TWI803605B - Adhesive composition and adhesive tape - Google Patents

Abstract

The subject of the present invention is to eliminate paste residues and end appearance defects on workpieces such as semiconductor wafers and wafers in adhesive tapes used as back grinding tapes and dicing tapes. The solution of the present invention is to provide an adhesive composition, characterized in that the storage modulus G'(23) at 23°C is above 1.0×10 ⁵ Pa, and the storage modulus G'(50) at 50°C is 2.5×10 ⁵ Pa or less, tan δ of dynamic viscoelasticity at 60°C is 0.5 or more, and contains an acrylic polymer as a main component.

Description

Adhesive composition and adhesive tape

The present invention relates to a tape for workpiece processing that temporarily protects the surface of a workpiece (hereinafter referred to as "workpiece") such as a semiconductor wafer, and can be suitably used as an adhesive tape for attaching and holding the workpiece during grinding, dicing, etc. Adhesive tape. Also, the present invention relates to an adhesive composition that can be suitably used for the adhesive tape.

Semiconductor wafers such as silicon, gallium arsenide, etc. can be manufactured in a large diameter state. After the circuit is formed on the surface of the semiconductor wafer, it is ground to a predetermined thickness by back grinding, cut and separated (diced) into small element pieces (semiconductor wafers), and then transferred to the next step of bonding. In these series of steps, various adhesive tapes are used.

In the back grinding step, an adhesive tape called a back grinding tape is used to hold the wafer during grinding and protect the circuit surface from contamination such as grinding debris. In addition, after the back grinding step, there are cases where circuit formation and the like are performed on the ground surface, and at this time, the wafer is also protected and fixed with an adhesive tape for processing. The surface protection tape for back surface processing such as back grinding tape consists of a base material and an adhesive layer with pressure-sensitive adhesive properties. In order to securely protect the circuit surface, an adhesive tape with a relatively soft adhesive with high stress relaxation properties may be used.

In addition, the adhesive tape used in the dicing process is also called a dicing tape, and is composed of a base material and an adhesive layer having pressure-sensitive adhesive properties, and is used to fix a workpiece such as a semiconductor wafer when dicing the workpiece, and To maintain wafers after dicing, an adhesive tape having a softer base material may be used in order to facilitate the expansion of the interval for separating wafers after dicing.

In recent years, not limited to semiconductor wafers having a two-dimensional pattern on which circuits are formed, semiconductor wafers having protrusions as three-dimensional structures have gradually been seen. For example, in the manufacture of a semiconductor device, a wireless bonding technique can be used when placing a wafer that has been singulated by dicing on a substrate. This method can also perform electrical connection between the chip and the substrate without using thin metal wires. As an example, by making the protruding electrodes called bumps provided on the circuit surface of the chip contact the electrodes on the substrate, the electrical connection can be ensured. connect. This packaging method is called face down packaging or flip chip packaging, and contributes to miniaturization of components.

In one example of a method of manufacturing a wafer having such protrusions formed thereon, after forming a circuit on the surface of a semiconductor wafer and forming protrusions on the circuit surface, a back grinding tape is attached to the surface, and the back side is ground and processed. Adjust the thickness. Subsequently, the semiconductor wafer is held on the dicing tape, and the semiconductor wafer is diced and singulated into wafers.

On the surface of the semiconductor wafer, there is a fine unevenness of about 5 to 100 μm due to the protrusions. The back grinding tape is required to follow the uneven surface and protect the circuit surface reliably. When the followability of the back grinding tape is insufficient, grinding debris and the like may intrude into the circuit surface during back grinding, contaminating or damaging the circuit. Therefore, the back grinding tape is required to embed the fine uneven surface.

As a back grinding tape for such a semiconductor wafer having a level difference, an adhesive tape comprising a base material, an intermediate layer, and an adhesive layer is known (Patent Documents 1 and 2). In this adhesive tape, the level difference on the wafer surface is absorbed by the intermediate layer and follows the circuit surface. However, in the aforementioned documents, the intermediate layer is mostly composed of polyolefin polymers, and the adhesive layer is mostly composed of acrylic polymers. Polyolefin-based polymers generally have low affinity with acrylic-based polymers. Therefore, when the back grinding tape is peeled off from the circuit surface of the semiconductor wafer, there is a problem that peeling occurs between the intermediate layer and the adhesive layer and the adhesive remains on the circuit surface of the semiconductor wafer.

Moreover, the adhesive tape of the two-layer structure which consists of a base material and an adhesive agent layer is also known as a back grinding tape. In such an adhesive tape, thickening of the adhesive layer or making the adhesive layer soft has been considered in order to follow the unevenness of the surface of the semiconductor wafer. However, such adhesive tapes may cause problems such as poor appearance and adhesive residue adhering to the circuit surface of the semiconductor wafer.

The adhesive tape is usually wound up into a roll and stored and transported. At this time, a winding pressure is applied to the adhesive tape, so that a part of the adhesive layer and the intermediate layer leaks to the end surface of the roll. Especially during summer storage and transportation at sea, it may be exposed to an environment of about 40°C, resulting in significant leakage of resin components. The resin component leaked to the end surface of the roll becomes the main cause of poor appearance of the end, and the adhesion of dust and the like also becomes the main cause of contamination of the semiconductor wafer. Also, when the adhesive layer is made softer, the followability to the unevenness of the surface of the semiconductor wafer is improved. However, when the adhesive tape is peeled from the surface of the semiconductor wafer, the adhesive layer is stretched and broken during peeling, and a part of the adhesive remains on the wafer circuit surface (paste residue), which may contaminate the circuit surface. [Prior Art Literature] [Patent Document]

[Patent Document 1] Japanese Patent No. 3773358 [Patent Document 2] Japanese Patent No. 4918181

[Problem to be solved by the invention]

The purpose of the present invention is to eliminate paste residues and edge appearance defects on workpieces in adhesive tapes used as back grinding tapes, dicing tapes, and the like. [Means to solve the problem]

Usually, when attaching the adhesive tape to the concave-convex surface, the adhesive tape is heated to about 40~60°C, and the fluidity and embedding of the adhesive layer (or intermediate layer) are improved before attaching. On the other hand, leakage of the adhesive (or intermediate layer) during storage, which is the main cause of poor appearance at the end, is caused by the flow of the adhesive (or intermediate layer) at room temperature ~ 40°C. Therefore, the inventors of the present invention studied in detail the viscoelastic behavior of the adhesive composition constituting the adhesive layer (or intermediate layer). As a result, it was found that if an acrylic polymer having elasticity to the extent that fluidity can be suppressed at room temperature to about 40°C and having appropriate fluidity and shape retention under heating can be realized, the above-mentioned problems can be eliminated. subject, and completed the present invention. The object of this invention is to solve such a subject, and the summary is as follows.

(1) An adhesive composition having a storage modulus G'(23) at 23°C of not less than 1.0×10 ⁵ Pa and a storage modulus G'(50) at 50°C of not more than 2.5×10 ⁵ Pa. The tan δ of dynamic viscoelasticity at 60°C is 0.5 or more, and contains an acrylic polymer as a main component. (2) The adhesive composition as described in (1), which is the ratio of the storage modulus G'(60) at 60°C to the storage modulus G'(23) at 23°C, that is, G'(60)/G'(23) is 0.1~0.7. (3) An adhesive tape comprising a substrate and an adhesive layer, wherein the adhesive layer includes the adhesive composition as described in (1) or (2). (4) An adhesive tape comprising a substrate, an adhesive layer, and an intermediate layer between the substrate and the adhesive layer, wherein the intermediate layer comprises the adhesive composition as described in (1) or (2). [Invention effect]

For acrylic polymers used in adhesives, etc., a sharp peak of tan δ can usually be observed in a low temperature range of about -50 to 0°C, and tan δ decreases as the temperature rises. Also, the modulus of elasticity decreases as the temperature rises. The inventors of the present invention conducted various studies on the viscoelasticity of the acrylic polymer, which is the main component of the adhesive composition, and succeeded in designing one that has elasticity to the extent that fluidity can be suppressed at room temperature to about 40°C. Acrylic polymer with proper fluidity and shape retention at low temperature. By using such an acrylic polymer as the main component of the adhesive composition, it is possible to provide an adhesive tape that is easy to control the fluidity of the adhesive layer (or intermediate layer) at the time of attachment and storage, and that is easy to control during attachment. It follows the uneven surface of the workpiece, and there is less leakage of the adhesive composition during storage.

[Mode for Carrying Out the Invention]

Hereinafter, the adhesive tape of this invention is demonstrated concretely. First, main terms used in this specification will be described. In this specification, for example, "(meth)acrylate" is used as a term representing both "acrylate" and "methacrylate", and the same applies to other similar terms.

The adhesive tape means a laminate including a base material and an adhesive layer, and may include other constituent layers than these. For example, there may be an intermediate layer between the base material and the adhesive layer; in order to improve the adhesion of the interface between the base material surface and the adhesive layer, or the interface between the base material surface and the intermediate layer, and prevent low molecular weight components from migrating For other purposes, a primer layer can also be formed on the surface of the substrate on the side of the adhesive layer; a release film can also be laminated on the surface of the adhesive layer to protect the adhesive layer until it is used. In addition, the substrate may be a single layer or a multilayer having functional layers such as a buffer layer. The adhesive composition of this invention demonstrated below can be suitably used for the adhesive agent layer or intermediate|middle layer of an adhesive tape.

The so-called back grinding tape refers to an adhesive tape used to protect the circuit surface of the wafer when grinding the back of the semiconductor wafer. The so-called dicing tape refers to the adhesive tape used to hold the wafer and the chip when the wafer-connected circuit is sliced into chips. The "surface" of the semiconductor wafer refers to the surface on which circuits are formed, and the so-called "back surface" refers to the surface on which no circuits are formed.

(adhesive composition) The adhesive composition of the present invention includes an acrylic polymer and satisfies the following viscoelastic behavior. Moreover, the viscoelasticity of an adhesive composition is based on the viscoelasticity of a solid content, and when an adhesive composition is a solution form, it means the viscoelasticity of the adhesive material obtained by drying a solution. Moreover, when an adhesive composition consists only of an acrylic polymer, it means the property of an acrylic polymer itself. In addition, when the adhesive composition is energy ray curable, the following physical properties refer to physical properties before the adhesive composition is cured by energy ray irradiation.

The storage modulus G'(23) of the adhesive composition at 23°C is preferably at least 1.0×10 ⁵ Pa, more preferably at least 1.2×10 ⁵ Pa, more preferably 1.3×10 ⁵ ~8.0×10 ⁵ Pa , especially 1.7×10 ⁵ ~7.0×10 ⁵ pa.

When the storage modulus G'(23) of the adhesive composition is in the above-mentioned range, the fluidity at room temperature to about 40°C can be suppressed. As a result, even if the adhesive tape is stored and conveyed in the form of a roll, the adhesive composition does not leak from the end surface of the roll, and the appearance of the end of the roll can be maintained favorably.

