阅读说明：本技术 背面研磨带 (Back grinding belt ) 是由 尹美善 金色拉 李光珠 延博拉 金相还 金殷英 于 2019-06-04 设计创作，主要内容包括：本公开内容涉及背面研磨带,包括含有氨基甲酸酯(甲基)丙烯酸酯树脂的聚合物树脂层,所述氨基甲酸酯(甲基)丙烯酸酯树脂包含10重量％至40重量％的源自玻璃化转变温度为0℃或更高的(甲基)丙烯酸酯单体或低聚物的重复单元,其中聚合物树脂层的玻璃化转变温度为-30℃至0℃。本公开内容还涉及使用背面研磨带研磨晶片的方法。(The present disclosure relates to a back-grinding tape comprising a polymer resin layer containing a urethane (meth) acrylate resin comprising 10 to 40% by weight of a repeating unit derived from a (meth) acrylate monomer or oligomer having a glass transition temperature of 0 ℃ or higher, wherein the glass transition temperature of the polymer resin layer is-30 to 0 ℃. The present disclosure also relates to methods of grinding wafers using back side grinding tape.)

1. A back grinding tape comprising a polymer resin layer containing a urethane (meth) acrylate resin comprising 10 to 40% by weight of a repeating unit derived from a (meth) acrylate monomer or oligomer having a glass transition temperature of 0 ℃ or higher,

wherein the glass transition temperature of the polymer resin layer is-30 ℃ to 0 ℃.

2. The backgrinding tape of claim 1,

wherein the (meth) acrylate monomer or oligomer having a glass transition temperature of 0 ℃ or higher comprises at least one compound selected from the group consisting of: o-phenylphenoxyethyl acrylate, isobornyl (meth) acrylate, methyl acrylate, and cyclohexyl (meth) acrylate.

3. The backgrinding tape of claim 1,

wherein the urethane (meth) acrylate resin further comprises a (meth) acrylate-based repeating unit containing a C2 to C12 alkyl group or a (meth) acrylate-based repeating unit containing a crosslinkable functional group, together with the repeating unit derived from a (meth) acrylate monomer or oligomer having a glass transition temperature of 0 ℃ or more.

4. The backgrinding tape of claim 1,

wherein the back-side polishing tape has an absolute value of a difference between the following recovery ratio 1 and the following recovery ratio 2 of 10% or less:

the recovery ratio 1 is a ratio of a recovery length to a stretched length when the back side grinding film is stretched 5% in a first direction at room temperature, and

the recovery rate 2 is a ratio of a recovery length to a stretched length when the back side grinding film is stretched 5% in a second direction perpendicular to the first direction at room temperature.

5. The backgrinding tape of claim 4,

wherein an absolute value of a difference between the recovery rate 1 and the recovery rate 2 of the back-grinding tape is 5% or less.

6. The backgrinding tape of claim 4,

wherein the first direction is an MD direction of the polymer resin layer included in the back-grinding tape, and the second direction is a TD direction of the polymer resin layer.

7. The backgrinding tape of claim 1,

wherein the polymer resin layer has a thickness of 5 to 200 μm.

8. The backgrinding tape of claim 1,

also comprises an adhesive layer with the thickness of 1-100 μm.

9. The backgrinding tape according to claim 1 or claim 8,

also included is a light transmissive substrate having a thickness of 5 μm to 200 μm.

10. The backgrinding tape of claim 9,

wherein the polymer resin layer is formed on one surface of the light-transmitting substrate, and the adhesive layer is formed on the other surface of the light-transmitting substrate.

11. The backgrinding tape of claim 1,

wherein the back grinding tape is used for polishing a thin film wafer having a thickness of 50 μm or less.

12. A method of grinding a wafer using the back side grinding tape of claim 1.

Technical Field

Cross Reference to Related Applications

This application claims the benefit of korean patent application No. 10-2018-0064315, filed on 4.6.2018 to the korean intellectual property office, the disclosure of which is incorporated herein by reference in its entirety.

