporation under the trade name "Epoligo 40E"), propylene glycol diglycidyl ether (manufactured by Kyowa chemical corporation under the trade name "Epoligo 70P"), polyethylene glycol diglycidyl ether (manufactured by Japanese fat Co., ltd.), trade name "EPIOL E-400"), polypropylene glycol diglycidyl ether (manufactured by Japanese oil and fat Co., ltd., trade name "EPIOL P-200"), sorbitol polyglycidyl ether (manufactured by Nagase ChemteX Corporation, trade name "Denacol EX-611"), glycerol polyglycidyl ether (manufactured by Nagase ChemteX Corporation, trade name "Denacol EX-314"), pentaerythritol polyglycidyl ether, polyglycidyl ether (manufactured by Nagase ChemteX Corporation, trade name "Denacol EX-512"), sorbitan polyglycidyl ether, trimethylolpropane polyglycidyl ether, adipic acid diglycidyl ester, phthalic acid diglycidyl ester, triglycidyl-tris (2-hydroxyethyl) isocyanurate, resorcinol diglycidyl ether, bisphenol-S-diglycidyl ether, epoxy resins having 2 or more epoxy groups in the molecule, and the like. The amount of the epoxy-based crosslinking agent to be used may be set to any appropriate amount according to the target characteristics. In some embodiments, the epoxy-based crosslinking agent may be used in an amount of, for example, 0.01 to 50 parts by weight, preferably 0.6 to 15 parts by weight, more preferably 2 to 13 parts by weight, and still more preferably 3 to 10 parts by weight, based on 100 parts by weight of the base polymer.

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-toluene diisocyanate, 4' -diphenylmethane diisocyanate and xylylene diisocyanate; isocyanate adducts such as trimethylolpropane/toluene diisocyanate trimer adduct (trade name "Coronate L" manufactured by Tosoh corporation), trimethylolpropane/hexamethylene diisocyanate trimer adduct (trade name "Coronate HL" manufactured by Tosoh corporation), and isocyanurate body of hexamethylene diisocyanate (trade name "Coronate HX" manufactured by Tosoh corporation); etc. The amount of the isocyanate-based crosslinking agent to be used may be set to any appropriate amount depending on the adhesive force required. In some embodiments, the isocyanate-based crosslinking agent is typically used in an amount of 0.1 to 20 parts by weight, preferably 1 to 10 parts by weight, based on 100 parts by weight of the base polymer.

In some embodiments, as the crosslinking agent used in the layer a, an epoxy-based crosslinking agent may be preferably used. The preferred indentation hardness H1 disclosed herein can be suitably achieved according to the layer a having a crosslinked structure in which the base polymer is crosslinked by an epoxy-based crosslinking agent. Further, an adhesive sheet which can preferably reduce the level difference between the semiconductor chip and the sealing resin can be obtained. In addition, an adhesive layer having high cohesive force can be formed, and positional displacement of an adherend can be more effectively prevented.

In some embodiments, as the above-mentioned crosslinking agent, a crosslinking agent containing a nitrogen (N) atom may be suitably used. The crosslinking agent containing an N atom is advantageous in that the crosslinking reaction (for example, reaction with carboxyl groups in the base polymer) is promoted by the catalysis of the N atom, and the gel fraction of the adhesive is easily improved. As specific examples of the crosslinking agent containing an N atom, in addition to the isocyanate crosslinking agent described above, epoxy crosslinking agents containing an N atom (for example, epoxy crosslinking agents having a glycidylamino group such as N, N' -tetraglycidyl m-xylylenediamine or 1, 3-bis (N, N-glycidylaminomethyl) cyclohexane and the like) are also cited. In some embodiments using a crosslinking agent containing an N atom, the amount of the crosslinking agent to be used is preferably set so that the amount of nitrogen generated is 0.06 wt% or more and 1.0 wt% or less (more preferably 0.06 wt% or more and 0.9 wt% or less). By setting the amount to be used, an adhesive sheet having excellent adhesion to a substrate and surface shape following properties can be easily obtained.

In some embodiments, the amount of the crosslinking agent used (preferably a crosslinking agent that forms a crosslinked structure by reaction with carboxyl groups, for example, an epoxy-based crosslinking agent, an isocyanate-based crosslinking agent, or the like) is preferably 0.08 molar equivalents or more and 2 molar equivalents or less, more preferably 0.1 molar equivalents or more and 1 molar equivalent or less, relative to the amount of carboxyl groups present in the base polymer (for example, an acrylic polymer). According to this amount used, the preferred indentation hardness H1 disclosed herein can be accurately achieved. In addition, by crosslinking the crosslinking agent in the above amount to react with carboxyl groups in the base polymer, an adhesive sheet having less residual carboxyl groups in the adhesive layer can be obtained.

(other additives)

The adhesive constituting the layer a may contain, as an optional component, an appropriate additive other than the above. Examples of such additives include: tackifiers, plasticizers (e.g., trimellitic acid ester plasticizers, pyromellitic acid ester plasticizers, etc.), pigments, dyes, fillers, anti-aging agents, conductive materials, antistatic agents, ultraviolet absorbers, light stabilizers, release modifiers, softeners, surfactants, flame retardants, antioxidants, and the like.

As the thickener, any suitable thickener may be used. As the tackifier, for example, a tackifier resin can be used. Specific examples of the tackifying resin include: rosin-based tackifying resins (e.g., unmodified rosin, modified rosin, rosin phenolic resins, rosin ester-based resins, and the like), terpene-based tackifying resins (e.g., terpene-based resins, terpene-based phenolic resins, styrene-modified terpene-based resins, aromatic-modified terpene-based resins, hydrogenated terpene-based resins), hydrocarbon-based tackifying resins (e.g., aliphatic-based hydrocarbon resins, aliphatic cyclic hydrocarbon resins, aromatic-based hydrocarbon resins (e.g., styrene-based resins, xylene-based resins, and the like), aliphatic/aromatic-based petroleum resins, aliphatic/alicyclic-based petroleum resins, hydrogenated hydrocarbon resins, coumarone-indene-based resins, and the like), phenol-based tackifying resins (e.g., alkylphenol-based resins, xylene-formaldehyde-based resins, resol-type phenolic resins, novolac-based resins, and the like), ketone-based tackifying resins, polyamide-based tackifying resins, epoxy-based tackifying resins, elastomeric-based tackifying resins, and the like. Among them, rosin-based tackifying resins, terpene-based tackifying resins, or hydrocarbon-based tackifying resins (styrene-based resins, etc.) are preferable. The tackifier may be used alone or in combination of 2 or more.

In some embodiments, as the tackifying resin, a resin having a higher softening point or glass transition temperature (Tg) may be used. When a resin having a high softening point or glass transition temperature (Tg) is used, an adhesive layer which can exhibit high adhesion can be formed even in a high-temperature environment (for example, in a high-temperature environment in processing at the time of sealing a semiconductor chip). The softening point of the tackifier is preferably 100 to 180 ℃, more preferably 110 to 180 ℃, and still more preferably 120 to 180 ℃. The glass transition temperature (Tg) of the thickener is preferably 100℃to 180℃and more preferably 110℃to 180℃and even more preferably 120℃to 180 ℃.

In some embodiments, as the tackifying resin, a tackifying resin having low polarity may be used. The use of a tackifying resin of low polarity is advantageous from the standpoint of forming an adhesive layer having a low affinity with the sealing material. Examples of the low-polarity tackifying resin include: hydrocarbon tackifying resins such as aliphatic hydrocarbon resins, aliphatic cyclic hydrocarbon resins, aromatic hydrocarbon resins (e.g., styrene resins, xylene resins, etc.), aliphatic/aromatic petroleum resins (also sometimes referred to as C5/C9 petroleum resins), aliphatic/alicyclic petroleum resins, and hydrogenated hydrocarbon resins. Among them, aliphatic/aromatic petroleum resins are preferable. Such a tackifying resin has low polarity, is excellent in compatibility with an acrylic polymer, does not phase separate in a wide temperature range, and can form an adhesive layer excellent in stability.

