CN115141569A

CN115141569A - Sheet for processing workpiece

Info

Publication number: CN115141569A
Application number: CN202210122678.1A
Authority: CN
Inventors: 山口征太郎; 渡边周平; 小田直士
Original assignee: Lintec Corp
Current assignee: Lintec Corp
Priority date: 2021-03-31
Filing date: 2022-02-09
Publication date: 2022-10-04
Also published as: TW202239586A; KR20220136091A

Abstract

The invention provides a sheet for processing a workpiece, which has excellent expansibility. The sheet for processing a workpiece is a sheet (1) for processing a workpiece, which is provided with a base material (11) and an adhesive layer (12), wherein the base material (11) is provided with a surface layer (111), a back layer (113) and an intermediate layer (112), the breaking elongation of a test piece obtained by cutting the base material (11) into strips with a short side of 15mm is more than 600% in the MD direction and the CD direction, respectively, and the tensile stress when the base material (11) is stretched in the MD direction to elongate the base material by 25% and the tensile stress when the base material (11) is stretched in the CD direction to elongate the base material by stretching the base material (11) in the CD directionTensile stress ratio (R) at 25% _25％ ) Is 1.3 or less, and the ratio (R) of the tensile stress when the base material (11) is stretched in the MD direction to 50% elongation to the tensile stress when the base material (11) is stretched in the CD direction to 50% elongation _50％ ) Is 1.3 or less.

Description

Sheet for processing workpiece

Technical Field

The present invention relates to a workpiece processing sheet used for processing a workpiece such as a semiconductor wafer.

Background

Semiconductor wafers such as silicon and gallium arsenide, and various packages (packages) are manufactured in a large-diameter state, cut (diced) into chips, and then peeled (picked up), and then transferred to a mounting (mount) step which is a next step. In this case, a work such as a semiconductor wafer is subjected to processing such as back grinding, dicing, cleaning, drying, expanding (expanding), picking up, and mounting in a state of being laminated on an adhesive sheet (hereinafter, sometimes referred to as "work processing sheet") provided with a base material and an adhesive layer.

In the pickup step, in order to facilitate the pickup of the chips, the chips may be lifted one by one from a surface of the workpiece processing sheet opposite to the surface on which the chips are stacked. In particular, in order to prevent the chips from colliding with each other at the time of picking up and to facilitate the picking up, the workpiece processing sheet is generally stretched (expanded) to separate the chips from each other. Therefore, the workpiece-processing sheet is required to have excellent flexibility that enables good expansion.

Patent document 1 discloses a base film for dicing comprising a base layer and a surface layer containing a predetermined polystyrene-based resin and a predetermined vinyl aromatic hydrocarbon-conjugated diene copolymer or a hydrogenated product thereof, and aims to provide a sheet for processing a workpiece having excellent expandability.

Documents of the prior art

Patent literature

Patent document 1: japanese patent No. 6146616

Disclosure of Invention

Technical problems to be solved by the invention

However, in recent years, as semiconductor devices have become finer, chips that are handled using a workpiece processing sheet have become increasingly smaller. Therefore, in order to pick up such minute chips well, the work processing sheet is required to have more excellent expandability than the conventional work processing sheet.

The present invention has been made in view of such circumstances, and an object thereof is to provide a sheet for workpiece processing having excellent expandability.

Means for solving the problems

In order to achieve the above object, a first aspect of the present invention provides a work processing sheet comprising a substrate and an adhesive layer laminated on one surface side of the substrate, wherein the substrate comprises a surface layer close to the adhesive layer, a back surface layer distant from the adhesive layer, and an intermediate layer located between the surface layer and the back surface layer, wherein a tensile test is performed on a test sheet obtained by cutting the substrate into a strip shape having a short side of 15mm under conditions of a collet pitch of 100mm and a tensile rate of 200 mm/min at 23 ℃, a ratio (R) of a tensile stress at 25% elongation measured when the substrate is stretched in the MD direction to a tensile stress at 25% elongation measured when the substrate is stretched in the CD direction is 600% or more in both of the MD direction and the CD direction, and the ratio (R) of the tensile stress at 25% elongation measured when the substrate is stretched in the CD direction _25％ ) Is 1.3 or less, and the ratio (R) of the tensile stress at 50% elongation measured when the substrate is subjected to a tensile test in which the substrate is stretched in the MD direction to the tensile stress at 50% elongation measured when the substrate is subjected to a tensile test in which the substrate is stretched in the CD direction _50％ ) Is 1.3 or less (invention 1).