The storage modulus G'(50) of the adhesive composition at 50°C is preferably less than 2.5×10 ⁵ Pa, more preferably less than 2.4×10 ⁵ Pa, more preferably 7.0×10 ⁴ ~2.3×10 ⁵ Pa , especially 8.0×10 ⁴ ~2.2×10 ⁵ pa.

When the storage modulus G'(50) of the adhesive composition is in the above range, when the adhesive tape is heated to about 40-60°C and attached, appropriate fluidity can be obtained, and the unevenness of the surface of the semiconductor wafer can be obtained. Embedding enhancement.

The tanδ of the dynamic viscoelasticity of the adhesive composition at 60°C (hereinafter referred to as "tanδ(60)") is preferably 0.5 or higher, more preferably 0.51 or higher, preferably 0.52 to 0.8, particularly preferably 0.53~0.75.

The tan δ of the adhesive composition can be obtained as follows. That is, it is possible to obtain a sample of a predetermined shape from the adhesive composition, apply a strain at a frequency of 1 Hz to the sample, and measure the storage modulus G' and the loss modulus G'' at each measurement temperature, and calculate the The loss tangent at 60°C is tan δ(G''/G') to obtain tan δ(60).

When tan δ(60) is in the above-mentioned range, the adhesive layer or the intermediate layer once deformed tends to maintain the deformed shape high. As a result, since the uneven adhesive layer or intermediate layer buried in the surface of the semiconductor wafer maintains its shape, it is possible to prevent cutting water from penetrating the wafer surface, and to reduce contamination and damage of circuits.

Moreover, it is preferable that the adhesive composition of this invention satisfies the following viscoelasticity. The ratio of the storage modulus G'(60) at 60°C to the storage modulus G'(23) at 23°C of the adhesive composition, G'(60)/G'(23) is preferably 0.1~0.7 , more preferably 0.2-0.6, more preferably 0.21-0.45, particularly preferably 0.23-0.41.

When G'(60)/G'(23) is in the above range, the adhesive layer or the intermediate layer does not fluidize excessively even when heated, and therefore the adhesive composition does not intrude into the fine structure of the circuit surface. Therefore, even if the adhesive tape is peeled off after the predetermined step is completed, the adhesive composition does not leave a fine structure adhering to the circuit surface.

Also, the adhesive composition has a plurality of maximum values of tanδ of dynamic viscoelasticity, preferably two. In the case of using the following zwitterion-containing acrylic polymer as the main component of the acrylic polymer of the adhesive composition, in this polymer, the part corresponding to the usual adhesive polymer and the part derived from the zwitterion-containing The parts of the unit coexist. It is considered that because the viscoelastic behaviors of the two are different, there are plural maximum values of tan δ. In a preferred embodiment, the maximum value of tanδ on the low temperature side appears in the range of -50°C to 0°C, and the maximum value of tanδ on the high temperature side appears in the range of 10°C to 60°C.

Since it has the maximum value of tanδ at the low temperature side, it has excellent adhesive force, especially initial adhesive force at room temperature. Also, since the high temperature side has the maximum value of tanδ, after heating the adhesive tape to about 40~60°C and embedding the adhesive into the unevenness on the surface of the semiconductor wafer, the deformation of the adhesive layer can be maintained and the damage caused by chipping can be reduced. Pollution and damage to the circuit surface caused by water.

The adhesive composition of the present invention includes an acrylic polymer as a main component. The acrylic polymer is a polymer having a repeating unit derived from esters of (meth)acrylic acid or its derivatives as a main constituent, and may be a modified polymer. The various physical properties of the above-mentioned adhesive composition are mainly attributable to the acrylic polymer. Therefore, the adhesive composition of the present invention can be obtained by selecting an acrylic polymer having appropriate viscoelasticity. Hereinafter, acrylic polymers that can be suitably used will be described, but these are non-limiting examples, and the acrylic polymer of the present invention is not limited to the following. Other acrylic polymers usable in the present invention can be obtained by appropriately adjusting the structure of the polymer based on the following description and common technical knowledge.

The adhesive composition of the present invention preferably includes, as the acrylic polymer, an acrylic polymer having a repeating unit containing a zwitterionic structure and a repeating unit derived from a (meth)acrylic monomer. Hereinafter, a repeating unit containing a zwitterionic structure is referred to as a "zwitterionic-containing unit", and a repeating unit derived from a (meth)acrylic monomer is referred to as a "(meth)acrylic unit". And the polymer containing these repeating units is called "zwitterion-containing acrylic polymer".

(Zwitterion-Containing Acrylic Polymer) The zwitterion-containing acrylic polymer includes a repeating unit having a zwitterion structure. Here, the so-called zwitterionic structure refers to a polarized structure including positive charges and negative charges. The zwitterion-containing acrylic polymer preferably has a zwitterion structure in the side chain of the polymer. The zwitterionic structure is not particularly limited as long as it has a polarized structure. In terms of manufacturing convenience, the positive charge is preferably derived from quaternary ammonium, nitrogen-containing heterocycle or quaternary phosphonium. The sulfo residue (SO ₃ ^- ) from sultone (sultone). The main chain structure of the polymer is not particularly limited, but is preferably composed of a carbon skeleton. Therefore, a preferable zwitterion-containing unit is represented by the following formula (1). In addition, in the following, the case where the positive charge is derived from quaternary ammonium will be described as an example, but the positive charge may be derived from a nitrogen-containing heterocycle or quaternary phosphonium.

In formula (1), R ¹ represents a hydrogen atom or a methyl group, R ² and R ³ each independently represent a hydrogen atom, an alkyl group having 1 to 10 carbons with or without an ether bond, an alkyl group with or without an ether bond Cyanoalkyl with 2 to 11 carbons, alkenyl with 2 to 10 carbons with or without an ether bond, or aryl with 6 to 20 carbons with or without substituents. R ² and R ³ may also be bonded to each other to form a ring. m is an integer of 2 to 5, preferably 3 or 4.

The alkyl group having 1-10 carbon atoms of R ² and R ³ may or may not have an ether bond, the alkyl group having 1-10 carbon atoms preferably has 1-8 carbon atoms, more preferably 1-5 carbon atoms. A methyl group, an ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group etc. are mentioned as an alkyl group which does not have an ether bond. As an alkyl group which has an ether bond, the group represented by following formula (2) or (3), etc. are mentioned.

In formula (2), R ⁴ represents an alkyl group having 1 to 8 carbons, Z ¹ represents an alkylene group having 2 to 9 carbons, and the total number of carbons of R ⁴ and Z ¹ is 3 to 10. * Indicates a link key. In formula (3), R ⁵ represents an alkyl group with 1 to 6 carbons, Z ² represents an alkylene group with 2 to 7 carbons, Z ³ represents an alkylene group with 2 to 7 carbons, R ⁵ , Z ² , The sum of the carbon numbers of Z ³ is 5-10. * Indicates a link key.

R ² and R ³ are cyanoalkyl groups with or without ether linkages and carbon numbers of 2 to 11. The carbon number of the cyanoalkyl groups with 2 to 11 carbon numbers is preferably 2 to 9, and more preferably 2 to 6. good. Examples of the cyanoalkyl group not having an ether bond include cyanomethyl, 2-cyanoethyl, 3-cyanopropyl, 4-cyanobutyl, 6-cyanohexyl and the like. Examples of the cyanoalkyl group having an ether bond include groups represented by the following formula (4) or (5).

In formula (4), R ⁶ represents a cyanoalkyl group with 2 to 9 carbons, Z ⁴ represents an alkylene group with 2 to 9 carbons, and the total carbon number of R ⁶ and Z ⁴ is 4 to 11. * Indicates a link key. In formula (5), R ⁷ represents a cyanoalkyl group with 2 to 7 carbons, Z ⁵ represents an alkylene group with 2 to 7 carbons, Z ⁶ represents an alkylene group with 2 to 7 carbons, R ⁷ , Z ⁵ , The sum of the carbon numbers of Z ⁶ is 6~11. * Indicates a link key.

The alkenyl group having 2-10 carbon atoms of R ² and R ³ may or may not have an ether bond, the alkenyl group having 2-10 carbon atoms preferably has 2-9 carbon atoms, more preferably 2-6 carbon atoms. As an alkenyl group which does not have an ether bond, a vinyl group, an allyl group, 1-butenyl group, 2-butenyl group, 1-pentenyl group etc. are mentioned. As an alkenyl group which has an ether bond, the group represented by following formula (6) or (7), etc. are mentioned.

In formula (6), R ⁸ represents an alkenyl group with 2 to 8 carbons, Z ⁷ represents an alkylene group with 2 to 8 carbons, and the total number of carbons of R ⁸ and Z ⁷ is 4 to 10. * Indicates a link key. In formula (7), R ⁹ represents an alkenyl group with 2 to 6 carbons, Z ⁸ represents an alkylene group with 2 to 6 carbons, Z ⁹ represents an alkylene group with 2 to 6 carbons, R ⁹ , Z ⁸ , The sum of the carbon numbers of Z ⁹ is 6-10. * Indicates a link key.

R ² and R ³ are aryl groups with or without substituents having 6-20 carbon atoms, preferably 6-10 aryl groups with 6-20 carbon atoms. Examples of the unsubstituted aryl group include phenyl, 1-naphthyl, 2-naphthyl and the like. Examples of substituents for aryl groups having substituents include alkyl groups having 1 to 6 carbon atoms such as methyl and ethyl groups; alkoxy groups having 1 to 6 carbon atoms such as methoxy and ethoxy groups; fluorine atoms, halogen atoms such as chlorine atoms, etc.

Examples of the ring formed by bonding R ² and R ³ include a pyrrolidine ring, a piperidine ring, and a morpholine ring. In formula (1), A ¹ represents a divalent group represented by any one of the following formulas (8) to (10).

In formulas (8) to (10), A ² and A ³ each independently represent an alkylene group having 1 to 10 carbon atoms, and n represents an integer of 1 to 10. *1 represents a bond with a carbon atom, and *2 represents a bond with a nitrogen atom.

The carbon number of the alkylene group having 1-10 carbons in A ² and A ³ is preferably 1-8, more preferably 1-6. Examples of the alkylene group having 1 to 10 carbon atoms include straight-chain alkylene groups such as methylene, ethylidene, trimethylene, tetramethylene, and pentamethylene; propane-1,2- Branched chain alkylene such as diyl and butane-1,3-diyl. n is an integer of 1-10, preferably an integer of 1-5.

Also, in the case where the positive charge of the zwitterionic structure is derived from a nitrogen-containing heterocycle or a quaternary phosphonium, the quaternary ammonium site (N ⁺ R ² R ³ ) is substituted into a zwitterion-containing unit having a structure of the following formulas (11) to (14).

