TW202338049A - adhesive sheet - Google Patents

Abstract

The present invention provides an adhesive sheet having a satisfactory balance of reduced adhesive residue when peeling and excellent conformability to the surface shape of an adherend. Provided is an adhesive sheet comprising a base material and an adhesive layer that is disposed on at least one side of the base material. The indentation hardness H1 of the surface of the adhesive layer of the adhesive sheet is 0.10-0.50 MPa, and, in a cross-section of the adhesive sheet, the indentation hardness H2 measured at a position 4 [mu]m from the base material in the direction of the surface of the adhesive layer is 0.001-0.090 MPa.

Description

adhesive sheet

The present invention relates to an adhesive sheet. This application claims priority based on Japanese Patent Application No. 2021-115926 filed on July 13, 2021, and all the contents of this application are incorporated into this specification by reference.

In the manufacturing of semiconductor parts including semiconductor wafers, the semiconductor wafers are sometimes resin-sealed to prevent damage to the semiconductor wafers, expansion of metal wiring, and the like. In the resin sealing step, from the viewpoint of workability and the like, the semiconductor wafer may be resin-sealed on an adhesive sheet. For example, a plurality of semiconductor wafers are arranged on an adhesive layer of an adhesive sheet serving as a temporary fixing material, and the semiconductor wafers are once sealed on the adhesive layer. Thereafter, in a specific subsequent step, the adhesive sheet is peeled off from the structure including the sealing resin and the semiconductor chip. Prior technical literature patent documents

Patent Document 1: Japanese Patent Application Publication No. 2001-308116 Patent Document 2: Japanese Patent Application Publication No. 2001-313350

[Problem to be solved by the invention]

As the adhesive sheet used in the above-mentioned step, it is required that no paste residue (adhesive residue) is generated on the structure when the adhesive sheet is peeled off from the structure containing the sealing resin and the semiconductor chip. In order to suppress the above-mentioned paste residue, the adhesive layer in which the semiconductor chip is arranged in the above-mentioned adhesive sheet is usually formed with an adhesive having a very high elastic modulus. However, there may be steps on the surface of the semiconductor wafer caused by metal wiring formed in advance. As a result, if the adhesive layer has a high elastic modulus, the adhesive will not be able to fully adhere to the steps on the surface of the wafer, and it is easy to Defects occur when the sealing resin invades the interface between the chip and the adhesive.

The present invention was innovated in view of the above situation, and an object of the present invention is to provide an adhesive sheet that has a good balance between suppression of paste residue during peeling and good followability to the surface shape of the adherend. [Technical means to solve problems]

The adhesive sheet provided by this specification includes a base material and an adhesive layer arranged on at least one side of the base material. Regarding the above-mentioned adhesive sheet, in the indentation hardness measurement using a nanoindentation instrument, the indentation hardness H1 of the surface of the above-mentioned adhesive layer is 0.10 MPa or more and 0.50 MPa or less, and in the cross section of the above-mentioned adhesive sheet The indentation hardness H2 measured at a distance of 4 μm from the base material to the surface side of the adhesive layer is 0.001 MPa or more and 0.090 MPa or less. By setting the indentation hardness H1 measured at the surface of the adhesive layer as the measurement position (hereinafter also referred to as "measurement position A") to be 0.10 MPa or more, paste residue during peeling can be suppressed. In addition, by measuring the inner side (substrate side) of the above-mentioned measurement position A, specifically, in the cross section of the above-mentioned adhesive sheet, the position 4 μm away from the above-mentioned substrate to the surface side of the above-mentioned adhesive layer (hereinafter also referred to as The indentation hardness H2 measured at the "measurement position B") is 0.090 MPa or less, which can improve the ability to follow the surface shape of the adherend. Therefore, an adhesive sheet with indentation hardness H1 and H2 in the above range can achieve a well-balanced combination of suppression of paste residue during peeling and good followability to the surface shape of the adherend.

In some aspects, the ratio (H2/H1) of the above-mentioned indentation hardness H2 [MPa] to the above-mentioned indentation hardness H1 [MPa] is 0.002 or more and 0.90 or less. According to the adhesive sheet, the indentation hardness H2 at the measured position B (inside) is less than 0.90 times the indentation hardness H1 at the measured position A (surface), which can better balance the suppression of paste residue and the surface shape. The following nature.

In some aspects, in the evaluation of stringiness using a nanoindentation instrument, the stringiness D1 of the surface of the adhesive layer is 50 nm or more and 500 nm or less. The stringiness D1 on the surface of the adhesive layer (measurement position A) is 500 nm or less. From the viewpoint of suppressing paste residue, the stringiness D1 on the surface of the adhesive layer (measurement position A) is 500 nm. nm and below are more advantageous. In the above evaluation of stringiness, the stringiness D2 measured at a position (measurement position B) 4 μm away from the base material to the surface side of the adhesive layer in the cross section of the adhesive sheet is preferably 150 nm. Above 1000 nm and below. With the adhesive layer having the drawability D2 in the above range, it is easy to achieve good followability to the surface shape.

In some aspects, the ratio (D2/D1) of the stringability D2 [nm] to the stringability D1 [nm] (D2/D1) is 0.3 or more and 20.0 or less. An adhesive sheet with a ratio (D2/D1) within the above range is likely to achieve a better balance between the suppression of paste residue and the ability to follow the surface shape.

In some aspects, the initial thickness T0 [μm] of the adhesive layer and the thickness of the adhesive layer after dropping 4-tert-butylphenyl glycidyl ether onto the surface of the adhesive layer and leaving it for 1 minute The difference in T1 [μm] (T1-T0; hereinafter also referred to as “thickness variation”) is 20 μm or less. Regarding an adhesive sheet having an adhesive layer with a small change in thickness, for example, in a usage state in which a semiconductor wafer is disposed on the adhesive layer and the semiconductor wafer is sealed with a resin, it is difficult to separate the semiconductor wafer from the adhesive layer. It is preferable because a step difference (gap) is generated between the sealing resins.

Regarding certain types of adhesive sheets, a thermomechanical analyzer (TMA) was used to measure the needle penetration under the conditions of an ambient temperature of 23°C, a press-in load of 0.01 N, and a press-in load time of 60 minutes. The sinking amount of the needle from the surface of the above-mentioned adhesive layer is 3.50 μm or more and 20.0 μm or less. An adhesive sheet with a sinking amount within the above range can be used in a manner in which, for example, a semiconductor chip is disposed on the adhesive layer and the semiconductor chip is sealed with a resin. Surface shape followability and suppression of semiconductor chip embedding in the adhesive sheet.

In some aspects of the adhesive sheet disclosed herein, the thickness of the adhesive layer is from 5 μm to 110 μm. According to the adhesive layer having the above thickness, the effect caused by having different characteristics between the measurement position A and the measurement position B can be better exerted.

In some aspects, the above-mentioned substrate is a substrate film including a resin material with a glass transition temperature (Tg) of 25°C or above. The adhesive sheet having the above-described adhesive layer on the base film is used, for example, in a method of arranging a 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, embedding of the semiconductor wafer in the adhesive sheet can be suppressed, and the step difference (gap) between the semiconductor wafer and the sealing resin can be suppressed.

The adhesive force of certain types of adhesive sheets to polyethylene terephthalate (PET) film is 0.05 N/20 mm or more and 1.00 N/20 mm or less. If it is within this range, the adherend (for example, a semiconductor wafer) can be suitably fixed, and the load applied to the adherend when peeling off the adhesive sheet can be suppressed.

In some aspects, after heating the above-mentioned adhesive sheet at 150°C for 1 hour, the gripping force of the above-mentioned adhesive layer on the above-mentioned substrate measured at 23°C is more than 4.00 N/20 mm. Regarding the adhesive sheet that exhibits the above-mentioned gripping force, for example, in the use mode of carrying out the step of arranging a 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 , is also preferable because it can suppress paste residue in the subsequent peeling step.

In some aspects, the adhesive constituting at least the surface of the adhesive layer is an acrylic adhesive using an acrylic polymer as a base polymer. The technology disclosed here can be preferably implemented in an adhesive sheet having an adhesive layer including an acrylic adhesive on at least the surface (adhesive surface).

In some aspects, the SP (Solubility Parameter) value of the acrylic polymer is 18.0 to 20.0. By forming an adhesive surface with an acrylic adhesive using an acrylic polymer with an SP value in the above range as the base polymer, the indentation hardness H1 in the above range can be easily achieved, and for example, a semiconductor wafer can be placed on the adhesive surface. In the usage mode of the step of sealing the semiconductor chip with resin, it is also easy to prevent the adhesive force to the sealing resin from becoming too high.

In some aspects of the adhesive sheet disclosed here, the above-mentioned adhesive layer includes: an A layer constituting the surface of the adhesive layer, and a layer disposed between the above-mentioned A layer and the above-mentioned base material and adjacent to the base material. B floor. The adhesive sheet disclosed here can be preferably implemented as having an adhesive layer having a structure including layer A (surface layer) and layer B (undercoat layer).

The thickness L1 of the above-mentioned layer A is preferably 1 μm or more and 10 μm or less, for example. With such a thickness of the A layer, it is easy to achieve a better balance between the suppression of paste residue and the ability to follow the surface shape. The thickness L2 of the above-mentioned B layer is preferably not less than 4 μm and not more than 100 μm, for example. With such a thickness of the B layer, it is easy to achieve a better balance between the suppression of paste residue and the ability to follow the surface shape. The ratio (L2/L1) of the thickness L2 [μm] of the above-mentioned layer B to the thickness L1 [μm] of the above-mentioned layer A is preferably 1.0 to 100.0.

In some aspects, the T ₂ relaxation time (T _2s ) of the S component obtained by pulse NMR (Nuclear Magnetic Resonance, Nuclear Magnetic Resonance) of the above-mentioned layer A is 45 μsec or less, and the S component obtained by pulse NMR of the above-mentioned layer B is The T ₂ relaxation time (T _2s ) of the component is longer than 45 μsec. According to the adhesive sheet having the adhesive layer including the A layer and the B layer that satisfies the above relaxation time (T _2s ), it is easy to achieve a better balance between the suppression of component migration between the adhesive layer/sealing resin and the improvement of the surface shape. Followability.

In some aspects, the above-mentioned layer A is cross-linked by an epoxy-based cross-linking agent, and the above-mentioned layer B is cross-linked by an isocyanate-based cross-linking agent. The adhesive sheet disclosed here can be preferably implemented in the form of an adhesive layer having such a structure.

In some aspects of the adhesive sheet disclosed here, the adhesive sheet includes the above-mentioned base material, the above-mentioned adhesive layer (first adhesive layer) arranged on one side of the above-mentioned base material, and the above-mentioned adhesive layer arranged on one side of the above-mentioned base material. The second adhesive layer on the opposite side to the above-mentioned adhesive layer. Since the adhesive sheet with such a structure can be fixed on an appropriate carrier using the second adhesive layer, and the resin sealing step on the first adhesive layer is performed in this state, it has better usability.

In some aspects, at least the surface of the second adhesive layer includes an adhesive containing thermally expandable microspheres. This aspect of the adhesive sheet is preferably heated for an appropriate period of time to expand the thermally expandable microballoons, thereby easily releasing the bond between the second adhesive layer and the adherend.

Furthermore, what can be obtained by appropriately combining the various elements described in this specification may also be included in the scope of the invention that is protected by the patent application in this case.

Preferred embodiments of the present invention will be described below. Matters other than matters specifically mentioned in this specification, that is, matters necessary to implement the present invention, can be understood by those skilled in the art based on the teachings regarding the implementation of the invention described in this specification and the technical common sense at the time of filing. The present invention can be implemented based on the content disclosed in this specification and the technical common sense in this field. Furthermore, in the following drawings, members and parts that perform the same functions are sometimes labeled with the same symbols for description, and sometimes repeated descriptions are omitted or simplified. In addition, the embodiments described in the drawings are schematic in order to clearly explain the present invention, and do not necessarily accurately represent the dimensions or reduction ratio of the products actually provided.

In this specification, the "base polymer" of the adhesive refers to the main component of the rubber-like polymer contained in the adhesive, and other than that, it is not to be interpreted in any way. The above-mentioned rubber-like polymer refers to a polymer that exhibits rubber elasticity in a temperature range near room temperature. In addition, in this specification, the "main ingredient" refers to the ingredient contained in more than 50% by weight unless otherwise specified. In addition, in this specification, "acrylic polymer" refers to a polymer containing a monomer unit derived from a monomer having at least one (meth)acrylyl group per molecule as a monomer unit constituting the polymer. . Hereinafter, a monomer having at least one (meth)acrylyl group in one molecule is also referred to as an "acrylic monomer". Therefore, an acrylic polymer in this specification is defined as a polymer containing monomer units derived from acrylic monomers. Typical examples of acrylic polymers include: the proportion of acrylic monomers in all monomers used in the synthesis of the acrylic polymer exceeds 50% by weight (preferably exceeds 70% by weight, for example, exceeds 90% by weight) polymer. Hereinafter, the monomers used in the synthesis of the polymer are also referred to as monomer components constituting the polymer. In addition, in this specification, "(meth)acrylyl group" means an acrylyl group and a methacrylyl group inclusively. Similarly, "(meth)acrylate" refers to acrylate and methacrylate inclusively, and "(meth)acrylic acid" refers to acrylic acid and methacrylic acid inclusively. Therefore, the concept of the acrylic monomer here can include both a monomer having an acrylic group (acrylic monomer) and a monomer having a methacrylic group (methacrylic monomer).

＜Overview of adhesive sheets＞ The adhesive sheet disclosed here can be preferably used as a temporary fixing material when resin sealing a semiconductor chip. More specifically, regarding the adhesive sheet of the present invention, when a semiconductor chip is arranged on the adhesive layer of the adhesive sheet, the semiconductor chip is covered with a sealing resin (usually an epoxy resin), so that the sealing When the resin is hardened and the semiconductor chip is resin-sealed, the adhesive sheet of the present invention can be used as a temporary fixing material for the semiconductor chip. When the semiconductor wafer is sealed with resin and specific subsequent steps are performed (for example, back grinding of the sealing resin, pattern formation, bump formation, wafering (cutting)), the above-mentioned adhesive sheet can self-contain the sealing resin and the semiconductor wafer. The structure is peeled off. The epoxy equivalent of the sealing resin is, for example, 50 g/eq to 500 g/eq.

FIG. 1 is a schematic cross-sectional view showing one embodiment of the adhesive sheet disclosed here. The adhesive sheet 100 includes a base material 10 and an adhesive layer (first adhesive layer) 20 arranged on one side of the base material 10 . Regarding this adhesive sheet 100, the indentation hardness H1 of the surface of the adhesive layer (first adhesive layer) 20, that is, the measurement position A (arrow A in Figure 1) is 0.10 MPa or more, and is at least 0.10 MPa. The indentation hardness H2 measured at a position 4 μm away from the base material 10 to the surface side of the adhesive layer 20 in the cross section (measurement position B indicated by arrow B in Figure 1) is 0.09 MPa or less.

