KR20220011155A - backgrind tape - Google Patents

Abstract

It has a sheet-like substrate and a pressure-sensitive adhesive layer formed on one side of the substrate, the pressure-sensitive adhesive layer contains a cured product of the pressure-sensitive adhesive composition, the thickness is 50 to 500 μm, the pressure-sensitive adhesive composition is polyurethane (A) and (meth) An acrylate monomer (B), a chain transfer agent (C), a photoinitiator (D), and 0.4-6 mass % of ionic liquid (E) are contained, and a polyurethane (A) is derived from a polyoxyalkylene polyol It is set as the backgrind tape containing the polyurethane (a1) which has frame|skeleton containing the structure of and polyisocyanate-derived structure, and has (meth)acryloyl group at several terminals.

Description

backgrind tape

The present invention relates to a backgrind tape suitably used for processing a semiconductor wafer.

This application claims priority based on Japanese Patent Application No. 2019-162092 for which it applied to Japan on September 5, 2019, and uses the content here.

In accordance with the demand for thinning semiconductor devices, a backgrinding process of a semiconductor wafer is performed in a semiconductor device manufacturing process. In the backgrinding process of a semiconductor wafer, after protecting the front surface (front) of a semiconductor wafer with a backgrind tape, the back surface of a semiconductor wafer is grinded and a semiconductor wafer is thinned.

BACKGROUND ART Various types of backgrind tapes used to protect the surface of semiconductor wafers have been conventionally proposed. In recent years, a backgrind tape having sufficient unevenness absorbency has been demanded also for semiconductor wafers having uneven portions on the surface, such as semiconductor wafers on which bumps (electrodes) containing solder or the like are formed.

In addition, conventionally, when peeling a backgrind tape from a semiconductor wafer, static electricity called peeling electrification may generate|occur|produce, the circuit of a semiconductor wafer may be destroyed, or a foreign material may adhere to a semiconductor wafer. For this reason, in a backgrind tape, it is calculated|required that it has sufficient antistatic property.

As a backgrind tape having both performance of uneven water absorption and antistatic properties, for example, in Patent Document 1, a substrate layer, an uneven water absorption resin layer, an antistatic layer, and an adhesive resin layer are provided in this order for processing a semiconductor wafer. A tacky film is disclosed.

Japanese Patent Laid-Open No. 2018-6540

However, since it is necessary to bond and manufacture the adhesive film for semiconductor wafer processes of patent document 1 after each layer is formed into a sheet, a manufacturing procedure is complicated.

Moreover, in a backgrind tape, it is calculated|required that it has adhesive force which can fix to-be-adhered bodies, such as a semiconductor wafer, to a backgrind tape with sufficient intensity|strength. However, if a backgrind tape with high adhesive strength is affixed to an adherend and then the adherend is processed, and then the backgrind tape is peeled off, there is a case where an adhesive residue is generated in which the adhesive layer of the backgrind tape is transferred to the adherend. have.

The present invention has been made in view of the above circumstances, and provides a backgrind tape that has sufficient unevenness absorbency, antistatic property, and adhesive strength, and is less likely to cause adhesive residue after peeling off the backgrind tape, and which can be manufactured in a small manufacturing process. aim to do

A first aspect of the present invention is the following backgrind tape.

[1] A backgrind tape having a sheet-like substrate and an adhesive layer formed on one side of the substrate,

The pressure-sensitive adhesive layer includes a cured product of the pressure-sensitive adhesive composition, and has a thickness of 50 to 500 μm,

The said adhesive composition contains a polyurethane (A), a (meth)acrylate monomer (B), a chain transfer agent (C), a photoinitiator (D), and an ionic liquid (E),

The polyurethane (A) contains a polyurethane (a1) having a skeleton comprising a structure derived from a polyoxyalkylene polyol and a structure derived from a polyisocyanate, and having a (meth)acryloyl group at a plurality of terminals;

The said adhesive composition contains 0.4-6.0 mass % of an ionic liquid (E), The back grind tape characterized by the above-mentioned.

The backgrind tape of the first aspect of the present invention may preferably include the following features, as described below. Two or more of the following characteristics may be combined preferably.

[2] The backgrind tape according to [1], wherein the pressure-sensitive adhesive layer has a single-layer structure.

[3] The backgrind tape according to [1] or [2], wherein the (meth)acrylate monomer (B) contains a monofunctional (meth)acrylate and a polyfunctional (meth)acrylate.

[4] The bag according to any one of [1] to [3], wherein the ionic liquid (E) is a compound containing an organic cation selected from the group consisting of quaternary ammonium ions, iminium ions and sulfonium ions. grind tape.

[5] The backgrind tape according to any one of [1] to [4], wherein the ionic liquid (E) is a compound containing a fluorine-containing organic anion.

[6] The ionic liquid (E) comprises a 1-ethyl-3-methylimidazolium cation and/or a 4-methyl-1-octylpyridinium cation, and a bis(fluorosulfonyl)imide anion ((FSO) ₂ ) The backgrind tape according to any one of [1] to [5], which is a compound containing ₂ N ^{− ).}

[7] The backgrind tape according to any one of [1] to [6], wherein the chain transfer agent (C) is a polyfunctional thiol.

[8] The backgrind tape according to any one of [1] to [7], wherein a gel fraction of the pressure-sensitive adhesive layer is 50 to 65 mass%.

[9] The backgrind tape according to any one of [1] to [8], wherein the surface resistivity of the pressure-sensitive adhesive layer is ^{less than 1×10 11 Ω/□.}

[10] When the total of the (meth)acrylate monomer (B) is 100 mol%, the monofunctional (meth)acrylate is 85 to 99 mol%, and the polyfunctional (meth)acrylate is 1 to 15 mol% The backgrind tape according to any one of [3] to [9], which contains mol%.

[11] The pressure-sensitive adhesive composition,

20-50 mass % of the said polyurethane (A),

35-79 mass % of the said (meth)acrylate monomer (B),

0.5-8.0 mass % of the said chain transfer agent (C),

0.01-5.0 mass % of the said photoinitiator (D),

0.4-6.0 mass % of the said ionic liquid (E) is included,

The backgrind tape according to any one of [1] to [10].

[12] The backgrind tape according to any one of [1] to [11], wherein the pressure-sensitive adhesive composition further contains a fatty acid ester (F).

ADVANTAGE OF THE INVENTION According to this invention, the back grind tape which has sufficient uneven|corrugated water absorption, antistatic property, and adhesive force, and is hard to produce an adhesive residue after peeling off a back grind tape can be provided.

Furthermore, in the backgrind tape of this invention, an adhesive layer is hardened|cured material of an adhesive composition, and has sufficient uneven|corrugated water absorption, antistatic property, and adhesive force. For this reason, it is not necessary to separately provide a layer having unevenness-absorbing property, a layer having antistatic property, and a layer having adhesive force, and the tape can be manufactured in a small number of manufacturing steps.

Therefore, the backgrind tape of the present invention is suitable as a backgrind tape used to protect the surface when performing a backgrind process of an adherend having an uneven portion on its surface, such as a semiconductor wafer having bumps formed on its surface.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment which is a preferable example of this invention is described in detail. However, this invention is not limited only to embodiment described below. Within the scope of the present invention, it is also possible to omit, change, and/or add to the type, amount, composition, ratio, shape, size, and the like, if necessary.

<Background Tape>

The backgrind tape (henceforth a "BG tape") in this embodiment has a sheet-like base material, and the adhesive layer formed in the single side|surface of the base material. An adhesive layer contains the hardened|cured material of the adhesive composition mentioned later, Preferably it has a single-layer structure. In addition, the shape of the "tape" referred to herein is not limited to a band-like one, any shape may be sufficient, and a rectangular or disk-shaped sheet is also included.

(write)

The material of the base material can be appropriately selected, and examples thereof include a resin material. Examples of the resin material include polyolefins such as polyethylene (PE) and polypropylene (PP); polyester sheets such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate; polyvinyl chloride (PVC); polyimide (PI); polyphenylene sulfide (PPS); ethylene vinyl acetate (EVA); Polytetrafluoroethylene (PTFE), etc. are mentioned. Among these resin materials, it is preferable to use PE, PP, or PET because a sheet having moderate flexibility can be obtained. A resin material may be used individually by 1 type, and may mix and use 2 or more types. The substrate may be transparent or opaque.

When using the resin sheet containing a resin material as a base material, the single layer may be sufficient as a resin sheet, and the multilayer structure (for example, three-layer structure) of two or more layers may be sufficient as it. A resin sheet having a multilayer structure WHEREIN: The resin material which comprises each layer may be a resin material containing only 1 type individually, and the resin material containing 2 or more types may be sufficient as it.

As a base material, you may use the thing to which the antistatic process was given. Although it does not specifically limit as antistatic treatment performed to a base material, The method of providing an antistatic layer on at least one side of a base material, the method of pouring antistatic agent into a base material, etc. can be used.

In addition, the adhesion-facilitating process, such as acid treatment, alkali treatment, primer treatment, corona treatment, plasma treatment, ultraviolet treatment, ozone treatment, etc., may be given to the surface on which the adhesive layer of a base material is formed as needed.

The thickness of the base material can be appropriately selected according to the material of the base material or the like. The BG tape is used for a purpose in which a BG tape is affixed to a semiconductor wafer having an uneven portion on the surface and is peeled off after that. and preferably 50 to 300 μm. When the thickness of the base material is 10 µm or more, the rigidity (stiffness) of the BG tape increases. Therefore, when sticking or peeling a BG tape to a to-be-adhered semiconductor wafer, there exists a tendency for a wrinkle and a float to become difficult to produce in a BG tape. Moreover, when the thickness of a base material is 1000 micrometers or less, it will become easy to peel the BG tape affixed to a semiconductor wafer from a semiconductor wafer, and workability|operativity (handleability, handling) becomes favorable.