The sheet for processing a workpiece of the invention (invention 1) has excellent extensibility by providing the substrate with the three layers and satisfying the conditions of the ratio of the elongation at break and the tensile stress at the same time.

In the above invention (invention 1), it is preferable that the surface layer, the intermediate layer, and the back surface layer each contain a polyolefin resin and a thermoplastic elastomer, and the surface layer and the back surface layer each contain an antistatic agent (invention 2).

In the above invention (invention 2), it is preferable that the intermediate layer does not contain the antistatic agent, or the intermediate layer contains the antistatic agent and has a content (unit: mass%) less than the content of the antistatic agent in each of the surface layer and the back surface layer (invention 3).

In the above invention (invention 1), it is preferable that the surface layer, the intermediate layer and the back layer each contain polyethylene, and the polyethylene contained in the intermediate layer has a Melt Flow Rate (MFR) measured according to JIS K7210-1 different from the polyethylene contained in the surface layer and the back layer (invention 4).

In the above inventions (inventions 1 to 4), the work processing sheet is preferably a dicing sheet (invention 5).

Effects of the invention

The sheet for processing a workpiece of the present invention has excellent expandability.

Drawings

Fig. 1 is a sectional view of a workpiece-processing sheet according to an embodiment of the present invention.

Description of the reference numerals

1: a workpiece processing sheet; 11: a substrate; 111: a surface layer; 112: an intermediate layer; 113: a back layer; 12: an adhesive layer.

Detailed Description

Hereinafter, embodiments of the present invention will be described.

Fig. 1 shows a cross-sectional view of a workpiece processing sheet according to an embodiment. The work processing sheet 1 shown in fig. 1 includes a base material 11 and an adhesive layer 12 laminated on one surface of the base material 11.

As shown in fig. 1, the substrate 11 includes a surface layer 111 close to the adhesive layer 12, a back layer 113 distant from the adhesive layer 12, and an intermediate layer 112 located between the surface layer 111 and the back layer 113.

The work piece 1 of the present embodiment has an elongation at break of 600% or more in both MD and CD directions, as measured in a tensile test performed on a test piece obtained by cutting a base material 11 into a strip shape having a short side of 15mm under conditions of a chuck pitch of 100mm and a tensile rate of 200 mm/min at 23 ℃.

In addition, in the sheet 1 for processing a workpiece of the present embodiment, the tensile stress at 25% elongation measured in the tensile test in which the base material 11 is stretched in the MD direction and the tensile stress in the tensile test in which the base material 11 is stretched in the CD direction are performedThe ratio of tensile stress (R) at 25% elongation measured _25％ ) Is 1.3 or less.

Further, in the sheet 1 for processing a workpiece of the present embodiment, the ratio (R) of the tensile stress at 50% elongation measured when the tensile test in which the base material 11 is stretched in the MD direction is performed to the tensile stress at 50% elongation measured when the tensile test in which the base material 11 is stretched in the CD direction is performed is set to _50％ ) Is 1.3 or less.

Generally, dicing of a wafer is performed on a work processing sheet, followed by curing of an adhesive layer by ultraviolet irradiation, and further, a chip is picked up in a spread state. In general, a notch is also generated in the base material when the above-described dicing is performed. Therefore, the conventional work processing sheet is very likely to be broken when performing expansion.

However, by making the base material 11 satisfy the above physical properties, the sheet 1 for processing a workpiece according to the present embodiment is less likely to be broken in the expanding step even after the cutting as described above. In particular by making the ratio of the tensile stresses (R) _25％ ) And the ratio of tensile stress (R) _50％ ) In each of the above ranges, the difference between the tensile stress when the substrate is stretched in the MD and the tensile stress when the substrate is stretched in the CD is relatively small, whereby the stress concentration in a part of the substrate 11 can be suppressed and the substrate is less likely to break. Therefore, the sheet 1 for workpiece processing of the present embodiment has excellent expandability.

Further, by providing the substrate 11 of the present embodiment with at least three layers, i.e., the surface layer 111, the intermediate layer 112, and the back surface layer 113, it is possible to easily impart other desired properties to the workpiece-processing sheet 1 while ensuring excellent expandability. For example, as described later, by containing an antistatic agent in the surface layer 111 and the back surface layer 113, excellent antistatic properties can be imparted. Further, by designing the elastic modulus of the surface layer 111 and the back surface layer 113 to be relatively high, it is possible to suppress sticking to a metal roller when forming a film on the substrate 11 and to impart high film formability.