(wherein, R ¹⁰ represents an alkyl group with or without ether linkages having 1 to 10 carbon atoms, a cyanoalkyl group with or without ether linkages having 2 to 11 carbon atoms, or a carbon atom with or without ether linkages An alkenyl group with a number of 2 to 10, R ¹¹ represents a hydrogen atom, or an alkyl group with or without an ether bond with a carbon number of 1 to 10. However, either R ¹⁰ or R ¹¹ does not have an atom or a group and is a free radical state and represents the bond to the aforementioned A ^1. * represents the bond to (CH ₂ ) _m ).

(In the formula, R ¹² to R ¹⁶ each independently represent a hydrogen atom, or an alkyl group having 1 to 10 carbon atoms with or without an ether bond. However, one of R ¹² to R ¹⁶ does not have an atom or group but is in a radical state and represents a bond to the aforementioned A ^1. * represents a bond to (CH ₂ ) _m ).

(In the formula, R ¹⁷ to R ²¹ each independently represent a hydrogen atom, or an alkyl group having 1 to 10 carbon atoms with or without an ether bond. However, one of R ¹⁷ to R ²¹ does not have an atom or group but is in a radical state and represents a bond to the aforementioned A ^1. * represents a bond to (CH ₂ ) _m ).

(wherein, ^R22 represents an alkyl group with or without ether linkages with 1 to 10 carbon atoms, a cyanoalkyl group with or without ether linkages with carbon number 2 to 11, or a carbon number with or without ether linkages with 2 ~10 alkenyl groups, or substituted or unsubstituted aryl groups with 6 to 20 carbon atoms. R ²³ and R ²⁴ each independently represent a hydrogen atom, an alkyl group with or without an ether bond with 1 to 10 carbon atoms, A cyanoalkyl group with or without ether linkages having 2 to 11 carbons, an alkenyl group with or without ether linkages having 2 to 10 carbons, or a substituted or unsubstituted aryl group with 6 to 20 carbons. But One of R ²² to R ²⁴ does not have an atom or a group but is in a free radical state and represents a bond to the aforementioned A ^1. * represents a bond to (CH ₂ ) _m ).

The zwitterion-containing acrylic polymer includes the aforementioned zwitterion-containing units and (meth)acrylic acid units. The ratio of the zwitterion-containing unit in the zwitterion-containing acrylic polymer is less than 100% by mass, preferably 30% by mass or less, more preferably 15% by mass or less, preferably 0.1-10% by mass, most preferably 0.5-5.0% by mass. When the ratio of the zwitterion-containing unit in the zwitterion-containing acrylic polymer is too small, the characteristics of the adhesive composition are not easy to show the characteristics derived from the zwitterion-containing unit, and the embedding property to the concave-convex surface is low. , and there are cases where the appearance of the end is poor. Also, when the ratio of the zwitterion-containing unit is too large, sufficient adhesiveness may not be obtained in the ratio.

As a (meth)acrylic acid unit, the repeating unit derived from (meth)acrylate, the repeating unit derived from (meth)acrylic acid, the repeating unit derived from (meth)acrylamide, etc. are mentioned. The ratio of (meth)acrylic acid units is greater than 0% by mass, preferably at least 70% by mass, more preferably at least 85% by mass, particularly preferably at least 85% by mass, based on the total amount of the zwitterion-containing acrylic polymer. 90~99.9% by mass, preferably 95~99.5% by mass.

As (meth)acrylate, alkyl (meth)acrylate is preferable. Examples of the alkyl (meth)acrylate include those having 1 to 20 carbon atoms in the alkyl group, and the alkyl group may be straight or branched. Specific examples of alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-propyl (meth)acrylate, ( n-butyl methacrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, (meth) Decyl acrylate, undecyl (meth)acrylate, lauryl (meth)acrylate, etc. Alkyl (meth)acrylate can be used individually or in combination of 2 or more types.

Moreover, from a viewpoint of improving the adhesive force of an adhesive composition, it is preferable to contain the repeating unit derived from the C4 or more alkyl (meth)acrylate of an alkyl group. As carbon number of this alkyl (meth)acrylate, Preferably it is 4-12, More preferably, it is 4-6. Also, the alkyl (meth)acrylate having an alkyl group having 4 or more carbon atoms is preferably an alkyl acrylate.

In the zwitterion-containing acrylic polymer, the proportion of the repeating unit derived from the alkyl (meth)acrylate having an alkyl group having 4 or more carbon atoms is based on the total amount of the zwitterion-containing acrylic polymer , preferably 40-98% by mass, preferably 45-95% by mass, more preferably 50-90% by mass.

The zwitterion-containing acrylic polymer, in addition to repeating units derived from alkyl (meth)acrylates with a carbon number of 4 or more, can also be used to adjust the elastic modulus and adhesive properties of the adhesive composition. It is a copolymer comprising repeating units of alkyl (meth)acrylates with 1 to 3 carbon atoms derived from an alkyl group. In addition, the alkyl (meth)acrylate is preferably an alkyl (meth)acrylate having 1 or 2 carbon atoms, more preferably methyl (meth)acrylate, most preferably methyl methacrylate. In the zwitterion-containing acrylic polymer, the ratio of the repeating unit of the (meth)acrylic acid alkyl ester having 1 to 3 carbon atoms derived from the alkyl group, the total amount of the zwitterion-containing acrylic polymer is given as The standard is preferably 0 to 30% by mass, preferably 0 to 26% by mass, more preferably 0 to 22% by mass.

The zwitterion-containing acrylic polymer can be obtained by copolymerizing a zwitterion-containing polymerizable monomer and a (meth)acrylic monomer. In addition, it is also possible to copolymerize a polymerizable monomer having a structure capable of introducing a zwitterionic structure and a (meth)acrylic monomer, and make a sultone compound or the like act on the obtained copolymer to obtain a Zwitterionic acrylic polymer. Also, when synthesizing these polymers, in addition to polymerizable monomers containing zwitterions or polymerizable monomers having a structure capable of introducing zwitterionic structures and (meth)acrylic monomers, it is also possible to make Copolymerization of other monomers such as copolymerization.

First, the case where a zwitterion-containing acrylic polymer is obtained by copolymerizing the former zwitterion-containing polymerizable monomer and a (meth)acrylic monomer will be described. The zwitterion-containing polymerizable monomer used in the synthesis of the zwitterion-containing acrylic polymer refers to a compound having a polymerizable carbon-carbon double bond and the aforementioned polarized structure in the molecule. As a (meth)acrylic-type monomer, the said (meth)acrylate, (meth)acrylic acid, (meth)acrylamide etc. are mentioned.

In the present invention, the zwitterion-containing polymerizable monomer can be appropriately determined according to the target zwitterion-containing acrylic polymer. For example, a zwitterion-containing acrylic polymer having a repeating unit represented by the above formula (1) can be synthesized using a zwitterion-containing polymerizable monomer represented by the following formula (1a). In addition, it is also possible to use amphoteric amphoteric monomers that substitute the quaternary ammonium site (N ⁺ R ² R ³ ) of the zwitterion-containing polymerizable monomer of the following formula (1a) into the structure of the aforementioned formulas (11) to (14). Ionic polymerizable monomer.

In the formula (1a), R ¹ , R ² , R ³ , A ¹ , and m each represent the same meaning as above. The zwitterion-containing polymerizable monomer represented by formula (1a) is not particularly limited. For example, as shown in the following formula, the polymerizable monomer containing the formula (1a) can be obtained by reacting the corresponding amine compound (1b) with the sultone compound (1c).

(In the above formula, R ¹ to R ³ and A ¹ have the same meaning as above, and p is (m-2)). The amine compound (1b) can be produced and obtained by a known method. In addition, among the above-mentioned amine compounds (1b), compounds in which the amine moieties (NR ² R ³ ) are substituted into structures capable of introducing zwitterions represented by the following formulas (15) to (18) can also be used.

(In the formula, R ¹⁰ to R ²⁴ represent the same meaning as above. However, one of R ¹⁰ or R ¹¹ does not have an atom or a group, but is in a free radical state and represents a bond to the aforementioned A ^1. R ¹² to R ¹⁶ One of them does not have an atom or a radical but is in a free radical state and represents a bond to the aforementioned A ^1. One of R ¹⁷ ~ R ²¹ does not have an atom or a radical but is in a free radical state and represents a bond to the aforementioned A ¹ A bond. One of R ²² to R ²⁴ does not have an atom or a group but is in a free radical state and represents a bond to the aforementioned A ¹ ).

Examples of the aforementioned sultone compound (1c) include 1,2-ethane sultone, 1,3-propane sultone, 1,4-butane sultone, 2,4-butane sultone, Esters, 1.5-pentane sultone. These are known compounds and can be produced and obtained using known methods, and commercially available products can also be used.

In the reaction between the amine compound (1b) and the sultone compound (1c), the amount of the sultone compound (1c) is preferably 0.8-1.2 equivalents, preferably 0.9-1.1 equivalents, relative to the amine compound (1b). . By making the usage-amount of sultone compound (1c) into the said range, the process of removing an unreacted substance can be omitted, or the time taken for removal can be shortened.

The reaction of the amine compound (1b) and the sultone compound (1c) may be performed without a solvent or in the presence of an inert solvent. Examples of the inert solvent used include ether-based solvents such as tetrahydrofuran and diglyme; propionitrile-based solvents such as acetonitrile and propionitrile; and ketone-based solvents such as acetone and methyl ethyl ketone. ; Aromatic hydrocarbon solvents such as toluene and xylene; Halogenated hydrocarbon solvents such as chloroform, etc.

When using an inert solvent, the usage-amount is not specifically limited, Usually, it is 1-100 mass parts with respect to 1 mass part of amine compound (1b). The reaction temperature is not particularly limited, but is usually in the range of 0 to 200°C, preferably in the range of 10 to 100°C, more preferably in the range of 20 to 60°C. In addition, the reaction may be carried out under normal pressure (atmospheric pressure), or may be carried out under pressurized conditions.

The reaction time is not particularly limited, and is usually 12 to 332 hours, preferably 24 to 168 hours. From the viewpoint of preventing oxidation due to oxygen and hydrolysis of the sultone compound (1c) due to moisture in the air, resulting in a decrease in yield, it is preferable to carry out the reaction under an inert gas atmosphere such as nitrogen or argon. The progress of the reaction can be confirmed using common analytical means such as gas chromatography, high performance liquid chromatography, thin layer chromatography, NMR, and IR.

After the reaction is completed, the usual post-processing operations in organic synthetic chemistry can also be used to refine and isolate the target zwitterion-containing polymerizable monomer as required by using known purification methods such as recrystallization and column chromatography. . Moreover, in this invention, a commercial item can also be used as a zwitterion-containing polymerizable monomer. In addition, it is also possible to substitute the amine of the above-mentioned amine compound (1b) into a compound having a structure capable of introducing a zwitterionic structure of the formulas (15) to (18) in the same manner as when using the above-mentioned amine compound (1b), by This is reacted with the sultone compound (1c) to obtain a zwitterion-containing polymerizable monomer.