(Adhesive layer)

A single-layered pressure-sensitive adhesive layer is formed on one side of the substrate. An adhesive layer contains the hardened|cured material of the adhesive composition mentioned later. When the BG tape is applied to an adherend such as a semiconductor wafer having an uneven surface on its surface and is used for peeling off after that, the pressure-sensitive adhesive layer is backgrinded by fixing the BG tape to the surface of the adherend with sufficient adhesive force. It has a role to protect the surface of the to-be-adhered body during a process. In addition, the pressure-sensitive adhesive layer absorbs and smoothes the unevenness of the surface of the adherend, that is, the gap between the unevenness of the adherend is more preferably filled in the pressure-sensitive adhesive layer, thereby increasing the precision of the backgrinding process. In addition, the pressure-sensitive adhesive layer reduces peeling charging that occurs when the BG tape is peeled from an adherend. Moreover, even if the adhesive layer which the BG tape of this embodiment has peels off a BG tape, an adhesive agent residue does not arise. Moreover, in the adhesive layer which the BG tape of this embodiment has, it is hard to produce the contamination by the ionic liquid (E) mentioned later to the to-be-adhered body after peeling a BG tape.

Although the thickness of the adhesive layer of this embodiment can be selected arbitrarily, Preferably it is 50-500 micrometers, It is more preferable that it is 60-400 micrometers, It is still more preferable that it is 70-300 micrometers. When the thickness of an adhesive layer is 50 micrometers or more, the unevenness|corrugation water absorption and adhesive force of a BG tape become favorable. Moreover, film thickness control of an adhesive layer becomes easy as the thickness of an adhesive layer is 500 micrometers or less.

When the BG tape of the present embodiment is a tape affixed to an adherend having an uneven portion on the surface, the thickness of the pressure-sensitive adhesive layer largely depends on the height of the uneven portion on the surface of the adherend. It is preferable that the thickness of an adhesive layer sets it as the height of the surface uneven|corrugated part or more so that sufficient uneven|corrugated water absorption may be obtained. Therefore, for example, when the surface unevenness|corrugation is a bump formed in the semiconductor wafer, it is preferable to make the thickness of an adhesive layer into twice the height dimension of a bump or more. The height of the bump is usually 30 to 200 µm. For example, when the height of the bump is 100 µm, the thickness of the pressure-sensitive adhesive layer is preferably 200 µm or more, and when the height of the bump is 200 µm, the thickness of the pressure-sensitive adhesive layer is preferably 400 µm or more do.

A single layer structure may be sufficient as an adhesive layer, and the multilayer structure which laminated|stacked the adhesive layer of this embodiment, and one or more other adhesive layers different from the adhesive layer of this embodiment may be sufficient as it. As another adhesive layer, a conventionally well-known adhesive layer can be used. In this embodiment, when an adhesive layer has a multilayer structure, it is necessary for the adhesive layer of this embodiment to exist in the outermost surface. In addition, in the BG tape of this embodiment, layers other than an adhesive layer may exist between an adhesive layer and a base material within the range which does not inhibit hardening of an adhesive layer. From the viewpoint of shortening the process, it is preferable that the pressure-sensitive adhesive layer has a single-layer structure.

Although the gel fraction of an adhesive layer can be selected arbitrarily, it is preferable that it is 50-65 mass %. When a gel fraction is 50 mass % or more, generation|occurrence|production of the adhesive agent residue by peeling the BG tape affixed to a to-be-adhered body can be suppressed more effectively. Moreover, when a gel fraction is 65 mass % or less, an adhesive layer will have sufficient fluidity|liquidity, and the unevenness|corrugation water absorption of a BG tape becomes still more favorable. As for the gel fraction of an adhesive layer, it is more preferable that it is 52 mass % or more. Moreover, as for the gel fraction of an adhesive layer, it is more preferable that it is 63 mass % or less.

(Measurement of the gel fraction of the pressure-sensitive adhesive layer)

The measurement of the gel fraction of an adhesive layer can be performed with the following method. First, a sheet is cut out from the BG tape to a size of about 1 g, the base material is peeled from the sheet to be a measurement sample, and the mass of the measurement sample is measured. Then, the sample for a measurement is immersed in 50 ml of toluene, and it is left still at room temperature for 72 hours. Then, the sample for measurement is taken out in toluene, dried at 80 degreeC for 5 hours, and the mass is measured again. And the gel fraction is measured based on the following formula.

Gel fraction (%) = [A/B] × 100

A: Mass of sample for measurement after immersion in toluene (mass of toluene is not included)

B: Mass of sample for measurement before immersion in toluene

It is preferable that it is less than ^{1x10 11} ohm/square, and, as for the surface resistivity of an adhesive layer, it is more preferable that it is less than ^{1x10 10 ohm/square.} When the surface resistivity is ^{less than 1×10 11} Ω/□, peeling electrification at the time of peeling off the BG tape affixed to the adherend is reduced, resulting in a BG tape having further excellent antistatic properties. Although the lower limit of the surface resistivity of an adhesive layer can be selected arbitrarily, 1x10 ⁶ ohm/square or more may be sufficient, for example.

(separator)

In the BG tape, for the purpose of protecting the pressure-sensitive adhesive layer, a transparent or opaque separator may be provided on the surface on the opposite side to the base material of the pressure-sensitive adhesive layer. It is preferable that the separator is laminated directly on the surface of an adhesive layer. Although it can select arbitrarily as a material of a separator, For example, paper, a plastic film, etc. can be used, It is preferable to use a plastic film at the point which is excellent in surface smoothness. The plastic film used as the separator is not particularly limited as long as it can protect the pressure-sensitive adhesive layer, and examples thereof include polyethylene, polypropylene, polyethylene terephthalate (PET) and polybutene. The thickness of the separator can be arbitrarily selected. For example, it is preferable that they are 5-300 micrometers, It is more preferable that they are 10-200 micrometers, It is more preferable that they are 25-100 micrometers.

<Adhesive composition>

Next, the BG tape of this embodiment WHEREIN: The adhesive composition used as a material of an adhesive layer is demonstrated in detail.

The adhesive composition of this embodiment contains a polyurethane (A), a (meth)acrylate monomer (B), a chain transfer agent (C), a photoinitiator (D), and an ionic liquid (E). In addition, a (meth)acrylate monomer should just mean a methacrylate monomer and/or an acrylate monomer.

(Polyurethane (A))

Polyurethane (A) contains the polyurethane (a1) mentioned later. Although only the polyurethane (a1) may be included, the polyurethane (a2) mentioned later for the purpose of adjusting the cohesion force in the hardened|cured material of an adhesive composition as well as polyurethane (a1) may be contained in polyurethane (A) . It is preferable that components other than a polyurethane (a1) and the polyurethane (a2) contained as needed are not contained in a polyurethane (A).

[Polyurethane (a1)]

Polyurethane (a1) has frame|skeleton containing the structure derived from a polyoxyalkylene polyol, and the structure derived from polyisocyanate. Moreover, polyurethane (a1) has a (meth)acryloyl group at several terminals. You may have a (meth)acryloyl group in all the terminals. It is preferable that the (meth)acryloyl group of the terminal which a polyurethane (a1) has is a part of (meth)acryloyloxy group. A (meth)acryloyl group should just mean a methacryloyl group and/or an acryloyl group. The (meth)acryloyloxy group should just mean a methacryloyloxy group and/or an acryloyloxy group.

In the present invention, "a plurality of terminals" of polyurethane means two or more terminals. "A plurality of terminals" means two terminals when the polyurethane is a linear polymer, and two or more terminals among the number of terminals equal to the number of each branched chain when the polyurethane is a branched polymer.

In addition, in the present invention, the (meth)acryloyl group is one selected _{from a functional group represented by the formula CH 2} =CH-CO-, and a functional group represented by the formula CH ₂ =C(CH ₃ )-CO- means more than

[Polyurethane (a2)]

Polyurethane (a2) has frame|skeleton containing the structure derived from a polyoxyalkylene polyol, and the structure derived from polyisocyanate, similarly to a polyurethane (a1). Unlike polyurethane (a1), polyurethane (a2) has a (meth)acryloyl group only at one terminal. It is preferable that the (meth)acryloyl group of the terminal which a polyurethane (a2) has is a part of (meth)acryloyloxy group. It is preferable that the terminal which does not have a (meth)acryloyl group which the polyurethane (a2) has has any selected from an isocyanato group, a structure derived from an alkyl alcohol, and a structure derived from an alkyl isocyanate, It is a structure derived from an alkyl alcohol It is more preferable to have

"Structure derived from polyoxyalkylene polyol"

As the polyoxyalkylene polyol having a structure derived from the polyoxyalkylene polyol contained in the skeleton of the polyurethane (a1) and the polyurethane (a2), it is preferable that the polyoxyalkylene polyol has an alkylene chain having 2 to 4 carbon atoms. Specific examples include polyoxyethylene polyol, polyoxypropylene polyol, and polyoxybutylene polyol.

The polyoxyalkylene polyol having a structure derived from the polyoxyalkylene polyol may include one type of alkylene chain or may include two or more types of alkylene chains.

The polyoxyalkylene polyol having a structure derived from polyoxyalkylene polyol is preferably one having two or three hydroxyl groups at the terminal (diol-type or triol-type polyoxyalkylene polyol), and polyoxyalkylene It is more preferable that it is glycol (diol type), and it is especially preferable that it is polypropylene glycol which has a C3 alkylene chain.

For example, when the polyoxyalkylene polyol is polypropylene glycol, the hydroxyl value is preferably 20 to 120 mgKOH/g, more preferably 30 to 100 mgKOH/g, and still more preferably 40 to 80 mgKOH/g. . As a specific example of polypropylene glycol, for example, polypropylene glycol (Actcall D-2000; Mitsui Chemicals make, number average molecular weight 2000, diol type) etc. which has a hydroxyl group (hydroxy group) with a hydroxyl value of 56 mgKOH/g at the terminal. can be heard

Here, the hydroxyl value of polyoxyalkylene polyol is the hydroxyl value of polyoxyalkylene polyol measured according to JISK0070. That is, it means the number of mg of potassium hydroxide required to neutralize free acetic acid when 1 g of polyoxyalkylene polyol is acetylated. Specifically, it can obtain|require by acetylating the hydroxyl group in a sample (polyoxyalkylene polyol) using acetic anhydride, and titrating the free acetic acid produced in that case with potassium hydroxide solution.

It is preferable that it is 500-5,000, as for the number average molecular weight of a polyoxyalkylene polyol, it is more preferable that it is 800-4,000, It is more preferable that it is 1,000-3,000. When the number average molecular weight of polyoxyalkylene polyol is 500 or more, the BG tape which has an adhesive layer containing the hardened|cured material of the adhesive composition containing the polyurethane (A) synthesize|combined using this will become a thing with high peeling strength. Moreover, if the number average molecular weight of polyoxyalkylene polyol is 5,000 or less, the polyurethane (A) synthesize|combined using this will contain the urethane bond of sufficient quantity. For this reason, the hardened|cured material which hardened the adhesive composition containing a polyurethane (A) becomes a thing with favorable cohesive force.