1. Constitution of sheet for working workpiece

(1) Base material

As described above, the substrate 11 of the present embodiment includes the surface layer 111, the intermediate layer 112, and the back layer 113. The composition of these layers is not particularly limited as long as the substrate 11 satisfies the above physical properties.

The material of each layer constituting the substrate 11 is not particularly limited as long as the layers can be formed, and for example, a resin is preferably used. In particular, from the viewpoint of achieving better spreadability and easily suppressing the occurrence of cut pieces, it is preferable to use at least one of a polyolefin resin and a thermoplastic elastomer as a main material. The compositions of the front surface layer 111 and the back surface layer 113 may be different from each other or may be completely the same.

(1-1) polyolefin-based resin

Specific examples of the polyolefin resin are not particularly limited. In the present specification, the polyolefin-based resin is a homopolymer or copolymer comprising an olefin as a monomer, or a copolymer comprising an olefin and a molecule other than an olefin as a monomer, and the mass ratio of the portion based on the olefin unit in the resin after polymerization is 1.0 mass% or more.

The polymer constituting the polyolefin resin may be linear or have side chains. The polymer may have an aromatic ring or an aliphatic ring.

Examples of the olefin monomer constituting the polyolefin resin include an olefin monomer having 2 to 8 carbon atoms, an α -olefin monomer having 3 to 18 carbon atoms, an olefin monomer having a cyclic structure, and the like. Examples of the olefin monomer having 2 to 8 carbon atoms include ethylene, propylene, 2-butene, octene, and the like. Examples of the α -olefin monomer having 3 to 18 carbon atoms include propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, and 1-octadecene. Examples of the olefin monomer having a cyclic structure include norbornene, cyclopentadiene, cyclohexadiene, dicyclopentadiene, tetracyclododecene, and derivatives thereof.

The polyolefin-based resin may be used singly or in combination of two or more.

In the specific example of the polyolefin-based resin, at least one of polyethylene containing ethylene as a main polymerization unit and polypropylene containing propylene as a main polymerization unit is preferably used.

As the polypropylene, for example, homopolypropylene, random polypropylene and block polypropylene are preferably used. These polypropylenes can be used singly or in combination of two or more. Particular preference is given to using homopolypropylene in combination with atactic polypropylene.

As the above-mentioned homopolypropylene, random polypropylene and block polypropylene, commercially available products can be used. Examples of commercially available products of homopolypropylene include a product name "Prime Polypro E111G", a product name "Prime Polypro E-100GV", a product name "Prime Polypro E-100GPL", and a product name "Prime Polypro E-200GP", all manufactured by Prime Polymer co. Examples of commercially available products of random polypropylene include product name "Prime polypror B221WA", product name "Prime polypror B241", product name "Prime polypror E222", product name "Prime polypror E-333GV", and the like, all manufactured by Prime Polymer co. Examples of commercially available products of block polypropylene include a product name "Prime Polypro E701G", a product name "Prime Polypro E702G", and a product name "Prime Polypro E702MG", all manufactured by Prime Polymer co.

The polyethylene may be any one of high-density polyethylene, medium-density polyethylene, low-density polyethylene, ultra-low-density polyethylene, and linear low-density polyethylene, or a mixture of two or more of these polyethylenes.

In particular, low-density polyethylene is preferably used as the polyethylene, and examples of commercially available products thereof include NOVATEC LL manufactured by Mitsubishi Chemical Corporation, prime Polymer Co., NEO-ZEX series manufactured by Ltd, ULTZEX series, and the like.

The Melt Flow Rate (MFR) of the polyethylene is preferably 1g/10 min or more, particularly preferably 2g/10 min or more, and more preferably 3g/10 min or more. The melt flow rate is preferably 10g/10 min or less, particularly preferably 9g/10 min or less, and more preferably 8g/10 min or less. By making the melt flow rate in these ranges, the work processing sheet 1 of the present embodiment is easily made to have better expandability. The melt flow rate was measured according to JIS K7210:2014 under the conditions of a temperature of 190 ℃ and a load of 2.16 kg.