The synthesis method of the zwitterion-containing acrylic polymer is not particularly limited. For example, it can be obtained by including a zwitterion-containing polymerizable monomer, a (meth)acrylic monomer, and optionally a zwitterion-containing polymerizable monomer in the presence of a radical polymerization initiator. A monomer mixture of copolymerized monomers is polymerized to synthesize a zwitterion-containing acrylic polymer.

As a radical polymerization initiator, an organic peroxide, an azo compound, etc. are mentioned. Examples of organic peroxides include diacyl peroxides such as lauryl peroxide and benzoyl peroxide; 1,1-bis(tertiary butylperoxy)cyclohexane, Peroxyketals such as 1,1-bis(tertiary butyl peroxide) 3,3,5-trimethylcyclohexane; diisopropyl peroxydicarbonate, diisopropyl peroxydicarbonate - peroxydicarbonate such as 2-ethylhexyl ester; peroxyester such as tertiary butyl peroxy 2-ethylhexanoate and tertiary butyl peroxyisobutyrate wait.

Examples of azo compounds include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane -1-carbonitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile ), dimethyl 2,2'-azobis(2-methylpropionate), 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2- hydroxymethylpropionitrile), 2,2'-azobis[2-(2-imidazolin-2-yl)propane] (2,2'-azobis[2-(2-imidazolin-2-yl) propane )wait. These can be used individually by 1 type or in combination of 2 or more types.

The amount of the radical polymerization initiator used is usually 0.0001 to 0.1000 moles relative to 1 mole of monomers used in the polymerization reaction (however, in the case of a copolymer, it is the total moles of monomers), Preferably it is 0.0005~0.0050 mole.

The conditions of the radical polymerization reaction are not particularly limited as long as the intended polymerization reaction proceeds. The heating temperature is usually 40 to 150° C., and the reaction time can be appropriately set within a range of 1 minute to 24 hours. The obtained reaction liquid can be directly used in the preparation of the adhesive composition, and the zwitterion-containing acrylic polymer can also be isolated and purified according to a common method.

In addition, as mentioned above, the zwitterion-containing acrylic polymer can also copolymerize a polymerizable monomer having a structure capable of introducing a zwitterion structure and a (meth)acrylic monomer, and allow the sultone compound, etc. The resulting polymer works to obtain.

Examples of structures capable of introducing a zwitterionic structure include amine groups, nitrogen-containing heterocycles, phosphine, and the like. As the polymerizable monomer having a structure capable of introducing a zwitterionic structure, the aforementioned amine compound (1b) can be suitably used. The copolymerization of the amine compound (1b) and the (meth)acrylic monomer can be carried out under the same conditions as the aforementioned copolymerization of the zwitterion-containing polymerizable monomer and the (meth)acrylic monomer, and the copolymerization During the polymerization, a monomer mixture including a monomer copolymerizable with the amine compound (1b) and a (meth)acrylic monomer is optionally polymerized to synthesize a polymer having a structure capable of introducing a zwitterionic structure.

Next, a zwitterion-containing acrylic polymer is obtained by reacting the aforementioned sultone compound (1c) with a structure capable of introducing a zwitterion structure in the obtained acrylic polymer. The reaction of a functional group such as an amine group with the sultone compound can be carried out under the same conditions as the reaction of the aforementioned amine compound (1b) with the sultone compound (1c). Instead of the amine compound (1b), it is also possible to use a compound in which the amine portion (NR ² R ³ ) of the amine compound (1b) is substituted into a structure capable of introducing a zwitterionic structure of the aforementioned formulas (15) to (18).

The zwitterion-containing acrylic polymer may have a repeating unit derived from a functional group-containing monomer in addition to the above-mentioned repeating unit. As a functional group of a functional group containing monomer, a hydroxyl group, a carboxyl group, an amino group, an epoxy group etc. are mentioned. The functional group-containing monomer reacts with a crosslinking agent described later to become a crosslinking origin, or reacts with an unsaturated group-containing compound to introduce an unsaturated group into the side chain of the zwitterion-containing acrylic polymer.

Examples of the functional group-containing monomer include a hydroxyl group-containing monomer, a carboxyl group-containing monomer, an amino group-containing monomer, an epoxy group-containing monomer, and the like. These monomers can be used individually or in combination of 2 or more types. Among these, hydroxyl-containing monomers and carboxyl-containing monomers are preferred, and hydroxyl-containing monomers are more preferred.

Examples of hydroxyl-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, (meth)acrylic acid Hydroxyalkyl (meth)acrylates such as 2-hydroxybutyl, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; unsaturated alcohols such as vinyl alcohol and allyl alcohol class etc.

As the carboxyl group-containing monomer, for example, ethylenically unsaturated monocarboxylic acids such as crotonic acid; ethylenically unsaturated dicarboxylic acids such as fumaric acid, itaconic acid, citraconic acid and their anhydrides, 2-carboxyethyl methacrylate, etc.

The ratio of the repeating unit derived from the functional group-containing monomer is 70% by mass or less, preferably 50% by mass or less, based on the total amount of the zwitterion-containing acrylic polymer.

In addition, the zwitterion-containing acrylic polymer may contain compounds derived from styrene, α-methylstyrene, vinyltoluene, vinyl formate, vinyl acetate, acrylonitrile, acrylamide, etc. A repeating unit of a monomer copolymerized with the above-mentioned acrylic monomer.

The glass transition temperature (Tg) of the obtained zwitterion-containing acrylic polymer is preferably -60~-20°C, more preferably -50~-22°C. The Tg of the zwitterion-containing acrylic polymer refers to the loss tangent (tanδ) in the region of -60 to 50°C in the dynamic viscoelasticity measurement of a sample composed of the zwitterion-containing acrylic polymer at a frequency of 1 Hz Displays the maximum temperature. When the Tg of the zwitterion-containing acrylic polymer is too low, paste residues tend to be generated. Also, when Tg is too high, the embedding property to the unevenness of the circuit surface may be reduced.

The glass transition temperature of the zwitterion-containing acrylic polymer tends to decrease when, for example, the proportion of repeating units derived from an alkyl group having 4 or more carbon atoms is increased.

Moreover, the mass average molecular weight (Mw) of the zwitterion-containing acrylic polymer is preferably from 10,000 to 300,000, more preferably from 20,000 to 200,000. In addition, in this specification, a mass average molecular weight is the value of standard polystyrene conversion measured using the gel permeation chromatography. When the Mw of the zwitterion-containing acrylic polymer is too low, paste residues tend to be generated. Also, when Mw is too high, the embedding property to the unevenness of the circuit surface may be reduced.

For example, when the radical polymerization initiator used in the production of the zwitterion-containing acrylic polymer is increased, the mass average molecular weight of the zwitterion-containing acrylic polymer tends to decrease. Also, when the polymerization reaction time is prolonged, the mass average molecular weight tends to increase. When the polymerization reaction temperature is increased, the mass average molecular weight tends to decrease.

Moreover, the molecular weight distribution (Mw/Mn, Mn is a number average molecular weight) of the zwitterion-containing acrylic polymer is preferably 15 or less, more preferably 2-11. When the molecular weight distribution of the zwitterion-containing acrylic polymer is too wide, paste residues are likely to be generated.

Distribution For example, the zwitterion-containing acrylic polymer can be prepared by using an active radical method, whereby the molecular weight of the zwitterion-containing acrylic polymer can also be narrowed. In the living radical method, for example, a tellurium-containing compound is used as a radical polymerization initiator. In addition, the molecular weight distribution can also be narrowed by using polymerization methods such as atom transfer radical polymerization (ATRP) and reversible addition/fragmentation chain transfer polymerization (RAFT).

(ingredients of adhesive composition) The adhesive composition of the present invention comprises an acrylic polymer, preferably a zwitterion-containing acrylic polymer. When using a zwitterion-containing acrylic polymer, it may use individually by 1 type, and may use it in combination of 2 or more types. The adhesive composition may consist only of the zwitterion-containing acrylic polymer, or may include components other than the zwitterion-containing acrylic polymer. The ratio of the zwitterion-containing acrylic polymer in the adhesive composition of the present invention is preferably at least 80% by mass, preferably at least 85% by mass, more preferably at least 85% by mass, based on the total amount of the adhesive composition. More than 90% by mass.

In addition to the zwitterion-containing acrylic polymer, the adhesive composition of the present invention may also include, for example, energy ray-curing compounds, crosslinking agents, photopolymerization initiators, zwitterion-containing acrylic polymers other than Adhesive polymers, and other additives.

(energy ray hardening compound) The energy ray curable compound is preferably a monomer or oligomer having an unsaturated group in the molecule and capable of being polymerized and cured by irradiation of energy ray. As such an energy ray-curing compound, for example, trimethylolpropane tri(meth)acrylate, neopentylthritol (meth)acrylate, neopentylthritol tetra(meth)acrylate Polyvalent (meth) Acrylate monomers, oligomers of urethane (meth)acrylate, polyester (meth)acrylate, polyether (meth)acrylate, epoxy (meth)acrylate, etc.

Among them, the urethane (meth)acrylate oligomer is preferable from the viewpoint that the molecular weight is relatively high and the modulus of elasticity of the adhesive layer is not easily reduced. The molecular weight of the energy ray-curable compound (mass average molecular weight in the case of an oligomer) is preferably 100-12000, preferably 200-10000, more preferably 400-8000, and most preferably 600-6000.

When the energy ray-curing compound is used in the adhesive composition, the blending ratio is preferably 1 to 99% by mass, preferably 10 to 85% by mass, more preferably 20% based on the total amount of the adhesive composition. ~80% by mass.

(crosslinking agent) The adhesive composition may further contain a crosslinking agent. The crosslinking agent is, for example, reacting a functional group derived from a functional group-containing monomer contained in an acrylic polymer to crosslink acrylic polymers. Examples of the crosslinking agent include isocyanate crosslinking agents such as toluene diisocyanate, hexamethylene diisocyanate, and their adducts; ethylene glycol glycidyl ether, 1,3 - Epoxy-based crosslinking agents such as bis(N,N'-diecidylaminomethyl)cyclohexane; hexa[1-(2-methyl)-aziridinyl]triphosphatriazine Aziridine-based crosslinking agents such as (hexa[1-(2-methyl)-aziridinyl]triphosphatriazine); chelate-based crosslinking agents such as aluminum chelates; These crosslinking agents can be used individually or in combination of 2 or more types.

Among them, an isocyanate-based crosslinking agent is preferable from the viewpoint of enhancing the cohesive force to enhance the adhesive force, and the ease of acquisition. When the crosslinking agent is used in the adhesive composition, from the viewpoint of accelerating the crosslinking reaction, the blending ratio is preferably 0.01 to 20% by mass, preferably 0.05 to 20% by mass, based on the total amount of the adhesive composition. 15% by mass, more preferably 0.1 to 10% by mass.

(photopolymerization initiator) Also, when the adhesive composition is energy ray curable, it is preferable that the adhesive composition further contains a photopolymerization initiator. By containing a photoinitiator, even the energy rays of low energy, such as an ultraviolet-ray, can fully progress the hardening reaction of an adhesive composition.