The acid value of the tackifying resin is preferably 40 or less, more preferably 20 or less, and still more preferably 10 or less. When the content is within this range, an adhesive layer having low affinity with 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. When the content is within this range, an adhesive layer having low affinity with the sealing material and suitable for suppressing transfer of components between the adhesive layer and the sealing resin can be formed.

The amount of the tackifier to be used may be, for example, 5 parts by weight or more and 100 parts by weight or less, 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 pressure-sensitive adhesive sheet disclosed herein, the amount of the tackifier to be blended per 100 parts by weight of the base polymer constituting the pressure-sensitive adhesive of the layer a is preferably less than 3 parts by weight, less than 1 part by weight, or less than 0.5 part by weight, from the viewpoint of light releasability of the adherend, suppression of residual glue, or the like, and it is preferable that the pressure-sensitive adhesive (particularly, tackifier resin) is not blended in the pressure-sensitive adhesive constituting the layer a.

(T ₂ Relaxation time

In some embodiments of the adhesive sheet disclosed herein, T of S component of layer A obtained by pulse NMR ₂ Relaxation time (T) _2s ) Preferably 45 musec or less. T according to A layer constituting at least the surface of the 1 st adhesive layer ₂ Relaxation time (T) _2s ) 45 musec or lessFor example, in the use mode of the adhesive sheet of (1) for sealing the semiconductor chip with the resin on the 1 st adhesive layer, the component transfer between the adhesive layer and the sealing resin is suppressed, and the level difference between the semiconductor chip and the sealing resin can be suitably suppressed.

The relaxation time refers to the time required for the excited atom (group) to return to the ground state after irradiation of energy suitable for exciting the atom to be measured in the pulse NMR measurement. Which excited state an atom (group) is in can be controlled by the amount and time of energy irradiation. In addition, in order to restore the excited atom (group) to the ground state, various energy relaxation mechanisms are known, from which the relaxation time can be determined (for example, "latest NMR overview towards chemists", "latest NMR overview of chemists", kagaku-Dojin Publishing (1997)). The present inventors have excited an acrylic adhesive (essentially an acrylic polymer contained in the adhesive) under the following conditions ¹ H atoms and measuring the subsequent relaxation behavior, and further analyzing the measurement value, as a result, found that T ₂ S component of relaxation time (T _2s ) Useful as information for knowing the molecular motion related to the degree of crosslinking of the base polymer (typically, acrylic polymer) contained in the adhesive constituting the adhesive layer, it was found that by specifying the T ₂ S component of relaxation time (T _2s ) The above-described effects can be obtained. T (T) _2s The shorter is represented as a state in which molecular movement related to the degree of crosslinking of the base polymer is restricted, that is, a state in which crosslinking is performed and the degree of freedom of movement of the polymer as a whole is also reduced. In the pressure-sensitive adhesive in such a state, gaps between the base polymers are small, and transfer of the pressure-sensitive adhesive layer component to the sealing resin or transfer of the low molecular weight component contained in the sealing resin to the pressure-sensitive adhesive layer tends to be suppressed. As a result, when the adhesive sheet is peeled off after the semiconductor chip is sealed with the resin, the occurrence of a level difference between the semiconductor chip and the sealing resin can be prevented.

T of S component obtained by pulse NMR of A layer ₂ Relaxation time (T) _2s ) From the viewpoint of better suppressing the transfer of components of the self-sealing resinPreferably 40 musec or less, more preferably 35 musec or less (e.g., 30 musec or less). T of layer A _2s The lower limit of (2) may be, for example, 5 musec or more, and is not particularly limited. In some embodiments, T of the A layer from the standpoint of easily exhibiting moderate tackiness in the adhesive layer surface _2s The ratio may be 10 musec or more, 15 musec or more, or 20 musec or more. T of layer A _2s However, the short is preferable from the viewpoint of improving the adhesion between the layer a and the layer adjacent thereto (which may be a substrate, an adherend, a layer B described below, or the like).

T of layer A _2s The method can be obtained as follows: about 100mg of the adhesive constituting the A layer was obtained as a measurement sample and T was measured by the Solid Echo method ₂ Relaxation curve of T ₂ The relaxation curve is fitted to the following equation (1), and is obtained therefrom. T of S component obtained by pulse NMR of layer B described below ₂ Relaxation time (T) _2s ) The measurement can also be performed in the same manner.

M(t)＝α·exp(-(1/Wa)(t/T _2s ) ^Wa )+β·exp(-(1/Wa)(t/T _2L ) ^Wa )···(1)

M (t): free induction decay

Alpha: proton ratio (%)

T _2s : t of S component ₂ Relaxation time (msec)

Beta: proton ratio (%)

T _2L : t of L component ₂ Relaxation time (msec)

t: observation time (msec)

Wa: shape factor (=1)

The measurement conditions in the above measurement are as follows.

90 ° pulse width: 2.1 musec

Repetition time: 1sec

Cumulative number of times: 32 times

Measurement temperature: 30 DEG C

(gel fraction)

The gel fraction of the adhesive constituting the layer a is preferably 75% or more, more preferably 85% or more, and still more preferably 90% or more. If the amount is within such a range, the molecular movement of the base polymer can be preferably restricted by crosslinking, and the transfer of components between the adhesive layer and the sealing resin can be suppressed. From the viewpoint of suppressing the transfer of the component, it is more advantageous that the gel fraction constituting the layer a is higher. In some embodiments, the gel fraction of the adhesive constituting the layer a may be 99.5% or less, or 99% or less, for example, in consideration of balance with other characteristics (for example, moderate tackiness or adhesiveness in the surface of the adhesive layer, follow-up property to the surface shape of the adherend, and the like). The gel fraction was obtained by immersing the adhesive collected from the layer a in ethyl acetate for 7 days, and then drying the immersed adhesive, and (dry weight of the immersed adhesive/weight of the adhesive before immersion) ×100.

(Nitrogen production amount)

In the pressure-sensitive adhesive sheet of some embodiments, the nitrogen generation amount in the heat treatment of the pressure-sensitive adhesive constituting the layer a is preferably 0.06 to 1.0 wt%, more preferably 0.06 to 0.9 wt% based on 100 wt% of the weight of the pressure-sensitive adhesive used for the heat treatment. If the nitrogen generation amount is 0.06 wt% or more, the adhesive sufficiently exerts cohesive force, and the step tends not to be easily generated at the interface between the semiconductor chip and the sealing resin by suppressing the transfer of components between the adhesive layer and the sealing resin. The nitrogen gas generation amount of 1.0 wt% or less is advantageous from the viewpoint of suppressing positional displacement of the adherend disposed on the a layer.

The nitrogen generation amount can be determined as follows: the amount of nitrogen generated by heating in a thermal decomposition furnace at 800 c/oxidation furnace at 900 c was analyzed by a TN (micro total nitrogen analysis) device for a sample obtained by putting 2mg of the binder into a ceramic plate and weighing the same by a microbalance, and the amount of nitrogen generated was determined. The conditions for measurement are as follows.

Carrier gas: o (O) ₂ (300mL/min)、Ar(300mL/min)

Standard sample: pyridine/toluene solution

Detector: reduced pressure chemiluminescent detector

Range: high concentration of

< layer B >)

In some embodiments of the adhesive sheet disclosed herein, the 1 st adhesive layer includes: a layer a constituting at least a surface of the adhesive layer, and a layer B disposed between the layer a and the base material and adjacent to the base material. That is, the outer surface (surface on the adherend side) of the 1 st adhesive layer is formed of the a layer, and the inner surface (surface on the substrate side) of the 1 st adhesive layer is formed of the B layer. According to the 1 st adhesive layer having this structure, the characteristics (indentation hardness, stringiness, T of S component) at the measurement position A, B can be easily determined by, for example, selection of the adhesive constituting each of the A layer and the B layer, selection of the thickness of each layer, and the like ₂ Relaxation time, etc.) or a ratio of these.