When any one of the layers constituting the substrate 11 contains a polyolefin-based resin, the content of the polyolefin-based resin in the layer is preferably 10% by mass or more, particularly preferably 15% by mass or more, and further preferably 20% by mass or more. The content is preferably 100% by mass or less, particularly preferably 95% by mass or less, and more preferably 90% by mass or less. By making the content of the polyolefin-based resin within the above range, the sheet 1 for workpiece processing of the present embodiment is likely to have more favorable expandability.

When the surface layer 111, the intermediate layer 112, and the back surface layer 113 each contain polyethylene, the polyethylene contained in the intermediate layer 112 preferably has a melt flow rate measured according to JIS K7210-1 different from that of the polyethylene contained in each of the surface layer 111 and the back surface layer 113. It is particularly preferable that the melt flow rate of the polyethylene contained in the intermediate layer 112 is higher than the melt flow rates of the polyethylenes contained in the surface layer 111 and the back surface layer 113, respectively. Thus, the work processing sheet 1 of the present embodiment can easily obtain more favorable expandability.

(1-2) thermoplastic elastomer

The thermoplastic elastomer is not particularly limited as long as it is a material other than the polyolefin resin and can form the substrate 11. Examples of the thermoplastic elastomer include olefin elastomers, rubber elastomers, urethane elastomers, styrene elastomers, acrylic elastomers, vinyl chloride elastomers, and the like. These thermoplastic elastomers may be used alone, or two or more of them may be used in combination.

Among the elastomers, olefin-based elastomers are preferred from the viewpoint of easy acquisition of good expandability. In particular, it is preferable that at least one of the surface layer 111 and the back layer 113 contains an olefin elastomer. In the present specification, the "olefin elastomer" is a copolymer containing a structural unit derived from an olefin or a derivative thereof (olefin compound), and is a material having rubber-like elasticity and thermoplastic properties in a temperature range including normal temperature.

As examples of the olefinic elastomer, olefinic elastomers containing at least one resin selected from the group consisting of ethylene-propylene copolymers, ethylene- α -olefin copolymers, propylene- α -olefin copolymers, butene- α -olefin copolymers, ethylene-propylene- α -olefin copolymers, ethylene-butene- α -olefin copolymers, propylene-butene- α -olefin copolymers, and ethylene-propylene-butene- α -olefin copolymers can be cited. Among them, an ethylene-propylene copolymer is preferable.

When any one of the layers constituting the substrate 11 contains an olefin-based elastomer, the content of the olefin-based elastomer in the layer is preferably 1% by mass or more, particularly preferably 10% by mass or more, and more preferably 15% by mass or more. The content is preferably 90% by mass or less, particularly preferably 80% by mass or less, and more preferably 70% by mass or less. By setting the content of the olefinic elastomer to the above range, the work processing sheet 1 of the present embodiment can easily obtain more favorable extensibility.

In addition, from the viewpoint of easily obtaining more favorable expandability, a styrene-based elastomer is also preferably used. It is particularly preferable that the intermediate layer 112 contains a styrene-based elastomer. In the present specification, the "styrene-based elastomer" is a copolymer containing a structural unit derived from styrene or a derivative thereof (styrene-based compound), and is a material having rubber-like elasticity and thermoplastic properties in a temperature range including normal temperature.

Examples of the styrene-based elastomer include a styrene-conjugated diene copolymer and a styrene-olefin copolymer, and among them, a styrene-conjugated diene copolymer is preferable. Specific examples of the styrene-conjugated diene copolymer include unhydrogenated styrene-conjugated diene copolymers such as styrene-butadiene copolymer, styrene-butadiene-styrene copolymer (SBS), styrene-butadiene-butylene-styrene copolymer, styrene-isoprene-styrene copolymer (SIS), and styrene-ethylene-isoprene-styrene copolymer; hydrogenated styrene-conjugated diene copolymers such as styrene-ethylene/propylene-styrene copolymers (SEPS: hydrogenated product of styrene-isoprene-styrene copolymer) and styrene-ethylene-butylene-styrene copolymers (SEBS: hydrogenated product of styrene-butadiene copolymer). The styrenic thermoplastic elastomer may be a hydrogenated product (hydride) or an unhydrogenated product, but is preferably a hydrogenated product. Among the above-mentioned styrene-conjugated diene copolymers, a hydrogenated styrene-conjugated diene copolymer is preferable from the viewpoint of easy availability of good expandability, and a styrene-ethylene-butylene-styrene copolymer (SEBS) is particularly preferable.