(thioxanthone)化合物、過氧化化合物、以及胺、苯醌(quinone)等的光敏化劑等，更具體而言，可舉出，例如，1-羥基環己基苯基酮、2-羥基-2-甲基-1-苯基-丙烷-1-酮、苯偶姻、苯偶姻甲醚、苯偶姻乙醚、苯偶姻異丙醚、苄基苯基硫醚(benzyl phenyl sulfide)、一硫化四甲基秋蘭姆(tetramethylthiuram monosulfide)、偶氮雙異丁腈(azobisisobutyronitrile)、聯苄(dibenzyl)、聯乙醯、8-氯蒽醌(8-chloroanthraquinone)、雙(2,4,6-三甲基苯甲醯基)苯基氧化膦(bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide)等。Examples of photopolymerization initiators include benzoin compounds, acetophenone compounds, acylphosphine oxide compounds, titanocene compounds, 9-oxo sulfur

Photosensitizers such as (thioxanthone) compounds, peroxide compounds, amines, and quinones (quinone), etc., more specifically, include, for example, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2- Methyl-1-phenyl-propan-1-one, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyl phenyl sulfide, monosulfide Tetramethylthiuram monosulfide, azobisisobutyronitrile, dibenzyl, diacetyl, 8-chloroanthraquinone, bis(2,4,6- Trimethylbenzoyl) phenylphosphine oxide (bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide), etc.

These photopolymerization initiators can be used individually or in combination of 2 or more types. When a photopolymerization initiator is used, the blending ratio is preferably 0.1 to 10% by mass, preferably 0.3 to 8.0% by mass, more preferably 0.5 to 5% by mass, based on the total amount of the energy ray-curable component.

(other adhesive polymers) In addition to the zwitterion-containing acrylic polymer, the adhesive composition may also contain an adhesive polymer other than the zwitterion-containing acrylic polymer. Examples of such adhesive polymers include acrylic adhesive polymers that do not have a zwitterionic structure, urethane adhesive polymers, and rubber adhesive polymers that are widely used as the main material of adhesives. , Silicone-based adhesive polymers, etc. In particular, an acrylic adhesive is preferable from the viewpoint of compatibility and affinity. These adhesive polymers can be used individually or in combination of 2 or more types.

(other additives) The adhesive composition may contain other additives in the range which does not impair the effect of this invention. Examples of other additives include antistatic agents, antioxidants, tackifiers, softeners (plasticizers), fillers, antirust agents, pigments, and dyes.

Moreover, from a viewpoint of improving applicability to a base material, a peeling film, etc., an adhesive composition may be in the form of the solution which diluted with an organic solvent further and became an adhesive composition. Examples of organic solvents include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexane, n-hexane, toluene, xylene, n-propanol, isopropanol wait.

In addition, the organic solvent used in the synthesis of the adhesive resin may be used as it is, or the organic solvent used in the synthesis may be added so that the solution of the adhesive composition can be uniformly coated. 1 or more organic solvents.

(Control of Viscoelasticity of Adhesive Composition) The storage modulus G'(23) of the adhesive composition can be controlled by, for example, the monomer composition of the zwitterion-containing acrylic polymer. The storage modulus G'(23) tends to decrease as the content of the repeating unit derived from an alkyl group having 4 or more carbon atoms (meth)acrylate increases. In addition, it is considered that when the content of the zwitterion-containing unit increases, a harder structure can be formed by association of the zwitterion structures at around 23°C. This is considered to be because ionic bonds are generated between negatively charged sites of zwitterionic structures and positively charged sites of other zwitterionic structures. As a result, the storage modulus G'(23) tends to increase.

The storage modulus G'(50) of the adhesive composition can be controlled by, for example, the monomer composition of the zwitterion-containing acrylic polymer. The storage modulus G'(50) tends to decrease as the content of the repeating unit derived from an alkyl group having 4 or more carbon atoms (meth)acrylate increases. In addition, it is considered that when the content of the zwitterion-containing unit increases, a harder structure can be formed by association of the zwitterion structures at around 50°C. This is considered to be because ionic bonds are generated between negatively charged sites of zwitterionic structures and positively charged sites of other zwitterionic structures. As a result, the storage modulus G'(50) tends to increase.

tan δ(60) can be controlled by, for example, the monomer composition of the zwitterion-containing acrylic polymer. It is considered that when the content of the zwitterion-containing unit increases, because around 60°C, energy is consumed in the cracking of the association site of the zwitterion structure and the loss modulus G'' increases. As a result, when the adhesive tape is heated, the deformation of the adhesive layer or the intermediate layer can be maintained, and contamination and damage of the circuit surface due to cutting water can be reduced.

G'(60)/G'(23) of the adhesive composition can be controlled by, for example, the monomer composition of the zwitterion-containing acrylic polymer. The storage modulus G'(23) tends to decrease as the content of the repeating unit derived from an alkyl group having 4 or more carbon atoms (meth)acrylate increases. Also, when the content of zwitterion-containing units increases, the storage modulus G'(23) tends to increase.

The storage modulus G'(60) tends to decrease as the content of repeating units derived from alkyl (meth)acrylates having 4 or more carbon atoms increases. The content of the zwitterionic unit has little effect on the storage modulus G'(60), because even at around 60°C, the association sites of the zwitterionic structures remain partially, so the storage modulus G'(60) can be suppressed. ) is excessively reduced.

The temperature at which the maximum value of tan δ appears can be controlled by, for example, the monomer composition of the zwitterion-containing acrylic polymer. When the content of zwitterion-containing units increases, the maximum temperature of tanδ presents a trend of a peak at the low temperature side and a peak at the high temperature side shifting to the high temperature side at the same time. Therefore, by controlling the monomer composition of the zwitterion-containing acrylic polymer, it is possible to achieve good embedding properties and shape retention properties at a desired attachment temperature.

(adhesive tape) The adhesive tape of the present invention has an adhesive layer or an intermediate layer comprising the above-mentioned adhesive composition. The use of the adhesive tape is not particularly limited, and for example, it can be used as a back grinding tape, a dicing tape, a tape for transferring a picked-up wafer, and the like. In addition, the adhesive tape can also be pre-cut according to the shape of the object to be attached. For example, when used for back grinding of semiconductor wafers, it can also be cut into the shape of semiconductor wafers. Moreover, when using it as a dicing tape, it can also be cut|disconnected according to the shape of a ring frame. Hereinafter, the case where it is used as a back grinding tape (semiconductor wafer surface protection tape) or a dicing tape will be mainly demonstrated. Hereinafter, the adhesive tape which has the adhesive layer which consists of the said adhesive composition as a 1st form, and the adhesive tape which has an intermediate|middle layer which consists of the said adhesive composition are demonstrated as a 2nd form.

(The first form of adhesive tape) The adhesive tape of the first aspect includes a base material and an adhesive layer, and is characterized in that the adhesive layer includes the above-mentioned adhesive composition.

(Substrate) The base material of the adhesive tape of the first form is not particularly limited as long as the adhesive tape can properly perform functions in the steps required for the dicing step, back grinding step, etc. composed of thin films. Specific examples of the film include ethylene-based copolymer films such as ethylene-vinyl acetate copolymer films, ethylene-(meth)acrylic acid copolymer films, and ethylene-(meth)acrylate copolymer films; Polyethylene films such as high-density polyethylene (LDPE) films, linear low-density polyethylene (LLDPE) films, and high-density polyethylene (HDPE) films, polypropylene films, polybutene films, polybutadiene films, polyformaldehyde Polyolefin-based films such as amylpentene films, ethylene-norcamphene copolymer films, and norbornene resin films; polyvinyl chloride-based films such as polyvinyl chloride films and vinyl chloride copolymer films; polyethylene terephthalate Polyester films such as diester films and polybutylene terephthalate films; polyurethane films; polyimide films; polystyrene films; polycarbonate films; fluororesin films, etc. Furthermore, modified thin films such as cross-linked membranes and ionomer membranes such as these can also be used. The above-mentioned base material may be a thin film composed of one of these types, or may be a laminated film obtained by combining two or more types of these types.

The film constituting the substrate preferably has at least one of an ethylene-based copolymer film and a polyolefin-based film. The ethylene-based copolymer film can easily control its mechanical properties in a wide range by changing the copolymerization ratio and the like. Therefore, the base material provided with the ethylene-based copolymer film can easily satisfy the mechanical properties required as the base material of the adhesive tape of this embodiment. In addition, since the ethylene-based copolymer film has high adhesion to the adhesive layer, it is difficult to cause peeling at the interface between the base material and the adhesive layer when used as an adhesive tape.

Here, some films such as polyvinyl chloride-based films contain many components that adversely affect the properties of the adhesive tape. For example, in a polyvinyl chloride-based film, etc., the plasticizer contained in the film migrates from the base material to the adhesive layer, and is distributed on the side of the adhesive layer opposite to the base material, and has the effect of making the adhesive When the adhesiveness of the agent layer to the workpiece (semiconductor wafer, chip, etc.) is low. However, since the ethylene-based copolymer film and the polyolefin-based film contain less components that adversely affect the properties of the adhesive tape, problems such as decreased adhesion to workpieces of the adhesive layer are less likely to occur. That is, ethylene-based copolymer films and polyolefin-based films have excellent chemical stability.

The base material may also contain various additives such as coloring agents such as pigments, flame retardants, plasticizers, antistatic agents, lubricants, fillers, etc. in a film mainly made of the above-mentioned resin-based materials. As a pigment, titanium dioxide, carbon black, etc. are mentioned, for example. Further, examples of fillers include organic materials such as melamine resin, inorganic materials such as fumed silica, and metal materials such as nickel particles. The content of such additives is not particularly limited, but should be limited to a range in which the base material can perform the required functions without losing smoothness and softness.

When the adhesive layer is energy ray curable, the base material is preferably transparent to predetermined energy rays such as ultraviolet rays and electron rays.

In addition, in order to improve the adhesion with the adhesive layer, the surface of the substrate on the side of the adhesive layer (hereinafter also referred to as "the surface to be adhered to the substrate") may also be treated with corona treatment or provided with a primer ( primer) layer. In addition, various coating films may be provided on the surface of the substrate opposite to the surface to be adhered.

The thickness of the base material is not limited as long as the adhesive tape can properly function in the required steps. It is preferably in the range of 20 to 450 μm, preferably in the range of 25 to 400 μm, and particularly preferably in the range of 50 to 350 μm.

(adhesive layer) An adhesive layer comprising the aforementioned adhesive composition is formed on one side of the substrate. When the adhesive tape is used as a dicing tape, the thickness of the adhesive layer is preferably 5-50 μm, particularly preferably 1-40 μm, and more preferably 10-20 μm. When the thickness of the adhesive layer is less than 5 μm, there is a possibility that the adhesive layer may cause a problem of large variation in adhesiveness.