The number of structures derived from the polyoxyalkylene polyol contained in frame|skeleton of a polyurethane (a1) and a polyurethane (a2) may be one, respectively, and the structure containing two or more types may be sufficient as them.

The polyurethane (a1) and the polyurethane (a2) may have a structure in which the structures derived from 2 or more types of other polyoxyalkylene polyols were couple|bonded with the structure derived from polyisocyanate interposed therebetween.

The structure derived from the polyoxyalkylene polyol contained in the skeleton of the polyurethane (a1) and the structure derived from the polyoxyalkylene polyol contained in the skeleton of the polyurethane (a2) may be the same or different.

"Structure derived from polyisocyanate"

As the polyisocyanate having a structure derived from the polyisocyanate contained in the skeleton of the polyurethane (a1) and the polyurethane (a2), a compound having a plurality of isocyanato groups can be used, and it is preferable to use a diisocyanate.

As diisocyanate, for example, tolylene diisocyanate and its hydrogenated substance, xylylene diisocyanate and its hydrogenated substance, diphenylmethane diisocyanate and its hydrogenated substance, 1, 5- naphthylene diisocyanate and its hydrogenated substance, 1,5-naphthylene diisocyanate and its hydrogenated substance, hexamethylene di Isocyanate, trimethylhexamethylene diisocyanate, tetramethylxylylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexyl diisocyanate, 1,3-bis(isocyanatemethyl)cyclohexane, norbornane diisocyanate, etc. are mentioned. can

Among these polyisocyanates, the use of a hydrogenated product of isophorone diisocyanate or diphenylmethane diisocyanate is preferred from the viewpoint of controlling the light resistance of the polyurethane (A) synthesized using this and reactivity with polyoxyalkylene polyol. It is preferable, and it is more preferable to use the hydrogenated substance of diphenylmethane diisocyanate from a reactive point with polyoxyalkylene polyol.

Specific examples of the polyisocyanate having a structure derived from polyisocyanate include a hydrogenated product of diphenylmethane diisocyanate (Desmodure W, manufactured by Sumika Covestro Urethane), isophorone diisocyanate (Desmodure I, Sumica Covestro Urethane) manufacture) and the like.

The number of structures derived from the polyisocyanate contained in frame|skeleton of a polyurethane (a1) and a polyurethane (a2) may be one, respectively, and the structure containing two or more types may be sufficient as them.

In addition, the structure derived from the polyisocyanate contained in frame|skeleton of a polyurethane (a1), and the structure derived from the polyisocyanate contained in frame|skeleton of a polyurethane (a2) may be same or different.

When the polyisocyanate-derived structure and the polyoxyalkylene polyol-derived structure included in the backbones of polyurethane (a1) and polyurethane (a2) are the same, polyurethane (a1) and polyurethane (a2) can be synthesized simultaneously Therefore, polyurethane (A) can be efficiently produced, which is preferable.

The proportion of the polyurethane (a1) contained in the polyurethane (A) is preferably 80 to 100% of the polyurethane (A) based on the number of molecules, more preferably 90 to 100%, and still more preferably 100% .

The proportion of the polyurethane (a2) contained in the polyurethane (A) is preferably 0 to 20%, more preferably 0 to 10%, and still more preferably 0%, based on the number of molecules, of the polyurethane (A). .

When the ratio of the polyurethane (a1) contained in the polyurethane (A) is 80% or more, the cured product of the pressure-sensitive adhesive composition containing the polyurethane (A) has sufficiently large cohesive force, which is preferable.

Among all the terminal numbers contained in the polyurethane (A) (the total number of the terminal numbers of the polyurethane (a1) and the polyurethane (a2) contained as necessary), 90 to 100% ( It is preferable that the meth)acryloyl group is introduce|transduced, 95 to 100 % is more preferable, and 100 % is still more preferable. 90 to 93%, 93 to 97%, 97 to 100%, etc. may be sufficient as needed. Among all the terminal numbers included in the polyurethane (A), if the amount of (meth)acryloyl group introduced is 90% or more based on the number of molecules, the cohesive force of the cured product obtained by curing the pressure-sensitive adhesive composition containing the polyurethane (A) is sufficiently high it will be

Among all the terminal numbers included in the polyurethane (A), the ratio of the number of terminals into which a (meth)acryloyl group is introduced based on the number of molecules is determined by infrared absorption spectrum (IR) method, nuclear magnetic resonance spectrum (NMR) method, etc. It is computable using the result of having analyzed the polyurethane (A) using it.

The ratio of the content of the polyurethane (a1) and the polyurethane (a2) contained in the polyurethane (A), that is, among all the terminal numbers contained in the polyurethane (A), the (meth)acryloyl group based on the number of molecules The ratio of the number of the terminals introduced can be adjusted by the manufacturing method of the polyurethane (A) mentioned later.

It is preferable that it is 30,000-200,000, as for the mass average molecular weight of a polyurethane (A), it is more preferable that it is 50,000-150,000, It is still more preferable that it is 60,000-100,000. The hardened|cured material obtained by hardening|curing the adhesive composition containing a polyurethane (A) as the mass average molecular weight of a polyurethane (A) is 30,000 or more will have favorable softness|flexibility. Moreover, handling becomes easy for the adhesive composition containing a polyurethane (A) as the mass average molecular weight of a polyurethane (A) is 200,000 or less, and workability|operativity becomes favorable.

(Method for measuring the mass average molecular weight of polyurethane (A))

The mass average molecular weight of the polyurethane (A) is a value in terms of polystyrene measured by gel permeation chromatography (GPC-101; Shodex (registered trademark) manufactured by Showa Denko Co., Ltd.) (hereinafter referred to as GPC) to be. The measurement conditions of GPC are as follows.

Column: LF-804 (manufactured by Showa Denko Co., Ltd.)

Column temperature: 40°C

Sample: 0.2 mass % tetrahydrofuran solution of polyurethane (A)

Flow: 1ml/min

Eluent: tetrahydrofuran

Detector: RI detector (differential refractive index detector)

Although content of the polyurethane (A) in the adhesive composition of this embodiment can be selected arbitrarily, it is preferable that it is 20-50 mass %, It is more preferable that it is 25-45 mass %, It is still more that it is 30-40 mass % desirable. When content of a polyurethane (A) is 20 mass % or more, the hardened|cured material obtained by hardening|curing an adhesive composition will have sufficient cohesive force, and the outstanding adhesive force will be acquired. Moreover, in the BG tape using this hardened|cured material as an adhesive layer, the softness|flexibility of an adhesive layer becomes an appropriate range, and it is hard to produce the entrapment of air bubbles between an adhesive layer and a to-be-adhered body. Moreover, the hardened|cured material obtained by hardening|curing an adhesive composition as content of a polyurethane (A) is 50 mass % or less will have sufficient softness|flexibility. Therefore, the BG tape using this hardened|cured material as an adhesive layer has favorable wettability with respect to a to-be-adhered body.

((meth)acrylate monomer (B))

A (meth)acrylate monomer (B) should just be a compound which has a (meth)acryloyloxy group other than a polyurethane (A), and is not specifically limited. As a (meth)acrylate monomer (B), the compound which has a (meth)acryloyloxy group may be used individually by 1 type, and may be used in mixture of 2 or more type. As the (meth)acrylate monomer (B), monofunctional (meth)acrylate may be used, polyfunctional (meth)acrylate may be used, and monofunctional (meth)acrylate and polyfunctional (meth)acrylate You may use both. In addition, (meth)acrylate should just mean a methacrylate and/or an acrylate.

In this invention, the "monofunctional" in monofunctional (meth)acrylate means the (meth)acrylate whose number of (meth)acryloyloxy groups is only one.

In addition, in this invention, "polyfunctional" in polyfunctional (meth)acrylate means the (meth)acrylate whose number of (meth)acryloyloxy groups is two or more.

As the (meth)acrylate monomer (B), it is preferable to use a combination of monofunctional (meth)acrylate and polyfunctional (meth)acrylate from the viewpoint of cohesive force of a cured product obtained by curing the pressure-sensitive adhesive composition and curability of the pressure-sensitive adhesive composition. And, it is more preferable to contain a monofunctional (meth)acrylate and a trifunctional or more (meth)acrylate, and in particular, a monofunctional (meth)acrylate and a trifunctional (meth) having three (meth)acryloyloxy groups It is most preferred to contain meth)acrylate.

As monofunctional (meth)acrylate, For example, cyclic alkyl (meth)acrylates, such as alkyl (meth)acrylate and isobornyl (meth)acrylate, alkoxyalkyl (meth)acrylate, alkoxy (poly)alkyl Renglycol (meth)acrylate, hydroxyl group-containing (meth)acrylate, carboxyl group-containing (meth)acrylate, fluorinated alkyl (meth)acrylate, dialkylaminoalkyl (meth)acrylate, (meth)acrylamide, epoxy group-containing (meth)acrylate, (meth)acryloylmorpholine, etc. are mentioned.

Among these monofunctional (meth)acrylates, the adhesive strength (peel force) and gel fraction of the cured product obtained by curing the pressure-sensitive adhesive composition tend to fall within more appropriate ranges when the cured product is used as the pressure-sensitive adhesive layer of the BG tape. It is preferable to contain meth)acrylate.

It is more preferable to use the alkyl (meth)acrylate which has a C4-C10 alkyl group as an alkyl (meth)acrylate. Specific examples of the alkyl (meth)acrylate include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. Among these, it is especially preferable to use 2-ethylhexyl (meth)acrylate and/or n-butyl (meth)acrylate.

Polyfunctional (meth)acrylate is a compound other than a polyurethane (A) and has two or more (meth)acryloyloxy groups. As polyfunctional (meth)acrylate, it is preferable to use the poly(meth)acrylate which is a polyol compound.

Specific examples of the polyfunctional (meth)acrylate include polyethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, and triethylene glycol di(meth)acryl. Rate, tripropylene glycol di(meth)acrylate, hydroxypivalate ester neopentyl glycol di(meth)acrylate, 1,3-bis(hydroxyethyl)-5,5-dimethylhydantoindi(meth)acryl Rate, α,ω-di(meth)acrylbisdiethylene glycol phthalate, trimethylolpropane tri(meth)acrylate, ethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, 1,4- Butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, diacryloxyethyl phosphate, pentaerythritol tetra(meth)acrylate, etc. are mentioned. Among these, as polyfunctional (meth)acrylate, it is preferable to use trimethylolpropane tri(meth)acrylate from a sclerosis|hardenable viewpoint of an adhesive composition.