The adhesive sheet 100 may be used for resin sealing of semiconductor wafers as shown in FIG. 2 . First, a plurality of semiconductor wafers 1 are bonded to the adhesive layer (first adhesive layer) of the adhesive sheet 100 (step (i)). Secondly, the semiconductor wafers 1 are covered with the semi-hardened product 2' of the sealing resin (step (i)). Step (ii)): Curing the semi-hardened material 2' to seal the semiconductor wafer 1 with the sealing resin 2 (step (iii)). The semi-hardened product 2' can be formed using a composition containing a naphthalene-type bifunctional epoxy resin (epoxy equivalent: 144), for example. Thereafter, when a specific subsequent step is performed, the adhesive sheet 100 is peeled off from the structure 50 including the semiconductor chip 1 and the sealing resin 2 (step (iv)).

Regarding the adhesive sheet disclosed here, by setting the indentation hardness H1 at the measurement position A to be 0.10 MPa or more, paste residue is less likely to occur on the structure 50 in step (iv) shown in FIG. 2 . In addition, by setting the indentation hardness H2 inside the adhesive layer, specifically at the measurement position B, to be 0.09 MPa or less, the adhesive layer can be made to follow the surface shape of the adherend well (for example, it can be present in The step difference caused by the metal wiring on the side surface of the adhesive layer of the semiconductor chip 1) can prevent the occurrence of defects (model flash) in which the sealing resin 2 invades the interface between the adhesive sheet and the semiconductor chip 1.

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

FIG. 4 is a schematic cross-sectional view showing another embodiment of the adhesive sheet disclosed here. The adhesive sheet 300 further includes a second adhesive layer 30 on the back side of the base material 10 (the side opposite to the adhesive layer 20). That is, the adhesive sheet 300 is provided with the adhesive layer 20, the base material 10, and the 2nd adhesive layer 30 in this order. By having the second adhesive layer 30, when performing resin sealing on the carrier, the adhesive sheet 300 can be easily fixed to the carrier by attaching the second adhesive layer 30 side to the carrier. Tool.

In some embodiments, at least the surface of the second adhesive layer includes an adhesive containing thermally expandable microspheres. By heating the adhesive layer containing thermally expandable microspheres above a specific temperature, the thermally expandable microspheres can expand, causing unevenness on the surface of the adhesive layer, thereby reducing or disappearing the adhesive force. By forming at least the surface of the second adhesive layer with an adhesive containing thermally expandable microspheres, the required adhesiveness can be expressed when the adhesive sheet is fixed (for example, fixed to a carrier) through the second adhesive layer. , when peeling off the adhesive sheet (for example, when peeling off from the above-mentioned carrier), heating can be used to reduce or disappear the adhesive force, thereby exhibiting good peelability. An elastic intermediate layer (which may be an adhesive layer) that does not contain thermally expandable microspheres or has a small content of thermally expandable microspheres can also be disposed between the adhesive layer containing thermally expandable microspheres and the substrate.

(indentation hardness) Regarding the indentation hardness H1 of the adhesive sheet disclosed here, from the viewpoint of suppressing paste residue, it is more appropriate for the indentation hardness H1 of the adhesive sheet to be 0.10 MPa or more (for example, more than 0.10 MPa), and preferably 0.12 MPa or above. In certain aspects, the indentation hardness H1 may be 0.15 MPa or more, 0.18 MPa or more, or 0.20 MPa or more. Regarding the adhesive layer with a high indentation hardness H1, generally speaking, in the use mode of carrying out the steps of arranging the semiconductor wafer on the adhesive layer and sealing the semiconductor wafer with resin, it is suppressed that the semiconductor wafer and the adhesive layer can be separated. From the perspective of the step (gap) generated at the boundary of the sealing resin, an adhesive layer with a higher indentation hardness H1 tends to be more advantageous. In addition, the indentation hardness H1 is suitably 0.50 MPa or less, preferably 0.40 MPa or less. From the viewpoint of easily expressing adhesion to the surface of the adherend or moderate viscosity on the surface of the adhesive layer, in some aspects, the indentation hardness H1 may be, for example, 0.30 MPa or less or 0.28 MPa or less. , it may be 0.25 MPa or less, it may be 0.23 MPa or less, or it may be 0.21 MPa or less.

Regarding the indentation hardness H2 of the adhesive sheet disclosed here, it is more appropriate to be lower than the above-mentioned indentation hardness H1. From the perspective of improving the ability to follow the surface shape of the adherend, the indentation hardness H2 of the adhesive sheet is lower than the above-mentioned indentation hardness H1. Preferably, it is below 0.090 MPa. From the viewpoint of obtaining higher followability, in some aspects, the indentation hardness H2 may be 0.080 MPa or less, 0.060 MPa or less, or 0.050 MPa or less. The lower limit of the indentation hardness H2 may be, for example, 0.001 MPa or more, and is not particularly limited. From the viewpoint of preventing aggregation damage inside the adhesive layer, in some aspects, the indentation hardness H2 is more appropriately 0.005 MPa or more, preferably 0.010 MPa or more, and may be 0.030 MPa or more, or 0.040 MPa. Above, it may be 0.050 MPa or above, or 0.060 MPa or above.

The ratio (H2/H1) of the above-mentioned indentation hardness H2 [MPa] to the above-mentioned indentation hardness H1 [MPa] is suitably 0.90 or less, for example, preferably 0.70 or less, 0.50 or less, or 0.40 or less. It can also be below 0.30. Moreover, the said ratio (H2/H1) is suitably 0.002 or more, for example, Preferably it is 0.005 or more, More preferably, it is 0.01 or more. An adhesive sheet with the ratio (H2/H1) in this range can easily achieve a well-balanced combination of suppression of paste residue and ability to follow surface shapes.

(drawn) In the adhesive sheet disclosed here, the range of the drawability D1 at the measurement position A can be, for example, 800 nm or less, and is not particularly limited. In some aspects, from the viewpoint of improving the prevention of paste residue, it is more appropriate for the stringiness D1 to be 500 nm or less, preferably 300 nm or less, or 250 nm or less, or 200 nm or less, or Can be below 150 nm. In addition, from the viewpoint of exerting moderate viscosity on the surface of the adhesive layer, for example, making it easy to place a semiconductor chip on the surface of the adhesive layer, the stringiness D1 is preferably 50 nm or more, and may be 80 nm or more. It is above 100 nm, and it can also be above 120 nm.

In the adhesive sheet disclosed here, the range of the drawability D2 at the measurement position B can be, for example, 100 nm or more, and is not particularly limited. From the perspective of improving the ability to follow the surface shape of the adherend, the drawability The property D2 is preferably 150 nm or more, and more preferably 200 nm or more. In certain aspects, the drawability D2 may be above 300 nm, above 400 nm, or above 500 nm. In addition, the stringability D2 may be, for example, 2500 nm or less. From the viewpoint of preventing aggregation damage inside the adhesive layer, the stringiness D2 is preferably 1500 nm or less, more preferably 1000 nm or less, and may also be 800 nm or less. It can also be below 600 nm.

The ratio (D2/D1) of the stringability D2 [nm] to the stringability D1 [nm] (D2/D1) may be, for example, 0.3 or more, 0.5 or more, or 1.0 or more. In certain aspects, the above ratio (D2/D1) is preferably more than 1.0 (for example, more than 1.2), may be more than 2.5, may be more than 3.5, may also be more than 5.0. Moreover, the said ratio (D2/D1) is suitably 20.0 or less, for example, 15.0 or less is more advantageous, Preferably it is 10.0 or less, It may be 8.0 or less, It may be 7.0 or less, It may be 6.0 or less. An adhesive sheet whose ratio (D2/D1) is within the range specified by any combination of the above upper and lower limits can easily achieve a well-balanced combination of suppression of paste residue and ability to follow the surface shape.

Regarding the indentation hardness H1, H2 and drawability D1, D2, use a nanoindentation instrument to press the indenter vertically from the surface of the sample to a specific depth at a specific measurement position, and then pull it out. At this time, the change of the load (vertical axis) applied by the above-mentioned indenter is plotted against the displacement (horizontal axis) of the indenter using the surface of the above-mentioned sample as a reference, and based on the load (pressure) thus obtained - The indentation hardness H1, H2 and the drawability D1, D2 were obtained from the unloading (pull-out) curve. Here, in the measurement of the indentation hardness H1 and the drawability 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 drawability D2, the position 4 μm away from the base material to the surface side of the adhesive layer in the cross section of the adhesive sheet was set as the measurement position (measurement position B).

Regarding the indentation hardness [MPa], the maximum load (Pmax) [μN] of the load curve when the indenter is pressed into a specific depth is divided by the contact projected area (A) of the indenter, that is, the following formula: Indentation The indentation hardness [MPa] is obtained by calculating the indentation hardness [MPa]=Pmax/A. The indentation hardness can be set 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 cross-linking, the type of cross-linking agent, etc.) the above range.

Drawnability [nm] is schematically shown in Figure 5 and can be defined as the displacement amount when the unloading curve becomes zero load on the negative displacement side. The stringiness can be set within the above range by appropriately selecting the composition of the adhesive constituting the adhesive layer (for example, the composition of the base polymer, the degree of cross-linking, the type of cross-linking agent, etc.).

Regarding the indentation hardness and drawability, specifically, the nanoindentation instrument manufactured by Hysitron Corporation, product name "Triboindenter TI-950" or its equivalent can be measured under the following conditions. [Measurement conditions] Indenter used: Berkovich (triangular pyramid) type diamond indenter Measuring method: single intrusion measurement Measuring temperature: room temperature (25℃) Intrusion depth setting: 800 nm at measurement position A, 1000 nm at measurement position B Pressing speed: 200 nm/second Pull-out speed: 200 nm/second

(swellability) In some aspects of the adhesive sheet disclosed here, the initial thickness T0 [μm] of the above-mentioned adhesive layer (first adhesive layer) is determined by dropping 4-tert-butylphenyl glycidyl ether (TBPGE) to The difference (T1-T0) in the thickness T1 [μm] of the adhesive layer after it has been left standing for 1 minute on the surface of the above-mentioned adhesive layer, that is, the thickness change is 20 μm or less. Regarding an adhesive sheet having an adhesive layer with a small change in thickness due to swelling of TBPGE, for example, in the usage state of performing resin sealing of semiconductor wafers on the adhesive layer, there is an adhesive layer/sealing resin. The tendency of component migration between them is suppressed, thereby suppressing the step difference (gap) between the semiconductor chip and the sealing resin. From this point of view, in some aspects, the above-mentioned thickness variation is preferably 15 μm or less, more preferably 10 μm or less. The closer the above-mentioned thickness variation is to 0 (zero) μm, the better, and it may also be 0 μm. In some aspects, from a practical viewpoint such as a balance with other characteristics or cost, the thickness variation may be, for example, 0.1 μm or more, 0.5 μm or more, 1 μm or more, or 1 μm or more. 2 μm or more or 3 μm or more.

In some aspects of the adhesive sheet disclosed here, the thickness change rate of the adhesive layer after dropping TBPGE onto the surface of the adhesive layer of the adhesive sheet and leaving it for 1 minute is preferably less than 160%, and more preferably The best is less than 150%. For an adhesive sheet having an adhesive layer that suppresses the thickness change rate caused by swelling of TBPGE, for example, in a usage state where a semiconductor chip is resin-sealed on the adhesive layer, there is an adhesive layer/sealing resin. The tendency of the component migration between the components to be inhibited, thereby suppressing the gap. From this point of view, in certain aspects, the thickness change rate may be, for example, 120% or less, 100% or less, 80% or less, or 60% or less. The smaller the thickness change rate, the better, and the lower limit is not particularly limited. In some aspects, from a practical viewpoint such as a balance with other characteristics or cost, the thickness change rate may be, for example, 5% or more, 10% or more, or 20% or more.

Regarding the above thickness change, drop a specific amount (using a 22 mm diameter syringe, 0.02 g) of TBPGE onto the surface of the adhesive layer, place it in an environment of 23°C and 50% RH for 1 minute, and wipe away the remaining residue on the adhesive layer. The TBPGE on the surface can be calculated based on the thickness T1 of the adhesive layer at the location where TBPGE was dropped after erasing, and the thickness (initial thickness) T0 of the adhesive layer at the location before TBPGE was dropped, and by the formula T1-T0. Find the above thickness change. The thickness change rate can be obtained by the equation (T1-T0)/T0 based on the above-mentioned T0 and T1. The above-mentioned thickness change amount and thickness change rate can be appropriately determined by, for example, the composition of the base polymer (for example, an acrylic polymer) constituting at least the surface A layer of the adhesive layer, the degree of cross-linking, the type of cross-linking agent, etc. Select and set to the above range. For example, by making 30% by weight or more (more preferably 40% by weight or more) of the monomer components constituting the acrylic polymer have an ester terminal having a large number of carbon atoms (for example, 4 or more, preferably 8 or more). Alkyl (meth)acrylate can form an adhesive layer with a small thickness change and/or a small thickness change rate.

(TMA sinking amount) In some aspects of the adhesive sheet disclosed herein, the sinking amount of the adhesive sheet using TMA in a 23°C environment can be approximately 20.0 μm or less (for example, approximately 1.00 μm or more and 20.0 μm or less). Here, "the sinking amount of the adhesive sheet obtained by using TMA in a 23°C environment" (hereinafter, also referred to as "TMA sinking amount") means using a thermomechanical analyzer (Thermomechanical Analyzer; TMA). The amount of needle sinking after 60 minutes of contact with the adhesive layer (first adhesive layer). The measurement conditions for the TMA sinking amount are as follows: probe: needle insertion (cylindrical, tip diameter 1 mmΦ), nitrogen gas flow: 50.0 ml/min, and pressing load: 0.01 N. As a thermomechanical analysis device, product name "TMA Q400" manufactured by TA Instruments Co., Ltd. or its equivalent can be used.

Furthermore, when the adhesive sheet has an adhesive layer only on one side of the base material (that is, when it does not have the second adhesive layer described below), between the base material and the adhesive layer (the second adhesive layer) 1 Adhesive layer) After setting a standard adhesive layer on the opposite side, perform the above measurement. The above standard adhesive layer uses an acrylic polymer (including ethyl acrylate (EA)/2-ethylhexyl acrylate (2EHA)/methyl methacrylate (MMA)/2-hydroxyethyl acrylate (HEA) = Acrylic polymer with a monomer component of 30/70/5/5 (weight ratio). 100 parts by weight of a weight average molecular weight of 450,000, and 10 parts by weight of a tackifier (manufactured by Yasuhara Chemical Co., Ltd., trade name "MightyAce G125") parts, 2 parts by weight of an isocyanate cross-linking agent (manufactured by Tosoh Corporation, trade name "Coronate L"), 30 parts by weight of heat-expandable microspheres (manufactured by Matsumoto Oils & Fats Pharmaceutical Co., Ltd., trade name "Matsumoto Microsphere F-190D"), and The adhesive composition obtained by mixing toluene formed an adhesive layer with a thickness of 45 μm.