When an adhesive tape is used as a back grinding tape, the adhesive layer should just have the thickness which can bury the uneven|corrugated surface of a semiconductor wafer. Therefore, when the adhesive tape is attached to the surface of the semiconductor wafer provided with bumps, the thickness of the adhesive layer should be greater than the height of the bumps. Specifically, the thickness of the adhesive layer is preferably at least 1.0 times the bump height, more preferably 1.2-3 times, more preferably 1.4-2 times. In addition, the term "bump height" here refers to the maximum value of the height of the bumps provided on the semiconductor wafer. In addition, the thickness of the adhesive layer at this time is, specifically, preferably 20 to 300 μm, more preferably 30 to 200 μm, and more preferably 40 to 150 μm.

(other) Between the base material and the adhesive layer, an intermediate layer made of various soft polymers may also be provided. The configuration of the intermediate layer in the first aspect is optional and does not necessarily have to be provided. For example, when using a zwitterion-containing acrylic polymer as the main component of the adhesive composition, it is preferable to use an acrylic soft polymer to form the intermediate layer. By providing such an intermediate layer, the adhesiveness between the adhesive layer and the intermediate layer can be improved, and delamination between layers can be prevented. When the intermediate layer is provided, the thickness of the adhesive layer can also be smaller than the height of the bump. That is, it is only necessary to embed the unevenness on the surface of the semiconductor wafer through the two layers of the intermediate layer and the adhesive layer. At this time, the thickness of the intermediate layer is preferably 30-500 μm, more preferably 50-300 μm, more preferably 80-250 μm. Also, the thickness of the adhesive layer laminated with the intermediate layer is preferably 5 to 50 μm, particularly preferably 7 to 40 μm, and further preferably 10 to 20 μm.

In addition, the adhesive tape may have a release film laminated on the surface of the adhesive layer opposite to the substrate side for the purpose of protecting the adhesive layer until the adhesive layer is attached to the workpiece. The structure of the release film is optional, and what is obtained by peeling a plastic film using a release agent or the like can be exemplified. Specific examples of plastic films include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, and polyester films such as polypropylene and polyethylene. Olefin film. As the release agent, silicone-based, fluorine-based, long-chain alkyl-based, etc. can be used, and among them, silicone-based, which is inexpensive and can provide stable performance, is preferable. The thickness of the release film is not particularly limited, but is usually about 20 to 250 μm.

(Second form of adhesive tape) The adhesive tape of the second aspect includes a base material, an adhesive layer, and an intermediate layer disposed between them, wherein the intermediate layer contains the above-mentioned adhesive composition. The adhesive tape of this form can be used suitably especially as a back grinding tape. The base material is the same as that described for the above-mentioned first embodiment, and the surface of the base material on the side of the intermediate layer (the surface to be adhered to the base material) can also be subjected to the same treatment as described above.

(middle layer) An intermediate layer comprising the aforementioned adhesive composition is formed on one side of the substrate. When the adhesive tape is used as the back grinding tape, the total thickness of the adhesive layer and the intermediate layer may have a thickness capable of embedding the irregularities on the surface of the semiconductor wafer. Therefore, when the adhesive tape is attached to the surface of the semiconductor wafer provided with bumps, the total thickness of the adhesive layer and the intermediate layer should be greater than the height of the bumps. Specifically, the total thickness is preferably at least 1.0 times the bump height, more preferably 1.2 to 3 times, more preferably 1.4 to 2 times. In addition, the term "bump height" here refers to the maximum value of the height of the bumps provided on the semiconductor wafer. In addition, the total thickness of the intermediate layers of the adhesive layer at this time is, specifically, preferably 20 to 300 μm, more preferably 30 to 200 μm, more preferably 40 to 150 μm.

(adhesive layer) The adhesive is not particularly limited as long as it has appropriate pressure-sensitive adhesiveness at room temperature, but one with a storage modulus of 0.05-0.50 MPa at 23° C. is preferable. Circuits and the like are formed on the surface of the semiconductor wafer and generally have unevenness. When the adhesive tape has a storage modulus within the above-mentioned range, when it is attached to the surface of the wafer with unevenness, the unevenness of the wafer surface can be fully contacted with the adhesive layer, and the adhesion of the adhesive layer can be properly maintained. play. Therefore, the adhesive tape securely fixes the semiconductor wafer and properly protects the wafer surface during back grinding. From these viewpoints, the storage modulus of the adhesive is preferably 0.10-0.35 MPa. In addition, when the adhesive layer is formed of an energy ray-curable adhesive, the storage modulus of the adhesive means the storage modulus before hardening by irradiation of energy rays.

The thickness of the adhesive layer is preferably less than 40 μm, more preferably 5-35 μm, more preferably 10-30 μm. When the adhesive layer is thinned in this way, since the ratio of the less rigid portion of the adhesive tape can be reduced, the grinding accuracy is improved, and it is easy to further prevent chipping of the semiconductor wafer that occurs during back grinding. In addition, it is also possible to reduce the residual adhesion of the adhesive on the surface of the semiconductor wafer.

The adhesive layer can be formed of, for example, acrylic adhesives, urethane adhesives, rubber adhesives, silicone adhesives, etc., preferably acrylic adhesives. Also, the adhesive layer is preferably formed of an energy ray curable adhesive. Since the adhesive layer is formed of an energy ray-curable adhesive, the elastic modulus at 23°C is within the above range before curing by irradiation with energy rays, and the peeling force can be easily set after curing. Below 1000mN/50mm.

(other) In the adhesive tape of the second aspect, as in the first aspect, for the purpose of protecting the adhesive layer until the adhesive layer is attached to the workpiece, the surface of the adhesive layer on the substrate side may be A release film is laminated on the opposite surface.

(Manufacturing method of adhesive tape) It does not specifically limit as a manufacturing method of the adhesive tape 10 of this invention, It can manufacture using a well-known method. For example, the adhesive tape of the first form in which the release film is bonded to the surface of the adhesive layer can be produced by bonding the adhesive layer provided on the release film to one surface of the substrate. The release film attached to the surface of the adhesive layer may be properly peeled off and removed before use of the adhesive tape.

In addition, the intermediate layer provided on the release film is bonded to one side of the base material, and after the release film is peeled off, the adhesive layer provided on the release film is bonded to the exposed intermediate layer, and the release film can be manufactured. Adhesive tape of the second form attached to the surface of the adhesive layer. The release film attached to the surface of the adhesive layer may be properly peeled off and removed before use of the adhesive tape. As a method of forming an adhesive layer or an intermediate layer on a release film, the adhesive composition of the present invention is directly coated on the release film using a known coating method, and then heated and dried to evaporate the solvent from the coated film. for simplicity.

Moreover, it is also possible to apply an adhesive composition directly on one surface of a base material, and form an adhesive layer or an intermediate layer. Examples of coating methods for the adhesive composition include spin coating, spray coating, bar coating, knife coating, roll coating, blade coating, die coating, and gravure coating. Buffalo, etc.

(How to use the adhesive tape) The adhesive tape of this invention can be used suitably as a dicing tape and a back grinding tape. As a dicing tape, it can be used for dicing of a semiconductor wafer, a BGA type package, etc. It is especially suitable as a dicing tape for semiconductor wafers and BGA-type packages with large unevenness on the surface contacting the dicing tape. The cutting method is not particularly limited, and may be blade cutting using a rotating circular blade, or cutting using laser light.

Next, a wafer backside grinding method using the adhesive tape of the present invention will be described. Grinding on the back of the wafer is to attach an adhesive tape to the circuit surface of a semiconductor wafer with a circuit formed on the surface, and grind the back of the wafer while protecting the circuit surface to obtain a wafer of predetermined thickness.

The semiconductor wafer may be a silicon wafer, and may also be a compound semiconductor wafer such as gallium‧arsenic. Forming circuits on the wafer surface can be performed using various methods including conventional methods such as an etching method and a lift-off method. A predetermined circuit is formed in a circuit forming step of a semiconductor wafer. In addition, bumps may be formed on the surface of the semiconductor wafer. The thickness of such a wafer before grinding is not particularly limited, but is usually about 500 to 1000 μm. Also, the surface shape of the semiconductor wafer is not particularly limited, but the adhesive tape of the present invention can be used particularly suitably for protecting the surface of a wafer on which bumps are formed on the circuit surface.

The adhesive tape of the present invention has an adhesive layer or an intermediate layer exhibiting the above-mentioned unique elastic behavior, and exhibits viscoelasticity capable of sufficiently following unevenness of bumps under heating conditions. When affixing the adhesive tape of this invention, it is preferable to carry out in the state which lowered the storage modulus of an adhesive layer or an intermediate layer. Therefore, it is better to attach the adhesive tape to the semiconductor wafer at a temperature of about 40-60°C. If the temperature at the time of attaching is too high, the intermediate layer and the adhesive layer are excessively softened and fluidized, and may leak from the side of the adhesive tape.

When the adhesive tape is attached under heating, the adhesive layer or the intermediate layer is buried on the surface of the wafer on which the bumps are formed, and the unevenness is eliminated. In addition, since the elastic modulus of the adhesive layer or the intermediate layer recovers and becomes higher by allowing the adhesive layer or the intermediate layer to cool down after attaching, the wafer can be kept in a flat state. Also, because the adhesive tape of the present invention has a high followability to the surface shape of the wafer, and the adhesive layer or intermediate layer is relatively hard under normal conditions, even if the adhesive tape is rolled into a roll shape, the adhesive will not The end part leaks out, and can reduce the appearance defect of the end part.

The backside grinding is carried out by a known method using a grinder, a suction table for fixing the wafer, etc. in a state where the adhesive tape is attached. After the back grinding step, a treatment for removing the pulverized layer generated by grinding may also be performed. The thickness of the semiconductor wafer after backside grinding is not particularly limited, but is preferably 10-400 μm, and most preferably about 25-300 μm.

After the back grinding step, the adhesive tape is peeled off the circuit face. When the adhesive tape of the present invention is used, the wafer can be reliably held during backside grinding of the wafer, and infiltration of cutting water onto the circuit surface can be prevented.

Furthermore, the adhesive tape of the present invention can be suitably used for wafering of wafers with bumps by a so-called pre-dicing method, and specifically, can be suitably used for the following semiconductor wafer manufacturing methods, In the step of grinding the back surface of the semiconductor wafer with grooves formed on the surface of the semiconductor wafer or with the modified region formed thereon, and separating the semiconductor wafer into semiconductor wafers by the grinding, From the surface of the semiconductor wafer with bumps, forming a groove with a shallower incision depth than the thickness of the wafer, or forming a modified region inside the semiconductor wafer from the surface or back of the semiconductor wafer, The above-mentioned adhesive tape is attached to the circuit formation surface as a surface protection tape, A semiconductor wafer with an adhesive tape attached to the surface and the aforementioned groove or modified region formed is ground from the back side, and the aforementioned groove or modified region is taken as a starting point to be sliced into a plurality of wafers (wafer assembly ).