When both monofunctional (meth)acrylate and polyfunctional (meth)acrylate are contained as (meth)acrylate monomer (B), when the sum total of (meth)acrylate monomer (B) is 100 mol% It is preferable to contain 85-99 mol% of monofunctional (meth)acrylate, and 1-15 mol% of polyfunctional (meth)acrylate. In this case, as for content of monofunctional (meth)acrylate, it is more preferable that it is 90-99 mol%, and it is still more preferable that it is 95-98 mol%. Moreover, it is more preferable that it is 1-10 mol%, and, as for content of polyfunctional (meth)acrylate, it is still more preferable that it is 2-5 mol%.

When monofunctional (meth)acrylate and polyfunctional (meth)acrylate are contained, the fluidity|liquidity of the hardened|cured material obtained by hardening|curing an adhesive composition as content of monofunctional (meth)acrylate is 85 mol% or more is hardened|cured material When it uses as an adhesive layer of a BG tape, it becomes a preferable range. Therefore, the BG tape using this cured product as the pressure-sensitive adhesive layer is preferable because sufficient absorbency of unevenness is obtained, and when affixed to an adherend having an uneven portion on the surface, it is difficult to generate a void between the uneven portion of the adherend. do. Moreover, when content of a monofunctional (meth)acrylate is 99 mol% or less, when the BG tape using the hardened|cured material of an adhesive composition as an adhesive layer is peeled from a to-be-adhered body, it is difficult to leave an adhesive agent residue, and it is preferable.

When monofunctional (meth)acrylate and polyfunctional (meth)acrylate are contained, if content of polyfunctional (meth)acrylate is 1 mol% or more, the fluidity|liquidity of the hardened|cured material obtained by hardening|curing an adhesive composition does not become large too much, it is preferable do. Moreover, when content of polyfunctional (meth)acrylate is 15 mol% or less, the fluidity|liquidity of the hardened|cured material obtained by hardening|curing an adhesive composition becomes a preferable range, when hardened|cured material is used as an adhesive layer of a BG tape. Therefore, it is preferable that the BG tape using the cured product as the pressure-sensitive adhesive layer has sufficient uneven water absorption, and when it is attached to an adherend having an uneven portion on its surface, it is difficult to generate a void between the uneven portion of the adherend. do.

Although content of the (meth)acrylate monomer (B) in the adhesive composition of this embodiment can be selected arbitrarily, it is preferable that it is 35-79 mass %, It is more preferable that it is 40-73 mass %, It is 40-66 mass % is more preferable, and it is especially preferable that it is 45-65 mass %. 45-60 mass %, 50-58 mass %, etc. may be sufficient as needed. When content of a (meth)acrylate monomer (B) is 35 mass % or more, since the viscosity of an adhesive composition does not become high too much and it is excellent in coating property, it is preferable. Moreover, when content of a (meth)acrylate monomer (B) is 79 mass % or less, the viscosity of an adhesive composition does not become low too much, it is easy to control the thickness of the coating film containing an adhesive composition, and it is preferable.

(Chain Transfer Agent (C))

A chain transfer agent (C) is made to contain in an adhesive composition in order to control the uneven|corrugated water absorption and a gel fraction of the hardened|cured material which hardened the adhesive composition.

It is preferable to use a thiol compound as a chain transfer agent (C). In particular, polyfunctional thiol can be preferably used. A polyfunctional thiol is a compound which has two or more mercapto groups in a molecule|numerator.

Although it does not specifically limit as polyfunctional thiol, For example, 1,2-ethanedithiol, 1, 4-bis (3-mercaptobutyryloxy) butane, tetraethylene glycol bis (3-mercaptopropionate) , trimethylol ethane tris (3-mercapto butyrate), trimethylol propane tris (3-mercapto butyrate), trimethylol propane tris (3-mercapto propionate), pentaerythritol tetrakis (3-mercapto butyrate) ), pentaerythritol tetrakis (3-mercaptopropionate, 1,3,5-tris (3-mercaptobutyloxyethyl) -1,3,5-triazine-2,4,6 (1H, 3H,5H)-trione, tris-[(3-mercaptopropionyloxy)-ethyl]-isocyanurate, dipentaerythritol hexakis(3-mercaptopropionate), etc. are mentioned. As a chain transfer agent (C), it is preferable to use pentaerythritol tetrakis (3-mercaptobutyrate) from a reactive viewpoint of an adhesive composition among the above-mentioned.

Although content of the chain transfer agent (C) in the adhesive composition of this embodiment can be selected arbitrarily, it is preferable that it is 0.5-8.0 mass %, It is more preferable that it is 0.7-6.0 mass %, It is further more preferable that it is 1.0-5.0 mass % It is preferable, and it is especially preferable that it is 3.0-4.5 mass %. When content of a chain transfer agent (C) is 0.5 mass % or more, when the fluidity|liquidity of the hardened|cured material obtained by hardening|curing an adhesive composition uses hardened|cured material as an adhesive layer of a BG tape, it becomes a preferable range. Therefore, the BG tape using the cured product as the pressure-sensitive adhesive layer is preferable because it has sufficient uneven water absorbency, and it is difficult to form a gap between the adhesive layer and the uneven portion of the adherend. When the BG tape using the hardened|cured material of an adhesive composition as an adhesive layer is peeled from a to-be-adhered body that content is 8.0 mass % or less, an adhesive agent residue is hard to remain, and it is preferable.

(Photoinitiator (D))

Although a photoinitiator (D) is not specifically limited, A radical photopolymerization initiator is preferable. As the photopolymerization initiator (D), for example, a carbonyl-based photopolymerization initiator, a sulfide-based photopolymerization initiator, an acylphosphine oxide-based photopolymerization initiator, a quinone-based photopolymerization initiator, a sulfochloride-based photopolymerization initiator, or a thioxanthone-based photopolymerization initiator may be used. can Among these photoinitiators (D), it is preferable to use a carbonyl-based photoinitiator and/or an acylphosphine oxide-based photoinitiator from the viewpoint of transparency of a cured product obtained by photocuring the pressure-sensitive adhesive composition, specifically, 2,4 It is preferable to use a ,6-trimethylbenzoyldiphenylphosphine oxide agent and/or 1-hydroxycyclohexyl-phenylketone.

It is preferable that content of the photoinitiator (D) in the adhesive composition of this embodiment is 0.01-5.0 mass %, It is more preferable that it is 0.05-3.0 mass %, It is more preferable that it is 0.1-2.0 mass %. As needed, 0.2-1.5 mass %, 0.3-1.2 mass %, etc. may be sufficient. Photocuring of an adhesive composition fully advances that content of a photoinitiator (D) is 0.01 mass % or more. Moreover, a low molecular-weight component does not increase too much at the time of photocuring of an adhesive composition as content of a photoinitiator (D) is 5 mass % or less. For this reason, when the BG tape using the hardened|cured material of an adhesive composition as an adhesive layer is peeled from a to-be-adhered body, an adhesive agent residue is hard to remain, and it is preferable.

(ionic liquid (E))

The ionic liquid (E) in this embodiment points out the molten salt compound (ionic compound) whose melting|fusing point is 100 degrees C or less. More preferably, it is a molten salt compound whose melting|fusing point is room temperature (25 degreeC) or less. The ionic liquid (E) may contain 1 type of compound, and may contain 2 or more types of compounds. The said ionic liquid may mean the salt compound which exists in a liquid state in the said temperature range, and does not need to contain a solvent.

As the ionic liquid (E), it is preferable to use an organic salt compound in which an organic cation and an inorganic anion or an organic anion are combined.

Examples of the organic cation include onium. Specifically, ammonium (representative structure: Q ¹ ₄ N ⁺ ), iminium (representative structure: Q ² ₂ C=N ⁺ Q ¹ ₂ ) of a quaternary nitrogen atom, sulfonium (representative structure: Q ¹ ₃ S) ⁺ ), oxonium (representative structure: Q ¹ ₂ O ⁺ ), phosphonium of a quaternary phosphorus atom (representative structure: Q ¹ ₄ P ⁺ ), iodonium (representative structure: Q ¹ ₂ I ⁺ ), etc. can be heard

In the representative structure of the organic cation, Q ¹ represents a substituent such as an alkyl group, an aryl group, or a heterocyclic group. Q ² represents a hydrogen atom or a substituent. A plurality of Q ¹ in a molecule, a plurality of Q ^{2 in a} molecule, or Q ¹ and Q ² in a molecule may be bonded to each other to form a ring. In addition, a group of the double bond with two joint of Q ¹ or Q ² in the two molecules (e.g., = O, = S, = NQ 2) may be formed to.

Among the organic cations, ammonium, iminium, and sulfonium of a quaternary nitrogen atom are preferable. Examples of these organic cations include pyridinium cation, piperidinium cation, pyrrolidinium cation, imidazolium cation, tetrahydropyrimidinium cation, dihydropyrimidinium cation, pyrazolium cation, tetraalkylammonium cation, and trialkylsulfonium cations. Among these organic cations, an imidazolium cation and a pyridinium cation are preferably used.

As an organic cation, since it is excellent in antistatic property, the adhesive layer containing the ionic liquid (E) using an imidazolium cation and a pyridinium cation is preferable.

Specific examples of the imidazolium cation used as the organic cation include 1-methylimidazolium cation, 1-ethyl-3-methylimidazolium cation, 1-ethyl-2,3-dimethylimidazolium cation, 1-butyl-3-methylimidazolium cation, 1,2,3-trimethylimidazolium cation, etc. are mentioned. Among these imidazolium cations, 1-ethyl-3-methylimidazolium cations are preferably used.

Specific examples of the pyridinium cation used as the organic cation include 1-ethylpyridinium cation, 1-butylpyridinium cation, 1-hexylpyridinium cation, 1-butyl-3-methylpyridinium cation, 1- Butyl-4-methylpyridinium cation, 1-hexyl-3-methylpyridinium cation, 1-hexyl-4-methylpyridinium cation, 1-butyl-3,4-dimethylpyridinium cation, 4-methyl-1- An octylpyridinium cation etc. are mentioned. Among these pyridinium cations, 1-hexyl-4-methylpyridinium cation, 4-methyl-1-octylpyridinium cation, etc. are preferably used.