As the adhesive constituting the B layer, any suitable adhesive may be used. The B layer may contain, for example, 1 or 2 or more kinds of known various adhesives selected from the group consisting of acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, polyether adhesives, polyamide adhesives, and fluorine adhesives.

In some preferred embodiments, the adhesive constituting the layer B is an acrylic adhesive containing an acrylic polymer as a base polymer. In the case where the layer a is made of an acrylic adhesive, it is particularly preferable to use an acrylic adhesive as the adhesive constituting the layer B from the viewpoint of improving the interlayer adhesiveness of the layer contained in the 1 st adhesive layer.

In the case where the adhesive constituting the layer B is an acrylic adhesive, the acrylic polymer as the base polymer of the acrylic adhesive may be appropriately selected from the same materials as the acrylic polymer described above as the base polymer of the layer a. The acrylic polymer as the base polymer of layer a may be the same as or different from the acrylic polymer as the base polymer of layer B. In some embodiments, the base polymers of the a layer and the B layer may be the same acrylic polymer from the viewpoint of the adhesion between the a layer and the B layer. In this embodiment, the characteristics at the measurement position A, B and the ratio of these can be adjusted according to the selection of the presence or absence of the use of a material other than the base polymer (a crosslinking agent, a tackifier, or the like) for forming each layer, the type, amount, or the like of the material other than the base polymer (a crosslinking agent, a tackifier, or the like) for forming each layer, and the like.

The base polymer of layer B is preferably crosslinked in the binder constituting the layer B. For example, by using an adhesive composition containing a base polymer and an appropriate crosslinking agent, a B layer composed of an adhesive in which the base polymer is crosslinked by the crosslinking agent can be obtained. The type of the crosslinking agent used in the layer B is not particularly limited, and may be appropriately selected from those exemplified above as the crosslinking agent usable in the layer a. The crosslinking agent used in the layer a and the crosslinking agent used in the layer B may be the same type of crosslinking agent (e.g., the same or different isocyanate-based crosslinking agents), or may be different types of crosslinking agents (e.g., one epoxy-based crosslinking agent and the other isocyanate-based crosslinking agent).

In some preferred embodiments, the layer a uses an epoxy-based crosslinking agent and the layer B uses an isocyanate-based crosslinking agent. In general, when an isocyanate-based crosslinking agent is used, a softer crosslinked structure tends to be formed as compared with an epoxy-based crosslinking agent, and therefore, according to the above-described embodiment, the 1 st adhesive layer having an indentation hardness H2 smaller than the indentation hardness H1 can be suitably realized.

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

In order to more effectively carry out the crosslinking reaction, a crosslinking catalyst may also be used. Examples of the crosslinking catalyst include: metal crosslinking catalysts such as tetra-n-butyl titanate, tetra-isopropyl titanate, iron triacetylacetonate, butyltin oxide, and dioctyltin dilaurate. The amount of the crosslinking catalyst used is not particularly limited. In some embodiments, the amount of the crosslinking catalyst used may be, for example, 0.0001 parts by weight or more and 1 part by weight or less (preferably 0.001 parts by weight or more and 0.5 parts by weight or less) based on 100 parts by weight of the base polymer, considering the balance between the rate of the crosslinking reaction and the pot life of the adhesive composition. The crosslinking catalysts described above can be used for the A layer, as well as for both the A layer and the B layer.

In some embodiments of the adhesive sheet disclosed herein, the B layer constituting the 1 st adhesive layer is T of S component obtained by pulse NMR ₂ Relaxation time (T) _2s ) In terms of improving the following property to the surface shape of the adherend disposed on the layer a of the pressure-sensitive adhesive layer, it is preferable that the pressure-sensitive adhesive layer is formed of a material having a specific shape than the T of the layer a _2s Long. T of layer A _2s T with layer B _2s The difference (d) may be, for example, 5 musec or more, preferably 10 musec or more, more preferably 15 musec or more, still more preferably 20 musec or more, or 25 musec or more, or 30 musec or more. In addition, T from layer B is prevented _2s T of layer A from the viewpoint of cohesive failure of the adhesive layer caused by excessive lengths _2s T with layer B _2s The difference (d) is, for example, 70 musec or less, preferably 60 musec or less, more preferably 50 musec or less, and may be 40 musec or less, or may be 35 musec or less.

In some embodiments, T of layer B _2s T greater than layer A _2s And is preferably 30 musec or more (for example, 35 musec or more, 40 musec or more, or 45 musec or more), the T of the B layer is preferably selected from the viewpoint of improving the following performance with respect to the surface shape of the adherend _2s Preferably longer than 45 musec, and may be 47 musec or more, or 50 musec or more. In addition, from the viewpoint of preventing cohesive failure of the B layer, T of the B layer _2s Preferably 80 musec or less, more preferably 70 musec or less, and may be 65 musec or less, 60 musec or less, or 57 musec or less.

In some embodiments of the pressure-sensitive adhesive sheet including a pressure-sensitive adhesive layer including a layer and a layer B, the thickness of the layer B may be, for example, 3 μm or more, preferably 4 μm or more, and from the viewpoint of improving the effect of imparting surface shape following properties, it is preferably 5 μm or more, or 7 μm or more, or 10 μm or more, or 15 μm or more. The upper limit of the thickness of the B layer may be, for example, 300 μm or less, 250 μm or less, 150 μm or less, or 130 μm or less, and is not particularly limited. In terms of suppressing the embedding of the semiconductor chip into the adhesive sheet in the use form of the resin sealing of the semiconductor chip on the adhesive layer, the thickness of the B layer is preferably 100 μm or less, more preferably 90 μm or less, and may be 70 μm or less, or may be 50 μm or less, or may be 30 μm or less, or may be 20 μm or less.

In the pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer composed of a layer a and a layer B, the thickness of the layer a may be, for example, 1 μm or more and 20 μm or less. In some embodiments, the thickness of the layer a is preferably 15 μm or less, more preferably 10 μm or less, and may be 8 μm or less, or 6 μm or less, from the viewpoint of suitably exhibiting the effect of improving the surface shape following property with the aid of the layer B. In some embodiments, the thickness of the a layer is preferably 2 μm or more, more preferably 3 μm or more, and may be 4 μm or more, or 5 μm or more, from the viewpoint of suitably exhibiting the effect of suppressing the transfer of components between the adhesive layer and the sealing resin with the aid of the a layer.

In the pressure-sensitive adhesive sheet including the pressure-sensitive adhesive layer including the layer A and the layer B, the ratio (L2/L1) of the thickness L2[ mu ] m of the layer B to the thickness L1[ mu ] m of the layer A may be, for example, about 0.5 to 100.0, and is not particularly limited. In some embodiments, the ratio (L2/L1) is preferably 0.5 or more, more preferably 0.7 or more, still more preferably 0.8 or more, still more preferably 0.9 or more, still more preferably 1.0 or more, from the viewpoint of easily and effectively performing the functions of the layers a and B. In the same point of view, the ratio (L2/L1) is preferably 50.0 or less, more preferably 30.0 or less, and may be 20.0 or less, or 15.0 or less, or 10.0 or less, or 5.0 or less, or 3.0 or less, or 2.0 or less.

< substrate >

The base material of the pressure-sensitive adhesive sheet disclosed herein may be, for example, a resin sheet, a nonwoven fabric, paper, a metal foil, a woven fabric, a rubber sheet, a foam sheet, a laminate of these (particularly, a laminate containing a resin sheet), or the like. Examples of the resin constituting the resin sheet include: polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polyethylene (PE), polypropylene (PP), ethylene-propylene copolymers, ethylene-vinyl acetate copolymers (EVA), polyamides (nylon), wholly aromatic polyamides (aramid), polyimides (PI), polyvinylchloride (PVC), polyphenylene Sulfide (PPs), fluorine-based resins, polyether ether ketone (PEEK), and the like. The nonwoven fabric may be: nonwoven fabrics obtained from natural fibers having heat resistance, such as nonwoven fabrics containing manila hemp; and synthetic resin nonwoven fabrics such as polypropylene resin nonwoven fabrics, polyethylene resin nonwoven fabrics, and ester resin nonwoven fabrics. As the metal foil, there may be mentioned: copper foil, stainless steel foil, aluminum foil, and the like. As the paper, there may be mentioned: japanese paper, kraft paper, and the like.