In certain aspects, the above-mentioned TMA sinking amount is preferably 15.0 μm or less, more preferably 10.0 μm or less, or 9.00 μm or less, or 6.00 μm or less. Regarding the adhesive sheet with a small amount of TMA sinking, for example, in the use mode of carrying out the step of arranging a semiconductor chip on the adhesive layer and sealing the semiconductor chip with resin, when sealing with resin (for example, as shown in FIG. The semiconductor chip embedded in the adhesive sheet tends to become smaller due to the force exerting load on the semiconductor chip in steps (ii) and (iii) of 2). By making the embedding smaller, the step (gap) between the semiconductor wafer and the sealing resin caused by the embedding can be reduced in the structure including the chip and the sealing resin. Regarding reducing the step difference, it is also preferable to reduce the step difference from the viewpoint of improving the prevention of paste residue when the adhesive sheet is peeled off from the structure.

In some aspects, from the viewpoint of improving the ability to follow the surface shape of the adherend (for example, the step that may exist on the surface of a semiconductor wafer), the TMA sinking amount may be, for example, 1.50 μm or more, as 2.00 μm or more is more appropriate, and may be 2.50 μm or more, 3.00 μm or more, or 3.50 μm or more. In an adhesive sheet that exhibits such a sinking amount of TMA, it is possible to better achieve both the ability to follow the surface shape of the semiconductor wafer and the suppression of the semiconductor wafer being embedded in the adhesive sheet. The amount of TMA sinking can be determined, for example, by the structure (thickness, layer composition, etc.) of the adhesive layer, the composition of the base polymer (such as acrylic polymer) of the adhesive that constitutes the adhesive layer, or the degree of cross-linking. The type of coupling agent, the type of base material, etc. are appropriately selected and set within the above range.

In some aspects of the adhesive sheet disclosed here, the sinking amount of the adhesive sheet obtained by using TMA in an environment of 145°C (hereinafter, may also be referred to as "high temperature TMA sinking amount") is 2.00 μm More than 60 μm and less than 60 μm are more appropriate, for example, they may be 3.00 μm or more and 50 μm or less, or they may be 4.00 μm or more and 40 μm or less. An adhesive sheet with a high-temperature TMA sinking amount within the above range can better prevent the semiconductor chip from being embedded in the adhesive sheet when it passes through a high-temperature environment (for example, a heat treatment environment during resin sealing). The high-temperature TMA sinking amount was measured in the same manner as the TMA sinking amount in the 23°C environment, except that the measurement atmosphere temperature was set to 145°C.

(Probe viscosity value) In some aspects of the adhesive sheet disclosed here, the probe viscosity value measured on the surface of the above-mentioned adhesive layer (first adhesive layer) is preferably 50 N/5 mmϕ or more, more preferably It is 75 N/5 mmϕ or more, and it is more preferable that it is 100 N/5 mmϕ or more. When the probe viscosity value is in this range, from the viewpoint of preventing the positional shift of the adherend (for example, a semiconductor wafer) disposed on the adhesive layer, it is preferable that the probe viscosity value is in this range. Scope. The probe viscosity value can be measured using a commercially available probe viscosity testing machine, in an environment of 23°C, 50%RH, the area and material of the probe area: 5 mmϕSUS (stainless steel), and the probe descent speed: 30 mm /min, close contact load: 100 gf, close contact retention time: 1 second, test speed: 30 mm/min.

(For the adhesion of PET) The adhesive force of the adhesive sheet disclosed here to the polyethylene terephthalate film (the adhesive force to PET) may be, for example, 5.00 N/20 mm or less, or 3.00 N/20 mm or less, or it may be 2.00 N/20 mm or less, no special limit. In some aspects, from the viewpoint of preventing damage to the adherend caused by load when peeling off the adhesive sheet, the above-mentioned adhesive force on PET is preferably 1.00 N/20 mm or less, and more preferably 0.05 N /20 mm or less. Furthermore, in some aspects, regarding the adhesive force of the adhesive sheet to PET, from the perspective of better fixing the adherend (for example, a semiconductor chip), the adhesive force of the adhesive sheet to PET is 0.03 N/20 mm or more is more appropriate, preferably 0.05 N/20 mm or more, 0.10 N/20 mm or more, or 0.15 N/20 mm or more. The adhesive force of PET means that the PET film (thickness 25 μm) as the adherend is bonded (laminated condition: 1 round trip using a 2 kg roller) on an adhesive sheet with a width of 20 mm and a length of 140 mm. The adhesive layer (first adhesive layer) was placed at an ambient temperature of 23°C for 30 minutes and then subjected to a tensile test (peel angle 180 degrees, tensile speed 300 mm/min) to measure the adhesive force.

(tensile elastic modulus) In certain aspects, the tensile elastic modulus of the first adhesive layer at 25°C is preferably less than 100 MPa, more preferably 0.1 MPa～50 MPa, and further preferably 0.1 MPa～10 MPa. If it is within this range, it will be easy to obtain an adhesive sheet in which the first adhesive layer exhibits appropriate adhesive force. In addition, the tensile elastic modulus can be measured in accordance with JISK7161:2008.

<Adhesive layer (1st adhesive layer)> In the adhesive sheet disclosed here, as the adhesive constituting the adhesive layer (first adhesive layer) disposed on at least one side of the base material, any appropriate adhesive may be used as long as the effects of the present invention can be obtained. agent. The above-mentioned adhesive layer may include, for example, an adhesive selected from the group consisting of acrylic adhesives, rubber adhesives (natural rubber systems, synthetic rubber systems, mixtures thereof, etc.), silicone adhesives, polyester adhesives, and amine-based adhesives. One or more of various known adhesives such as acid ester adhesives, polyether adhesives, polyamide adhesives, and fluorine adhesives. In an adhesive layer containing more than two types of adhesives, the adhesives may be two or more types of adhesives selected from the same system (for example, acrylic adhesives), or they may be selected from two or more different systems. Select one or two or more types of adhesives (for example, acrylic adhesives and polyester adhesives). In an adhesive layer containing more than two kinds of adhesives mentioned above, these adhesives can be mixed evenly, or they can be arranged in different positions in the thickness direction (such as stacking), or they can be arranged in the plane direction (such as separate coating). At different positions, it can also be a configuration that is a combination of these, or an intermediate configuration of these.

The thickness of the first adhesive layer is preferably 5 μm or more. If the thickness of the first adhesive layer is 5 μm or more, it can easily follow the surface shape of the adherend. The upper limit of the thickness of the first adhesive layer may be, for example, 200 μm or less, or 150 μm or less, and is not particularly limited. In some aspects, it is to prevent the paste residue caused by the aggregation damage of the adhesive layer, or to suppress the embedding of the semiconductor chip in the adhesive sheet in the use aspect of performing the resin sealing step of the semiconductor chip on the adhesive layer. From other viewpoints, it is more appropriate that the thickness of the first adhesive layer is 110 μm or less, preferably 60 μm or less, and more preferably 20 μm or less.

＜Level A＞ Typically, the adhesive layer (first adhesive layer) includes layer A constituting at least the surface of the adhesive layer. In some aspects, the adhesive layer may be a single-layer structure including the A layer. In this case, the above-mentioned A layer can be formed by directly bonding the opposite side of the above-mentioned surface to one side surface of the base material. In some other aspects, the above-mentioned adhesive layer may be composed as follows, that is, another adhesive layer different from the above-mentioned A layer is interposed between the above-mentioned A layer and one side surface of the above-mentioned substrate (for example, the following B layer). In this aspect, the difference between the adhesive constituting the A layer and the adhesive constituting the other adhesive layers may be, for example, the difference in the base polymer (for example, the composition of the monomer components constituting the base polymer). Differences, differences in weight average molecular weight, differences in polymer chain structures, etc.), differences in cross-linking agents (e.g., differences in type or dosage), differences in adhesion-imparting resins (e.g., whether it contains adhesion-imparting resin, adhesion-imparting resin, etc.) (differences in resin content, type of adhesion-providing resin, etc.), presence or absence of other additives, differences in content, type of other additives, etc., one or more types.

In some preferred aspects, the adhesive constituting the above-mentioned layer A is an acrylic adhesive using an acrylic polymer as a base polymer. By forming at least the surface of the first adhesive layer with an acrylic adhesive, the effects of the invention disclosed here can be better exerted.

(Acrylic polymer) The acrylic polymer as the base polymer of the acrylic adhesive preferably contains an alkyl (meth)acrylate as a main monomer and optionally further contains a sub-monomer copolymerizable with the main monomer. Body composition of polymers. Here, the main monomer refers to the main component among the monomer components constituting the acrylic polymer, that is, the component contained in the monomer component in an amount exceeding 50% by weight.

As the (meth)acrylic acid alkyl ester, for example, a compound represented by the following formula (A) can be preferably used. CH ₂ =C(R ¹ )COOR ² (A) Here, R ¹ in the above formula (A) is a hydrogen atom or a methyl group. Moreover, R ² is a chain alkyl group having 1 to 20 carbon atoms (hereinafter, this range of carbon atoms may be expressed as "C _1-20 "). From the viewpoint of ease of adjustment of adhesive properties, a (meth)acrylic acid alkyl ester in which R ² is a C _1-18 chain alkyl group is preferred, and R ² is a C _1-12 chain alkyl group. Alkyl (meth)acrylate.

Specific examples of the alkyl (meth)acrylate include (methyl)acrylate, ethyl(meth)acrylate, propyl(meth)acrylate, and isopropyl(meth)acrylate. , butyl (meth)acrylate, isobutyl (meth)acrylate, second butyl (meth)acrylate, third butyl (meth)acrylate, amyl (meth)acrylate, (meth) Hexyl acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, ( Isononyl methacrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, (meth)acrylate )Tridecyl acrylate, Tetradecyl (meth)acrylate, Pentadecyl (meth)acrylate, Cetyl (meth)acrylate, Heptadecyl (meth)acrylate C _1-20 alkyl (meth)acrylate such as ester, stearyl (meth)acrylate, nonadecyl (meth)acrylate, eicosanyl (meth)acrylate. Among them, (meth)acrylic acid alkyl esters having a linear or branched alkyl group of C _4-20 (more preferably C _6-20 , further preferably C _8-18 ) (for example, 2-Ethylhexyl (meth)acrylate).

In some aspects, at least 30% by weight of the monomer components constituting the acrylic polymer are R ² in the above formula (A) having a carbon number of 4 or more (preferably 8 or more. Also, preferably 18 or less) (For example, 12 or less) (meth)acrylic acid alkyl ester with a linear or branched alkyl group structure. By using this alkyl (meth)acrylate, component migration between the adhesive layer/sealing resin can be better suppressed. The content of the above-mentioned alkyl (meth)acrylate in the monomer component used in the synthesis of the acrylic polymer is preferably 40% by weight or more. In some embodiments, it may be 50% by weight or more. It is more than 70% by weight. Regarding the content of the above-mentioned (meth)acrylic acid alkyl ester in the monomer component, from the viewpoint of easily adjusting the indentation hardness H1 at the measurement position A to a preferable range, the above-mentioned (meth)acrylic acid alkyl ester in the monomer component is The content of alkyl acrylate is suitably 99.5% by weight or less, preferably 99% by weight or less, 98% by weight or less, or 97% by weight or less.

The submonomer copolymerizable with the alkyl (meth)acrylate as the main monomer can help introduce cross-linking points into the acrylic polymer, or improve the cohesion or heat resistance of the acrylic polymer. The secondary monomer can also help adjust the indentation hardness H1. As the secondary monomer, for example, the functional group-containing monomers shown below can be used alone or in combination of two or more types. For example, the functional group-containing monomers shown below can be used alone or in combination of two or more types.

Acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid and other carboxyl group-containing monomers; Anhydride monomers such as maleic anhydride and itaconic anhydride; Hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, hydroxyhexyl (meth)acrylate, hydroxyoctyl (meth)acrylate, (meth)acrylic acid Hydroxyl-containing monomers such as hydroxydecyl ester, hydroxylauryl (meth)acrylate, (4-hydroxymethylcyclohexyl)methyl methacrylate; (Meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-butyl(meth)acrylamide, N-hydroxymethyl(meth)acrylamide, N- (N-substituted) amide monomers such as hydroxymethylpropane (meth)acrylamide; N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperidine, N- Vinyl pyrrole, N-vinyl pyrrole, N-vinylimidazole, N-vinyl 㗁azole, N-vinyl pyroline, N-vinyl caprolactam, N-(meth)acrylamide Phenoline and other monomers with rings containing nitrogen atoms; Amino-containing monomers such as (meth)aminoethyl acrylate, N,N-dimethylaminoethyl (meth)acrylate, and tert-butylaminoethyl (meth)acrylate; Epoxy group-containing acrylic monomers such as glycidyl (meth)acrylate; Acrylonitrile, methacrylonitrile and other cyano group-containing monomers; Styrenesulfonic acid, allylsulfonic acid, 2-(meth)acrylamide-2-methylpropanesulfonic acid, (meth)acrylamidepropanesulfonic acid, (meth)acrylic acid sulfopropyl ester, (meth)acrylamide-2-methylpropanesulfonic acid Monomers containing sulfonic acid groups such as meth)acryloxynaphthalene sulfonic acid; Maleimide monomers such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, and N-phenylmaleimide; N-Methyl itonimide, N-ethyl itonimide, N-butyl itonimide, N-octyl itonimide, N-2-ethylhexyl itonide Iconidimine-based monomers such as imine, N-cyclohexyliconidimine, N-lauryl itonidimine; N-(meth)acryloxymethylenesuccinimide, N-(meth)acryloxy-6-oxyhexamethylenesuccinimide, N-(meth)propylene Succinimide monomers such as acyl-8-oxyoctamethylene succinimide; 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldi Methoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane and other alkoxysilyl-containing monomers.

Regarding the monomer component, other copolymerizable monomers other than the functional group-containing monomers exemplified above may be included as sub-monomers for the purpose of improving cohesion or the like. Examples of the other copolymerizable monomers include vinyl ester monomers such as vinyl acetate, vinyl propionate, and vinyl laurate; styrene, substituted styrene (α-methylstyrene, etc.) , vinyltoluene and other aromatic vinyl compounds; (meth)cycloalkyl acrylates such as (meth)cyclohexyl acrylate, (meth)cyclopentyl acrylate, (meth)isopropyl acrylate, etc.; Aryl acrylate (such as phenyl (meth)acrylate), aryloxyalkyl (meth)acrylate (such as phenoxyethyl (meth)acrylate), arylalkyl (meth)acrylate (meth)acrylates containing aromatic rings such as benzyl (meth)acrylate); olefin monomers such as ethylene, propylene, isoprene, butadiene, isobutylene; vinyl chloride, vinylidene Chlorine-containing monomers such as dichloroethylene; isocyanate-containing monomers such as 2-(meth)acryloyloxyethyl isocyanate; methoxyethyl (meth)acrylate, (meth)acrylic acid Alkoxy group-containing monomers such as ethoxyethyl ester; vinyl ether monomers such as methyl vinyl ether and ethyl vinyl ether; polyethylene glycol (meth)acrylate, polypropylene glycol (methyl) Diol monomers such as acrylate, methoxyethylene glycol (meth)acrylate, and methoxypolypropylene glycol (meth)acrylate; In addition, heterocyclic ring-containing monomers such as tetrahydrofurfuryl (meth)acrylate, fluorine (meth)acrylate, silicone (meth)acrylate, etc.