As an inorganic anion, if melting|fusing point can form a molten salt compound 100 degrees C or less, it will not specifically limit. Examples of the inorganic anion include Cl ^- , Br ^- , I ^- , AlCl ₄ ^- , Al ₂ Cl ₇ ^- , BF ₄ ^- , PF ₆ ^- , ClO ₄ ^- , NO ₃ ^- , AsF ₆ ^- , SbF ₆ ^- , NbF ₆ ^- , TaF ₆ ^- , F(HF) _m ^- (m is an integer greater than or equal to 0), (CN) ₂ N ^- and the like.

As an organic anion, if melting|fusing point can form the molten salt compound 100 degrees C or less, it will not specifically limit. Examples of the organic anion include CH ₃ COO ⁻ , CF ₃ COO ⁻ , CH ₃ SO ₃ ⁻ , CF ₃ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , (FSO ₂ ) ₂ N ⁻ , (CF _{3 )} SO ₂ ) ₃ C ^- , C ₄ F ₉ SO ₃ ^- , (C ₂ F ₅ SO ₂ ) ₂ N ^- , C ₃ F ₇ COO ^- , (CF ₃ SO ₂ )(CF ₃ CO)N ^- etc. can

As an inorganic anion or an organic anion, it is especially preferable to use the anion containing a fluorine atom among the above. By using the anion containing a fluorine atom, it becomes the ionic liquid (E) excellent in ion conductivity. Therefore, the BG tape using the ionic liquid (E) containing a fluorine-containing anion is especially excellent in antistatic property. From the viewpoint of antistatic properties, among the anions containing a fluorine atom, a fluorine-containing organic anion is preferable, and in particular (FSO ₂ ) ₂ N ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ is preferably used, (FSO ₂ ) It is more preferable to use ₂ N ^{− .}

As the ionic liquid (E), a commercially available one may be used. Among them, an ionic liquid containing 1-ethyl-3-methylimidazolium cation and bis(fluorosulfonyl)imide anion ((FSO ₂ ) ₂ N ⁻ ) (manufactured by Daiichi Kogyo Seyaku Co., Ltd.; Trade name: Elexel AS-110), an ionic liquid containing a 4-methyl-1-octyl-pyridinium cation and a bis(fluorosulfonyl)imide anion ((FSO ₂ ) ₂ N ^{- ) (Daichi Kogyo Seya} Co., Ltd. manufactured, trade name: Elexel AS-804) is preferable. As the ionic liquid (E), the pressure-sensitive adhesive layer containing AS-110 and/or AS-804 is preferred because of its excellent antistatic properties.

Although content of the ionic liquid (E) in the adhesive composition of this embodiment can be selected arbitrarily, it is preferable that it is 0.4-6.0 mass %, It is more preferable that it is 0.5-5.0 mass %, It is further more preferable that it is 1.0-3.0 mass % desirable. As needed, 0.4-2.0 mass %, 2.0-4.0 mass %, etc. may be sufficient. When content of an ionic liquid (E) is 0.4 mass % or more, the surface resistance value of an adhesive layer becomes low enough. As a result, the antistatic performance of the BG tape which has an adhesive layer becomes favorable. If the content of the ionic liquid (E) is 6.0% by mass or less, contamination (the surface of the adherend is wet) occurs due to the transfer of the ionic liquid (E) bleed out from the BG tape to the adherend after peeling the BG tape. it's difficult.

(fatty acid ester (F))

The adhesive composition of this embodiment contains a polyurethane (A), a (meth)acrylate monomer (B), a chain transfer agent (C), a photoinitiator (D), and an ionic liquid (E), and further You may contain fatty acid ester (F) as needed.

Fatty acid ester (F) controls the adhesive force in the BG tape using the cured product of the pressure-sensitive adhesive composition as the pressure-sensitive adhesive layer, and the lamination properties (wettability) and bubble release properties of the pressure-sensitive adhesive layer (when bonding the BG sheet to the adherend) It is contained in the pressure-sensitive adhesive composition for the purpose of improving the easiness of discharging air bubbles caught in the air.

As the fatty acid ester (F), an ester of a fatty acid and an alkyl alcohol can be used, and from the viewpoint of compatibility with other components, an ester of a fatty acid having 8 to 18 carbon atoms and a monofunctional alcohol having a branched hydrocarbon group having 3 to 18 carbon atoms, and / Alternatively, it is preferable to use a fatty acid ester selected from esters of unsaturated fatty acids having 14 to 18 carbon atoms and alcohols having 2 to 4 functions.

Esters of a fatty acid having 8 to 18 carbon atoms and a monofunctional alcohol having a branched hydrocarbon group having 3 to 18 carbon atoms include isostearyl laurate, isopropyl myristate, isocetyl myristate, octyldodecyl myristate, pal Isopropyl mitate, isostearyl palmitate, isocetyl stearate, 2-ethylhexyl stearate, octyldodecyl oleate, diisostearyl adipate, diisocetyl sebacate, trioleyl trimellitic acid, and tri Triisocetyl mellitic acid, etc. are mentioned. Among these, it is preferable to use isopropyl myristate, isopropyl palmitate, and 2-ethylhexyl stearate, and it is especially preferable to use isopropyl myristate and/or 2-ethylhexyl stearate.

Examples of the ester of an unsaturated fatty acid having 14 to 18 carbon atoms and a 2 to 4 functional alcohol include unsaturated fatty acids such as myristoleic acid, oleic acid, linoleic acid, linolenic acid, isopalmitic acid and isostearic acid, ethylene glycol, propylene glycol, glycerin, and trimethyl. and esters of alcohols such as allpropane, pentaerythritol and sorbitan.

Although content of the fatty acid ester (F) in the adhesive composition of this embodiment can be selected arbitrarily, it is preferable that it is 3-18 mass %, and it is more preferable that it is 5-15 mass %.

While the adhesive force in the BG tape which used the hardened|cured material of an adhesive composition as an adhesive layer as content of fatty acid ester (F) is 3 mass % or more becomes a preferable range, the lamination property and bubble discharge property of an adhesive layer become favorable. When the content of the fatty acid ester (F) is 18% by mass or less, when the BG tape using the cured product of the pressure-sensitive adhesive composition as the pressure-sensitive adhesive layer is peeled off from the adherend, it is preferable that the adhesive residue containing the fatty acid ester (F) is difficult to form. .

(solvent)

Although the adhesive composition of this embodiment may contain a solvent, it is more preferable that it is a non-solvent thing which does not contain a solvent substantially.

When the adhesive composition of this embodiment contains a solvent, a solvent can be used as a leveling agent and/or a softening agent, for example.

When the adhesive composition of this embodiment is a non-solvent, when using this and forming the adhesive layer of a BG tape, since the process of heat-drying a solvent can be skipped, the outstanding productivity is acquired. In particular, in the case of manufacturing a BG tape having a pressure-sensitive adhesive layer having a thickness of more than 50 μm using the pressure-sensitive adhesive composition of the present embodiment, the productivity improvement effect due to omitting the step of heating and drying the solvent becomes remarkable, It is preferable that it is solvent-free.

In this invention, the meaning that an adhesive composition "does not contain a solvent substantially" means that content of the solvent in an adhesive composition is 0-1.0 mass %, Preferably it is 0-0.5 mass %, more Preferably it is 0-0.1 mass %.

(Etc)

The adhesive composition of this embodiment is a range which does not impair the effect of this invention, and may contain other additives as needed. Examples of the additive include plasticizers, surface lubricants, antioxidants, antioxidants, light stabilizers, ultraviolet absorbers, polymerization inhibitors, light stabilizers such as benzotriazoles, phosphoric acid esters and other flame retardants, and dyes.

<Method for producing pressure-sensitive adhesive composition>

Next, an example is given and the manufacturing method of the adhesive composition of this embodiment is demonstrated in detail. Hereinafter, among the components contained in the adhesive composition of this embodiment, about a polyurethane (A), a preferable synthetic|combination method is given and demonstrated. Among the components contained in the pressure-sensitive adhesive composition of the present embodiment, (meth)acrylate monomer (B), chain transfer agent (C), photoinitiator (D), ionic liquid (E), fatty acid ester (F), etc., polyurethane ( About each component except A), a commercial item can be easily purchased and since a synthesis method differs according to the kind of compound used as each component, description of a synthesis method is abbreviate|omitted.

<Synthesis method of polyurethane (A)>

Hereinafter, an example of the preferable synthesis method of the polyurethane (A) contained in the adhesive composition of this embodiment is demonstrated. In addition, the synthesis method of a polyurethane (A) is not limited to the synthesis method shown below, According to conditions, such as raw material used for synthesis|combination, equipment, and equipment, it can be changed suitably.

In the synthesis method of polyurethane (A) shown below, in any process, the reaction of a hydroxyl group and an isocyanato group is carried out in the presence of an organic solvent inactive to an isocyanato group, dibutyltin dilaurate, dibutyl It can carry out using urethanization catalysts, such as tin diethyl hexoate and dioctyl tin dilaurate. Moreover, in any process, it is preferable to carry out reaction of a hydroxyl group and an isocyanato group continuously at 30-100 degreeC for 1 to 5 hours. It is preferable that the usage-amount of a urethanation catalyst is 50-500 mass ppm with respect to the total mass of a reactant (raw material).

In order to synthesize the polyurethane (A), first, the polyoxyalkylene polyol and polyisocyanate are mixed in a ratio in which the amount of isocyanato groups (based on the number of molecules, hereinafter the same) is greater than the amount of hydroxy groups (based on the number of molecules, hereinafter the same). put in Then, polyoxyalkylene polyol and polyisocyanate are made to react, and the polyurethane which has an isocyanato group at the terminal is synthesize|combined as a precursor of polyurethane (A). Specific examples of the polyoxyalkylene polyol and polyisocyanate used as the raw material are as exemplified in the section of the polyurethane (A).

At this time, the molecular weight (polymerization degree) of the polyurethane which has an isocyanato group at the terminal can be adjusted by adjusting ratio of the amount of isocyanato groups with respect to the amount of hydroxyl groups contained in a raw material. Specifically, the molecular weight of the polyurethane which has an isocyanato group at the terminal becomes large, so that there is little excess amount of the amount of isocyanato groups with respect to the amount of hydroxyl groups. Moreover, the molecular weight of the polyurethane which has an isocyanato group at the terminal becomes small, so that there is much excess amount of the amount of isocyanato groups with respect to the amount of hydroxyl groups. In this embodiment, the mass average molecular weight of the polyurethane (A) which is a target object is adjusted by adjusting the molecular weight of the polyurethane which has an isocyanato group at the terminal.