The present disclosure relates to back side grinding tapes, and more particularly, to adhesive tapes that are attached to a surface of a semiconductor wafer to protect the surface during a back side grinding process in a semiconductor manufacturing process.

Background

Recently, as the trend of electronic devices toward miniaturization, high functionality, and capacity increase is increasing, the demand for densification and high integration of semiconductor packages is rapidly increasing. Therefore, the size of the semiconductor chip becomes larger while the thickness becomes thinner, which increases the degree of integration of the circuit. However, the modulus of the semiconductor chip itself is lowered, causing a problem in the manufacturing process or in the reliability of the final product.

According to the demand for enlargement and thinning of semiconductors, a back grinding process is basically performed by grinding the back surface of a wafer with a polishing wheel composed of fine diamond particles to reduce the thickness of a chip, thereby facilitating assembly. During the grinding process, damage to the wafer, such as contamination and cracks, often occurs due to large amounts of silicon residues (dust) and particles. Therefore, an adhesive film or a back grinding tape for protecting the surface of the semiconductor wafer becomes more important.

In particular, when a semiconductor wafer is ground to an extremely thin thickness, the rigidity of the wafer is lowered and warpage is liable to occur, so that uniformity of physical properties of a back-grinding tape used in the grinding process becomes more important.

Disclosure of Invention

Technical problem

The present disclosure is to provide a back grinding tape which can be easily applied to a grinding process of a wafer having a thin thickness and can exhibit improved wafer protection performance.

The present disclosure will also provide a method of grinding a wafer using the back side grinding tape.

Technical scheme

Provided is a back-grinding tape comprising a polymer resin layer containing a urethane (meth) acrylate resin comprising 10 to 40% by weight of a repeating unit derived from a (meth) acrylate monomer or oligomer having a glass transition temperature of 0 ℃ or higher, wherein the glass transition temperature of the polymer resin layer is-30 to 0 ℃.

Methods of grinding wafers using the back side grinding tape are also provided.

Hereinafter, a back-grinding tape and a grinding method according to an exemplary embodiment of the present disclosure will be described in more detail.

In the present disclosure, (meth) acrylates include both acrylates and methacrylates.

As described above, according to one embodiment of the present disclosure, there is provided a back grinding tape including a polymer resin layer including a urethane (meth) acrylate resin including 10 to 40% by weight of a repeating unit derived from a (meth) acrylate monomer or oligomer having a glass transition temperature of 0 ℃ or more, wherein the polymer resin layer has a glass transition temperature of-30 to 0 ℃.

The present inventors prepared a polymer resin layer having a glass transition temperature of-30 to 0 ℃ by using a urethane (meth) acrylate resin comprising 10 to 40 wt% of a repeating unit derived from a (meth) acrylate monomer or oligomer having a glass transition temperature of 0 ℃ or more, and found through experiments that it can be easily applied to a grinding process of a wafer having a thin thickness of about 50 μm when the polymer resin layer is used as a back grinding tape. The present inventors have also found that a back grinding tape has a recovery rate less than a certain level so that deformation due to stress or heat during processing can be prevented, thereby achieving improved wafer protection performance, thereby completing the present invention.

More specifically, when the polymer resin layer has a glass transition temperature of-30 ℃ to 0 ℃ and includes a urethane (meth) acrylate resin containing 10 wt% to 40 wt% of a repeating unit derived from a (meth) acrylate monomer or oligomer having a glass transition temperature of 0 ℃ or higher, the absolute value of the difference between the following recovery rate 1 and the following recovery rate 2 measured for the back-grinding tape may be 10% or less.

[ recovery ratio 1 and recovery ratio 2]

The recovery ratio 1 is a ratio of a recovery length to a stretched length when the back side grinding film is stretched 5% in either direction (first direction) at room temperature.

The recovery ratio 2 is a ratio of a recovery length to a stretched length when the back side grinding film is stretched 5% in a second direction perpendicular to the first direction at room temperature.