The monomer component may also include polyfunctional monomers as other copolymerizable monomers mentioned above for cross-linking and the like. Non-limiting examples of such multifunctional monomers may include: hexylene glycol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate ) Acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexacrylate Multifunctional monomers such as (meth)acrylates, multifunctional epoxy acrylates, multifunctional polyester acrylates, and multifunctional urethane acrylates; etc. A polyfunctional monomer can be used individually by 1 type, or in combination of 2 or more types.

In some preferred aspects, the acrylic polymer preferably contains a homopolymer with a glass transition temperature (Tg) of -5°C to 150°C (preferably 50°C to 150°C, more preferably 80 ℃ ~ 120 ℃) structural unit of the monomer a. By including such a structural unit a, it is possible to realize an A layer in which the molecular movement of the acrylic polymer is restricted and the T ₂ relaxation time of the S component obtained by pulse NMR can be better adjusted. Furthermore, by including the above-mentioned A layer on at least the surface of the first adhesive layer, an adhesive sheet excellent in low-temperature adhesiveness can be obtained. Regarding the content of the above-mentioned structural unit a, relative to the total structural units constituting the acrylic polymer, the content of the above-mentioned structural unit a is preferably 0.1% to 20% by weight, more preferably 1% to 10% by weight, and particularly preferably The content is 1.5% to 8% by weight, preferably 3% to 6% by weight.

Examples of monomers whose Tg of the homopolymer is -5°C to 150°C include: 2-hydroxyethyl acrylate (Tg: -3°C), 2-hydroxyethyl methacrylate (Tg: 77°C) , Acrylic acid (Tg: 102℃), Cyclohexyl methacrylate (Tg: 83℃), Dicyclopentyl acrylate (Tg: 120℃), Dicyclopentyl methacrylate (Tg: 175℃), Isoacrylate ester (Tg: 94℃), isoester methacrylate (Tg: 150℃), tert-butyl methacrylate (Tg: 118℃), methyl methacrylate (Tg: 105℃), styrene (Tg: 80°C), acrylonitrile (Tg: 97°C), N-acrylamide (Tg: 145°C), etc. As the glass transition temperature of homopolymers of monomers other than the above, values described in publicly known materials such as "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc., 1989) are used. For monomers with multiple values recorded in the above-mentioned Polymer Handbook, the highest value is used. When the Tg of the homopolymer is not described in publicly known documents, the value obtained by the measurement method described in Japanese Patent Application Publication No. 2007-51271 is used. These monomers can be used individually by 1 type, or in combination of 2 or more types. Among them, methyl methacrylate is preferable when improving the visibility of the adherend during processing because methyl methacrylate improves the transparency of the adhesive layer. In addition, since acrylic acid strongly adheres to the adherend through intermolecular interactions, acrylic acid is preferred when strong adhesion is required. In addition, since 2-hydroxyethyl (meth)acrylate exhibits high reactivity with various cross-linking agents, it is suitable for forming an adhesive with a short T ₂ relaxation time as described below.

In some preferred aspects, the acrylic polymer includes structural units derived from carboxyl group-containing monomers. Regarding the content of the structural units derived from the carboxyl group-containing monomer, the content of the structural units derived from the carboxyl group-containing monomer is preferably 0.1% by weight or more, more preferably 1% by weight, relative to the total structural units constituting the acrylic polymer. Above, more preferably 2 wt% or more, more preferably 15 wt% or less, more preferably 10 wt% or less, still more preferably 7 wt% or less.

In some preferred aspects, the acrylic polymer includes structural units derived from hydroxyl-containing monomers. Regarding the content of the structural units derived from the hydroxyl-containing monomer, the content of the structural units derived from the hydroxyl-containing monomer is preferably 0.01% by weight or more, more preferably 0.03% by weight relative to the total structural units constituting the acrylic polymer. The above amount is, for example, 0.05% by weight or more, and preferably 20% by weight or less, more preferably 10% by weight or less, for example, 7% by weight or less.

(SP value) In some aspects, the SP value of the base polymer (preferably an acrylic polymer) constituting the adhesive of the A layer is, for example, 10 to 30, which is more appropriate, and preferably 15 to 25, especially Preferably 18 or above and 20 below. If it is within this range, migration of components between the adhesive layer/sealing resin can be better prevented. Furthermore, the numerical units used to express SP values in this specification are all "(cal/cm ³ ) ^1/2 ".

Here, the SP value refers to the value calculated based on the basic structure of the compound by the method proposed by Fedors. Specifically, the SP value is calculated according to the following formula based on the evaporation energy Δe (cal) of each atom or atomic group at 25°C and the molar volume Δv (cm ³ ) of each atom or atomic group at the same temperature. SP value = (ΣΔe/ΣΔv) ^1/2 (Reference: Hideki Yamamoto, "SP Value Basics, Applications and Calculation Methods", No. 4, published by Johokiko Co., Ltd., issued on April 3, 2006, No. 66 ~page 67).

When the polymer is a copolymer, its SP value is calculated by calculating the SP value of each individual copolymer of each structural unit constituting the copolymer, and multiplying each of these SP values by The molar fractions of each structural unit were totaled to calculate the SP value of the copolymer. In the above case, the analysis method of each structural unit (polymer composition analysis) is to collect only the adhesive layer appropriately from the adhesive sheet, recover it, and immerse it in dimethylformamide (DMF), acetone, methanol, The solvent-soluble fraction obtained from organic solvents such as tetrahydrofuran (THF) is determined based on the analytical methods of gel filtration permeation chromatography (GPC), nuclear magnetic resonance spectroscopy (NMR), infrared spectroscopy (IR), and mass analysis. Pick.

(cross-linking agent) From the viewpoint of easily realizing the above-mentioned preferable indentation hardness H1, it is preferable that the base polymer of the above-mentioned A layer is cross-linked in the adhesive constituting the A layer. For example, by using an adhesive composition including a base polymer and an appropriate cross-linking agent, an A layer including an adhesive in which the base polymer is cross-linked by the cross-linking agent can be obtained.

The type of cross-linking agent is not particularly limited. For example, it can be selected from isocyanate-based cross-linking agents, epoxy-based cross-linking agents, melamine-based cross-linking agents, peroxide-based cross-linking agents, urea-based cross-linking agents, and metal alkoxides. Physical cross-linking agent, metal chelate cross-linking agent, metal salt cross-linking agent, carbodiimide cross-linking agent, oxazoline cross-linking agent, aziridine cross-linking agent, amine cross-linking agent Cross-linking agents and the like are appropriately selected and used. A cross-linking agent can be used individually by 1 type, or in combination of 2 or more types. Among them, preferred cross-linking agents include epoxy cross-linking agents and isocyanate cross-linking agents.

Examples of the epoxy cross-linking agent include: N,N,N',N'-tetraglycidyl m-xylylenediamine, diglycidyl aniline, 1,3-bis(N,N- Glycerylamine methyl)cyclohexane (manufactured by Mitsubishi Gas Chemical Co., Ltd., trade name "Tetrad C"), 1,6-hexanediol diglycidyl ether (manufactured by Kyeisha Chemical Co., Ltd., trade name "Epolight 1600"), Neopentyl glycol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolight 1500 NP"), ethylene glycol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolight 40E"), propylene glycol diglycidyl ether Glycidyl ether (manufactured by Kyeisha Chemical Co., Ltd., trade name "Epolight 70P"), polyethylene glycol diglycidyl ether (manufactured by Nippon Oils and Fats Co., Ltd., trade name "EPIOL E-400"), polypropylene glycol diglycidyl ether ( Manufactured by Nippon Oils and Fats Corporation, trade name "EPIOL P-200"), sorbitol polyglycidyl ether (manufactured by Nagase Chemical Co., Ltd., trade name "Denacol EX-611"), glycerol polyglycidyl ether (manufactured by Nagase Chemical Co., Ltd., Trade name "Denacol EX-314"), pentaerythritol polyglycidyl ether, polyglycerol polyglycidyl ether (manufactured by Nagase Chemical Co., Ltd., trade name "Denacol EX-512"), sorbitan polyglycidyl ether, trimethylol Propane polyglycidyl ether, diglycidyl adipate, diglycidyl phthalate, triglycidyl-tris(2-hydroxyethyl)isocyanurate, resorcinol diglycidyl Ether, bisphenol-S-diglycidyl ether, epoxy resins with two or more epoxy groups in the molecule, etc. The usage amount of the epoxy cross-linking agent can be set to any appropriate amount according to the target properties. In some aspects, the usage amount of the epoxy cross-linking agent relative to 100 parts by weight of the base polymer can be, for example, 0.01 to 50 parts by weight, preferably 0.6 to 15 parts by weight, and more preferably It is 2 parts by weight or more and 13 parts by weight or less, and more preferably 3 parts by weight or more and 10 parts by weight or less.

Specific examples of isocyanate cross-linking agents include lower aliphatic polyisocyanates such as butyl diisocyanate and hexamethylene diisocyanate; cyclopentyl diisocyanate, cyclohexyl diisocyanate, isophor Alicyclic isocyanates such as ketone diisocyanate; aromatic isocyanates such as 2,4-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate; trimethylolpropane/toluene diisocyanate Isocyanate trimer adduct (manufactured by Tosoh Corporation, trade name "Coronate L"), trimethylolpropane/hexamethylene diisocyanate trimer adduct (manufactured by Tosoh Corporation, trade name "Coronate HL") "), isocyanate adducts such as the isocyanurate body of hexamethylene diisocyanate (manufactured by Tosoh Corporation, trade name "Coronate HX"); etc. The usage amount of the isocyanate cross-linking agent can be set to any appropriate amount according to the required adhesive force. In some aspects, representatively, the usage amount of the isocyanate cross-linking agent is 0.1 to 20 parts by weight relative to 100 parts by weight of the base polymer, preferably 1 to 10 parts by weight.

In some aspects, as the cross-linking agent used in layer A, an epoxy cross-linking agent can be preferably used. According to the A layer having a cross-linked structure in which the base polymer is cross-linked by an epoxy cross-linking agent, the better indentation hardness H1 disclosed here can be better achieved. Furthermore, it is possible to obtain an adhesive sheet in which the step difference between the semiconductor chip and the sealing resin can be relatively reduced. In addition, it can form an adhesive layer with higher cohesive force, which can more effectively prevent the position of the adherend from shifting.

In some aspects, as the above-mentioned cross-linking agent, a cross-linking agent containing nitrogen (N) atoms may be preferably used. The cross-linking agent containing N atoms promotes the cross-linking reaction (for example, the reaction with the carboxyl group in the base polymer) through the catalytic effect of the N atom, and it is easy to increase the gel fraction of the adhesive. In other words, cross-linking agents containing N atoms are advantageous. Specific examples of the crosslinking agent containing N atoms include, in addition to the isocyanate crosslinking agents described above, epoxy crosslinking agents containing N atoms (for example, epoxy crosslinking agents having a glycidylamine group). Coupling agent, such as N,N,N',N'-tetraglycidyl m-xylylenediamine or 1,3-bis(N,N-glycidylaminemethyl)cyclohexane, etc.). In some aspects of using a cross-linking agent containing N atoms, it is preferable to set the cross-linking agent so that the amount of nitrogen generated is 0.06% by weight or more and 1.0% by weight or less (more preferably 0.06% by weight or more and 0.9% by weight or less). The dosage of combined agent. By setting this usage amount, it is easy to obtain an adhesive sheet that has both the prevention of paste residue and the ability to follow the surface shape.

In some aspects, the cross-linking agent (preferably a cross-linking agent that forms a cross-linked structure by reacting with carboxyl groups. For example, an epoxy cross-linking agent, an isocyanate cross-linking agent, etc.) relative to the base polymer ( For example, the usage amount of the carboxyl group contained in the acrylic polymer) is preferably 0.08 molar equivalent or more and 2 molar equivalent or less, more preferably 0.1 molar equivalent or more and 1 molar equivalent or less. Based on this usage amount, the preferred indentation hardness H1 disclosed herein can be accurately achieved. Furthermore, by cross-linking the cross-linking agent in the above-mentioned amount with the carboxyl groups in the base polymer, an adhesive sheet with less residual carboxyl groups in the adhesive layer can be obtained.

(Other additives) The adhesive constituting the A layer may contain appropriate additives other than the above as optional components if necessary. Examples of such additives include tackifiers, plasticizers (for example, trimellitate-based plasticizers, pyromellitate-based plasticizers, etc.), pigments, dyes, fillers, Anti-aging agents, conductive materials, antistatic agents, ultraviolet absorbers, light stabilizers, peeling adjusters, softeners, surfactants, flame retardants, antioxidants, etc.

As the above-mentioned tackifier, any appropriate tackifier can be used. As the tackifier, for example, a tackifier resin can be used. Specific examples of the tackifier-imparting resin include rosin-based tackifier-imparting resins (eg, unmodified rosin, modified rosin, rosin phenolic resin, rosin ester-based resin, etc.), terpene-based tackifier-imparting resins (eg, unmodified rosin, modified rosin, rosin phenolic resin, rosin ester resin, etc.). , terpene-based resin, terpene-phenol-based resin, styrene-modified terpene-based resin, aromatic modified terpene-based resin, hydrogenated terpene-based resin), hydrocarbon-based tackifier resin (for example, aliphatic hydrocarbon resin , aliphatic cyclic hydrocarbon resin, aromatic hydrocarbon resin (for example, styrenic resin, xylene resin, etc.), aliphatic/aromatic petroleum resin, aliphatic/alicyclic petroleum resin, hydrogenated hydrocarbon resins, benzofuran-based resins, benzofuran-indene-based resins, etc.), phenolic adhesive-imparting resins (e.g., alkylphenol-based resins, xylene-formaldehyde-based resins, soluble phenolic resins, novolaks, etc.), ketones Adhesion-imparting resins, polyamide-based adhesion-imparting resins, epoxy-based adhesion-imparting resins, elastic system adhesion-imparting resins, etc. Among these, preferred are rosin-based tackifier resins, terpene-based tackifier resins, or hydrocarbon-based tackifier resins (styrene-based resins, etc.). The adhesive imparting agent can be used individually by 1 type, or in combination of 2 or more types.

In some aspects, as the above-mentioned adhesion-imparting resin, a resin with a higher softening point or glass transition temperature (Tg) may be used. If a resin with a high softening point or glass transition temperature (Tg) is used, it is possible to form an adhesive that exhibits high adhesion even in a high-temperature environment (for example, in a high-temperature environment during processing of semiconductor wafer sealing). agent layer. The softening point of the tackifier is preferably 100°C to 180°C, more preferably 110°C to 180°C, further preferably 120°C to 180°C. The glass transition temperature (Tg) of the tackifier is preferably 100°C to 180°C, more preferably 110°C to 180°C, further preferably 120°C to 180°C.