Next, a polyurethane having an isocyanato group at the terminal is reacted with a compound having a hydroxyl group and a (meth)acryloyl group to have a skeleton comprising a structure derived from polyoxyalkylene polyol and a structure derived from polyisocyanate, A polyurethane (A) containing a polyurethane (a1) having a (meth)acryloyl group at a plurality of terminals is produced. It is preferable that the (meth)acryloyl group of the terminal which the produced|generated polyurethane (A) has is a part of (meth)acryloyloxy group.

Although it does not specifically limit as a compound which has a hydroxyl group and a (meth)acryloyl group, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate hydroxyalkyl (meth)acrylates such as; 1,3-butanediol mono(meth)acrylate, 1,4-butanediol mono(meth)acrylate, 1,6-hexanediol mono(meth)acrylate, 3-methylpentanediol mono(meth)acrylate, etc. The monool etc. which have a (meth)acryloyl group derived from various polyols are mentioned. The compound which has these hydroxyl groups and a (meth)acryloyl group may be used independently and may be used in combination of 2 or more types. Among the compounds having a hydroxyl group and a (meth)acryloyl group, 2-hydroxyethyl (meth)acryl from the viewpoint of reactivity with the isocyanato group of the polyurethane having an isocyanato group at the terminal and the photocurability of the pressure-sensitive adhesive composition It is preferred to use the rate.

Moreover, polyurethane (A) uses together the alkyl alcohol which does not have a (meth)acryloyl group and has one hydroxyl group with the compound which has a hydroxyl group and a (meth)acryloyl group, and isocyanato group at the terminal You may produce|generate by making it react with the polyurethane which has.

As alkyl alcohol, it does not have a (meth)acryloyl group, and what is necessary is just to have one hydroxyl group, A linear, branched, alicyclic alkyl alcohol etc. can be used, It does not specifically limit. The said alkyl alcohol may be used individually by 1 type, and may be used in combination of 2 or more type.

Polyurethane (A) ), the introduction amount of the (meth)acryloyl group to the polyurethane having an isocyanato group at the terminal can be adjusted.

In more detail, according to the said reaction, as a polyurethane (A), the thing containing multiple types of polyurethane from which the introduction amount of the (meth)acryloyl group at the terminal differs is produced|generated. Polyurethane (a1) which has a (meth)acryloyl group at some terminal among several types of polyurethane is contained. In addition, among the plurality of types of polyurethane, not only polyurethane (a1), but also polyurethane in which at least one terminal among the plurality of terminals has a structure derived from the above-mentioned alkyl alcohol is contained. Therefore, among the produced|generated multiple types of polyurethane, the polyurethane which does not have a (meth)acryloyl group at the terminal of at least one part of a some terminal is contained. Moreover, the polyurethane (a2) which has a (meth)acryloyl group only at one terminal among the produced|generated multiple types of polyurethane may also be contained.

<Another example of the synthesis method of polyurethane (A)>

Next, another example of the preferable synthesis method of a polyurethane (A) is demonstrated.

In the synthesis method of the polyurethane (A) shown below, similarly to the example of the synthesis method, the reaction of the hydroxyl group and the isocyanato group is carried out in either step in the presence of an organic solvent inert to the isocyanato group, dibutyltin It can carry out using urethanization catalysts, such as dilaurate, dibutyltin diethylhexoate, and dioctyltin dilaurate. Moreover, in any process, it is preferable to carry out reaction of a hydroxyl group and an isocyanato group continuously at 30-100 degreeC for 1 to 5 hours. It is preferable that the usage-amount of a urethanation catalyst is 50-500 mass ppm with respect to the total mass of a reactant (raw material).

When a polyurethane (A) is synthesized using this synthesis method, unlike the example of the above synthesis method, a polyurethane having a hydroxyl group at the terminal is synthesized as a precursor of the polyurethane (A).

Specifically, first, the polyoxyalkylene polyol and polyisocyanate are added in such a proportion that the amount of hydroxyl groups (based on the number of molecules, hereinafter the same) is greater than the amount of isocyanato groups (based on the number of molecules, hereinafter the same). Thereafter, the polyoxyalkylene polyol and polyisocyanate are reacted to synthesize a polyurethane having a hydroxyl group at the terminal as a precursor of the polyurethane (A).

At this time, the molecular weight (polymerization degree) of the polyurethane which has a hydroxyl group at the terminal can be adjusted by adjusting ratio of the amount of hydroxyl groups with respect to the amount of isocyanato groups contained in a raw material. Specifically, the molecular weight of the polyurethane which has a hydroxyl group at the terminal becomes large, so that there are few excess amounts of the amount of hydroxyl groups with respect to the amount of isocyanato groups. Moreover, the molecular weight of the molecular weight of the polyurethane which has a hydroxyl group at the terminal becomes small, so that there is much excess amount of the amount of hydroxyl groups with respect to the amount of isocyanato groups. In this embodiment, the mass average molecular weight of the polyurethane (A) which is a target object is adjusted by adjusting the molecular weight of the molecular weight of the polyurethane which has a hydroxyl group at the terminal.

Next, the polyurethane having a hydroxyl group at the terminal is reacted with a compound having an isocyanato group and a (meth)acryloyl group to have a skeleton comprising a structure derived from polyoxyalkylene polyol and a structure derived from polyisocyanate, A polyurethane (A) containing a polyurethane (a1) having a (meth)acryloyl group at a plurality of terminals is produced. It is preferable that the (meth)acryloyl group of the terminal which the produced|generated polyurethane (A) has is a part of (meth)acryloyloxy group.

Although it does not specifically limit as a compound which has an isocyanato group and a (meth)acryloyl group, 2-(meth)acryloyloxyethyl isocyanate, 2-(meth)acryloyloxypropyl isocyanate, 1, 1-bis (acryloyloxymethyl) ethyl isocyanate etc. are mentioned. Moreover, as a commercial item of the compound which has an isocyanato group and a (meth)acryloyl group, for example, Showa Denko Corporation Karenz MOI (registered trademark), Karenz AOI (registered trademark), etc. are exemplified. can The compound which has these isocyanato group and (meth)acryloyl group may be used independently and may be used in combination of 2 or more type. Among the compounds having an isocyanato group and a (meth)acryloyl group, 2-(meth)acryloyloxyethyl from the viewpoint of the reactivity with the hydroxyl group of the polyurethane having a hydroxyl group at the terminal and the photocurability of the pressure-sensitive adhesive composition. Preference is given to using isocyanates.

In addition, polyurethane (A) uses together the alkyl isocyanate which does not have a (meth)acryloyl group with the compound which has an isocyanato group and a (meth)acryloyl group, and has one isocyanato group, You may produce|generate by making it react with the polyurethane which has a hydroxyl group at the terminal.

As an alkyl isocyanate, it does not have a (meth)acryloyl group, What is necessary is just to have one isocyanato group, A linear, branched, alicyclic alkyl isocyanate etc. can be used, It does not specifically limit. The said alkyl isocyanate may be used individually by 1 type, and may be used in combination of 2 or more type.

A compound having an isocyanato group and a (meth)acryloyl group, an alkyl isocyanate that does not have a (meth)acryloyl group and has one isocyanato group, and a polyurethane having a hydroxyl group at the terminal are reacted to form a poly By producing the urethane (A), the amount of (meth)acryloyl group introduced into the polyurethane having a hydroxyl group at the terminal can be adjusted.

In more detail, according to the said reaction, as a polyurethane (A), the thing containing multiple types of polyurethane from which the introduction amount of the (meth)acryloyl group at the terminal differs is produced|generated. Polyurethane (a1) which has a (meth)acryloyl group at some terminal among several types of polyurethane is contained. In addition, among the plurality of types of polyurethane, not only polyurethane (a1) but also polyurethane in which at least one terminal among the plurality of terminals has a structure derived from the alkyl isocyanate is contained. Therefore, among the produced|generated multiple types of polyurethane, the polyurethane which does not have a (meth)acryloyl group at the terminal of at least one part of a some terminal is contained. Moreover, the polyurethane (a2) which has a (meth)acryloyl group only at one terminal among the produced|generated multiple types of polyurethane may also be contained.

<Method of mixing each component contained in the pressure-sensitive adhesive composition>

The adhesive composition of this embodiment is a polyurethane (A) obtained by the said synthesis|combining method, a (meth)acrylate monomer (B), a chain transfer agent (C), a photoinitiator (D), and an ionic liquid (E) ) and, if necessary, it can be prepared by mixing the fatty acid ester (F) and other additives.

The method of mixing each component contained in the adhesive composition of this embodiment is not specifically limited, For example, it can perform using the stirring apparatus which provided stirring blades, such as a homodisper and a paddle blade.

<Manufacturing method of BG tape>

Next, the example of the manufacturing method of the BG tape of this embodiment is demonstrated.

The manufacturing method of the BG tape of this embodiment is not specifically limited, It can manufacture using a well-known method.

For example, on a sheet-like base material, an adhesive composition is apply|coated, a separator is laminated, and it is set as a laminated body. Then, an ultraviolet-ray is irradiated to an adhesive composition through a separator, and an adhesive composition is photocured. Thereby, the BG tape in which the adhesive layer containing the hardened|cured material of an adhesive composition was formed on the base material is obtained.

The method of apply|coating an adhesive composition to a base material is not specifically limited, It can select suitably. For example, as a method of applying the pressure-sensitive adhesive composition to the substrate, various coaters such as a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, a spray coater, a comma coater, and a direct coater are used method, the screen printing method, etc. are mentioned.

As a light source at the time of photocuring an adhesive composition, a black light, a low-pressure mercury-vapor lamp, a high-pressure mercury-vapor lamp, an ultra-high pressure mercury vapor lamp, a metal halide lamp, a xenon lamp, etc. are mentioned.

It is preferable that the irradiation intensity of light is the conditions which can fully harden an adhesive composition and the gel fraction of hardened|cured material becomes in the range of 50-65 mass %, For example, it is preferable that it is ^{50-3000 mW/cm<2>.} Moreover, when the irradiation intensity|strength of light is weak, hardening takes time and productivity will fall.