When the absolute value of the difference between the recovery rate 1 and the recovery rate 2 exceeds 10%, a gap between chips (hereinafter referred to as a notch (kerf)) expands or contracts due to heat or stress generated during a grinding process, causing chip cracking or alignment problems, which may cause process errors. When the absolute value of the difference between the recovery rate 1 and the recovery rate 2 is less than 10%, there is less deformation due to expansion or contraction, and chip cracking or notch contraction can be prevented, thereby achieving improved wafer protection performance.

Hereinafter, the absolute value of the difference between the recovery rate 1 and the recovery rate 2 may be 10% or less, 7% or less, or 5% or less.

The first direction may be an MD direction of a polymer resin layer included in the back-grinding tape, and the second direction may be a TD direction of the polymer resin layer.

The glass transition temperature of the polymer resin layer may be-30 ℃ to 0 ℃, because the resin layer includes a urethane (meth) acrylate resin containing 10 wt% to 40 wt% of a repeating unit derived from a (meth) acrylate monomer or oligomer having a glass transition temperature of 0 ℃ or higher. More specifically, the glass transition temperature of the (meth) acrylate monomer or oligomer having a glass transition temperature of 0 ℃ or more may be 0 ℃ to 100 ℃.

Examples of the (meth) acrylate monomer or oligomer having a glass transition temperature of 0 ℃ or higher may be at least one of the following compounds: o-phenylphenoxyethyl acrylate (OPPEA), isobornyl (meth) acrylate (IBOA), methyl acrylate, and cyclohexyl (meth) acrylate.

The urethane (meth) acrylate resin may further include a (meth) acrylate-based repeating unit containing a C2 to C12 alkyl group or a (meth) acrylate-based repeating unit containing a crosslinkable functional group, along with a repeating unit derived from a (meth) acrylate monomer or oligomer having a glass transition temperature of 0 ℃ or more.

The (meth) acrylate-based repeating unit containing a C2 to C12 alkyl group may be a repeating unit derived from at least one monomer or oligomer selected from the group consisting of: pentyl (meth) acrylate, n-butyl (meth) acrylate, ethyl (meth) acrylate, hexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, dodecyl (meth) acrylate, and decyl (meth) acrylate.

Examples of the (meth) acrylate-based repeating unit containing a crosslinkable functional group may include a (meth) acrylate-based repeating unit containing a hydroxyl group, a carboxyl group, a nitrogen-containing functional group, and the like. The (meth) acrylate-based repeating unit containing a crosslinkable functional group may be derived from a (meth) acrylate-based monomer containing a crosslinkable functional group.

Examples of the hydroxyl group-containing (meth) acrylate monomer include 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate. Examples of the (meth) acrylate monomer having a carboxyl group may include (meth) acrylic acid, and examples of the (meth) acrylate monomer having a nitrogen-containing functional group may include (meth) acrylonitrile, N-vinylpyrrolidone and N-vinylcaprolactam. However, examples are not limited thereto.

The urethane (meth) acrylate resin may include 10 to 40% by weight of a repeating unit derived from a (meth) acrylate monomer or oligomer having a glass transition temperature of 0 ℃ or more, and may further include a urethane (meth) acrylate-based repeating unit or segment derived from a urethane (meth) acrylate oligomer or polymer.

Examples of the urethane (meth) acrylate oligomer or polymer are not particularly limited. For example, a urethane (meth) acrylate-based oligomer or a polycarbonate-modified aliphatic urethane (meth) acrylate oligomer having a molecular weight of 100 to 15,000, or a polycarbonate urethane (meth) acrylate having a molecular weight of 20,000 to 100,000 may be used.

The thickness of the polymer resin layer is not particularly limited, but may be 5 μm to 200 μm.

Meanwhile, the back-grinding tape of the present embodiment may further include an adhesive layer having a thickness of 1 μm to 100 μm.

The specific composition of the adhesive layer is not particularly limited. For example, the adhesive layer may comprise an adhesive resin, a photoinitiator, and a crosslinking agent.