The content (styrene ratio) of the structural units derived from styrene or a styrene compound in the styrene-based elastomer is preferably 1% by mass or more, particularly preferably 5% by mass or more, and more preferably 10% by mass or more. In addition, the content of the structural unit is preferably 80% by mass or less, particularly preferably 70% by mass or less, and further preferably 60% by mass or less, from the viewpoint of easily achieving excellent film-forming properties. Thereby, excellent expandability is easily achieved.

When any one of the layers constituting the substrate 11 contains a styrene-based elastomer, the content of the styrene-based elastomer in the layer is preferably 1% by mass or more, particularly preferably 10% by mass or more, and more preferably 15% by mass or more. The content is preferably 90% by mass or less, particularly preferably 80% by mass or less, and more preferably 70% by mass or less. By setting the content of the styrene-based elastomer to the above range, the work processing sheet 1 of the present embodiment can easily obtain more favorable extensibility.

(1-3) antistatic agent

Each layer constituting the substrate 11 also preferably contains an antistatic agent. It is particularly preferable that the surface layer 111 and the back surface layer 113 each contain an antistatic agent. Thus, the sheet 1 for processing a workpiece of the present embodiment is likely to have excellent antistatic properties, and peeling electrification at the time of separating a release sheet or a workpiece from the sheet 1 for processing a workpiece can be favorably suppressed.

In addition, although the intermediate layer 112 may contain an antistatic agent, from the viewpoint of suppressing the occurrence of cut pieces at the time of cutting, it is preferable that the intermediate layer 112 does not contain an antistatic agent, or that the intermediate layer 112 contains an antistatic agent in an amount smaller than the respective contents (unit: mass%) of the surface layer 111 and the back surface layer 113. As described above, by having the intermediate layer 112 containing no antistatic agent or a small amount of antistatic agent between the surface layer 111 and the back surface layer 113, it is possible to favorably suppress the generation of cut pieces from the intermediate layer 112 when the cutting blade reaches the intermediate layer 112 at the time of cutting.

The antistatic agent of the present embodiment is not particularly limited, and a known antistatic agent can be used. Examples of the antistatic agent include a low-molecular antistatic agent and a high-molecular antistatic agent, but a high-molecular antistatic agent is preferable because the generation of cut pieces is easily suppressed and bleeding (bleedout) from the surface layer 111 or the back surface layer 113 is less likely to occur.

Examples of the polymer type antistatic agent include copolymers having polyether units such as polyether ester amides and polyether polyolefin block copolymers, and these copolymers may contain metal salts such as alkali metal salts and alkaline earth metal salts, or ionic liquids.

The content of the antistatic agent in the surface layer 111 is preferably 3% by mass or more, particularly preferably 5% by mass or more, and more preferably 10% by mass or more. By setting the content of the antistatic agent to 3% by mass or more, good antistatic properties can be easily exhibited. The content of the antistatic agent in the surface layer 111 is preferably 40% by mass or less, particularly preferably 35% by mass or less, and more preferably 30% by mass or less. By setting the content of the antistatic agent to 40% by mass or less, the generation of chips is easily suppressed.

The content of the antistatic agent in the back surface layer 113 is preferably 10% by mass or more, particularly preferably 20% by mass or more, and more preferably 30% by mass or more. By setting the content of the antistatic agent to 10% by mass or more, good antistatic properties can be easily exhibited. The content of the antistatic agent in the back surface layer 113 is preferably 50% by mass or less, particularly preferably 45% by mass or less, and more preferably 40% by mass or less. By setting the content of the antistatic agent to 50% by mass or less, the generation of cutting chips is easily suppressed.

As described above, the intermediate layer 112 preferably does not contain an antistatic agent, or the intermediate layer 112 preferably contains an antistatic agent and has a content (unit: mass%) less than the content of the antistatic agent in each of the surface layer 111 and the back surface layer 113. When the intermediate layer 112 contains an antistatic agent, the content of the antistatic agent in the intermediate layer 112 is preferably 10% by mass or less, particularly preferably 5% by mass or less, and further preferably 3% by mass or less. By setting the content of the antistatic agent in the intermediate layer 112 to 5% by mass or less, the generation of chips is easily suppressed. The lower limit of the content may be, for example, 0.01 mass% or more.