In some aspects, as the above-mentioned adhesion-imparting resin, a low-polarity adhesion-imparting resin may be used. Regarding the use of a low-polarity tackifier resin, it is advantageous to use a low-polarity tackifier resin from the viewpoint of forming an adhesive layer with low affinity for the sealing material. Examples of low-polarity tackifying resins include aliphatic hydrocarbon resins, aliphatic cyclic hydrocarbon resins, aromatic hydrocarbon resins (for example, styrene-based resins, xylene-based resins, etc.), aliphatic/ Aromatic petroleum resins (sometimes also called C5/C9 petroleum resins), aliphatic/alicyclic petroleum resins, and hydrocarbon-based tackifier resins equivalent to hydrogenated hydrocarbon resins. Among them, aliphatic/aromatic petroleum resins are preferred. This kind of adhesive-imparting resin has low polarity and excellent compatibility with acrylic polymers. It does not phase separate in a wide temperature range and can form an adhesive layer with excellent stability.

The acid value of the above-mentioned tackifying resin is preferably 40 or less, more preferably 20 or less, still more preferably 10 or less. If it is within this range, an adhesive layer having low affinity with the sealing material can be formed. The hydroxyl value of the above-mentioned tackifying resin is preferably 60 or less, more preferably 40 or less, and still more preferably 20 or less. If it is within this range, it is possible to form an adhesive layer that has low affinity with the sealing material and is suitable for suppressing component migration between the adhesive layer/sealing resin.

Regarding the usage amount of the tackifier, relative to 100 parts by weight of the base polymer, the usage amount of the tackifier may be, for example, 5 to 100 parts by weight, preferably 8 to 50 parts by weight. In some aspects of the adhesive sheet disclosed here, the adhesive imparting agent is polymerized to the base of the adhesive constituting the A layer from the viewpoint of easy peelability from the adherend or suppression of paste residue. It is more appropriate to set the compounding amount of 100 parts by weight to less than 3 parts by weight, less than 1 part by weight, or less than 0.5 parts by weight. It is preferable that no adhesive imparting agent (especially adhesive imparting agent) is included in the adhesive constituting the A layer. resin).

(T ₂ Relaxation Time) In some aspects of the adhesive sheet disclosed here, the T ₂ relaxation time (T _2s ) of the S component of the A layer obtained by pulse NMR is preferably 45 μsec or less. An adhesive sheet whose T ₂ relaxation time (T _2s ) of layer A constituting at least the surface of the first adhesive layer is 45 μsec or less is used, for example, for resin sealing of semiconductor wafers on the first adhesive layer. In this aspect, the component migration between the adhesive layer and the sealing resin is suppressed, thereby better suppressing the step difference between the semiconductor chip and the sealing resin.

The above-mentioned relaxation time means the time required for atoms (groups) excited by irradiation with an energy suitable for exciting atoms to be measured in pulse NMR measurement to return to the ground state. How to change atoms (groups) into an excited state can be controlled by the amount or time of energy irradiation. In addition, in order to return the excited atoms (groups) to the ground state, various energy relaxation mechanisms are known, and the relaxation time can be determined based on the relaxation mechanism (for example, "Latest Introduction to NMR for Chemists", Kagaku- Dojin Publishing (1997)). The present inventors discovered that they excited ¹ H atoms of an acrylic adhesive (essentially, an acrylic polymer contained in the adhesive) under the following conditions, measured the subsequent relaxation behavior, and then measured the measured values. Analysis was conducted, and it was found that T ₂ relaxation was used as information for obtaining the molecular movement related to the degree of cross-linking of the base polymer (representatively, an acrylic polymer) contained in the adhesive constituting the adhesive layer. The S component of time (T _2s ) is useful, and by specifying the S component (T _2s ) of the T ₂ relaxation time, the above effects can be obtained. A short T _2s indicates a state in which molecular movement is restricted in relation to the degree of cross-linking of the base polymer, that is, a state in which cross-linking proceeds and the freedom of movement of the polymer as a whole is also reduced. In the adhesive in this state, the gap between the base polymers is small, and the migration of the adhesive layer components to the sealing resin, or the migration of the low molecular weight components contained in the sealing resin to the adhesive layer, tends to be inhibited. As a result, when the semiconductor chip is resin-sealed on the adhesive sheet and then the adhesive sheet is peeled off, it is possible to prevent the occurrence of a step difference between the semiconductor chip and the sealing resin.

Regarding the T ₂ relaxation time (T _2s ) of the S component of the A layer obtained by pulse NMR, from the viewpoint of better suppressing the component migration of the self-sealing resin, the T 2 relaxation time (T 2s ) of the S component of the A layer obtained by pulse NMR _2. The relaxation time (T _2s ) is preferably 40 μsec or less, more preferably 35 μsec or less (for example, 30 μsec or less). The lower limit of T _2s of layer A can be, for example, 5 μsec or more, and is not particularly limited. From the viewpoint of easily expressing moderate viscosity on the surface of the adhesive layer, in some aspects, T _2s of layer A may be 10 μsec or more, 15 μsec or more, or 20 μsec or more. The T _2s of the A layer is not too short. From the perspective of improving the adhesion between the A layer and the layer adjacent thereto (which can be the base material, the adherend, the below-mentioned B layer, etc.), the T 2s of the A layer is preferably _2s is not too short.

The T _2s of the A layer can be determined by obtaining a T ₂ relaxation curve measured by the Solid Echo method using approximately 100 mg of the adhesive constituting the A layer as a measurement sample, and dividing the T ₂ The relaxation curve is fitted to the following equation (1) to determine T _2s of the A layer. The T ₂ relaxation time (T _2s ) of the S component of the B layer described below obtained by pulse NMR can also be measured 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 attenuation α: Proton ratio (%) of the component with a short relaxation time (S component) T _2s : T ₂ relaxation time of the S component (msec) β: A component with a long relaxation time (L component) ) proton ratio (%) T _2L : T ₂ relaxation time of L component (msec) t: Observation time (msec) Wa: Shape coefficient (=1)

The measurement conditions in the above measurement are as follows. ・90° pulse width: 2.1 μsec ・Repetition time: 1 sec ・Cumulative number of times: 32 times ・Measurement temperature: 30℃

(gel fraction) The gel fraction of the adhesive constituting layer A is preferably 75% or more, more preferably 85% or more, and further preferably 90% or more. If it is within this range, the molecular movement of the base polymer can be better restricted through cross-linking, and the migration of components between the adhesive layer/sealing resin can be suppressed. From the viewpoint of suppressing the migration of components, it is advantageous to have a higher gel fraction constituting layer A. In addition, taking into consideration the balance with other characteristics (for example, moderate viscosity or adhesiveness on the surface of the adhesive layer, ability to follow the surface shape of the adherend, etc.), the adhesion of the A layer is constituted in some aspects. The gel fraction of the agent may be, for example, 99.5% or less, or 99% or less. The gel fraction is calculated by dipping the adhesive collected from layer A in ethyl acetate for 7 days and then drying it by (dry weight of the adhesive after immersion/weight of the adhesive before immersion) × 100 .

(Nitrogen gas generation amount) In some aspects of the adhesive sheet, regarding the nitrogen gas generation amount when the adhesive constituting the A layer is heat-treated, the weight of the adhesive used for the heat treatment is set to 100% by weight, and the nitrogen gas The production amount is preferably 0.06 to 1.0% by weight, more preferably 0.06 to 0.9% by weight. If the above-mentioned amount of nitrogen generated is 0.06% by weight or more, the adhesive will fully exert its cohesion force and suppress component migration between the adhesive layer/sealing resin, thereby making it less likely that a step will occur at the interface between the semiconductor chip and the sealing resin. From the viewpoint of suppressing the positional shift of the adherend arranged on the A layer, it is advantageous that the nitrogen generation amount is 1.0 wt% or less. The above-mentioned amount of nitrogen generated can be determined by collecting 2 mg of the adhesive on a ceramic plate and measuring it with a microbalance, and then using a TN (Trace Total Nitrogen Analysis) device to measure the temperature of the sample. The amount of nitrogen generated was determined by analyzing the amount of nitrogen generated by heating under the conditions of decomposition furnace 800°C/oxidation furnace 900°C. The conditions for measurement are as follows.・Carrier gas: O ₂ (300 mL/min), Ar (300 mL/min) ・Standard sample: pyridine/toluene solution ・Detector: reduced pressure chemiluminescence detector ・Range: high concentration

<Layer B> In some aspects of the adhesive sheet disclosed here, the above-mentioned first adhesive layer includes: A layer constituting at least the surface of the adhesive layer, and disposed between the A layer and the above-mentioned base material And the B layer adjacent to the substrate. That is, the outer surface of the first adhesive layer (the surface on the adherend side) is formed of the A layer, and the inner surface (the surface on the base material side) of the first adhesive layer includes the B layer. According to the first adhesive layer having this structure, for example, the characteristics (pressure) at positions A and B can be easily measured based on the selection of the adhesive constituting the layers A and B, the selection of the thickness of each layer, etc. Mark hardness, drawability, _T2 relaxation time of S component, etc.) or the ratio of these can be adjusted.

As the adhesive constituting the B layer, any appropriate adhesive can be used. The above-mentioned B layer may include, for example, an acrylic adhesive, a rubber adhesive, a silicone adhesive, a polyester adhesive, a urethane adhesive, a polyether adhesive, and a polyamide adhesive. One or more of various well-known adhesives such as adhesives and fluorine-based adhesives.

In some preferred aspects, the adhesive constituting the above-mentioned B layer is an acrylic adhesive using an acrylic polymer as a base polymer. In the case where the A layer contains an acrylic adhesive, from the viewpoint of improving the interlayer adhesion of the layers included in the first adhesive layer, it is particularly preferable to use an acrylic adhesive as the adhesive constituting the B layer.

In the case where the adhesive constituting the B layer is an acrylic adhesive, the acrylic polymer as the base polymer of the acrylic adhesive can be the same as the acrylic polymer as the base polymer of the A layer. Make appropriate selections. The acrylic polymer used as the base polymer of layer A and the acrylic polymer used as the base polymer of layer B may be the same or different. In some aspects, from the viewpoint of the adhesion between layer A and layer B, the base polymer of layer A and layer B can be the same acrylic polymer. In this aspect, materials other than the base polymer used to form each layer (crosslinking agent, adhesion-imparting agent, etc.) may be used depending on whether or not materials other than the base polymer used to form each layer (crosslinking agent, adhesive agent, etc.) are used. The type, amount, etc. of the adhesion-imparting agent, etc.) are selected to adjust the characteristics of the measurement positions A and B or the ratio between them.

The base polymer of the B layer is preferably cross-linked in the adhesive constituting the B layer. For example, by using an adhesive composition including a base polymer and an appropriate cross-linking agent, a layer B including an adhesive in which the base polymer is cross-linked by the above-mentioned cross-linking agent can be obtained. The type of cross-linking agent used in layer B can be appropriately selected from those exemplified above as cross-linking agents that can be used in layer A, and is not particularly limited. The cross-linking agent used in layer A and the cross-linking agent used in layer B may be the same type of cross-linking agent (for example, the same or different isocyanate-based cross-linking agents), or they may be different types of cross-linking agents. (For example, one is an epoxy-based cross-linking agent and the other is an isocyanate-based cross-linking agent).

In some preferred aspects, layer A uses an epoxy cross-linking agent, and layer B uses an isocyanate cross-linking agent. Generally speaking, compared with epoxy cross-linking agents, isocyanate-based cross-linking agents tend to form a softer cross-linked structure. Therefore, according to the above aspect, the indentation hardness H2 can be better achieved to be smaller than the indentation hardness H1. The first adhesive layer.

When an isocyanate cross-linking agent is used as the cross-linking agent of the B layer, the usage amount of the isocyanate cross-linking agent relative to 100 parts by weight of the base polymer of the B layer (for example, an acrylic polymer) can obtain the desired properties. There are no special restrictions on how to make appropriate adjustments. In some aspects, the usage amount of the isocyanate cross-linking agent relative to 100 parts by weight of the base polymer of the B layer is, for example, 0.1 to 20 parts by weight, preferably 1 to 10 parts by weight, and more preferably It may be 1 to 7 parts by weight, it may be 1 to 5 parts by weight, or it may be 2 to 5 parts by weight.

In order to carry out the cross-linking reaction more effectively, a cross-linking catalyst can also be used. Examples of cross-linking catalysts include metal-based cross-linking catalysts such as tetra-n-butyl titanate, tetraisopropyl titanate, iron triacetyl acetonate, butyl tin oxide, and dioctyl tin dilaurate. . The amount of cross-linking catalyst used is not particularly limited. In some aspects, taking into account the balance between the speed of the cross-linking reaction and the length of the pot life of the adhesive composition, the usage amount of the cross-linking catalyst relative to 100 parts by weight of the base polymer can be set to, for example, 0.0001 parts by weight. 1 part by weight or less (preferably 0.001 part by weight or more and 0.5 part by weight or less). The above-mentioned cross-linking catalyst can be used for the A layer, or for both the A layer and the B layer.

In some aspects of the adhesive sheet disclosed here, the T ₂ relaxation time (T _2s ) of the S component of the B layer constituting the first adhesive layer obtained by pulse NMR improves the response to the adhesive sheet disposed thereon. From the viewpoint of following the surface shape of the adherend on the A layer of the adhesive layer, the T ₂ relaxation time (T _2s ) of the S component obtained by pulse NMR of the B layer constituting the first adhesive layer is better It is longer than T _2s of layer A mentioned above. The difference between T _2s of layer A and T _2s of layer B can be, for example, 5 μsec or more, preferably 10 μsec or more, more preferably 15 μsec or more, more preferably 20 μsec or more, or 25 μsec or more, or is more than 30 μsec. Furthermore, from the viewpoint of preventing aggregation damage of the adhesive layer caused by excessively long T _2s of the B layer, it is appropriate that the difference between the T _2s of the A layer and the T _2s of the B layer is, for example, 70 μsec or less, and preferably 60 μsec. μsec or less, more preferably 50 μsec or less, 40 μsec or less, or 35 μsec or less.

In some aspects, it is more appropriate for the T _2s of the B layer to be greater than the T _2s of the A layer and to be above 30 μsec (for example, above 35 μsec, above 40 μsec, or above 45 μsec), so as to better enhance the effect on the surface of the adherend. From the viewpoint of the effect of shape followability, T _2s of the B layer is preferably longer than 45 μsec, may be 47 μsec or more, or may be 50 μsec or more. Furthermore, from the viewpoint of preventing aggregation damage of the B layer, it is more appropriate for the T _2s of the B layer to be 80 μsec or less, preferably 70 μsec or less, or 65 μsec or less, or 60 μsec or less, or is 57 μsec or less.

In some aspects of an adhesive sheet having an adhesive layer composed of an A layer and a B layer, the thickness of the B layer may be, for example, 3 μm or more, and more preferably 4 μm or more, so as to improve the ability to impart a surface shape. From the viewpoint of the effect of followability, it is preferably 5 μm or more, 7 μm or more, 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. From the viewpoint of suppressing the semiconductor chip from being embedded in the adhesive sheet in a usage state where the semiconductor chip is resin-sealed on the adhesive layer, the thickness of the B layer is preferably 100 μm or less, and preferably 90 μm. It may be 70 μm or less, 50 μm or less, 30 μm or less, or 20 μm or less.