The crosslinking agent may include at least one compound selected from the group consisting of: isocyanate-based compounds, aziridine-based compounds, epoxy-based compounds, and metal chelate-based compounds. The adhesive layer may include 0.1 to 40 parts by weight of a crosslinking agent based on 100 parts by weight of the adhesive resin. When the content of the crosslinking agent is too small, the cohesion of the adhesive layer may be insufficient. On the other hand, when the content of the crosslinking agent is too high, the adhesive layer may not sufficiently secure adhesiveness before photocuring, and a chip scattering phenomenon (chip scattering phenomenon) may occur.

Specific examples of the photoinitiator are not limited, but photoinitiators known in the art may be used. The adhesive layer may include 0.1 to 20 parts by weight of a photoinitiator based on 100 parts by weight of the adhesive resin.

The adhesive resin may include a (meth) acrylate-based resin. In the present disclosure, (meth) acrylates include both acrylates and methacrylates.

Examples of the (meth) acrylate-based resin may include a copolymer of a (meth) acrylate-based monomer and a monomer having a crosslinkable functional group. Herein, examples of the (meth) acrylate-based monomer may include alkyl (meth) acrylates, specifically, monomers containing C1 to C12 alkyl groups, such as amyl (meth) acrylate, n-butyl (meth) acrylate, ethyl (meth) acrylate, methyl (meth) acrylate, hexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, dodecyl (meth) acrylate, decyl (meth) acrylate, or a mixture thereof.

Examples of the monomer having a crosslinkable functional group may include a hydroxyl group-containing monomer, a carboxyl group-containing monomer, a nitrogen-containing monomer, or a mixture thereof.

Examples of the hydroxyl group-containing compound may include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 2-hydroxyethylene glycol (meth) acrylate, 2-hydroxypropanediol (meth) acrylate, and the like.

Examples of the carboxyl-group-containing compound may include (meth) acrylate, 2- (meth) acryloyloxyacetic acid, 3- (meth) acryloyloxypropionic acid, 4- (meth) acryloyloxybutyric acid, acrylic acid dimer, itaconic acid, maleic anhydride, and the like.

Examples of the nitrogen-containing monomer may include (meth) acrylonitrile, N-vinylpyrrolidone, N-vinylcaprolactam and the like.

In the (meth) acrylate-based resin, vinyl acetate, styrene, acrylonitrile, etc. may be additionally included to improve other functionalities such as compatibility, etc.

The adhesive layer may further comprise a UV curable compound.

The kind of the UV curable compound is not particularly limited, and for example, a polyfunctional compound (e.g., polyfunctional urethane acrylate, polyfunctional acrylate monomer or oligomer, etc.) having a weight average molecular weight of 500 to 300,000 may be used. One of ordinary skill in the art can readily select the appropriate compound depending on the desired use. The UV curable compound may be contained in an amount of 1 to 400 parts by weight, preferably 5 to 200 parts by weight, based on 100 parts by weight of the adhesive resin. When the content of the UV-curable compound is less than 1 part by weight, the decrease in adhesion after curing may be insufficient, and thus pick-up (pick-up) may be deteriorated. When the content of the UV curable compound is more than 400 parts by weight, the cohesion of the adhesive before UV irradiation may be insufficient, or delamination from a release film or the like may not be easy.

The UV curable adhesive may be used not only in the form of an addition type of a UV curable compound but also in the form of a carbon-carbon double bond bonded to an acrylic copolymer at the end of a side chain or a main chain. That is, the (meth) acrylate-based copolymer may further include a UV curable compound bonded to a side chain of the main chain including the (meth) acrylate-based monomer and the monomer having a crosslinkable functional group.

The type of the UV curable compound is not particularly limited as long as the compound contains 1 to 5, preferably 1 or 2 photocurable functional groups (e.g., UV polymerizable carbon-carbon double bond) and functional groups capable of reacting with the crosslinkable functional groups contained in the main chain per molecule. Examples of the functional group capable of reacting with the crosslinkable functional group of the main chain may include, but are not limited to, an isocyanate group, an epoxy group, and the like.