(1-4) acid-modified resin

Each layer constituting the substrate 11 preferably contains an acid-modified resin. It is particularly preferable that the surface layer 111 contains an acid-modified resin. In the present specification, the "acid-modified resin" refers to a resin obtained by adding a structure derived from an acid component to a polymer chain. The structure derived from the acid component may be in the form of an acid anhydride or may have a structure having a carboxyl group. By containing the acid-modified resin in the surface layer 111 as described above, the adhesion between the base material 11 and the adhesive layer 12 is improved, and the adhesive can be prevented from remaining on the chip side during pickup.

Examples of the main chain of the acid-modified resin include ethylene-acrylic acid copolymers such as ethylene- (meth) acrylic acid copolymers and ethylene- (meth) acrylate copolymers. This resin can easily improve the adhesion between the surface layer 111 and the adhesive layer 12. In the present specification, (meth) acrylic acid refers to both acrylic acid and methacrylic acid. Other similar terms are also the same.

The (meth) acrylic acid ester is preferably an alkyl (meth) acrylate having an alkyl group with 1 to 4 carbon atoms. Examples of the (meth) acrylic acid include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and n-butyl (meth) acrylate. Among them, ethyl (meth) acrylate is more preferable, and ethyl acrylate is particularly preferable.

When the surface layer 111 contains the acid-modified resin, the content of the acid-modified resin in the surface layer 111 is preferably 5% by mass or more, and particularly preferably 10% by mass or more. This further improves the adhesion between the surface layer 111 and the adhesive layer 12. The content is preferably 30% by mass or less, particularly preferably 25% by mass or less, and further preferably 20% by mass or less. This makes it easy to satisfy the above properties.

(1-5) other Components

The layer constituting the substrate 11 may contain other components than the above components. In particular, the resin composition can contain a component of a base material used for a sheet for processing a workpiece.

Examples of such components include various additives such as flame retardants, plasticizers, lubricants, antioxidants, colorants, infrared absorbers, ultraviolet absorbers, and ion scavengers. The content of these additives is not particularly limited, but is preferably within a range in which the base material can perform a desired function.

(1-6) surface treatment of base Material

In order to improve the adhesion between the surface of the substrate 11 on which the adhesive layer 12 is laminated and the adhesive layer 12, the surface may be subjected to surface treatment such as primer treatment (primer treatment), corona treatment, plasma treatment, or roughening treatment (frosting). Examples of the roughening treatment include embossing and sand blasting. Among them, corona treatment is preferably performed.

(1-7) method for producing base Material

The method for producing the substrate 11 of the present embodiment is not particularly limited, and for example, a melt extrusion method such as a T-die method or a circular die method (pill ダイ method); a rolling method; solution methods such as dry method and wet method. Among them, the melt extrusion method is preferably used, and the T-die method is particularly preferably used, from the viewpoint of efficiently producing the base material.

In the case of producing the substrate 11 by the melt extrusion method, the components constituting each layer may be kneaded separately, and the obtained kneaded product may be directly formed into a film, or the obtained kneaded product may be first produced into pellets (pellets), and then a plurality of layers may be simultaneously extruded by a known extruder to form a film.

(1-8) physical Properties of base Material

As described above, the base material 11 of the present embodiment has an elongation at break of 600% or more in both MD and CD directions, as measured in a tensile test performed on a test piece obtained by cutting the base material 11 into a strip shape having a short side of 15mm under conditions of a chuck pitch of 100mm and a tensile speed of 200 mm/min at 23 ℃.

Here, from the viewpoint of easy realization of more excellent extensibility, the elongation at break is preferably 650% or more, and more preferably 700% or more, both when stretched in the MD direction and when stretched in the CD direction. The upper limit of the elongation at break is not particularly limited, and for example, the elongation at break may be 1000% or less, or particularly 800% or less, both when stretched in the MD and CD directions.

Further, the elongation at break when the test piece is stretched in the MD direction is preferably 650% or more, more preferably 700% or more, and particularly preferably 800% or more, from the viewpoint of easily achieving more excellent extensibility. The upper limit of the elongation at break is not particularly limited, and may be, for example, 1000% or less, and particularly 800% or less.

Further, the breaking elongation of the test piece when stretched in the CD direction is preferably 650% or more, more preferably 700% or more, and particularly preferably 800% or more, from the viewpoint of facilitating achievement of more excellent extensibility. The upper limit of the elongation at break is not particularly limited, and may be, for example, 1000% or less, and particularly 800% or less.