In an adhesive sheet having an adhesive layer composed of an A layer and a B layer, the thickness of the A layer may be, for example, 1 μm or more and 20 μm or less. From the perspective of better exerting the effect of improving the ability to follow the surface shape with the help of the B layer, in some aspects, the thickness of the above-mentioned A layer is more appropriately 15 μm or less, and preferably 10 μm or less. It may be 8 μm or less, or it may be 6 μm or less. Furthermore, from the viewpoint of better exerting the effect of inhibiting the migration of components between the adhesive layer/sealing resin with the help of the A layer, in some aspects, it is more advantageous for the thickness of the above-mentioned A layer to be 2 μm or more, which is better than It is preferably 3 μm or more, 4 μm or more, or 5 μm or more.

In an adhesive sheet having an adhesive layer composed of an A layer and a B layer, the ratio (L2/L1) of the thickness L2 [μm] of the above-mentioned layer B to the thickness L1 [μm] of the above-mentioned layer A (L2/L1) can be, for example It is about 0.5 to 100.0 and is not particularly limited. In some aspects, from the viewpoint of easily and effectively exerting the functions of the A layer and the B layer, the above ratio (L2/L1) is more appropriately 0.5 or more, preferably 0.7 or more, and may also be 0.8 or more. It may be 0.9 or more, or it may be 1.0 or more. Moreover, from the same viewpoint, the above-mentioned ratio (L2/L1) is more appropriately 50.0 or less, preferably 30.0 or less, 20.0 or less, 15.0 or less, 10.0 or less, or 5.0. below, it can also be below 3.0 or below 2.0.

＜Substrate＞ The base material of the adhesive sheet disclosed here may be, for example, a resin sheet, nonwoven fabric, paper, metal foil, woven fabric, rubber sheet, foam sheet, or a laminate of these (especially a laminate including a resin sheet). body) etc. Examples of the resin constituting the resin sheet include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), and polyethylene. (PE), polypropylene (PP), ethylene-propylene copolymer, ethylene-vinyl acetate copolymer (EVA), polyamide (nylon), fully aromatic polyamide (aramid), polyimide (PI) ), polyvinyl chloride (PVC), polyphenylene sulfide (PPS), fluorine resin, polyether ether ketone (PEEK), etc. Examples of nonwoven fabrics include nonwoven fabrics made from heat-resistant natural fibers such as abaca-based nonwoven fabrics; synthetic resin nonwoven fabrics such as polypropylene resin nonwoven fabrics, polyethylene resin nonwoven fabrics, and ester resin nonwoven fabrics. Examples of the metal foil include copper foil, stainless steel foil, aluminum foil, and the like. Examples of paper include Japanese paper, kraft paper, and the like.

In some aspects, it is preferable to use a resin sheet containing a resin with a glass transition temperature (Tg) of 25°C or higher (preferably 40°C or higher, more preferably 50°C or higher) as the base material. If such a resin sheet is used, the shape of the base material can be maintained even by heating during the sealing step, preventing the semiconductor chip from being embedded in the adhesive sheet. The resin constituting the resin sheet is preferably a polymer having an aromatic ring. Specific examples include polyethylene terephthalate (PET), polyimide, and polynaphthalenedicarboxylic acid. Ethylene glycol, etc., but are not limited to these.

The thickness of the above-mentioned base material can be set to any appropriate thickness according to required strength or flexibility, purpose of use, etc. The thickness of the substrate is preferably 1000 μm or less, more preferably 25 μm or more and 1000 μm or less, further preferably 40 μm or more and 500 μm or less, especially 60 μm or more and 300 μm or less, and most preferably 80 μm or more and 250 μm or more. the following. In one embodiment, a substrate with a thickness of 25 μm or more can be used. A substrate with such a thickness can easily maintain the shape of the substrate even after being pressurized during the sealing step, and is suitable for preventing the semiconductor chip from being embedded in the adhesive sheet.

In one embodiment, the thickness of the base material is 20% or more and 90% or less (preferably 20% or more and 89% or less, more preferably 20% or more and 88% or less) relative to the total thickness of the adhesive sheet. . In this range, the semiconductor chip can be preferably prevented from being embedded in the adhesive sheet.

The above-mentioned base material may also be subjected to surface treatment. Examples of surface treatment include corona treatment, chromic acid treatment, ozone exposure, flame exposure, high-voltage electric shock exposure, ionizing radiation treatment, and coating treatment using a primer.

As the above-mentioned primer, an organic coating material can be used. Examples of the above-mentioned organic coating materials include materials described in "Plastic Hard Coat Materials II" published by CMC (2004 publication). Urethane polymers can be preferably used, and polyacrylic urethane, polyester urethane or precursors thereof can be more preferably used. The reason for this is that it is relatively easy to coat and coat the base material, and a variety of products are industrially available and can be obtained cheaply. The urethane polymer is, for example, a polymer including a reaction mixture of an isocyanate monomer and an alcoholic hydroxyl-containing monomer (for example, a hydroxyl-containing acrylic compound or a hydroxyl-containing ester compound). The organic coating material may also contain chain extenders such as polyamine, anti-aging agents, oxidation stabilizers, etc. as optional additives. The thickness of the organic coating layer is not particularly limited, but for example, it is suitably about 0.1 μm to 10 μm, preferably about 0.1 μm to 5 μm, more preferably about 0.5 μm to 5 μm.

＜Second adhesive layer＞ Some aspects of the adhesive sheet include the base material, the adhesive layer disposed on one side of the base material, and a second adhesive layer disposed on the opposite side of the base material to the adhesive layer. The adhesive sheet (double-sided adhesive sheet with base material) having this structure can be fixed on an appropriate carrier (for example, SUS plate, glass plate, etc.) using the second adhesive layer, for example. The resin sealing step is performed on the above-mentioned first adhesive layer, so the usability is better. The above-mentioned second adhesive layer may be an adhesive layer containing any appropriate adhesive.

In some aspects of the adhesive sheet, at least the surface of the second adhesive layer includes an adhesive containing thermally expandable microspheres. The adhesive sheet in this form is preferably heated for an appropriate period of time to expand the thermally expandable microballoons, thereby easily releasing the bond between the second adhesive layer and the adherend (such as the carrier). .

The adhesive containing thermally expandable microspheres can be a hardening adhesive (for example, an active energy ray hardening adhesive) or a pressure-sensitive adhesive. Examples of the pressure-sensitive adhesive include acrylic adhesives, rubber adhesives, and the like. For details on the adhesive contained in the second adhesive layer, refer to the description of Japanese Patent Application Publication No. 2018-009050, for example. The entire description of this publication is incorporated into this specification by reference.

As the heat-expandable microspheres, any appropriate heat-expandable microspheres can be used as long as they can be expanded or foamed by heating. As the thermally expandable microspheres, for example, microspheres obtained by enclosing a substance that easily expands by heating can be used in an elastic shell. Such thermally expandable microspheres can be produced by any appropriate method, such as agglomeration method, interfacial polymerization method, etc.

Examples of substances that easily expand by heating include propane, propylene, butylene, n-butane, isobutane, isopentane, neopentane, n-pentane, n-hexane, isohexane, and heptane. , octane, petroleum ether, methane halides, tetraalkyl silanes and other low-boiling point liquids; azodimethylamide vaporized by thermal decomposition; etc.

Examples of substances constituting the shell include polymers containing the following components: nitrile monomers such as acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, α-ethoxyacrylonitrile, and fumaronitrile; Carboxylic acid monomers such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid; vinylidene chloride; vinyl acetate; methyl (meth)acrylate, ethyl (meth)acrylate Ester, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, isopropyl (meth)acrylate, cyclohexyl (meth)acrylate, (meth)acrylate (meth)acrylates such as benzyl acrylate and β-carboxyethyl acrylate; styrene monomers such as styrene, α-methylstyrene and chlorostyrene; acrylamide, substituted acrylamide, methyl Acrylamide, substituted methacrylamide and other amide monomers; etc. The polymer containing 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, and methyl methacrylate-acrylonitrile. Copolymer, acrylonitrile-methacrylonitrile-itaconic acid copolymer, etc.

As the thermally expandable microspheres, an inorganic foaming agent or an organic foaming agent can be used. Examples of inorganic foaming agents include ammonium carbonate, ammonium bicarbonate, sodium bicarbonate, ammonium nitrite, sodium borohydride, various azides, and the like. Examples of the organic foaming agent include: fluorochloroalkane compounds such as trichloromonofluoromethane and dichloromonofluoromethane; azobisisobutyronitrile, azodimethylamide, azobis Azo compounds such as barium formate; p-toluene sulfonyl hydrazine, diphenyl-3,3'-disulfonyl hydrazine, 4,4'-oxybis(benzenesulfonyl hydrazine), allyl bis(sulfonyl hydrazine) Hydrazine compounds such as hydrazine); amidourea compounds such as p-toluenesulfonamide amidourea and 4,4'-oxybis(benzenesulfonamide amidourea); 5-𠰌linyl-1,2,3,4 -Thiatriazole and other triazole compounds; N,N'-dinitrosopentamethylenetetramine, N,N'-dimethyl-N,N'-dinitrosoterephthalamide ; and other N-nitroso compounds, etc.

Commercially available products can be used as the thermally expandable microspheres. Specific examples of commercially available heat-expandable microspheres include: "Matsumoto Microsphere" (trade name: F-30, F-30D, F-36D, F-36LV, F- 50. F-50D, F-65, F-65D, FN-100SS, FN-100SSD, FN-180SS, FN-180SSD, F-190D, F-260D, F-2800D), product names manufactured by Japan Fillite Company "Expancel" (Grade: 053-40, 031-40, 920-40, 909-80, 930-120), "Daifoam" manufactured by Kureha Chemical Industry Co., Ltd. (Grade: H750, H850, H1100, S2320D, S2640D, M330, M430, M520), "AdvanCell" manufactured by Sekisui Chemical Industry Co., Ltd. (Grade: EML101, EMH204, EHM301, EHM302, EHM303, EM304, EHM401, EM403, EM501), etc.

The particle size of the thermally expandable microspheres before heating is preferably 0.5 μm to 80 μm, more preferably 5 μm to 45 μm, further preferably 10 μm to 20 μm, particularly preferably 10 μm to 15 μm. Therefore, when the particle size of the thermally expandable microspheres before heating is referred to as the average particle diameter, it is preferably 6 μm to 45 μm, more preferably 15 μm to 35 μm. The above-mentioned particle diameter and average particle diameter are values determined by the particle size distribution measurement method in the laser scattering method.

The thickness of the adhesive layer including the adhesive containing thermally expandable microspheres can be, for example, 3 μm or more, and is not particularly limited. From the viewpoint of suppressing the decrease in smoothness of the adhesive surface caused by the inclusion of thermally expandable microballoons, the thickness of the adhesive layer is usually more than 7 μm, preferably more than 10 μm, and may be more than 15 μm. It may be more than 25 μm or more than 35 μm. The upper limit of the thickness of the above-mentioned adhesive layer is usually 300 μm or less, which is more appropriate. It may be 200 μm or less, it may be 150 μm or less, it may be 100 μm or less, it may be 70 μm or less, and there is no particular limit. Regarding the thickness of the adhesive layer not being too large, it is advantageous to prevent the adhesive layer from being agglomerated and destroyed due to the expansion of thermally expandable microspheres. In some aspects, the thickness of the adhesive layer may be less than 60 μm, may be less than 50 μm, or may be less than 45 μm.

The thickness Ta of the adhesive layer is preferably greater than the average particle diameter D of the thermally expandable microspheres before heating. That is, it is preferable that Ta/D is larger than 1.0. From the viewpoint of the smoothness of the adhesive surface, in some aspects, Ta/D is preferably 2.0 or more, may be 3.0 or more, or may be 4.0 or more. In addition, from the viewpoint of easily exhibiting the peeling effect caused by the expansion of the thermally expandable microspheres, Ta/D is usually 50 or less, preferably 20 or less, and may be 15 or less, or may be 10 or less.

The thermally expandable microspheres preferably have appropriate strength so that they will not break before the volume expansion rate reaches preferably 5 times or more, more preferably 7 times or more, and further preferably 10 times or more. When using such thermally expandable microballoons, the adhesive force can be efficiently reduced by heat treatment.

The content ratio of the heat-expandable microspheres in the adhesive containing the heat-expandable microspheres can be appropriately set depending on the required reduction in adhesive force, etc. Regarding the content ratio of the heat-expandable microspheres, the content ratio of the heat-expandable microspheres is, for example, 1 to 150 parts by weight, preferably 10 parts by weight, relative to 100 parts by weight of the base polymer of the adhesive agent containing the heat-expandable microspheres. parts to 130 parts by weight, and more preferably 20 parts to 100 parts by weight.

When the adhesive constituting the surface of the second adhesive layer contains thermally expandable microspheres, the arithmetic mean roughness Ra of the surface of the second adhesive layer before expansion of the thermally expandable microspheres (that is, before heating) is preferably: 500 nm or less, more preferably 400 nm or less, further preferably 300 nm or less. If it is within this range, an adhesive sheet having excellent adhesion to the adherend on the side of the second adhesive layer can be obtained. Such a second adhesive layer with excellent surface smoothness can be obtained, for example, by: setting the thickness of the adhesive layer to the above range; applying an adhesive composition containing thermally expandable microspheres to a release liner and performing After drying, the formed adhesive layer is directly transferred to the substrate or transferred to an intermediate layer (such as an elastic intermediate layer) provided on the substrate.

When the second adhesive layer contains thermally expandable microspheres, the adhesive layer preferably contains a dynamic storage modulus in the range of 5 kPa to 1 MPa (more preferably 10 kPa to 0.8 MPa) at 80°C. Adhesive within the base polymer. With such an adhesive layer, an adhesive sheet can be formed that has moderate adhesiveness before heating and can easily reduce adhesive force by heating. Furthermore, the dynamic storage modulus can be measured using a dynamic viscoelasticity measuring device (for example, trade name "ARES" manufactured by Rheometrics) under the measurement conditions of a frequency of 1 Hz and a temperature rise rate of 10°C/min.

＜Manufacturing method of adhesive sheet＞ The adhesive sheet of the present invention can be produced by any suitable method. The adhesive sheet of the present invention can be produced, for example, by forming an adhesive layer (which may be a first adhesive layer, layer A or layer B constituting the first adhesive layer, a second adhesive layer, etc.) A method in which the adhesive composition of the ingredients is directly coated on the base material or on an intermediate layer (such as B layer, elastic intermediate layer, etc.) provided on the base material to form an adhesive layer; applying the adhesive composition A method of applying any appropriate release process material (such as a release liner) to form an adhesive layer on the release process material, and transferring the adhesive layer to the base material or the intermediate layer on the base material; Combinations of such; etc. The above-mentioned adhesive composition may be a solvent-based adhesive composition containing any suitable solvent.