The UV curable compound includes a functional group capable of reacting with a hydroxyl group included in the main chain, and examples thereof may include one or more of (meth) acryloyloxy isocyanate, (meth) acryloyloxymethyl isocyanate, 2- (meth) acryloyloxyethyl isocyanate, 3- (meth) acryloyloxypropyl isocyanate, 4- (meth) acryloyloxybutyl isocyanate, m-propenyl- α -dimethylbenzyl isocyanate, methacryloyl isocyanate or allyl isocyanate, an acryloyl monoisocyanate compound obtained by reacting a diisocyanate compound or a polyisocyanate compound with 2-hydroxyethyl (meth) acrylate, an acryloyl monoisocyanate compound obtained by reacting a diisocyanate compound or a polyisocyanate compound, a polyol compound with 2-hydroxyethyl (meth) acrylate, glycidyl (meth) acrylate or allyl glycidyl ether containing a functional group capable of reacting with a carboxyl group included in the main chain, but are not limited thereto.

The UV curable compound may be included in the side chain of the base resin by substituting 5 mol% to 90 mol% of the crosslinkable functional group included in the main chain. When the substitution amount is less than 5 mol%, the peel strength may not be sufficiently reduced by ultraviolet irradiation. When the substitution amount is more than 90 mol%, the cohesion of the adhesive before ultraviolet irradiation may be reduced.

The adhesive layer may suitably contain a tackifier such as rosin resin, terpene resin, phenol resin, styrene resin, aliphatic petroleum resin, aromatic petroleum resin, aliphatic aromatic copolymer petroleum resin, or the like.

A method of forming the adhesive layer on the base film is not particularly limited, and for example, the following method may be used: a method of coating the adhesive composition directly on a base film to form an adhesive layer; or a method in which the adhesive composition is first coated on a releasable substrate to prepare an adhesive layer, and then the adhesive layer is transferred to a base film using the releasable substrate.

Herein, the method of coating and drying the adhesive composition is not particularly limited, and for example, the following method may be used: the composition containing the above components is coated as it is, or diluted in an appropriate organic solvent and coated by a known tool such as comma coater, gravure coater, die coater, reverse coater, etc., and then the solvent is dried at a temperature of 60 to 200 ℃ for 10 seconds to 30 minutes. In addition, in the above process, an aging process may also be performed to perform sufficient crosslinking of the adhesive.

The adhesive layer may have a thickness of 1 μm to 100 μm.

In addition, the back-grinding tape of the present embodiment may further include a light-transmitting substrate having a thickness of 5 μm to 200 μm.

The light-transmitting substrate may be a substrate including a polymer resin having a transmittance of 50% or more with respect to a wavelength of 300nm to 600 nm.

The type of polymer resin that can be used as the light-transmitting substrate is not particularly limited. Examples of the material of the light-transmitting substrate may include polyester such as PET, cellulose such as triacetyl cellulose, cycloolefin-based (co) polymer, polyimide, styrene acrylonitrile copolymer (SAN), low density polyethylene, linear polyethylene, medium density polyethylene, high density polyethylene, ultra-low density polyethylene, random copolymer of polypropylene, block copolymer of polypropylene, homopolypropylene, polymethylpentene, ethylene-vinyl acetate copolymer, ethylene-methacrylic acid copolymer, ethylene-methyl methacrylate copolymer, ethylene-ionomer copolymer, ethylene-vinyl alcohol copolymer, polybutene, copolymer of styrene, and a mixture of two or more thereof.

Specifically, the back-grinding tape of the present embodiment may have a structure in which an adhesive layer is formed on one surface of a polymer resin layer, or a structure in which a polymer resin layer is formed on one surface of a light-transmitting substrate and an adhesive layer is formed on the other surface of the substrate.

Meanwhile, the back-grinding tape may further include an adhesive layer, if necessary.

The adhesive layer may include a thermoplastic resin, an epoxy resin, and a curing agent.

The thermoplastic resin may include at least one polymer resin selected from the group consisting of: polyimides, polyetherimides, polyesterimides, polyamides, polyethersulfones, polyetherketones, polyolefins, polyvinylchloride, phenoxy, reactive butadiene acrylonitrile copolymer rubbers, and (meth) acrylate based resins.