In some embodiments, it is preferable to use a resin sheet composed of a resin having a glass transition temperature (Tg) of 25 ℃ or higher (preferably 40 ℃ or higher, more preferably 50 ℃ or higher) as a base material. When such a resin sheet is used, the shape of the base material can be maintained even when heated during the sealing step, and the semiconductor chip can be prevented from being embedded in the adhesive sheet. The resin constituting such a resin sheet is preferably a polymer having an aromatic ring, and specific examples thereof include: polyethylene terephthalate (PET), polyimide, polyethylene naphthalate, and the like, but are not limited thereto.

The thickness of the base material may be set to any appropriate thickness depending on the strength and flexibility required, the purpose of use, and the like. The thickness of the base material is preferably 1000 μm or less, more preferably 25 μm or more and 1000 μm or less, still more preferably 40 μm or more and 500 μm or less, particularly preferably 60 μm or more and 300 μm or less, and most preferably 80 μm or more and 250 μm or less. In 1 embodiment, a substrate having a thickness of 25 μm or more may be used. The substrate having such a thickness is easy to maintain the shape of the substrate even when pressurized during the sealing process, and is suitable for preventing the semiconductor chip from being embedded in the adhesive sheet.

In 1 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) relative to the total thickness of the adhesive sheet. In such a range, the semiconductor chip can be suitably prevented from being embedded in the adhesive sheet.

The substrate may be subjected to surface treatment. Examples of the surface treatment include: corona treatment, chromic acid treatment, ozone exposure, flame exposure, high voltage electric shock exposure, ionizing radiation treatment, coating treatment with a primer, and the like.

As the primer, an organic coating material can be used. Examples of the organic coating material include: CMC published "plastic hard coating material II" (published 2004) is a material described in the publication. Preferably, urethane polymers are used, more preferably polyacrylic urethanes, polyester urethanes or precursors of these. The reason for this is that the coating and application to the substrate are easy, and various products can be industrially selected, and they can be obtained at low cost. The urethane polymer is, for example, a polymer comprising a reaction mixture of an isocyanate 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 a chain extender such as polyamine, an anti-aging agent, an oxidation stabilizer, and the like as optional additives. The thickness of the organic coating layer is not particularly limited, and is preferably about 0.1 μm to 10 μm, more preferably about 0.1 μm to 5 μm, and still more preferably about 0.5 μm to 5 μm.

< 2 nd adhesive layer >

The pressure-sensitive adhesive sheet according to some embodiments includes the base material, the pressure-sensitive adhesive layer disposed on one side of the base material, and the 2 nd pressure-sensitive adhesive layer disposed on the opposite side of the base material from the pressure-sensitive adhesive layer. The pressure-sensitive adhesive sheet (double-sided pressure-sensitive adhesive sheet with a base material) having this configuration can be used to perform the resin sealing step on the 1 st pressure-sensitive adhesive layer in a form of being fixed to an appropriate carrier (for example, SUS plate, glass plate, etc.) by using the 2 nd pressure-sensitive adhesive layer, and thus has good usability. The 2 nd adhesive layer may be an adhesive layer made of any suitable adhesive.

In the adhesive sheet according to some embodiments, at least the surface of the 2 nd adhesive layer is composed of an adhesive containing thermally expandable microspheres. The pressure-sensitive adhesive sheet of this embodiment is preferably used because the bonding between the 2 nd pressure-sensitive adhesive layer and the adherend (for example, the carrier) can be easily released by heating the pressure-sensitive adhesive sheet for an appropriate time to expand the thermally expandable microspheres.

The adhesive containing the thermally expandable microspheres may be a curable adhesive (for example, an active energy ray curable adhesive) or a pressure sensitive adhesive. Examples of the pressure-sensitive adhesive include: acrylic adhesives, rubber adhesives, and the like. The adhesive contained in the 2 nd adhesive layer can be described in detail in, for example, japanese patent application laid-open No. 2018-009050. The entire disclosure of this publication is incorporated by reference into this specification.

Any suitable thermally expandable microspheres may be used as long as they are expandable or foamable by heating. As the thermally expandable microspheres, for example, microspheres in which a substance that is easily expandable by heating is enclosed in a shell having elasticity can be used. Such thermally expandable microspheres can be produced by any suitable method, for example, a coagulation method, an interfacial polymerization method, or the like.

Examples of the substance that is easily swelled by heating include: low boiling point liquids such as propane, propylene, butene, n-butane, isobutane, isopentane, neopentane, n-pentane, n-hexane, isohexane, heptane, octane, petroleum ether, halides of methane, tetraalkylsilane, and the like; azodicarbonamide gasified by thermal decomposition; etc.

Examples of the material constituting the shell include polymers composed of: nitrile monomers such as acrylonitrile, methacrylonitrile, α -chloroacrylonitrile, α -ethoxyacrylonitrile, fumaronitrile, and the like; carboxylic acid monomers such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, and citraconic acid; vinylidene chloride; vinyl acetate; (meth) acrylic esters such as methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, and beta-carboxyethyl acrylate; styrene monomers such as styrene, α -methylstyrene, chlorostyrene, etc.; amide monomers such as acrylamide, substituted acrylamide, methacrylamide and substituted methacrylamide; etc. The polymer composed 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, and the like.

As the thermally expandable microspheres, inorganic foaming agents or organic foaming agents can be used. Examples of the inorganic foaming agent include: ammonium carbonate, ammonium bicarbonate, sodium bicarbonate, ammonium nitrite, sodium borohydride, various azides, and the like. Examples of the organic foaming agent include: a fluorinated alkane compound such as trichloromonofluoromethane and dichloromonofluoromethane; azo compounds such as azobisisobutyronitrile, azodicarbonamide and barium azodicarboxylate; hydrazine compounds such as p-toluenesulfonyl hydrazide, diphenyl sulfone-3, 3 '-disulfonyl hydrazide, 4' -oxybis (benzenesulfonyl hydrazide) and allylbis (sulfonyl hydrazide); semicarbazide compounds such as p-toluenesulfonyl semicarbazide and 4,4' -oxybis (benzenesulfonyl semicarbazide); triazole-based compounds such as 5-morpholino-1, 2,3, 4-thiatriazole; n, N ' -dinitroso pentamethylene tetramine, N ' -dimethyl-N, N ' -dinitroso terephthalamide; and N-nitroso compounds.

The thermally expandable microspheres may be commercially available ones. Specific examples of commercially available thermally expandable microspheres include: trade names "Matsumoto Microsphere" (grades: F-30, F-30D, F-36D, F-36LV, F-50D, F-65, F-65D, FN-100SS, FN-100SSD, FN-180SS, FN-180SSD, F-190D, F-260D, F-2800D), trade names "Expancel" made by Japan Fillite company (grades: 053-40, 031-40, 920-40, 909-80, 930-120), "Daifoam" made by Wulue chemical company (grades: H750, H850, H1100, S2320D, S2640D, M, M430, M520), and "Advancell" made by Water chemical company (grades: EML101, EMH204, EHM301, EHM302, EHM303, EM304, EHM401, EM403, EM 501), and the like.

The particle diameter of the thermally expandable microspheres before heating is preferably 0.5 to 80. Mu.m, more preferably 5 to 45. Mu.m, still more preferably 10 to 20. Mu.m, particularly preferably 10 to 15. Mu.m. Therefore, when the particle size of the thermally expandable microspheres before heating is described as the average particle size, the particle size is preferably 6 μm to 45 μm, more preferably 15 μm to 35 μm. The particle diameter and the average particle diameter are values obtained by a particle size distribution measurement method in a laser light scattering method.