When forming an adhesive layer containing thermally expandable microspheres, a composition containing thermally expandable microspheres, an adhesive, and any appropriate solvent can be applied to the substrate to form the adhesive layer. Alternatively, the thermally expandable microspheres may be sprinkled onto the adhesive coating layer, and then a laminating machine or the like may be used to embed the thermally expandable microspheres in the adhesive to form an adhesive layer containing the thermally expandable microspheres.

As the coating method of the above-mentioned adhesive and each composition, any appropriate coating method can be used. For example, each layer can be formed by drying after coating. Examples of the coating method include a coating method using a multifunctional coater, a die coater, a gravure coater, an applicator, and the like. Examples of drying methods include natural drying, heat drying, and the like. The heating temperature when performing heat drying can be set to any appropriate temperature according to the characteristics of the substance to be dried. [Example]

Several embodiments related to the present invention will be described below, but the present invention is not intended to be limited to those shown in the specific examples. In addition, in the following description, "parts" and "%" are based on weight unless otherwise specified.

＜Evaluation method＞ 1. Indentation hardness The indentation hardness H1 and H2 were measured by the above method using a nanoindentation instrument manufactured by Hysitron Corporation, product name "Triboindenter TI-950".

2. Drawnability A nanoindentation instrument manufactured by Hysitron Corporation, product name "Triboindenter TI-950" was used to measure drawability D1 and D2 by the above method.

3. Swelling test Using a syringe (syringe diameter: 22 mm), drop 0.02 g of 4-tert-butylphenyl glycidyl ether (TBPGE) onto the surface of the first adhesive layer, and let it stand for 1 hour in an environment of 23°C and 50%RH. minute. Use a rag to absorb the TBPGE remaining on the surface of the adhesive layer to remove it, and then measure the thickness T1 [μm] of the adhesive layer in the area where TBPGE was dropped. Based on the thickness (initial thickness) T0 [μm] of the adhesive layer at the site before TBPGE is dropped and the above-mentioned thickness T1 [μm], the thickness change amount and thickness change rate of the adhesive layer are calculated by the following formula. Thickness change [μm]=T1-T0 Thickness change rate [%] = ((T1-T0)/T0)×100

4.TMA sinking amount Use a thermomechanical analysis device manufactured by TA Instruments, product name "TMA Q400", with probe: needle insertion (cylindrical shape, tip diameter 1 mmΦ), nitrogen gas flow rate: 50.0 ml/min, intrusion load: 0.01 N, and measurement Under the conditions of atmosphere temperature: 23.0°C and press-in load time: 60 minutes, measure the sinking amount from the surface of the first adhesive layer. The measurement was performed with N=5, and the average value of N=3 obtained by excluding the maximum value and the minimum value from these measured values was taken as the TMA sinking amount. Furthermore, in the case where the adhesive sheet has an adhesive layer (first adhesive layer) only on one side of the base material and does not have a second adhesive layer on the opposite side (back side) of the base material, Regarding this adhesive sheet, the above-mentioned standard adhesive layer (100 parts of acrylic polymer based on EA/2EHA/MMA/HEA=30/70/5/5 (weight ratio)) was formed on the back side of the above-mentioned base material, containing After forming an adhesive layer of 10 parts of adhesive imparting agent, 2 parts of isocyanate cross-linking agent, and 30 parts of heat-expandable microspheres (thickness: 45 μm), the amount of TMA sinking was measured.

5. Relaxation time: Select and collect about 100 mg of adhesive from the adhesive layer that constitutes layer A, and measure the T ₂ relaxation curve by using it as a measurement sample for pulse NMR measurement. Using the above formula (1), fitting is performed by analysis software (TDNMR-A), and the T ₂ relaxation time of the S component is obtained by analyzing it approximately to one component (α). Furthermore, Wa all resolves to 1. The shortest one among the relaxation times calculated by the above analysis method is defined as the T ₂ relaxation time (T _2s ) of the S component of the A layer obtained by pulse NMR. In the same manner, the T ₂ relaxation time (T _2s ) of the S component of the B layer obtained by pulse NMR was obtained. In addition, regarding the pulse NMR measurement, a time domain NMR device manufactured by Bruker Corporation, device name "TD-NMR the minispec mq20" was used, and the temperature was measured at a 90° pulse width of 2.1 μ seconds, a repetition time of 1 second, and a cumulative count of 32 times. Pulse NMR measurement was performed by Solid Echo method at 30°C.

6. Adhesion to PET Cut the adhesive sheet into a size of 20 mm in width and 140 mm in length, and use a 2 kg hand roller to cover the entire back side (the side opposite to the side where the first adhesive layer is provided) with double-sided tape ( Manufactured by Nitto Denko Co., Ltd., trade name "No.531") and bonded to the SUS304 board. Regarding the adhesive sheet having a second adhesive layer on the back side of the base material, the back side of the adhesive sheet is bonded to the SUS304 board via the second adhesive layer instead of using the No. 531 double-sided tape. . In an environment of 23°C and 50% RH, the polyethylene terephthalate (PET) film (manufactured by Toray Corporation, trade name "Lumirror S-10", thickness 25 μm, width 30 mm) is attached to the adhesive surface of the adhesive sheet fixed to the SUS304 board on the back side as described above using a 2 kg roller in one round trip. After leaving it in the above environment for 30 minutes, use a tensile testing machine to measure the load when the PET film is peeled off from the adhesive sheet at a peeling angle of 180 degrees and a tensile speed of 300 mm/min. The average load is set as the adhesive force of the adhesive sheet to PET. As the above-mentioned tensile testing machine, a trade name "Autograph AG-120kN" manufactured by Shimadzu Corporation was used.

7. Grip after heating Cut the adhesive sheet into a size of 20 mm in width and 140 mm in length, and use a 2 kg hand roller to cover the entire back side (the side opposite to the side where the first adhesive layer is provided) with double-sided tape ( Manufactured by Nitto Denko Co., Ltd., trade name "No.531") and bonded to the SUS304 board. Regarding the adhesive sheet having a second adhesive layer on the back side of the base material, the adhesive sheet was bonded to the SUS304 board via the second adhesive layer instead of using the No. 531 double-sided tape. After maintaining it in an environment of 150°C for 1 hour, let it stand in an environment of 23°C and 50%RH for 2 hours. Next, in an environment of 23°C and 50% RH, use a cutter to cut a depth from the surface of the first adhesive layer to the surface of the base material, and cut a commercially available acrylic tape (manufactured by Nitto Denko Co., Ltd. Name: No.315) Use a 2 kg roller to press it in one round trip and let it sit for 30 minutes. Thereafter, the tensile testing machine was used to measure the load when peeling off the acrylic tape at a peeling angle of 180 degrees and a stretching speed of 50 mm/min, and the maximum load at this time was recorded as the post-heating gripping force.

8. Adhesion to sealing resin Cut the adhesive sheet into a size of 50 mm width and 140 mm length, and attach the mold frame (opening size: rectangle with width 35 mm and length 90 mm, thickness: 564 μm) to the first adhesive layer. Spread granular epoxy resin sealing material (G730 manufactured by Sumitomo Bakelite Co., Ltd.) in the above mold frame so that the thickness of the cured resin becomes 0.3 mm, cover it with a silicone-treated release liner, and use "Hydraulic forming machine NS-VPF-50" manufactured by Meisho-press Company operates at a temperature of 145°C, a forming time of 600 seconds, a pressure condition of 0.3 MPa (300 mm square platform size), a vacuum time of 600 seconds, and a vacuum degree of - Under the condition of 0.1 MPa, heat the sealing resin on the first adhesive layer and form it. Heat it at 150°C for 7 hours to harden the sealing resin. Next, after leaving it for 2 hours in an environment of 23°C and 50% RH, cut the part of the sealing resin in contact with the first adhesive layer into a width of 20 mm. The size of the length is 88 mm, and a sample for evaluation is prepared. After the evaluation sample was placed in an environment of 23°C and 50% RH for 30 minutes, the self-sealing resin peel adhesion was measured using the above-mentioned tensile testing machine at a peeling angle of 180 degrees and a tensile speed of 300 mm/min. The load at the time of sheet material, let the average load at this time be the adhesion force of the adhesive sheet to the sealing resin.

9. Paste residue prevention In the above-mentioned measurement of the adhesive force of the sealing resin, visual inspection was performed to confirm whether there was any paste remaining on the sealing resin after peeling off the adhesive sheet. Based on the results, when the presence of paste residue is confirmed, it is determined that the prevention of paste residue is "P" (Poor: Insufficient prevention of paste residue), and when the presence of paste residue is not confirmed, it is determined that the prevention of paste residue is "P" Preventive property "G" (Good: Paste residue prevention property is good).

10. Model overflow evaluation On the first adhesive surface of the adhesive sheet, the resin sealing step of the semiconductor wafer (Si wafer) was carried out under the following conditions, and the performance of preventing the sealing resin from intruding into the interface between the chip and the sealing resin (model flash) was evaluated. Vehicle: SUS vehicle (220 mmΦ) Chip: Dummy chip with step difference (with copper pad on one side of a 7 mm×7 mm×400 μm thick silicon substrate (pad target height 5.5 μm, mask: GNC-300 mm-G03-A-300S) Dummy chip. Manufactured by Globalnet Corporation) Bonding device: FC3000W manufactured by Toray Engineering Co., Ltd. Joining conditions: crimping time 6 seconds, crimping pressure 10 N, crimping temperature: 23°C Sealing equipment: MS-150HP manufactured by Apic Yamada Company Sealing resin: G730 manufactured by Sumitomo Bakelite Co., Ltd. Preheating conditions: 130℃×30 seconds Time from preheating to sealing start: 1 hour Sealing temperature: 145℃ Vacuum time: 5 seconds Sealing time: 600 seconds Clamping force: 3.6 MPa Sealing thickness: 600 μm

The sealing operation is carried out in the following order. 1) Attach the back side of the adhesive sheet to the SUS carrier through the adhesive layer containing thermally expandable microspheres (attachment conditions: 23°C atmosphere, attachment cylinder pressure 0.1 MPa, attachment speed 0.5 m/min) . As the adhesive layer containing thermally expandable microspheres, for an adhesive sheet having a second adhesive layer containing thermally expandable microspheres on the back side of the base material, the second adhesive layer is directly used. For an adhesive sheet that does not have a second adhesive layer on the back side of the base material, the above-mentioned standard adhesive layer (containing 30 parts of thermal expansion with respect to 100 parts of the acrylic polymer) is formed on the back side of the base material. The adhesive layer of microspheres (trade name "Matsumoto Microsphere F-190D" manufactured by Matsumoto Oil Pharmaceutical Co., Ltd.; thickness 45 μm) is used to fix the back side of the above-mentioned adhesive sheet to the SUS carrier through this standard adhesive layer. 2) On the first adhesive layer of the adhesive sheet fixed on the SUS carrier, use the above-mentioned bonding device to arrange a total of 25 dummy wafers with the above-mentioned steps in the following manner, that is, 8 wafers along the central angle of 45 degrees Radial straight lines are arranged with intervals gradually becoming larger from the center to the outer periphery. The orientation of the wafer is such that the step surface (pad formation surface) of the wafer faces the first adhesive layer. 3) Preheat the SUS carrier with a stepped dummy chip placed on the first adhesive layer of the adhesive sheet under specific conditions. 4) After preheating, let it stand for 1 hour in an environment of 23°C and 50% RH. Apply a specific sealing resin evenly by hand from the above-mentioned dummy chip, and use a specific sealing equipment to perform the process under sealing conditions. seal. 5) The obtained laminated body was heated at 150° C. for 4 hours to harden the sealing resin. 6) Place the heat-hardened laminate in an environment of 23°C and 50% RH for 5 days, and then heat it on a hot plate to cause thermal expansion in the adhesive layer where the adhesive sheet is fixed on the SUS carrier. The microscopic balls expand and the SUS carrier is separated from the above-mentioned laminate. 7) Peel off the adhesive sheet from the laminated body after separating the SUS carrier, and obtain a structure including a sealing resin and a dummy wafer with a step.

Regarding the above-mentioned structure, the surface in contact with the above-mentioned first adhesive surface was observed with a laser confocal microscope (OLS-4000 manufactured by OLYMPUS) to confirm whether the sealing resin had penetrated into the dummy wafer with the step. If residue of adhesive (paste residue) is found on the above surface, remove the residue with toluene and observe it. As a result, when sealing resin penetration is observed in all dummy wafers, the judgment is "P" (Poor: Insufficient model flash prevention). When sealing resin penetration is not observed in all dummy wafers, the judgment is "P" (Poor: insufficient model flash prevention). It is "G" (Good: the model has good anti-spill properties).

11. Gap evaluation On the first adhesive surface of the adhesive sheet, except that a Si mirror wafer (7 mm × 7 mm × 400 μm thick) is used as the semiconductor wafer (Si wafer), the semiconductor wafer (Si wafer) is implemented in the same manner as the above model flash evaluation. Si wafer), a structure including a sealing resin and a Si mirror wafer is obtained. Regarding this structure, the surface in contact with the above-mentioned first adhesive surface was observed with a laser confocal microscope (OLS-4000 manufactured by OLYMPUS), and the Si wafer placed in the center was used as an object, and the Si wafer and seal on the above-mentioned surface were measured. The step height (gap height) of the resin interface. When adhesive residue (paste residue), etc. is confirmed on the above surface, use toluene to remove the residue and then perform measurement. As a result, when the gap height is less than 3.3 μm, it is judged as "G" (Good: the gap is well suppressed), and when the gap height is 3.3 μm or more, it is judged as "P" (Poor: The gap is not suppressed well). full).

＜Example 1＞ In a toluene solution containing 100 parts of polymer P1 (an acrylic polymer containing monomer components of 2-ethylhexyl acrylate (2EHA)/acrylic acid (AA) = 95/5 (weight ratio). SP value: 19.3) 5 parts of an epoxy cross-linking agent (manufactured by Mitsubishi Gas Chemical Co., Ltd., trade name "Tetrad C") and toluene for dilution (100 parts in total) were added and mixed to prepare an adhesive composition 1a. This adhesive composition 1a was applied to a release film R1 (manufactured by Toray Film Processing Co., Ltd., trade name) containing polyethylene terephthalate (PET) that has been released on one side with a silicone-based release treatment agent. "Cerapeel MDAR", thickness 38 μm) on the peeling surface and dried to form an adhesive layer 1A (thickness L1 = 10 μm) on the above-mentioned peeling film R1. An adhesive composition was prepared in the same manner as the adhesive composition 1a except that 5 parts of the epoxy cross-linking agent was changed to 3 parts of an isocyanate cross-linking agent (manufactured by Tosoh Corporation, trade name "Coronate L") Thing 1b. The adhesive composition 1b was applied to one side of a PET film (manufactured by Toray Corporation, trade name "Lumirror S10", thickness 38 μm) as a base material and dried, thereby forming a layer of adhesive composition 1b on one side of the base material. Adhesive layer 1B (thickness L2 = 10 μm) is formed. The adhesive surface of the adhesive layer 1A formed on the above-mentioned release film R1 is bonded to the adhesive surface of the above-mentioned adhesive layer 1B, thereby obtaining a first adhesive layer including the adhesive layer 1B and the adhesive layer 1A arranged on the above-mentioned A single-sided adhesive sheet of a base material (an adhesive sheet consisting of base material/adhesive layer 1B (B layer)/adhesive layer 1A (A layer)).