As the epoxy resin, epoxy resins known in the art for general adhesives may be used. For example, an epoxy resin having two or more epoxy groups in the molecule and a weight average molecular weight of 100 to 2000 may be used.

The epoxy resin forms a hard cross-linked structure through a curing process, and may exhibit excellent adhesion, heat resistance, and mechanical strength. More specifically, the epoxy resin may have an average epoxy equivalent weight of 100 to 1000. When the epoxy equivalent weight of the epoxy resin is less than 100, the crosslinking density becomes too high, and the adhesive film may exhibit overall rigidity characteristics. When the epoxy equivalent weight is more than 1000, heat resistance may be reduced.

Examples of epoxy resins may include, but are not limited to, one or more of the following: difunctional epoxy resins such as bisphenol a epoxy resin and bisphenol F epoxy resin; polyfunctional epoxy resins having three or more functional groups such as cresol novolak epoxy resin, phenol novolak epoxy resin, tetrafunctional epoxy resin, biphenyl type epoxy resin, triphenol methane type epoxy resin, alkyl-modified triphenol methane type epoxy resin, naphthalene type epoxy resin, dicyclopentadiene modified phenol type epoxy resin.

A mixed resin of a bifunctional epoxy resin and a polyfunctional epoxy resin is preferably used as the epoxy resin. In the present disclosure, the term "multifunctional epoxy resin" refers to an epoxy resin having three or more functional groups. That is, in general, a bifunctional epoxy resin is excellent in flexibility and fluidity at high temperature, but has poor heat resistance and a low curing rate. On the other hand, a multifunctional epoxy resin having three or more functional groups has a high curing rate and exhibits excellent heat resistance due to a high crosslinking density, but has poor flexibility and flowability.

The curing agent contained in the adhesive layer is not particularly limited as long as it reacts with the epoxy resin and/or the thermoplastic resin to form a crosslinked structure. For example, the curing agent may include at least one compound selected from the group consisting of: a phenol-based resin, an amine-based curing agent, and an anhydride-based curing agent.

The adhesive layer may include 10 to 1000 parts by weight of a thermoplastic resin and 10 to 700 parts by weight of a curing agent, based on 100 parts by weight of the epoxy resin.

The curing catalyst is used to promote the action of a curing agent or curing of an adhesive resin composition for bonding semiconductors, and any curing catalyst known to be used in the field of adhesive films for semiconductors may be applied without particular limitation. For example, as the curing catalyst, at least one selected from the following may be used: phosphorus-based compounds, boron-based compounds, phosphorous-boron-based compounds, and imidazole-based compounds. The amount of the curing catalyst may be appropriately selected in consideration of the characteristics of the adhesive film to be finally produced, and the like. For example, 0.5 to 10 parts by weight of a curing catalyst may be used based on 100 parts by weight of the total amount of the epoxy resin, the (meth) acrylate-based resin, and the phenol resin.

The thickness of the adhesive layer may be 1 μm to 300 μm.

In accordance with another embodiment of the present disclosure, a method of grinding a wafer using a back side grinding tape is provided.

After the back-grinding tape is adhered to one surface of the semiconductor wafer, a grinding process of the semiconductor wafer may be performed. After the grinding process, the back-grinding tape may be peeled off after UV irradiation or heat treatment.

The method of using the back-grinding tape in the grinding process of the semiconductor wafer is not particularly limited. For example, a back-grinding tape may be attached to a circuit surface half-cut to a thickness of 50 μm at room temperature, and then the surface to which the back-grinding tape is attached may be fixed to a vacuum table (vacuum table) to grind the back surface of the circuit surface. Subsequently, the concentration of the active carbon can be controlled by controlling the concentration at 500mJ/cm²Or greater exposure of UV a removes the back side grinding tape from the ground wafer.

Advantageous effects

According to the present disclosure, there are provided a back grinding tape which can be easily applied to a grinding process of a wafer having a thin thickness and can exhibit improved wafer protection performance, and a grinding method of a wafer using the back grinding tape.

Detailed Description

The present invention will be described in more detail in the following examples. However, these examples are for illustrative purposes only, and the present invention is not intended to be limited by these examples.