In this embodiment, although ultraviolet-ray was irradiated to the adhesive composition through a transparent separator, when a base material is transparent, you may irradiate an ultraviolet-ray from the base material side, and an opaque thing may be used as a separator.

<Use of BG tape and required performance>

The BG tape of the present embodiment can be used, for example, in an application where it is affixed to an adherend having an uneven portion on its surface, and is then peeled off. Specifically, it can be preferably used as a backgrind tape for semiconductor wafer processing, which is adhered to the bumped surface of the semiconductor wafer, protects the surface of the semiconductor wafer, and is peeled off after a predetermined wafer processing step.

When the BG tape of the present embodiment is used for protecting the surface of a semiconductor wafer having bumps formed on its surface, the peel strength (adhesive force) of the BG tape is, for example, in the backgrind process in the semiconductor device processing process. , it is necessary to have a peel strength (adhesive force) with which the BG tape is firmly fixed to the semiconductor wafer. On the other hand, when peeling a BG tape from a semiconductor wafer after a predetermined processing process, the peeling strength of a BG tape needs to be intensity|strength of the grade which does not damage the components of a semiconductor device.

From this point of view, the peel strength of the BG tape used for this purpose is 0.3 m/min. It is more preferable that it is 200 gf/25 mm, and it is still more preferable that it is 20-150 gf/25 mm. When the thickness of the pressure-sensitive adhesive layer is 200 to 500 µm, it is preferably 50 to 500 gf/25 mm, more preferably 60 to 400 gf/25 mm, and still more preferably 70 to 300 gf/25 mm. The specific measuring method of the peeling strength of a BG tape is mentioned later in an Example.

The BG tape of this embodiment has an adhesive layer containing the hardened|cured material of the adhesive composition of this embodiment on single side|surface of a sheet-like base material. For this reason, the BG tape of this embodiment has sufficient adhesive force, and it is hard to produce the adhesive residue which an adhesive layer transcribe|transfers to the to-be-adhered body after peeling a BG tape, Moreover, it is excellent in uneven|corrugated water absorption and antistatic property. Therefore, the BG tape of this embodiment is suitable for the use which is affixed to the to-be-adhered body which has an uneven|corrugated part on the surface, and peels after that.

The BG tape of this embodiment can be suitably used as a BG tape which is affixed when performing the backgrind process of the semiconductor wafer whose surface has an uneven|corrugated part containing bumps, for example, and peels after a backgrind process, for example. In this case, the semiconductor wafer is fixed with sufficient adhesive force by the BG tape of this embodiment. Furthermore, since the BG tape has sufficient unevenness and absorbency, it is difficult to generate a gap between the BG tape affixed to the semiconductor wafer and the periphery of the bump. Accordingly, it is possible to prevent water used in the backgrinding process from entering the gap between the BG tape and the periphery of the bump and contaminating the semiconductor wafer. Moreover, since the BG tape of this embodiment has sufficient antistatic property, peeling electrification at the time of peeling the BG tape affixed on the semiconductor wafer after a backgrind process can be suppressed. In addition, it is preferable that, after the backgrind process, adhesive residue hardly occurs around the bump of the semiconductor wafer from which the BG tape is peeled off.

The BG tape of this embodiment can be set as the single-layer structure in which an adhesive layer contains the hardened|cured material of an adhesive composition. In this case, an adhesive layer can be formed only by performing the process of forming one layer. Therefore, the BG tape of this embodiment is easily manufactured with fewer manufacturing steps compared with the case of forming, for example, a BG tape provided with a layer having uneven water absorption, a layer having an antistatic property, and a layer having adhesive force. can do.

[Example]

Hereinafter, the present invention will be described in more detail by way of Examples and Comparative Examples. In addition, this invention is not limited only to the following example.

<Synthesis of polyurethane (A-1)>

In a reactor equipped with a thermometer, a stirrer, a dropping funnel, and a cooling tube equipped with a drying tube, 0.55 kg (2.1 mol) of a hydrogenated product of diphenylmethane diisocyanate (Desmodure W, manufactured by Sumika Covestro Urethane) and a hydroxyl value 4.01 kg (2.0 mol) of polypropylene glycol (Actcall D-2000; manufactured by Mitsui Chemicals, number average molecular weight 2000) having a hydroxyl group at the terminal of 56 mgKOH/g, and dioctyltin (Neostan U) as a urethanization catalyst -810, manufactured by Nitto Kasei Co., Ltd.) was added in 0.8 g.

Then, the reactor was heated up to 60 degreeC, and it was made to react for 4 hours, and the polyurethane which has an isocyanato group at both terminals as a precursor of a polyurethane (A) was obtained. Then, 23.22 g (0.2 mol) of 2-hydroxyethyl acrylate was added to the reactor, it heated up to 70 degreeC, it was made to react for 2 hours, and 4.58 kg of polyurethane (A-1) with a mass average molecular weight of 67,000 was obtained.

The obtained polyurethane (A-1) was analyzed using the infrared absorption spectrum (IR) method. As a result, a peak derived from an isocyanato group was not observed. Therefore, it was confirmed that the polyurethane (A-1) was the polyurethane (a1) in which the acryloyloxy group was introduce|transduced at all the terminals.

<Synthesis of polyurethane (A-2)>

In the same manner as in the synthesis method of polyurethane (A-1), except that 2.1 mol of isophorone diisocyanate (Desmodure I, manufactured by Sumika Covestro Urethane) was used instead of the hydrogenated substance of diphenylmethane diisocyanate, the mass Polyurethane (A-2) having an average molecular weight of 66,000 was obtained.

The obtained polyurethane (A-2) was analyzed using the infrared absorption spectrum (IR) method. As a result, a peak derived from an isocyanato group was not observed. Therefore, it was confirmed that the polyurethane (A-2) was the polyurethane (a1) in which the acryloyloxy group was introduce|transduced at all the terminals.

<Preparation of adhesive composition>

The polyurethane (A) thus obtained, the (meth)acrylate monomer (B), the chain transfer agent (C), the photopolymerization initiator (D), the ionic liquid (E), and the fatty acid ester (F) shown in Table 1 are shown in Table 1. It was mix|blended in the ratio described in 1, it mixed using the disper at 25 degreeC, and the adhesive composition of Examples 1-9 and Comparative Examples 1-4 was obtained.

The following symbols described in Table 1 are compounds shown below.

2EHA: 2-ethylhexyl acrylate (manufactured by Toagosei Co., Ltd.)

BUA: n-butyl acrylate (manufactured by Toagosei Co., Ltd.)

ACMO: acryloylmorpholine (manufactured by Shin-Nakamura Chemical High School Co., Ltd.)

TMPTA: trimethylolpropane triacrylate (manufactured by Toagosei Corporation)

PE1: pentaerythritol tetrakis (3-mercaptobutyrate) (manufactured by Showa Denko Corporation)

NR1: 1,3,5-tris(3-mercaptobutyloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione (Showa Denko Co., Ltd.) Produce)

TPO (Omnirad TPO H): 2,4,6-trimethylbenzoyldiphenylphosphine oxide (manufactured by IGM Resins B.V.)

184 (Omnirad 184): 1-hydroxycyclohexyl-phenyl ketone (manufactured by IGM Resins B.V.)

Elexel AS-110: 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (manufactured by Daiichi Kogyo Seyaku Co., Ltd.)

Elexel AS-804: 4-methyl-1-octyl-pyridinium bis(fluorosulfonyl)imide (manufactured by Daiichi Kogyo Seyaku Co., Ltd.)

Exepal IPM: isopropyl myristic acid (manufactured by Kao Corporation)

Exepal EH-S: stearic acid 2-ethylhexyl (manufactured by Kao Corporation)

<Production of BG tape>

As the sheet-like substrate, a PET film (manufactured by Toyobo Corporation, trade name: Ester (trademark) film E5100) having a thickness of 50 µm was prepared. And on the corona-treated surface of a base material, using the applicator, the adhesive composition of Example 1 was apply|coated so that the thickness after hardening might be set to 150 micrometers.

Next, as a separator, a silicone-based cemented carbide release PET film (manufactured by Toyobo Corporation, product name: E7006) having a thickness of 75 µm was bonded to the coated surface of the pressure-sensitive adhesive composition using a rubber roller.

Then, using the ultraviolet irradiation apparatus (The Eye Graphics Co., Ltd. make, UV irradiation apparatus 3kW, high pressure mercury lamp) is used for the adhesive composition through a separator, irradiation distance 25cm, lamp moving speed 1.0m/min, irradiation amount 1000mJ/cm Ultraviolet rays were irradiated on the conditions of ^{2, and the adhesive composition was photocured.} Thereby, the BG tape of Example 1 in which the adhesive layer which is hardened|cured material of the adhesive composition, and the separator were laminated|stacked on the base material was obtained.

Next, instead of the adhesive composition of Example 1, using Examples 2-9 and the adhesive compositions of Comparative Examples 1-4, respectively, it carried out similarly to the BG tape of Example 1, and produced the BG tape. In addition, about the comparative example 4, it adjusted so that the thickness after hardening of an adhesive composition might be set to 30 micrometers. As a result, the BG tapes of Examples 2 to 9 and Comparative Examples 1 to 4 were obtained.

Next, the items shown below were evaluated about the BG tape of Examples 1-9 and Comparative Examples 1-4.

<Measurement of surface resistivity>

The BG tape was cut out to a size of 120 mm long and 120 mm wide, and the humidity was controlled by leaving it to stand for 3 hours in an environment of a temperature of 23° C. and a relative humidity of 50% RH. Thereafter, the peeling PET film was peeled to expose the pressure-sensitive adhesive layer, and under the condition of an applied voltage of 100 V × 60 seconds, a high resistivity meter (manufactured by Mitsubishi Chemical Analytech, Hirestar-UX) was used to measure the pressure-sensitive adhesive layer side. The surface resistivity was measured. And the following criteria evaluated. It can be said that peeling electrification at the time of peeling off the BG tape affixed to a semiconductor wafer is hard to generate|occur|produce, so that the surface resistivity is small, and it can be said that it is a BG tape excellent in antistatic property.