The thickness of the pressure-sensitive adhesive layer made of the pressure-sensitive adhesive containing the thermally expandable microspheres may be 3 μm or more, for example, and is not particularly limited. The thickness of the pressure-sensitive adhesive layer is preferably 7 μm or more, more preferably more than 10 μm, and may be more than 15 μm, or more than 25 μm, or more than 35 μm, from the viewpoint of suppressing the decrease in the smoothness of the pressure-sensitive adhesive surface due to the inclusion of the thermally expandable microspheres. The upper limit of the thickness of the pressure-sensitive adhesive layer is usually 300 μm or less, preferably 200 μm or less, more preferably 150 μm or less, more preferably 100 μm or less, and most preferably 70 μm or less, and is not particularly limited. The thickness of the adhesive layer is not excessively large, which is 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 pressure-sensitive 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. In some embodiments, ta/D is preferably 2.0 or more, may be 3.0 or more, or may be 4.0 or more from the viewpoint of smoothness of the adhesive surface. In view of the ease of exhibiting the peeling effect due to the expansion of the thermally expandable microspheres, ta/D is usually 50 or less, preferably 20 or less, but may be 15 or less, or 10 or less.

The thermally expandable microspheres preferably have a suitable strength so as not to fracture until the volume expansion ratio reaches preferably 5 times or more, more preferably 7 times or more, still more preferably 10 times or more. In the case of using such thermally expandable microspheres, the adhesive force can be effectively reduced by the heat treatment.

The content ratio of the thermally expandable microspheres in the binder containing the thermally expandable microspheres can be appropriately set in accordance with the desired adhesive force lowering property and the like. The content of the thermally expandable microspheres is, for example, 1 to 150 parts by weight, preferably 10 to 130 parts by weight, and more preferably 20 to 100 parts by weight, based on 100 parts by weight of the base polymer of the binder containing the thermally expandable microspheres.

When the adhesive constituting the surface of the 2 nd adhesive layer contains thermally expandable microspheres, the arithmetic average roughness Ra of the surface of the 2 nd adhesive layer before expansion of the thermally expandable microspheres (i.e., before heating) is preferably 500nm or less, more preferably 400nm or less, and still more preferably 300nm or less. When the amount is within this range, an adhesive sheet excellent in adhesion to an adherend on the 2 nd adhesive layer side can be obtained. The 2 nd adhesive layer having excellent surface smoothness can be obtained, for example, by the following means: the thickness of the adhesive layer is set to the above range; an adhesive composition containing thermally expandable microspheres is applied to a release liner and dried, and the adhesive layer thus formed is directly transferred to a substrate or onto an intermediate layer (e.g., an elastic intermediate layer) provided on the substrate.

When the 2 nd pressure-sensitive adhesive layer contains thermally expandable microspheres, the pressure-sensitive adhesive layer preferably contains a pressure-sensitive adhesive composed of a base polymer having a dynamic storage modulus at 80℃in the range of 5kPa to 1MPa (more preferably 10kPa to 0.8 MPa). In the case of such an adhesive layer, an adhesive sheet having moderate adhesiveness before heating and having an adhesive strength that is easily reduced by heating can be formed. The dynamic storage modulus can be measured using a dynamic viscoelasticity measuring device (for example, the trade name "ARES" manufactured by Rheometrics corporation) under a measuring condition of a frequency of 1Hz and a heating rate of 10 ℃/min.

Method for producing pressure-sensitive 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 can be produced, for example, by the following method: a method in which an adhesive composition containing an adhesive layer (which may be a 1 st adhesive layer, an a layer or a B layer constituting the 1 st adhesive layer, a 2 nd adhesive layer, or the like) is directly applied to a substrate or directly applied to an intermediate layer (e.g., a B layer, an elastic intermediate layer, or the like) provided on the substrate to form an adhesive layer; a method of applying the adhesive composition to any suitable releasable process material (e.g., a release liner) to form an adhesive layer on the releasable process material, and transferring the adhesive layer to a substrate or an intermediate layer on the substrate; a combination of these; etc. The adhesive composition may be a solvent-based adhesive composition comprising any suitable solvent.

In the case of forming the adhesive layer containing thermally expandable microspheres, the composition containing thermally expandable microspheres, an adhesive and any appropriate solvent may be applied to a substrate to form the adhesive layer. Alternatively, the thermally expandable microspheres may be sprinkled on the adhesive coating layer, and then the thermally expandable microspheres may be embedded in the adhesive using a laminator or the like to form an adhesive layer containing the thermally expandable microspheres.

As a coating method of the above adhesive and each composition, any suitable coating method may be employed. For example, each layer may be formed by drying after coating. Examples of the coating method include: coating methods using a multi-function coater (Multicoater), a die coater, a gravure coater, an applicator, and the like. Examples of the drying method include: natural drying, heat drying, and the like. The heating temperature in the case of performing the heating drying may be set to any appropriate temperature according to the characteristics of the substance to be dried.

Examples

Hereinafter, some embodiments related to the present invention will be described, but the present invention is not intended to be limited to the embodiments shown in the specific examples. In the following description, "parts" and "%" are weight basis unless otherwise specified.

< evaluation method >)

1. Indentation hardness

The indentation hardness H1, H2 was measured by the method described above using a nanoindenter manufactured by Hysicron corporation under the product name "Triboindeter TI-950".

2. Wiredrawing property

Stringiness D1, D2 was measured by the method described above using a nanoindenter manufactured by Hysicron corporation under the product name "Triboindeter TI-950".

3. Swelling test

0.02g of 4-t-butylphenyl glycidyl ether (TBPGE) was added dropwise to the surface of the 1 st adhesive layer using a syringe (syringe diameter: 22 mm), and the mixture was allowed to stand at 23℃for 1 minute in an atmosphere of 50% RH. After absorbing and removing TBPGE remaining on the surface of the adhesive layer with a waste cloth, the thickness T1[ mu ] m of the adhesive layer at the location where TBPGE was dropped was measured. The thickness change amount and the thickness change rate of the pressure-sensitive adhesive layer were calculated from the thickness (initial thickness) T0[ mu ] m of the pressure-sensitive adhesive layer at the site before the TBPGE was dropped and the thickness T1[ mu ] m, by the following formulas.

Thickness variation [ μm ] =t1-T0

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

TMA sag amount

Using a thermo-mechanical analysis device manufactured by TAinstruments corporation under the product name "TMAQ400", at the probe: needle insertion (cylindrical, front end diameter 1mm Φ), nitrogen flow: 50.0ml/min, press-in load: 0.01N, measured ambient temperature: 23.0 ℃, press-in load time: the amount of sagging from the surface of the 1 st adhesive layer was measured under the condition of 60 minutes. The measurement was performed with n=5, and the average value of n=3 obtained by removing the maximum value and the minimum value from these measured values was set as the TMA subsidence amount.

In the case of the pressure-sensitive adhesive sheet having the configuration in which the pressure-sensitive adhesive layer (1 st pressure-sensitive adhesive layer) is provided only on one side of the substrate and the pressure-sensitive adhesive layer (2 nd pressure-sensitive adhesive layer) is not provided on the opposite side (back side) of the substrate, 100 parts of the acrylic polymer having the standard pressure-sensitive adhesive layer (30/70/5/5 (weight ratio to EA/2 EHA/MMA/hea=30) was formed on the back side of the substrate, and after the pressure-sensitive adhesive layer having a thickness of 45 μm, the TMA subsidence was measured.