The details of the above-described method for measuring the elongation at break are shown in the test examples described later.

Further, as described above, with respect to the base material 11 of the present embodiment, the ratio (R) of the tensile stress at 25% elongation measured when the tensile test in which the base material 11 is stretched in the MD direction is performed to the tensile stress at 25% elongation measured when the tensile test in which the base material 11 is stretched in the CD direction is performed is _25％ ) Is 1.3 or less.

Here, the more excellent expandability can be easily achievedThe ratio (R) of the tensile stresses _25％ ) Preferably 1.25 or less, and particularly preferably 1.2 or less. In addition, the ratio (R) to the tensile stress _25％ ) The lower limit of (b) is not particularly limited, and may be, for example, 0.8 or more, and particularly, 0.9 or more.

Further, as described above, with respect to the base material 11 of the present embodiment, the ratio (R) of the tensile stress at 50% elongation measured when the tensile test in which the base material 11 is stretched in the MD direction is performed to the tensile stress at 50% elongation measured when the tensile test in which the base material 11 is stretched in the CD direction is performed is _50％ ) Is 1.3 or less.

Here, the ratio of the tensile stress (R) is set to be easy to realize more excellent expandability _50％ ) Preferably 1.25 or less, and particularly preferably 1.2 or less. In addition, the ratio (R) to the tensile stress _50％ ) The lower limit of (b) is not particularly limited, and may be, for example, 0.8 or more, and particularly may be 0.9 or more.

Further, from the viewpoint of easily achieving further excellent extensibility, the ratio (R) of the tensile stress at 10% elongation measured when the tensile test in which the base material 11 is stretched in the MD direction is performed to the tensile stress at 10% elongation measured when the tensile test in which the base material 11 is stretched in the CD direction is performed _10％ ) Preferably 1.5 or less, particularly preferably 1.4 or less, and further preferably 1.3 or less. In addition, the ratio (R) to the tensile stress _10％ ) The lower limit of (b) is not particularly limited, and may be, for example, 0.8 or more, and particularly may be 0.9 or more.

The tensile stress at 10% elongation, as measured in a tensile test in which the substrate 11 is stretched in the MD direction, is preferably 6.5MPa or more, particularly preferably 8MPa or more, and more preferably 10MPa or more. The tensile stress is preferably 20MPa or less, particularly preferably 15MPa or less, and further preferably 13MPa or less. By setting the tensile stress in these ranges, the ratio (R) of the tensile stress described above can be easily satisfied _10％ )。

Further, the tensile stress at 25% elongation measured in the tensile test in which the substrate 11 is stretched in the MD direction is preferably 7MPa or moreAbove, it is particularly preferably 9MPa or more, and more preferably 10MPa or more. The tensile stress is preferably 20MPa or less, particularly preferably 15MPa or less, and further preferably 13MPa or less. By setting the tensile stress in these ranges, the ratio (R) of the tensile stress described above can be easily satisfied _25％ )。

The tensile stress at 50% elongation, as measured in a tensile test in which the substrate 11 is stretched in the MD direction, is preferably 8MPa or more, particularly preferably 9MPa or more, and more preferably 10MPa or more. The tensile stress is preferably 20MPa or less, particularly preferably 15MPa or less, and further preferably 13MPa or less. By setting the tensile stress in these ranges, the ratio (R) of the tensile stress described above can be easily satisfied _50％ )。

The tensile stress at 10% elongation, as measured in a tensile test in which the substrate 11 is stretched in the CD direction, is preferably 6.5MPa or more, particularly preferably 7MPa or more, and more preferably 10MPa or more. The tensile stress is preferably 20MPa or less, particularly preferably 15MPa or less, and further preferably 13MPa or less. By setting the tensile stress in these ranges, the ratio (R) of the tensile stress described above can be easily satisfied _10％ )。

The tensile stress at 25% elongation, as measured in a tensile test in which the substrate 11 is stretched in the CD direction, is preferably 7MPa or more, particularly preferably 8MPa or more, and more preferably 10MPa or more. The tensile stress is preferably 20MPa or less, particularly preferably 15MPa or less, and further preferably 13MPa or less. By setting the tensile stress in these ranges, the ratio (R) of the tensile stress can be easily satisfied _25％ )。

The tensile stress at 50% elongation, as measured in a tensile test in which the substrate 11 is stretched in the CD direction, is preferably 7.5MPa or more, particularly preferably 7MPa or more, and more preferably 10MPa or more. The tensile stress is preferably 20MPa or less, particularly preferably 15MPa or less, and further preferably 13MPa or less. By setting the tensile stress in these ranges, the ratio (R) of the tensile stress described above can be easily satisfied _50％ )。

The details of the above method for measuring tensile stress are shown in the test examples described later.