Evaluation standard

◎ (Excellent): Surface resistivity ^{less than 1×10 10} Ω/□

○ (Good): Surface resistivity of 1×10 ¹⁰ Ω/□ or more and ^{less than 1×10 11} Ω/□

△ (available): The surface resistivity is 1 × 10 ¹¹ Ω / □ or more and 1 × 10 ¹² Ω / □ under

× (not allowed): Surface resistivity of 1×10 ¹² Ω/□ or more

<Peel force (peel strength)>

The BG tape was cut out to the size of 25 mm long and 150 mm wide, the separator was peeled and the adhesive layer was exposed. Thereafter, the entire surface of the exposed pressure-sensitive adhesive layer was laminated on a glass plate, and a rubber roller (diameter: 85 mm, width: 50 mm) having a mass of 2 kg (load 19.6 N) was reciprocated on it to obtain a measurement sample. The obtained sample for measurement was left to stand for 30 minutes in the environment of the temperature of 23 degreeC and 50 %RH of relative humidity. Then, according to JISK6854-2, the tensile test of 180 degree direction was done at the peeling rate of 0.3 m/min., and the peeling strength (gf/25mm) with respect to a glass plate was measured. The results are shown in Table 1.

<Uneven Absorbency>

The BG tape was cut out to a size of 25 mm in length and 50 mm in width, and the separator was peeled off to expose the pressure-sensitive adhesive layer. Thereafter, the exposed surface of the pressure-sensitive adhesive layer and bumps of a wafer with bumps (WALTS-TEG FC150SCJY LF(PI), bump height: 75 µm, bump size: 90 µm in diameter) were installed so as to face each other. Then, on the base material of the BG tape, a rubber roller (diameter: 85 mm, width: 50 mm) having a mass of 2 kg (load 19.6 N) was reciprocated at a speed of 10 mm/sec to bond the BG tape and the wafer with bumps.

The wafer with bumps bonded to the BG tape was observed from the base side of the BG tape with a digital optical microscope (manufactured by Hyrox, Ltd., RH-2000), and the uneven absorption to the bumps was evaluated according to the following criteria. . The results are shown in Table 1.

"standard"

○ (Good): There is no gap between the adhesive layer of the BG tape and the periphery of the bump on the wafer with bumps

× (impossible): There is a gap between the adhesive layer of the BG tape and the periphery of the bump on the wafer with bumps

<Pollution by adhesive residues and ionic liquids>

The BG tape was cut out to a size of 25 mm in length and 50 mm in width, and the separator was peeled off to expose the pressure-sensitive adhesive layer. Thereafter, the exposed surface of the pressure-sensitive adhesive layer and the bumps of the wafer with bumps (WALTS-TEG FC150SCJY LF(PI), bump height: 75 µm, bump size: 90 µm in diameter) were installed to face each other. Then, on the base material of the BG tape, a rubber roller (diameter: 85 mm, width: 50 mm) having a mass of 2 kg (load 19.6 N) was reciprocated at a speed of 10 mm/sec to bond the BG tape and the wafer with bumps.

After leaving the wafer with bumps bonded to the BG tape to stand at 23° C. for 24 hours, the BG tape was applied at approximately 2 m/min. It was peeled by hand at a speed of about. Then, the surface of the bumped wafer was observed with a digital optical microscope (manufactured by Hyrox, Inc., RH-2000), and the presence or absence of contamination by adhesive residues or ionic liquids was evaluated according to the following criteria. The results are shown in Table 1. In addition, "adhesive residue" means that the adhesive layer itself remains attached to the wafer surface, and the wafer surface is in a sticky state. "Pollution by an ionic liquid" means that the ionic liquid bleed out from the pressure-sensitive adhesive layer adheres to the wafer surface, and the wafer surface is wet.

"standard"

○ (Good): No contamination by adhesive residue and ionic liquid around the bump

× (not allowed): There is contamination by adhesive residue and/or ionic liquid around the bump

<Measurement of gel fraction>

On a 75 µm-thick peeling PET film (manufactured by Higashiyama Film Co., Ltd., trade name: Clean Separ (trademark) HY-S10-2), the pressure-sensitive adhesive composition was applied using an applicator so that the thickness after curing became 150 µm. In addition, about the comparative example 4, it adjusted so that the thickness after hardening might be set to 30 micrometers. Next, the coated surface of the pressure-sensitive adhesive composition was covered with a silicone-based cemented carbide release PET film (manufactured by Toyobo Corporation, product name: E7006) having a thickness of 75 µm.

Then, using an ultraviolet irradiation device (manufactured by Eye Graphics Co., Ltd., UV irradiation device 3 kW, high pressure mercury lamp), carbide peeling is performed under conditions of an ^{irradiation distance of 25 cm, a lamp moving speed of 1.0 m/min, and an irradiation amount of 1000 mJ/cm 2 .} An ultraviolet-ray was irradiated through the PET film, the adhesive composition was hardened, and the hardened|cured material (adhesive layer) was obtained.

Next, the hardened|cured material (adhesive layer) was cut out to the size used as about 1 g, the PET film on both sides was peeled, it was set as the sample for a measurement, and the mass was measured. Then, the sample for a measurement was immersed in 50 ml of toluene, and it left still at room temperature for 72 hours. Then, the sample for measurement was taken out in toluene, dried at 80 degreeC for 5 hours, and the mass was measured again. And the gel fraction was measured based on the following formula.

Gel fraction (%) = [A/B] × 100

A: Mass of sample for measurement after immersion in toluene (mass of toluene is not included)

B: Mass of sample for measurement before immersion in toluene

As shown in Table 1, all of the BG tapes of Examples 1 to 9 using the pressure-sensitive adhesive composition containing 0.4 to 6 mass% of an ionic liquid have a surface resistivity of the pressure-sensitive adhesive layer of ^{less than 1×10 11} Ω/□, It was excellent in antistatic property. In addition, all of the BG tapes of Examples 1 to 9 had sufficient peel strength of 10 gf/25 mm or more, and evaluation of uneven water absorption and adhesive residue and contamination was "○ (good)".

On the other hand, as for the BG tape of the comparative example 1 using the adhesive composition which does not contain an ionic liquid, evaluation of the surface resistivity of an adhesive layer was "x (impossibility)". In addition, as for the BG tape of the comparative example 2 using the adhesive composition containing 7.0 mass % of ionic liquids, evaluation of adhesive agent residue and contamination was "x (impossibility)".

In addition, the BG tape of Comparative Example 3 using the pressure-sensitive adhesive composition containing no chain transfer agent and the BG tape of Comparative Example 4 having a thickness of the pressure-sensitive adhesive layer of 30 µm had a peeling force of less than 10 gf/25 mm, and the evaluation of uneven water absorption was “ × (impossible)”.

[Industrial Applicability]

Advantageous Effects of Invention According to the present invention, there is provided a backgrind tape which has sufficient unevenness absorption, antistatic property, and adhesive force, and is less likely to cause adhesive residue, and which can be manufactured with a small manufacturing process. This backgrind tape is a semiconductor wafer processing process WHEREIN: It can protect the semiconductor wafer surface, and can use it suitably for the use which peels after a processing process.

Claims (15)

It is a backgrind tape having a sheet-like substrate and an adhesive layer formed on one side of the substrate,
The pressure-sensitive adhesive layer includes a cured product of the pressure-sensitive adhesive composition, and has a thickness of 50 to 500 μm,
The said adhesive composition contains a polyurethane (A), a (meth)acrylate monomer (B), a chain transfer agent (C), a photoinitiator (D), and an ionic liquid (E),
The polyurethane (A) contains a polyurethane (a1) having a skeleton comprising a structure derived from a polyoxyalkylene polyol and a structure derived from a polyisocyanate, and having a (meth)acryloyl group at a plurality of terminals;
The said adhesive composition contains 0.4-6 mass % of ionic liquids (E), The back grind tape characterized by the above-mentioned. The backgrind tape according to claim 1, wherein the pressure-sensitive adhesive layer has a single-layer structure. The backgrind tape according to claim 1 or 2, wherein the (meth)acrylate monomer (B) contains monofunctional (meth)acrylate and polyfunctional (meth)acrylate. The bag according to any one of claims 1 to 3, wherein the ionic liquid (E) is a compound containing an organic cation selected from the group consisting of quaternary ammonium ions, iminium ions and sulfonium ions. grind tape. The backgrind tape according to any one of claims 1 to 4, wherein the ionic liquid (E) is a compound containing a fluorine-containing organic anion. The ionic liquid (E) according to any one of claims 1 to 5, wherein the 1-ethyl-3-methylimidazolium cation and/or 4-methyl-1-octylpyridinium cation and bis( A backgrind tape, which is a compound comprising a fluorosulfonyl)imide anion ((FSO ₂ ) ₂ N ^{− ).} The backgrind tape according to any one of claims 1 to 6, wherein the chain transfer agent (C) is a polyfunctional thiol. The backgrind tape in any one of Claims 1-7 whose gel fraction of the said adhesive layer is 50-65 mass %. The backgrind tape according to any one of claims 1 to 8, wherein the pressure-sensitive adhesive layer has a surface resistivity of ^{less than 1×10 11} Ω/□. The monofunctional (meth)acrylate according to any one of claims 3 to 9, wherein when the sum of the (meth)acrylate monomers (B) is 100 mol%, the monofunctional (meth)acrylate is 85 to 99 mol%, the A backgrind tape containing 1 to 15 mol% of polyfunctional (meth)acrylate. The method according to any one of claims 1 to 10, wherein the pressure-sensitive adhesive composition,
20-50 mass % of the said polyurethane (A),
35-79 mass % of the said (meth)acrylate monomer (B),
0.5-8.0 mass % of the said chain transfer agent (C),
0.01-5.0 mass % of the said photoinitiator (D),
The backgrind tape containing 0.4-6.0 mass % of the said ionic liquid (E). The backgrind tape according to any one of claims 1 to 11, wherein the pressure-sensitive adhesive composition further contains a fatty acid ester (F). The ionic liquid (E) contains an organic salt compound having a melting point of 100° C. or less in which an organic cation and an inorganic anion or an organic cation and an organic anion are combined. backgrind tape. 14. The method according to any one of claims 1 to 13, wherein the polyurethane (A) comprises only the polyurethane (a1),
The polyurethane (a1) is a backgrind tape comprising a (meth)acryloyloxy group at all ends. 15. The method according to any one of claims 1 to 14, comprising a transparent separator provided directly on the surface of the pressure-sensitive adhesive layer on the opposite side to the substrate,
Content of the solvent in the said adhesive composition is 0-1.0 mass %,
The pressure-sensitive adhesive layer is a cured product layer that is photocured by UV irradiation to the pressure-sensitive adhesive composition through the separator, a backgrind tape.