Example 1: preparation of Back-grinding tape

(1) Preparation of Polymer resin layer

25g of polycarbonate urethane acrylate (molecular weight: 30,000g/mol), 30g of 2-ethylhexyl acrylate (2-EHA), 15g of 2-hydroxyethyl acrylate (2-HEA), 15g of o-phenylphenoxyethyl acrylate (OPPEA, glass transition temperature: 33 ℃ C.) and 15g of isobornyl acrylate (IBOA, glass transition temperature: 94 ℃ C.) were put in and mixed.

0.5g of a photoinitiator (Irgacure 651) was added and mixed based on 100 parts by weight of the monomers. The mixture containing the photoinitiator was directly coated on a PET substrate (manufactured by SKC, grade T7650) having a thickness of 50 μm and coated with 1J/cm²Is irradiated to prepare a semi-finished product having a thickness of 100 μm including a polymer resin layer having a thickness of 50 μm.

The glass transition temperature of the polymer resin layer was determined to be-10 ℃, which was measured by a dynamic mechanical analyzer Q-800 (manufactured by TA Instruments).

(2) Preparation of adhesive layer

7g of a TDI-based isocyanate curing agent and 3g of a photoinitiator (Irgacure 184) were mixed with 100g of a (meth) acrylate-based polymer resin copolymerized from a mixture of 68.5 parts by weight of 2-ethylhexyl acrylate (2-EHA), 8.5 parts by weight of Methyl Acrylate (MA), and 23 parts by weight of hydroxyethyl acrylate (HEA) to prepare an adhesive composition.

The adhesive composition was coated on a silicone release PET film, and then dried at 110 ℃ for 3 minutes to form an adhesive layer having a thickness of 20 μm. An adhesive layer having a thickness of 20 μm was laminated on a semi-finished PET substrate including a polymer resin layer and a PET substrate (manufactured by SKC, T7650 grade) to prepare a back-grinding tape.

Comparative example 1: preparation of Back-grinding tape

(1) Preparation of Polymer resin layer

A semi-finished product comprising a polymer resin layer was prepared in the same manner as in example 1, except that 25g of polycarbonate urethane acrylate (molecular weight: 30,000g/mol), 10g of 2-ethylhexyl acrylate (2-EHA), 15g of 2-hydroxyethyl acrylate (2-HEA), 17g of o-phenylphenoxyethyl acrylate (OPPEA) and 33g of isobornyl acrylate (IBOA) were mixed.

The glass transition temperature of the polymer resin layer was determined to be 22 ℃, which was measured by a dynamic mechanical analyzer Q-800 (manufactured by TA Instruments).

(2) Preparation of adhesive layer

An adhesive layer having a thickness of 20 μm was formed on the semi-finished product in the same manner as in example 1 described above.

[ Experimental example: measurement of recovery Rate

The recovery rates of the back grinding tapes prepared in the above examples and comparative examples were measured by the following methods, and the results are shown in table 1 below.

(1) For the back-grinding tapes of example 1 and comparative example 1, samples having a width of 2.5cm and a length of 25cm were prepared.

(2) 2.5cm of each end of the sample was fixed on a measuring instrument, and then stretched 5% in the MD direction and the TD direction at room temperature using a texture analyzer (texture analyzer) in a stretching mode. The recovered length and the stretched length after holding for 1 minute were measured.

Recovery is measured as the percentage of recovered length relative to the stretched length.

Recovery (%) - (recovery length/extension length) × 100

[ Table 1]

Referring to table 1, the difference between the recovery rate (%) in the MD direction and the recovery rate (%) in the TD direction of the back-grinding tape of example 1 was 5%. That is, it is determined that the difference in recovery rate of the back-grinding tape is less than a certain level, so that there is less deformation due to expansion or contraction, and no notch contraction occurs during the back-grinding process.

On the other hand, it was determined that the difference between the recovery rate (%) in the MD direction and the recovery rate (%) in the TD direction of the back-grinding tape of comparative example 1 was 15%, so that the notch shrinkage occurred during the back-grinding process.