5. Relaxation time

About 100mg of the adhesive was collected from the adhesive layer constituting the layer A by sorting (stacking), and by pulse NMR measurement using the same as a measurement sample, T was obtained ₂ Relaxation curves. Fitting was performed by using the above formula (1) using analysis software (TDNMR-A), and analysis was performed approximately on 1 component (. Alpha.) to obtain T of the S component ₂ Relaxation time. Wa was all analyzed to be 1. The shortest relaxation time calculated by the analysis method is set as T of S component of A layer obtained by pulse NMR ₂ Relaxation time (T) _2s ). T of S component obtained by pulse NMR of B layer was obtained in the same manner ₂ Relaxation time (T) _2s ). The pulse NMR measurement was performed by the Solid Echo method under the conditions of a 90℃pulse width of 2.1. Mu.sec, a repetition time of 1 sec, and a cumulative number of times of 32, and a measurement temperature of 30℃using a time domain NMR apparatus manufactured by Bruker, apparatus name "TD-NMR the minispec mq".

6. Adhesion to PET

The adhesive sheet was cut into a size of 20mm in width and 140mm in length, and the entire surface of the back surface side (the side opposite to the side on which the 1 st adhesive layer was provided) was bonded to the SUS304 plate with a double-sided adhesive tape (trade name "No.531" manufactured by the eastern electric company). In the pressure-sensitive adhesive sheet having the structure of the 2 nd pressure-sensitive adhesive layer on the back surface side of the base material, the back surface side of the pressure-sensitive adhesive sheet was bonded to the SUS304 plate with the 2 nd pressure-sensitive adhesive layer instead of using the No.531 double-sided pressure-sensitive adhesive tape.

A polyethylene terephthalate (PET) film (trade name "Lumiror S-10", manufactured by Toli Co., ltd., thickness 25 μm, width 30 mm) as an adherend was bonded to the adhesive surface of the adhesive sheet having its back surface side fixed to the SUS304 plate as described above with 1 round trip by a 2kg roller at 23℃under 50% RH. After the PET film was left to stand in the above-mentioned atmosphere for 30 minutes, the load at the time of peeling the PET film from the adhesive sheet was measured under the conditions of a peeling angle of 180 degrees and a stretching speed of 300 mm/minute by using a tensile tester, and the average load at this time was taken as the adhesion force of the adhesive sheet to PET. As the tensile tester, the trade name "Autograph AG-120kN" manufactured by Shimadzu corporation was used.

7. Anchoring force after heating

The adhesive sheet was cut into a size of 20mm in width and 140mm in length, and the entire surface of the back surface side (the side opposite to the side on which the 1 st adhesive layer was provided) was bonded to the SUS304 plate with a double-sided adhesive tape (trade name "No.531" manufactured by the eastern electric company). In the adhesive sheet having the structure of the 2 nd adhesive layer on the back surface side of the base material, the adhesive sheet was bonded to the SUS304 plate with the 2 nd adhesive layer instead of using the No.531 double-sided adhesive tape. After being kept at 150℃for 1 hour, it was allowed to stand at 23℃for 2 hours in 50% RH. Subsequently, a commercially available acrylic pressure-sensitive adhesive tape (trade name: no.315 manufactured by Ridong electric company) was pressure-bonded thereto with a 2kg roller by 1 round trip and allowed to stand for 30 minutes by cutting a cut mark from the surface of the 1 st pressure-sensitive adhesive layer to the depth of the surface of the substrate using a cutter at 23℃under the environment of 50% RH. Thereafter, the load at the time of peeling the acrylic adhesive tape was measured under conditions of a peeling angle of 180 degrees and a stretching speed of 50 mm/min using the tensile tester, and the maximum load at this time was recorded as the anchoring force after heating.

8. Adhesion to sealing resin

The adhesive sheet was cut into a size of 50mm in width and 140mm in length, and a mold frame (opening size: rectangle of 35mm in width and 90mm in length, thickness: 564 μm) was attached to the 1 st adhesive layer. After dispersing a granular epoxy resin sealing material (G730, manufactured by Sumitomo electric Co., ltd.) in the mold frame so that the thickness of the cured resin becomes 0.3mm, the mold frame was covered with a release liner treated with silicone, and the sealing resin was heated and molded on the 1 st adhesive layer under the conditions of a temperature of 145 ℃, a molding time of 600 seconds, a pressurizing condition of 0.3MPa (300 mm square of the platform size), a vacuum time of 600 seconds, and a vacuum degree of-0.1 MPa using a "hydroforming machine NS-VPF-50", manufactured by Meisho-press Co., ltd. The resultant was heated at 150℃for 7 hours to cure the sealing resin, and then allowed to stand at 23℃under 50% RH for 2 hours, and then the portion of the sealing resin in contact with the 1 st adhesive layer was cut into a size of 20mm in width and 88mm in length to prepare an evaluation sample. After the test sample was left to stand at 23℃for 30 minutes in an atmosphere of 50% RH, the load when the self-sealing resin was peeled off the adhesive sheet was measured under conditions of a peeling angle of 180℃and a stretching speed of 300 mm/min by using the tensile tester, and the average load at this time was defined as the adhesive force of the adhesive sheet to the sealing resin.

9. Residual glue resistance

In the measurement of the adhesive force of the sealing resin, the presence or absence of the adhesive residue on the sealing resin after the release of the adhesive sheet was confirmed by visual observation. Based on the result, when the residual glue is confirmed, it is judged that the residual glue preventing property "P" (pool: residual glue preventing property is insufficient), and when the residual glue is not confirmed, it is judged that the residual glue preventing property "G" (Good: residual glue preventing property is Good).

10. Mold flash evaluation

The resin sealing step of the semiconductor chip (Si chip) was performed on the 1 st adhesive surface of the adhesive sheet under the following conditions, and the performance of preventing the sealing resin from penetrating into the interface (die burr) between the chip and the sealing resin was evaluated.

And (3) a carrier: SUS carrier (220 mm phi)

And (3) a chip: dummy chip with level difference (dummy chip manufactured by Global net company) having copper pad (pad target height 5.5 μm, mask: GNC-300 mm-G03-A-300S) on one side of silicon substrate having thickness of 7mm×7mm×400 μm

Engagement means: FC3000W manufactured by Toli engineering Co

Joining conditions: crimping time 6 seconds, crimping pressure 10N, crimping temperature: 23 DEG C

Sealing equipment: MS-150HP manufactured by Apic Yamada Co

Sealing resin: g730 manufactured by Sumitomo electric Co Ltd

Preheating conditions: 130 ℃ x 30 seconds

Time from preheating to beginning sealing: 1 hour

Sealing temperature: 145 DEG C

Vacuum time: 5 seconds

Sealing time: 600 seconds

Mode locking force: 3.6MPa

Sealing thickness: 600 μm

The sealing operation is performed in the following order.

1) The back side of the adhesive sheet was attached to the SUS support via an adhesive layer containing thermally expandable microspheres (attachment conditions: the pressure of an attaching roller is 0.1MPa and the attaching speed is 0.5m/min under the atmosphere of 23 ℃.

As the pressure-sensitive adhesive layer containing the thermally expandable microspheres, the pressure-sensitive adhesive sheet having a structure in which the 2 nd pressure-sensitive adhesive layer containing the thermally expandable microspheres is provided on the back surface side of the base material is directly used. The pressure-sensitive adhesive sheet having a structure in which the 2 nd pressure-sensitive adhesive layer was not provided on the back surface side of the base material, and the back surface side of the pressure-sensitive adhesive sheet was fixed to an SUS support via the standard pressure-sensitive adhesive layer (a pressure-sensitive adhesive layer having a thickness of 45 μm and containing 30 parts of thermally expandable microspheres (trade name "Matsumoto Microsphere F-190D", manufactured by sonpresent oil and fat pharmaceutical company) per 100 parts of the acrylic polymer).

2) The total of 25 dummy chips with level differences were arranged on the 1 st adhesive layer of the adhesive sheet fixed to the SUS carrier using the above-mentioned bonding device so that the interval gradually increased from the center to the outer periphery along 8 radial straight lines having a center angle of 45 degrees. The orientation of the chip is set as follows: the level difference surface (pad formation surface) of the chip is opposite to the 1 st adhesive layer.