＜Example 2＞ Except that the usage amount of the cross-linking agent and the thickness of layer A and layer B are as shown in Table 1, a base material/adhesive layer 2B (layer B)/adhesive layer 2A is obtained in the same manner as in Example 1. (A layer) consists of an adhesive sheet.

＜Example 3＞ 100 parts of toluene containing polymer P2 (acrylic polymer containing n-butyl acrylate (BA)/ethyl acrylate (EA)/AA=50/50/5 (weight ratio) monomer components. SP value 19.6) 5 parts of an epoxy cross-linking agent (manufactured by Mitsubishi Gas Chemical Co., Ltd., trade name "Tetrad C") and toluene for dilution (a total of 100 parts) were added to the solution and mixed to prepare an adhesive composition 3a. The adhesive composition 3a is applied to the release-treated surface of the release film R1 and dried to form an adhesive layer 3A (thickness L1 = 5 μm) on the release film R1. An adhesive composition was prepared in the same manner as the adhesive composition 3a except that 5 parts of the epoxy cross-linking agent was changed to 3 parts of an isocyanate cross-linking agent (manufactured by Tosoh Corporation, trade name "Coronate L") Thing 3b. The adhesive composition 3b was applied to one side of a PET film (manufactured by Toray Corporation, trade name "Lumirror S10", thickness 38 μm) as a base material and dried, thereby forming an adhesive composition 3b on one side of the base material. Adhesive layer 3B (thickness L2 = 35 μm) is formed. The adhesive surface of the adhesive layer 3A formed on the above-mentioned release film R1 is bonded to the adhesive surface of the above-mentioned adhesive layer 3B, thereby obtaining a base material/adhesive layer 3B (B layer)/adhesive layer 3A (A Adhesive sheet composed of layers).

＜Example 4＞ Except that the thicknesses of the A layer and the B layer are as shown in Table 1, a composition having the base material/adhesive layer 4B (B layer)/adhesive layer 4A (A layer) was obtained in the same manner as in Example 3. Adhesive sheet.

＜Example 5＞ Acrylic polymer containing monomer components of polymer P3 (containing EA/2EHA/methyl methacrylate (MMA)/2-hydroxyethyl acrylate (HEA)=30/70/5/4 (weight ratio) .SP value 20.7) Add 30 parts of thermally expandable microspheres (manufactured by Matsumoto Oil & Fat Pharmaceuticals Co., Ltd., trade name "Matsumoto Microsphere F-190D") and isocyanate cross-linking agent (manufactured by Tosoh Corporation, trade name " Coronate L") 1.4 parts, 10 parts of an adhesive imparting agent (manufactured by Yasuhara Chemical Co., Ltd., trade name "MightyAce G125"), and toluene for dilution (a total of 100 parts) were mixed to prepare an adhesive composition 5c. The adhesive composition 5c is applied to the release-treated surface of the release film R1 and dried, thereby forming an adhesive layer 5C (thickness 45 μm) on the release film R1. The adhesive surface of the adhesive layer 5C formed on the above-mentioned release film R1 was bonded to the back of the base material of the adhesive sheet of Example 4, thereby obtaining an adhesive layer 5C (second adhesive layer)/base material/adhesion A double-sided adhesive sheet composed of agent layer 4B (layer B)/adhesive layer 4A (layer A).

＜Example 6＞ To a toluene solution containing 100 parts of polymer P3, 1.5 parts of an isocyanate cross-linking agent (manufactured by Tosoh Corporation, trade name "Coronate L") and 10 parts of an adhesive imparting agent (manufactured by Yasuhara Chemical Co., Ltd., trade name "MightyAce G125") were added parts and toluene for dilution (100 parts in total) to prepare adhesive composition 6a. The adhesive composition 6c is applied to the release-treated surface of the release film R1 and dried, thereby forming an adhesive layer 6A (thickness: 30 μm) on the release film R1. To a toluene solution containing 100 parts of polymer P3, add 1 part of an isocyanate cross-linking agent (manufactured by Tosoh Corporation, trade name "Coronate L") and toluene for dilution (100 parts in total) and mix to prepare an adhesive. Composition 6b. The adhesive composition 6b was applied to one side of a PET film (manufactured by Toray Corporation, trade name "Lumirror S10", thickness 38 μm) as a base material and dried, thereby forming a layer of adhesive composition 6b on one side of the base material. Adhesive layer 6B (thickness L2 = 20 μm) is formed. The adhesive surface of the adhesive layer 6A formed on the release film R1 is bonded to the adhesive surface of the adhesive layer 6B, thereby obtaining a base material/adhesive layer 6B (B layer)/adhesive layer 6A (A Adhesive sheet composed of layers).

＜Example 7＞ Polymer P4 containing 2EHA/acrylamide (ACMO)/ An acrylic polymer obtained by modifying an acrylic polymer with a monomer component of HEA = 75/25/22 (mol ratio) is added to 100 parts of a toluene solution and an isocyanate cross-linking agent (manufactured by Tosoh Corporation, Trade name "Coronate L") 5 parts, UV curable oligomer (manufactured by Toagosei Co., Ltd., trade name "Aronix M321") 10 parts, photoinitiator (manufactured by IGM Resins Co., Ltd., trade name "Omnirad 651") 3 parts , and ethyl acetate for dilution are mixed to prepare adhesive composition 7a. The adhesive composition 7a is applied to the release-treated surface of the release film R1 and dried, thereby forming an adhesive layer 7A (thickness L1 = 5 μm) on the release film R1. To a toluene solution containing 100 parts of polymer P2, add 1 part of an isocyanate cross-linking agent (manufactured by Tosoh Corporation, trade name "Coronate L") and UV curable oligomer (manufactured by Toa Gosei Co., Ltd., trade name "Aronix M321" "), 3 parts of photoinitiator (manufactured by IGM Resins, trade name "Omnirad 651"), and ethyl acetate for dilution were mixed to prepare adhesive composition 7b. The adhesive composition 7b was applied to one side of a PET film (manufactured by Toray Corporation, trade name "Lumirror S10", thickness 38 μm) as a base material and dried, whereby the adhesive composition 7b was applied to one side of the base material. Adhesive layer 7B (thickness L2 = 150 μm) is formed. The adhesive surface of the adhesive layer 7A formed on the release film R1 is bonded to the adhesive surface of the adhesive layer 7B, thereby obtaining a base material/adhesive layer 7B (B layer)/adhesive layer 7A (A Adhesive sheet composed of layers).

The obtained adhesive sheet was evaluated by the above method. The results are shown in Table 1. Furthermore, in the measurement of grip strength after heating, peeling was performed at the interface between the acrylic tape and the adhesive surface of the measurement object, and no grip damage was observed with the base material (PET film).

[Table 1] Table 1 example 1 2 3 4 5 6 7 1st adhesive layer A layer [share] polymer P1 100 100 - - - - - P2 - - 100 100 100 - P3 - - - - - 100 - P4 - - - - - - 100 Isocyanate cross-linking agent - - - - - 1.5 4.5 Epoxy cross-linking agent 5 10 5 5 5 - - Adhesion imparting agent - - - - - 10 - UV curable oligomer - - - - - - 10 photoinitiator - - - - - - 3 Thickness L1 of layer A [μm] 10 5 5 6 6 30 5 B layer [share] polymer P1 100 100 - - - - - P2 - - 100 100 100 - 100 P3 - - - - - 100 - Isocyanate cross-linking agent 3 3 3 3 3 1 1 UV curable oligomer - - - - - - 10 photoinitiator - - - - - - 3 Thickness L2 of layer B [μm] 10 5 35 10 10 20 150 Thickness ratio (L2/L1) 1.0 1.0 7.0 1.7 1.7 0.7 30.0 Total thickness (L1＋L2)[μm] 20 10 40 16 16 50 155 Substrate thickness [μm] 38 38 38 38 38 38 38 Thickness of the second adhesive layer [μm] - - - - 45 - - Evaluation Indentation hardness H1[MPa] 0.161 0.204 0.224 0.224 0.224 0.050 0.098 H2[MPa] 0.074 0.074 0.046 0.046 0.046 0.037 0.010 Ratio(H2/H1) 0.46 0.36 0.20 0.20 0.20 0.74 0.10 Drawnability D1[nm] 124 106 135 135 135 1550 1105 D2[nm] 796 796 534 534 534 18600 3771 Ratio (D2/D1) 6.42 7.51 3.96 3.96 3.96 12.00 3.41 Swelling test Initial thickness T0[μm] 20 10 40 16 16 50 51 Thickness after swelling T1[μm] 29 16 52 twenty four twenty four 75 71 Thickness variation [μm] 9 6 12 8 8 25 20 Thickness change rate [%] 45% 60% 30% 50% 50% 50% 39% TMA sinking amount [μm] 4.20 4.00 9.80 4.80 4.80 8.60 10.70 Relaxation time T _2s A layer [μsec] 28 twenty two 26 26 26 52 48 B layer [μsec] 56 56 53 53 53 55 61 Adhesion to PET [N/20 mm] 0.30 0.20 0.85 0.54 0.54 5.40 7.15 Grip strength after heating [N/20 mm] 5.80 5.50 6.10 6.20 6.20 9.40 17.75 Adhesion to sealing resin [N/20 mm] 1.60 1.50 2.50 2.10 2.10 10.20 11.50 Paste residue evaluation G G G G G P P Model spillage evaluation G G G G G G G Gap evaluation G G G G G P P

As shown in Table 1, in the adhesive sheets of Examples 1 to 5 in which the indentation hardness H1 is 0.10 MPa or more and 0.50 MPa or less, and the indentation hardness H2 is 0.001 MPa or more and 0.090 MPa or less, the model flash prevention is good and the paste is The prevention of agent residue is also good.

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

1:Semiconductor wafer 2:Sealing resin 2': semi-hardened material 10: Substrate (substrate film) 20: Adhesive layer (1st adhesive layer) 22:A layer 24:B floor 30: 2nd adhesive layer 50:Construction 100:Adhesive sheet 200:Adhesive sheet 300: Adhesive sheet A: Measurement position A B: Measurement position B

FIG. 1 is a cross-sectional view schematically showing the structure of an adhesive sheet according to one embodiment. FIGS. 2(i) to 2(iv) are explanatory diagrams showing an example of resin sealing steps for a semiconductor chip 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. Figure 5 is a schematic diagram for explaining the definition of drawability.

10: Substrate (substrate film)

20: Adhesive layer (1st adhesive layer)

100:Adhesive sheet

A: Measurement position A

B: Measurement position B

Claims (19)

An adhesive sheet having a base material and an adhesive layer disposed on at least one side of the base material, In the indentation hardness measurement using a nanoindentation instrument, the indentation hardness H1 of the surface of the above-mentioned adhesive layer is 0.10 MPa or more and 0.50 MPa or less, and in the cross-section of the above-mentioned adhesive sheet from the above-mentioned base material to The indentation hardness H2 measured at a distance of 4 μm from the surface side of the above-mentioned adhesive layer is 0.001 MPa or more and 0.090 MPa or less. The adhesive sheet according to claim 1, wherein the ratio (H2/H1) of the above-mentioned indentation hardness H2 [MPa] to the above-mentioned indentation hardness H1 [MPa] is 0.002 or more and 0.90 or less. The adhesive sheet of claim 1 or 2, wherein in the stringability evaluation using a nanoindentation instrument, the stringiness D1 of the surface of the adhesive layer is 50 nm or more and 500 nm or less, and in the above-mentioned adhesive sheet The drawability D2 measured at a distance of 4 μm from the base material to the surface side of the adhesive layer in the cross section of the material is 150 nm or more and 1000 nm or less. The adhesive sheet according to claim 3, wherein the ratio (D2/D1) of the above-mentioned stringiness D2 [nm] to the above-mentioned stringiness D1 [nm] (D2/D1) is 0.3 or more and 20.0 or less. The adhesive sheet according to any one of claims 1 to 4, wherein 4-tert-butylphenyl glycidyl ether is dropped onto the surface of the above-mentioned adhesive layer and left to stand for 1 minute, the thickness of the adhesive layer is T1 The difference (T1-T0) between [μm] and the initial thickness T0 [μm] of the adhesive layer is 20 μm or less. For example, the adhesive sheet according to any one of claims 1 to 5, wherein a thermomechanical analysis device is used to measure the needle penetration measured under the conditions of an ambient temperature of 23°C, a press-in load of 0.01 N, and a press-in load time of 60 minutes. The sinking amount of the probe from the surface of the above-mentioned adhesive layer is 3.50 μm or more and 20.0 μm or less. 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. The adhesive sheet according to any one of claims 1 to 7, wherein the base material is a base film containing a resin material with a glass transition temperature of 25°C or above. For example, the adhesive sheet according to any one of claims 1 to 8 has an adhesive force to the polyethylene terephthalate film of 0.05 N/20 mm or more and 1.00 N/20 mm or less. The adhesive sheet according to any one of claims 1 to 9, wherein after heating the adhesive sheet at 150°C for 1 hour, the gripping force of the adhesive layer on the base material measured at 23°C is 4.00 N/20 mm or more. 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 using an acrylic polymer as a base polymer. The adhesive sheet of claim 11, wherein the SP value of the acrylic polymer is 18.0 to 20.0. The adhesive sheet according to any one of claims 1 to 12, wherein the adhesive layer includes: an A layer constituting the surface of the adhesive layer, and an A layer disposed between the A layer and the base material and with the base material The adjacent B floor. Such as the adhesive sheet of claim 13, wherein the thickness L1 of the above-mentioned layer A is 1 μm or more and 10 μm or less. For example, the adhesive sheet of claim 13 or 14, wherein the thickness L2 of the above-mentioned layer B is 4 μm or more and 100 μm or less. The adhesive sheet according to any one of claims 13 to 15, wherein the ratio (L2/L1) of the thickness L2 [μm] of the above-mentioned layer B to the thickness L1 [μm] of the above-mentioned layer A (L2/L1) is 1.0 to 100.0. The adhesive sheet according to any one of claims 13 to 16, wherein the T 2 relaxation time (T 2s ) of the S component of the above-mentioned layer A obtained by pulse NMR is 45 μsec or less, and the T ₂ relaxation time (T _2s ) of the above-mentioned B layer obtained by pulse NMR The T ₂ relaxation time (T _2s ) of the S component is longer than 45 μsec. The adhesive sheet according to any one of claims 13 to 17, wherein the above-mentioned layer A is cross-linked by an epoxy-based cross-linking agent, and the above-mentioned layer B is cross-linked by an isocyanate-based cross-linking agent. The adhesive sheet according to any one of claims 1 to 18, which includes: the above-mentioned base material, the above-mentioned adhesive layer arranged on one side of the above-mentioned base material, and an opposite side of the above-mentioned adhesive layer arranged on the above-mentioned base material. The second adhesive layer on the side, and At least the surface of the second adhesive layer includes an adhesive containing thermally expandable microspheres.