A preferred aspect of attaching the adhesive tape is the same as described above. By using the adhesive tape of the present invention, since high adhesion can be obtained between the wafer (chip) and the adhesive layer, the grinding water does not infiltrate the circuit surface and contamination of the wafer can be prevented.

Subsequently, wafer pickup is performed using a predetermined method. In addition, prior to wafer pickup, the wafer assembly may be transferred to another adhesive tape (pickup tape), and wafer pickup may be performed thereafter.

When the adhesive layer of the adhesive tape is energy ray curable, the adhesive layer is irradiated with energy rays to harden the adhesive layer. Next, a pick-up tape is attached to the back side of the wafer assembly, and the position and direction are aligned so that it can be picked up. At this time, the ring-shaped frame arranged on the outer peripheral side of the wafer assembly is also bonded to the pick-up tape, and the outer peripheral edge portion of the pick-up tape is fixed to the ring-shaped frame. The pick-up tape can be bonded to the wafer assembly and the ring frame at the same time, or it can be bonded at different timings. Next, only the adhesive tape is peeled off, and the wafer assembly is transferred onto the pick-up tape.

Then, if necessary, the pick-up tape is expanded to separate the wafers, and the individual semiconductor wafers on the pick-up tape are picked up and fixed on the upper surface of a substrate or the like to manufacture a semiconductor device.

Moreover, the pick-up tape is not specifically limited, For example, it can be comprised with the adhesive tape which has a base material and the adhesive agent layer provided in one side of the base material. It is sufficient that the pick-up tape adheres stronger than the backgrind tape when peeled. Moreover, it is preferable to have the property which can reduce the adhesive force when picking up a wafer from a pick-up tape. Therefore, as the pick-up tape, an energy ray-curable adhesive tape, a foamable easy-to-peel film, and the like can be suitably used.

Moreover, it is also possible to use an adhesive tape instead of a pick-up tape. Adhesive tapes include laminates of film-like adhesives and release films, laminates of dicing tapes and film-like adhesives, adhesive layers and release sheets that have both functions of dicing tapes and die-bonding tapes Dicing‧Die bonding tape, etc. In addition, before attaching the pick-up tape, a film-like adhesive may be attached to the back side of the singulated semiconductor wafer. When a film-form adhesive is used, the film-form adhesive may have the same shape as the wafer.

In the case of using an adhesive tape and the case where a film-like adhesive is bonded to the rear side of the singulated semiconductor wafer before attaching the pick-up tape, a plurality of The semiconductor wafer is picked up together with the adhesive layer divided into the same shape as the semiconductor wafer. Then, the semiconductor wafer is fixed on the upper surface of a substrate or the like through an adhesive layer to manufacture a semiconductor device. The division of the adhesive layer can be carried out by laser and expansion, and it can also be carried out by the tension when picking up.

As mentioned above, the use of the adhesive tape of the present invention as a dicing tape and back grinding tape has been roughly described, but the use of the adhesive tape of the present invention is not particularly limited, and it can be used for holding various workpieces with uneven surfaces, and temporarily protection and so on. Example

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited by these examples.

The measurement method and evaluation method in the present invention are as follows. [Mass average molecular weight (Mw)] The mass average molecular weight (Mw) of the acrylic polymer containing zwitterions is obtained by gel permeation chromatography (GPC) under the following conditions, Column: TSKgel Super AWM-H×2 pieces (6.0mmI. D.×15cml×2 pieces) Column LOT No.: S0095, S0096 Flow rate: 6.0mL/min Detector: HLC-8320GPC built-in RI detector/UV-8320 (option) Detector conditions: RI: Pol(+), Res(0.5s)/UV: λ(280nm).Pol(+), Res(0.5s) Sample concentration: 1.0g/L Injection volume: 40μL Pressure: 2.84MPa Column temperature: 40°C System temperature: 40°C Eluent: 10mM LiBr + 20mM TEA in DMAc

[Measurement of modulus of elasticity] The elastic modulus was measured on the following apparatus and conditions about the adhesive composition manufactured in the Example and the comparative example. Sample preparation: Each adhesive composition was apply|coated and dried on the release film, and it bonded together with another release film. Thereby, a laminate in which an adhesive layer with a thickness of 40 μm was laminated between release films was obtained. The peeling film of one side of this laminated body was removed and the adhesive layer was laminated|stacked repeatedly, and the sample for measurement of thickness 2000 micrometers was manufactured. Dynamic elastic modulus measurement device: manufactured by TA Instruments, product name "ARES" Measurement start temperature: -60°C Measurement end temperature: 120°C Heating rate: 4°C/min Frequency: 1Hz

[Paste residue evaluation] The adhesive tapes produced in Examples 1-4 and Comparative Examples 1 and 2 were cut into strips with a width of 25 mm, and attached to the mirror-polished surface of a silicon wafer (diameter 6 inches) that had been mirror-polished. The sticking of the adhesive tape was carried out under the conditions of 23°C and 50%RH (relative humidity), using a 2.5kg roller to reciprocate. After the adhesive tape was attached, it was left to stand for 20 minutes and the adhesive tape was peeled off. Peeling was performed under conditions of a peeling speed of 300 mm/min and a peeling angle of 180° using a tensile tester (manufactured by Orientec Corporation, product name "TENSILON"). After peeling, the wafer surface was visually observed to check for the presence or absence of paste residue. The paste residue was determined based on the following criteria. A: There is no paste residue visually B: There is paste residue visually

[cutting properties] Silicon wafers were diced using the adhesive tapes produced in Examples 1 to 4 and Comparative Examples 1 and 2, and the dicability was evaluated by calculating wafer scattering. Using a desktop laminating machine (manufactured by FUJiPLA, product name "LPD3226Meister6"), an adhesive tape was attached to the mirror-polished surface of a mirror-polished silicon wafer (diameter 6 inches, thickness 200 μm). The sticking conditions were set at a temperature of 23°C and a sticking speed of 0.4 m/min. In the state where the adhesive tape was attached to the silicon wafer, the silicon wafer was cut into a size of 10 mm×10 mm to obtain wafers. Using a cutting device (manufactured by DISCO Corporation, product name "DFD-6361"), the number of revolutions of the blade was set at 4500 rpm, and the cutting speed was set at 50 mm/sec. When the diced square wafers were peeled from the adhesive tape, the number of wafers after peeling was counted. At this time, wafers (triangular wafers) which are not wafer ends to be products are not included in the number of scattering. The evaluation was performed for the total number of square wafers. Cuttability was judged based on the following criteria. A: The number of chips scattered is less than 3 B: The number of wafer scattering is 3 or more and less than 10 C: The number of chips scattered is 10 or more

[Embedding property evaluation (for small bumps)] Embedding property evaluation was performed using the adhesive tape manufactured in Examples 5-8 and Comparative Examples 3 and 4. Using the laminating machine "RAD-3510F/12" manufactured by Lintec Co., Ltd., the adhesive tapes manufactured in Examples 5 to 8 and Comparative Examples 3 and 4 were attached to Cu pillars with a height of 10 μm and a pitch of 30 to 100 μm. Wafer (manufactured by Waltz, 8-inch wafer, wafer material Si) with pillars with a diameter of 42 μm in plan view. In addition, when sticking, the temperature of the bonding table of the apparatus was set at 23° C., the bonding roll was set at 60° C., the roll pressure was set at 0.3 MPa, and the sticking speed was set at 10 mm/sec. After bonding, the diameter of the circular void formed around the bump was measured from the substrate side using a digital microscope (manufactured by KEYENCE Co., Ltd., product name "VHX-1000"), and embedding properties were evaluated based on the following criteria. The smaller the diameter of the void, the higher the embedding property in the bump. A: The diameter of the void is less than 90 μm B: The diameter of the void is 90 μm or more and less than 100 μm C: The diameter of the void is 100 μm or more

[Embedding property evaluation (for middle bump)] A wafer (manufactured by Waltz, 8-inch wafer, wafer material Si) with pillars made of Cu with a height of 45 μm, a pitch of 30 to 100 μm, and a diameter of 42 μm in plan view was used. Embedding properties were evaluated in the same manner for the above-mentioned small bumps. The embedding property was evaluated based on the following criteria. A: The diameter of the void is less than 120 μm B: The diameter of the void is 120 μm or more and less than 130 μm C: The diameter of the void is 130 μm or more

[end appearance] The adhesive tapes produced in Examples 5 to 8 and Comparative Examples 3 and 4 were rolled into a core material with a diameter of 3 inches to form a roll, and placed in an environment of 23°C and 50%RH (relative humidity) Leave it for a week. After standing, the presence or absence of component leakage from the adhesive layer or intermediate layer was evaluated using an optical digital microscope (magnification: 100 times) on the side of the roll. A: Leakage of components cannot be observed B: Leakage of components can be observed

[Substrate] In the following examples and comparative examples, a FUNCREA LEA type (thickness 120 μm, manufactured by Gunze Corporation) of a low-density polyethylene polymer was used as a substrate. Moreover, the zwitterion-containing acrylic polymer was produced as follows.

[Zwitterion-containing acrylic polymer 1] In the reaction vessel with stirring device, add 93 parts by mass of n-butyl acrylate (BA), 5 parts by mass of dimethylaminoethyl acrylate (DMAEA), 2 parts by mass of 2-hydroxyethyl acrylate (HEA), starting Azobisisobutyronitrile (AIBN) as the solvent and 180 parts by mass of ethyl acetate as the solvent were introduced with nitrogen gas for 30 minutes while stirring. Then, after raising the reaction system to 60 degreeC, it stirred for 24 hours, and obtained the prepolymer solution 1 (mass average molecular weight 78000) whose BA/DMAEA/HEA (mass ratio) was 93/5/2. The obtained prepolymer solution 1 was diluted by adding methyl ethyl ketone so that the solid content would be 30%. Here, 3.88 parts by mass of propane sultone was slowly dropped and stirred at room temperature for 3 hours. After raising the reaction system to 60°C, it was further reacted for 48 hours to obtain a glass transition temperature (Tg) of -30°C, a mass average molecular weight (Mw) of 100,300, a molecular weight distribution (Mw/Mn) of 10.4, and Zwitterion-containing acrylic polymer 1 having extremely large peaks of tan δ at -30°C and 40°C and having a ratio of zwitterion-containing units of 3% by mass.

[Zwitterion-containing acrylic polymer 2] In a reaction vessel with a stirring device, add 95 parts by mass of n-butyl acrylate, 3 parts by mass of dimethylaminoethyl acrylate, 2 parts by mass of 2-hydroxyethyl acrylate, azobisisobutyronitrile, and 180 parts by mass of ethyl acetate. parts by mass, nitrogen gas was introduced for 30 minutes while stirring. Then, after raising the reaction system to 60 degreeC, it stirred for 24 hours, and obtained the prepolymer solution 2 (mass average molecular weight 128000) whose BA/DMAEA/HEA (mass ratio) was 95/3/2. The obtained prepolymer solution 2 was diluted by adding methyl ethyl ketone so that the solid content would be 30%. Here, 2.33 parts by mass of propane sultone was slowly dropped and stirred at room temperature for 3 hours. After raising the reaction system to 60°C, it was further reacted for 48 hours to obtain a Tg of -24°C, a Mw of 165,000, a Mw/Mn of 10.3, and a very large peak of tanδ at -24°C and 50°C, and containing The ratio of zwitterionic units is 3% by mass of the zwitterion-containing acrylic polymer 2 .