3) The SUS support in a state where the dummy chip with the level difference is disposed on the 1 st adhesive layer of the adhesive sheet is preheated under a prescribed condition.

4) After preheating, the chip was allowed to stand at 23℃under 50% RH for 1 hour, and then a predetermined sealing resin was spread over the entire surface of the dummy chip by hand, and the chip was sealed by a predetermined sealing device and sealing conditions.

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

6) After the heat-cured laminate was left to stand at 23℃for 5 days in an atmosphere of 50% RH, the heat-expandable microspheres in the adhesive layer having the adhesive sheet fixed to the SUS carrier were expanded by heating on a heating plate, and the SUS carrier was separated from the laminate.

7) The adhesive sheet was peeled from the laminate from which the SUS support was separated, and a structure including a sealing resin and a dummy chip with a level difference was obtained.

The surface of the structure in contact with the 1 st adhesive surface was observed by a laser confocal microscope (OLS-4000 OLYMPUS), and the presence or absence of the penetration of the sealing resin into the dummy chip with the level difference was confirmed. When residues (residual glue) of the adhesive were confirmed on the surface, the residues were removed by toluene and then observed. As a result, when the sealing resin invasion was observed in all the dummy chips, it was judged as "P" (pool: insufficient mold flash prevention), and when the sealing resin invasion was not observed in all the dummy chips, it was judged as "G" (Good: good mold flash prevention).

11. Evaluation of height difference

A resin sealing process of the semiconductor chip (Si chip) was performed in the same manner as the above mold flash evaluation except that a Si mirror chip (7 mm×7mm×400 μm thick) was used as the semiconductor chip (Si chip) on the 1 st adhesive surface of the adhesive sheet, to obtain a structure including a sealing resin and a Si mirror chip.

In this structure, the surface in contact with the 1 st adhesive surface was observed by a laser confocal microscope (OLS-4000 OLYMPUS), and the height of the interface between the Si chip and the sealing resin in the surface was measured with respect to the Si chip arranged at the center. When the surface was checked for residues (residual glue) of the adhesive, the residues were removed with toluene and then measured. As a result, when the height of the step is less than 3.3. Mu.m, it is judged as "G" (Good: the step is well suppressed), and when the height of the step is 3.3. Mu.m or more, it is judged as "P" (Good: the step is insufficiently suppressed).

< example 1 >

An epoxy-based crosslinking agent (trade name "tetra C", manufactured by mitsubishi gas chemical company) was added to 100 parts of a toluene solution containing 100 parts of a polymer P1 (an acrylic polymer composed of 2-ethylhexyl acrylate (2 EHA)/Acrylic Acid (AA) =95/5 (weight ratio)) and mixed with toluene for dilution (to a total of 100 parts), to prepare an adhesive composition 1a. The pressure-sensitive adhesive composition 1A was applied to a release treated surface of a release film R1 (trade name "ceramel MDAR", manufactured by origo film processing company, thickness 38 μm) formed of polyethylene terephthalate (PET) having one surface subjected to a release treatment with a silicone release treatment agent, and dried, and a pressure-sensitive adhesive layer 1A (thickness l1=10 μm) was formed on the release film R1.

Adhesive composition 1b was prepared in the same manner as in adhesive composition 1a, except that 5 parts of an epoxy-based crosslinking agent was changed to 3 parts of an isocyanate-based crosslinking agent (trade name "cornonate L", manufactured by eash co.). The pressure-sensitive adhesive composition 1B was applied to one side of a PET film (trade name "Lumirror S10", thickness 38 μm) as a base material, and dried, whereby a pressure-sensitive adhesive layer 1B (thickness l2=10 μm) was formed on one side of the base material.

The adhesive surface of the adhesive layer 1A formed on the release film R1 was bonded to the adhesive surface of the adhesive layer 1B, whereby an adhesive sheet (adhesive sheet having a structure of a base material/adhesive layer 1B (B layer)/adhesive layer 1A (a layer)) in which the 1 st adhesive layer including the adhesive layer 1B and the adhesive layer 1A was disposed on one side of the base material was obtained.

< example 2 >

An adhesive sheet having a structure of a base material/an adhesive layer 2B (B layer)/an adhesive layer 2A (a layer) was obtained in the same manner as in example 1 except that the amount of the crosslinking agent used and the thicknesses of the a layer and the B layer were as shown in table 1.

< example 3 >

An epoxy-based crosslinking agent (trade name "tetra C", manufactured by mitsubishi gas chemical company) was added to 100 parts of a toluene solution containing 100 parts of polymer P2 (acrylic polymer composed of n-Butyl Acrylate (BA)/Ethyl Acrylate (EA)/aa=50/50/5 (weight ratio) monomer components, and 5 parts of toluene for dilution (to a total of 100 parts) were mixed to prepare an adhesive composition 3a. The pressure-sensitive adhesive composition 3A was applied to the release treated surface of the release film R1, and dried to form a pressure-sensitive adhesive layer 3A (thickness l1=5 μm) on the release film R1.

Adhesive composition 3b was prepared in the same manner as in adhesive composition 3a, except that 5 parts of an epoxy-based crosslinking agent was changed to 3 parts of an isocyanate-based crosslinking agent (trade name "cornonate L", manufactured by eash co.). The pressure-sensitive adhesive composition 3B was applied to one side of a PET film (trade name "Lumirror S10", thickness 38 μm) as a base material, and dried, whereby a pressure-sensitive adhesive layer 3B (thickness l2=35 μm) was formed on one side of the base material.

An adhesive sheet having a structure of a base material/an adhesive layer 3B (layer B)/an adhesive layer 3A (layer a) is obtained by bonding an adhesive surface of the adhesive layer 3A formed on the release film R1 to an adhesive surface of the adhesive layer 3B.

< example 4 >

An adhesive sheet having a structure of a base material/an adhesive layer 4B (B layer)/an adhesive layer 4A (a layer) was obtained in the same manner as in example 3 except that the thicknesses of the a layer and the B layer were set as shown in table 1.

< example 5 >

To 100 parts of a toluene solution containing 100 parts of polymer P3 (an acrylic polymer having an SP value of 20.7 and composed of monomer components of EA/2 EHA/Methyl Methacrylate (MMA)/2-hydroxyethyl acrylate (HEA) =30/70/5/4 (weight ratio), 30 parts of thermally expandable microspheres (trade name "Matsumoto Microsphere F-190D", manufactured by sonpresent fat and oil pharmaceutical company), 1.4 parts of an isocyanate-based crosslinking agent (trade name "cornate L", manufactured by eastern co., ltd.), 10 parts of a tackifier (trade name "mightyoace G125", manufactured by Yasuhara Chemical) and toluene for dilution (in an amount of 100 parts total) were added and mixed to prepare an adhesive composition 5c. The pressure-sensitive adhesive composition 5C was applied to the release treated surface of the release film R1 and dried, whereby a pressure-sensitive adhesive layer 5C (thickness 45 μm) was formed on the release film R1.

The adhesive surface of the adhesive layer 5C formed on the release film R1 was bonded to the back surface of the substrate of the adhesive sheet of example 4, thereby obtaining a double-sided adhesive sheet having a structure of adhesive layer 5C (2 nd adhesive layer)/substrate/adhesive layer 4B (B layer)/adhesive layer 4A (a layer).

< example 6 >

To a toluene solution containing 100 parts of polymer P3, 1.5 parts of an isocyanate-based crosslinking agent (trade name "cornonate L" manufactured by eason corporation), 10 parts of a tackifier (trade name "mightyoace G125" manufactured by Yasuhara Chemical corporation), and toluene for dilution (in an amount of 100 parts total) were added and mixed to prepare an adhesive composition 6a. The pressure-sensitive adhesive composition 6c was applied to the release treated surface of the release film R1 and dried, whereby a pressure-sensitive adhesive layer 6A (thickness: 30 μm) was formed on the release film R1.

To a toluene solution containing 100 parts of polymer P3, 1 part of an isocyanate-based crosslinking agent (trade name "cornonate L" manufactured by eason corporation) was added and toluene for dilution (to a total of 100 parts) was mixed to prepare an adhesive composition 6b. The pressure-sensitive adhesive composition 6B was applied to one side of a PET film (trade name "Lumirror S10", thickness 38 μm) as a base material, and dried, whereby a pressure-sensitive adhesive layer 6B (thickness l2=20 μm) was formed on one side of the base material.

An adhesive sheet having a structure of a base material/an adhesive layer 6B (layer B)/an adhesive layer 6A (layer a) is obtained by bonding an adhesive surface of the adhesive layer 6A formed on the release film R1 to an adhesive surface of the adhesive layer 6B.

< example 7 >

To 100 parts of a toluene solution containing 100 parts of a polymer P4 (an acrylic polymer obtained by modifying 11 moles of 2-isocyanatoethyl methacrylate (Karenz MOI: manufactured by the company of zhaowa) with respect to the above-mentioned HEA22, a monomer component consisting of 2 EHA/Acryloylmorpholine (ACMO)/hea=75/25/22 (molar ratio), 5 parts of an isocyanate-based crosslinking agent (manufactured by eastern corporation, trade name "cornonate L"), 10 parts of a UV-curable oligomer (manufactured by the company of eastern synthesis, trade name "Aronix M321"), 3 parts of a photoinitiator (manufactured by the company of IGM Resins, trade name "Omnirad 651"), and ethyl acetate for dilution were added to prepare an adhesive composition 7a. The pressure-sensitive adhesive composition 7A was applied to the release treated surface of the release film R1 and dried, whereby a pressure-sensitive adhesive layer 7A (thickness l1=5 μm) was formed on the release film R1.

To a toluene solution containing 100 parts of polymer P, 1 part of an isocyanate-based crosslinking agent (trade name "cornonate L" manufactured by eastern co., ltd.), 10 parts of a UV-curable oligomer (trade name "Aronix M321" manufactured by eastern co., ltd.), 3 parts of a photoinitiator (trade name "Omnirad651" manufactured by IGM Resins co., ltd.), and ethyl acetate for dilution were added and mixed to prepare an adhesive composition 7b. The pressure-sensitive adhesive composition 7B was applied to one side of a PET film (trade name "Lumirror S10", thickness 38 μm) as a base material, and dried, whereby a pressure-sensitive adhesive layer 7B (thickness l2=150 μm) was formed on one side of the base material.

An adhesive sheet having a structure of a base material/an adhesive layer 7B (layer B)/an adhesive layer 7A (layer a) is obtained by bonding an adhesive surface of the adhesive layer 7A formed on the release film R1 to an adhesive surface of the adhesive layer 7B.

The obtained adhesive sheet was evaluated by the above-described method. The results are shown in Table 1. In the measurement of the anchoring force after heating, the peeling was performed at the interface between the acrylic pressure-sensitive adhesive tape and the surface to be measured, and no anchoring failure with the substrate (PET film) was observed.

TABLE 1

/>

As shown in table 1, in the adhesive sheets of examples 1 to 5 in which the indentation hardness H1 was 0.10MPa to 0.50MPa, and the indentation hardness H2 was 0.001MPa to 0.090MPa, the mold flash prevention performance was good, and the residual glue prevention performance was also good.

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of protection of the application. The claims include modifications and changes of the specific examples described above.

Description of the reference numerals

1: semiconductor chip

2: sealing resin

10: substrate (substrate film)

20: adhesive layer (1 st adhesive layer)

22: layer A

24: layer B

30: adhesive layer 2

100. 200, 300: pressure-sensitive adhesive sheet

A: determination of position A

B: determination of position B

Claims

1. An adhesive sheet comprising a base material and an adhesive layer disposed on at least one side of the base material,

in the indentation hardness measurement using a nanoindenter, the indentation hardness H1 of the surface of the adhesive layer is 0.10MPa or more and 0.50MPa or less, and the indentation hardness H2 measured at a position at a distance of 4 μm from the base material to the surface side of the adhesive layer in the cross section of the adhesive sheet is 0.001MPa or more and 0.090MPa or less.

2. The adhesive sheet according to claim 1, wherein a 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.

3. The adhesive sheet according to claim 1 or 2, wherein in the stringiness evaluation by a nanoindenter, the stringiness D1 of the surface of the adhesive layer is 50nm or more and 500nm or less, and the stringiness D2 measured at a position where the distance from the base material to the surface side of the adhesive layer is 4 μm in a cross section of the adhesive sheet is 150nm or more and 1000nm or less.

4. The adhesive sheet according to claim 3, wherein a ratio (D2/D1) of the stringiness D2[ nm ] to the stringiness D1[ nm ] is 0.3 or more and 20.0 or less.

5. The adhesive sheet according to any one of claims 1 to 4, wherein a difference (T1-T0) between a thickness T1[ μm ] of the adhesive layer and an initial thickness T0[ μm ] of the adhesive layer after dropping 4-T-butylphenyl glycidyl ether to a surface of the adhesive layer and standing for 1 minute is 20 μm or less.

6. The adhesive sheet according to any one of claims 1 to 5, wherein the amount of sinking of the needle probe from the surface of the adhesive layer measured under the conditions of a measured ambient temperature of 23 ℃, a pressing load of 0.01N, and a pressing load time of 60 minutes is 3.50 μm or more and 20.0 μm or less using a thermo-mechanical analysis device.

7. The adhesive sheet according to any one of claims 1 to 6, wherein the thickness of the adhesive layer is 5 μm or more and 110 μm or less.

8. The adhesive sheet according to any one of claims 1 to 7, wherein the substrate is a substrate film composed of a resin material having a glass transition temperature of 25 ℃ or higher.

9. The adhesive sheet according to any one of claims 1 to 8, which has an adhesive force to a polyethylene terephthalate film of 0.05N/20mm or more and 1.00N/20mm or less.

10. The adhesive sheet according to any one of claims 1 to 9, wherein an anchoring force of the adhesive layer to the substrate measured at 23 ℃ after heating the adhesive sheet at 150 ℃ for 1 hour is 4.00N/20mm or more.

11. The adhesive sheet according to any one of claims 1 to 10, wherein the adhesive constituting at least the surface of the adhesive layer is an acrylic adhesive having an acrylic polymer as a base polymer.

12. The adhesive sheet according to claim 11, wherein the acrylic polymer has an SP value of 18.0 to 20.0.

13. The adhesive sheet according to any one of claims 1 to 12, wherein the adhesive layer comprises: a layer a constituting a surface of the adhesive layer, and a layer B disposed between the layer a and the substrate and adjacent to the substrate.

14. The adhesive sheet according to claim 13, wherein the thickness L1 of the a layer is 1 μm or more and 10 μm or less.

15. The adhesive sheet according to claim 13 or 14, wherein the thickness L2 of the B layer is 4 μm or more and 100 μm or less.

16. The adhesive sheet according to any one of claims 13 to 15, wherein a ratio (L2/L1) of a thickness L2[ μm ] of the B layer to a thickness L1[ μm ] of the a layer is 1.0 to 100.0.

17. The adhesive sheet according to any one of claims 13 to 16, wherein T of S component of the a layer obtained by pulse NMR ₂ Relaxation time (T) _2s ) 45 musec or less, T of S component obtained by pulse NMR of the B layer ₂ Relaxation time (T) _2s ) Longer than 45 musec.

18. The adhesive sheet according to any one of claims 13 to 17, wherein the a layer is crosslinked by an epoxy-based crosslinking agent and the B layer is crosslinked by an isocyanate-based crosslinking agent.

19. The adhesive sheet according to any one of claims 1 to 18, comprising: the base material, the adhesive layer arranged on one side of the base material, and the 2 nd adhesive layer arranged on the opposite side of the base material from the adhesive layer,

at least the surface of the 2 nd adhesive layer is composed of an adhesive containing thermally expandable microspheres.