[Zwitterion-containing acrylic polymer 3] In the reaction vessel with stirring device, add 50 mass parts of n-butyl acrylate, 47 mass parts of 2-ethylhexyl acrylate (2EHA), 3 mass parts of dimethylaminoethyl acrylate, azobisisobutyronitrile, 180 parts by mass of ethyl acetate was stirred, and nitrogen gas was introduced for 30 minutes. Then, after raising the reaction system to 60 degreeC, it stirred for 24 hours, and obtained the prepolymer solution 3 (mass average molecular weight 86000) whose BA/2EHA/DMAEA (mass ratio) was 50/47/3. The obtained prepolymer solution 3 was diluted by adding methyl ethyl ketone so that the solid content would be 30%. Here, 2.33 parts by mass of propane sultone was slowly dropped and stirred at room temperature for 3 hours. After raising the reaction system to 60°C, it was further reacted for 48 hours to obtain a Tg of -40°C, a Mw of 110500, a Mw/Mn of 11.2, and a very large peak of tanδ at -40°C and 70°C, and containing The ratio of the zwitterionic unit is 5% by mass of the zwitterion-containing acrylic polymer 3 .

[Zwitterion-containing acrylic polymer 4] Add 97 parts by mass of n-butyl acrylate, 3 parts by mass of dimethylaminoethyl acrylate, 180 parts by mass of azobisisobutyronitrile, and 180 parts by mass of ethyl acetate into a reaction vessel with a stirring device, and introduce nitrogen gas for 30 minutes while stirring . Then, after raising the reaction system to 60 degreeC, it stirred for 24 hours, and obtained the prepolymer solution 4 (mass average molecular weight 111000) whose BA/DMAEA (mass ratio) was 97/3. The obtained prepolymer solution 4 was diluted by adding methyl ethyl ketone so that the solid content would be 30%. Here, 2.33 parts by mass of propane sultone was slowly dropped and stirred at room temperature for 3 hours. After raising the reaction system to 60°C, it was further reacted for 48 hours to obtain a Tg of -33°C, a Mw of 142700, a Mw/Mn of 10.9, and a very large peak of tanδ at -30°C and 60°C, and containing The ratio of zwitterionic units is 4% by mass of zwitterion-containing acrylic polymer 4 .

Preparation of an adhesive polymer and a composition for an intermediate layer that does not contain a zwitterionic structure. [Adhesive Polymer A] Prepare an acrylic copolymer consisting of 86 parts by mass of butyl acrylate (BA), 8 parts by mass of methyl methacrylate (MMA), 1 part by mass of acrylic acid (AA), and 5 parts by mass of 2-hydroxyethyl acrylate (2HEA). A solution of a material resin (adhesive main agent, mass average molecular weight 720,000, solid content 35.0% by mass). 0.2 parts by mass (solid content) of a polyvalent isocyanate compound (product name "BHS-8515", manufactured by TOYOCHEM Co., Ltd., solid content 37.5% by mass) as a crosslinking agent was added to 100 parts by mass of the main adhesive agent and stirred , to obtain adhesive polymer A.

[Adhesive Polymer B] Prepare acrylic acid composed of 59.5 parts by mass of 2-ethylhexyl acrylate (2EHA), 30 parts by mass of vinyl acetate (Vac), 0.5 parts by mass of acrylic acid (AA), and 10 parts by mass of 2-hydroxyethyl acrylate (2HEA). A solution of a copolymer resin (adhesive main agent, mass average molecular weight 700,000, solid content 35.0% by mass). After adding 1.9 parts by mass (solid content) of a polyvalent isocyanate compound (product name "BHS-8515", manufactured by TOYOCHEM Corporation, solid content 37.5% by mass) as a crosslinking agent to 100 parts by mass of the main adhesive agent, and stirring , to obtain adhesive polymer B.

[Composition C for middle layer] An acrylate copolymer having a mass average molecular weight of 600,000 composed of 91 parts by mass of butyl acrylate and 9 parts by mass of acrylic acid was prepared. In addition, acrylic acid composed of 62 parts by mass of n-butyl acrylate (BA), 10 parts by mass of methyl methacrylate (MMA), and 28 parts by mass of 2-hydroxyethyl acrylate (2HEA) was obtained. In the copolymer, 2-isocyanate ethyl methacrylate (2-isocyanate ethyl methacrylate; product name "KARENZ MOI" (registered trademark), manufactured by Showa Denko Co., Ltd.) was added at a rate of 80 mol to 100 mol% of 2HEA. The resin solution (solid content 35.0% by mass) obtained by adding in the form of ear %. The composition C for intermediate|middle layers was obtained by mixing the resin solution at the ratio of 10 mass parts with respect to 100 mass parts (solid content) of said acrylate copolymers based on solid content.

[Composition D for middle layer]

An acrylate copolymer having a mass average molecular weight of 600,000 composed of 91 parts by mass of butyl acrylate and 9 parts by mass of acrylic acid was prepared.

With respect to 100 parts by mass (solid content) of the acrylate copolymer, 2 to 3 functional urethane acrylate oligomers (product name "PU-5", manufactured by Dainichi Seika Chemical Co., Ltd.) were added in 2 parts by mass (solid content). ), to obtain the composition D for the intermediate layer.

The modulus of elasticity of zwitterion-containing acrylic polymers 1 to 4, adhesive polymers A, B, and intermediate layer compositions C and D were measured. The storage elastic modulus G' at 23°C, 40°C, 50°C, 60°C, 70°C, and 80°C, the tanδ of dynamic viscoelasticity at the same temperature, and the storage elastic modulus G' at 60°C (60) The ratio with respect to the storage elastic modulus G'(23) at 23°C, that is, G'(60)/G'(23), is shown in the table below.

(Examples 1 to 4, Comparative Examples 1 and 2)

An adhesive tape having an adhesive layer composed of zwitterion-containing acrylic polymers 1 to 4 and adhesive polymers A and B was produced.

Coat zwitterionic acrylic polymers 1~4, adhesive polymer A or B on polyterephthalene A ethylene formate (PET)-based release film (product name "SP-PET381031", thickness 38 μm, manufactured by Lintec Corporation) was dried to obtain an adhesive layer with a thickness of 20 μm. The adhesive layer is bonded to the aforementioned base material to manufacture an adhesive tape.

Using the obtained adhesive tape, evaluation of paste residue, evaluation of cuttability, evaluation of embedding property (for small bumps), evaluation of embedding properties (for medium bumps), and evaluation of end appearance were performed. The results are shown in Table 2.

(Examples 5 to 8, Comparative Examples 3 and 4)

An adhesive tape having an intermediate layer composed of zwitterion-containing acrylic polymers 1 to 4 and compositions C and D for an intermediate layer was produced.

(Manufacture of middle layer)

Coat zwitterion-containing acrylic polymers 1 to 4 and intermediate layer composition C or D on a polyethylene terephthalate (PET) release film (product name "SP-PET381031", thickness 38 μm, Lintec Corporation) and dried to obtain a resin layer with a thickness of 45 μm. A resin layer having a thickness of 90 μm was obtained by bonding to a resin layer having a thickness of 45 μm produced in the same manner. The resin layer and the aforementioned base material are bonded together to manufacture a laminate of the resin layer and the base material. This resin layer will later become the middle layer.

(manufacture of adhesive layer)

Preparation of 2-isocyanate ethyl methyl Acrylate (2-isocyanate ethyl methacrylate; product name "KARENZ MOI" (registered trademark), manufactured by Showa Denko Co., Ltd.) is a resin solution in which the addition rate is 50 mol% relative to 100 mol% of 2HEA (Adhesive main agent, solid content 35.0% by mass).

1.0 parts by mass of 1-hydroxycyclohexyl phenyl ketone (product name "Irgacure 184", manufactured by BASF Corporation) as a photopolymerization initiator and 0.2 parts by mass (solid content) were added to 100 parts by mass of the main adhesive agent A polyvalent isocyanate compound (product name "CORONATEL", manufactured by TOSOH Corporation) as a crosslinking agent was stirred to obtain an adhesive composition. Next, apply and dry a polyethylene terephthalate (PET) release film (product name "SP-PET381031", thickness 38 μm, manufactured by LINTEC Co., Ltd.) to form an adhesive with a thickness of 20 μm on the release film. layer, and bonded to a polyethylene terephthalate (PET)-based release film (product name "SP-PET382150", thickness 38 μm, manufactured by Lintec Corporation) to obtain a laminate having an adhesive layer.

(manufacture of adhesive tape)

One PET film was removed from the laminate having the adhesive layer, and bonded to the resin layer of the laminate of the resin layer and the base material. As a result, an adhesive tape composed of PET film/adhesive layer/resin layer/substrate was obtained. The resin layer becomes an intermediate layer between the adhesive layer and the base material.

Using the obtained adhesive tape, evaluation of paste residue, evaluation of cuttability, evaluation of embedding property (for small bumps), evaluation of embedding properties (for medium bumps), and evaluation of end appearance were performed. The results are shown in Table 3.

As described above, in the present invention, as the polymer of the main component of the adhesive composition, a polymer having a site having a different viscoelastic behavior depending on temperature, that is, a polymer having a repeating unit containing a zwitterion structure is used. thing. Therefore, it is possible to provide an adhesive tape that is easy to control the fluidity of the adhesive layer (or intermediate layer) during attachment and storage, and that follows the uneven surface of the workpiece during attachment, and that the adhesive composition leaks out during storage. less.

none.

Claims (3)

An adhesive tape comprising a base material and an adhesive layer, wherein the base material is a resin film, the adhesive layer comprises the following adhesive composition, and the storage modulus G'(23) at 23°C is 1.0×10 ⁵ Pa or more, the storage modulus G'(50) at 50°C is 2.5×10 ⁵ Pa or less, the dynamic viscoelasticity tanδ at 60°C is 0.5 or more, and contains acrylic polymer as the main component. An adhesive tape, comprising a base material, an adhesive layer, and an intermediate layer between the base material and the adhesive layer, wherein the base material is a resin film, and the intermediate layer includes an adhesive composition as follows, at 23°C The storage modulus G'(23) is above 1.0×10 ⁵ Pa, the storage modulus G'(50) at 50°C is below 2.5×10 ⁵ Pa, and the tanδ of dynamic viscoelasticity at 60°C is above 0.5, and Contains acrylic polymer as the main ingredient. The adhesive tape as described in item 1 or 2 of the patent application, wherein the ratio of the storage modulus G'(60) of the adhesive composition at 60°C to the storage modulus G'(23) at 23°C, G'(60)/G'(23) is 0.1~0.7.