(1-9) thickness of each layer of the substrate

The thickness of the surface layer 111 in the present embodiment is preferably 1 μm or more, particularly preferably 2 μm or more, and more preferably 4 μm or more. The thickness of the surface layer 111 is preferably 10 μm or less, particularly preferably 8 μm or less, and more preferably 4 μm or less. By making the thickness of the surface layer 111 in the above range, excellent expandability is easily achieved for the sheet for workpiece processing 1, and at the same time, desired performance is easily imparted to the sheet for workpiece processing 1.

The thickness of the intermediate layer 112 in the present embodiment is preferably 40 μm or more, particularly preferably 50 μm or more, and more preferably 60 μm or more. The thickness of the intermediate layer 112 is preferably 100 μm or less, particularly preferably 90 μm or less, and further preferably 80 μm or less. By setting the thickness of the intermediate layer 112 to the above range, excellent expandability can be easily achieved in the workpiece-processing sheet 1, and desired performance can be easily imparted to the workpiece-processing sheet 1.

The thickness of the back surface layer 113 of the present embodiment is preferably 2 μm or more, particularly preferably 4 μm or more, and more preferably 8 μm or more. The thickness of the back surface layer 113 is preferably 40 μm or less, particularly preferably 30 μm or less, and further preferably 25 μm or less. By setting the thickness of the back surface layer 112 to the above range, excellent expandability of the work processing sheet 1 is easily achieved, and desired performance is easily imparted to the work processing sheet 1.

(2) Adhesive layer

The adhesive constituting the adhesive layer 12 of the present embodiment is not particularly limited as long as it can exhibit sufficient adhesive force to an adherend (in particular, sufficient adhesive force to a work for work processing). Examples of the adhesive constituting the adhesive layer 12 include acrylic adhesives, rubber adhesives, silicone adhesives, urethane adhesives, polyester adhesives, polyvinyl ether adhesives, and the like. Among them, acrylic adhesives are preferably used from the viewpoint of easy development of desired adhesive force.

The adhesive constituting the adhesive layer 12 of the present embodiment may be an adhesive having no active energy ray-curing property, but is preferably an adhesive having an active energy ray-curing property (hereinafter, may be referred to as "active energy ray-curing adhesive"). By forming the adhesive layer 12 of an active energy ray-curable adhesive, the adhesive layer 12 can be cured by irradiation with active energy rays, and the adhesive strength of the work processing sheet 1 to an adherend can be easily reduced. In particular, the workpiece after processing can be easily separated from the workpiece processing sheet 1 by irradiation with active energy rays.

The active energy ray-curable adhesive constituting the adhesive layer 12 may contain, as a main component, a polymer having active energy ray-curability, or may contain, as a main component, a mixture of a non-active energy ray-curable polymer (a polymer not having active energy ray-curability) and a monomer and/or oligomer having at least one or more active energy ray-curable groups. The active energy ray-curable adhesive may be a mixture of a polymer having active energy ray-curability and a monomer and/or oligomer having at least one or more active energy ray-curable groups.

The active energy ray-curable polymer is preferably a (meth) acrylate polymer having a side chain to which an active energy ray-curable functional group (active energy ray-curable group) is introduced (hereinafter, sometimes referred to as "active energy ray-curable polymer"). The active energy ray-curable polymer is preferably obtained by reacting an acrylic polymer having a functional group-containing monomer unit with an unsaturated group-containing compound having a functional group bonded to a functional group of the acrylic polymer. In the present specification, (meth) acrylic acid refers to both acrylic acid and methacrylic acid. Other similar terms are also the same. Further, the term "copolymer" is also included in the term "polymer".

The acrylic polymer having a functional group-containing monomer unit may be a polymer obtained by polymerizing another monomer together with a functional group-containing monomer. As such a functional group-containing monomer and other monomers, and the unsaturated group-containing compound, known monomers and compounds can be used, and for example, the monomers and compounds disclosed in international publication No. 2018/084021 can be used.

The weight average molecular weight of the active energy ray-curable polymer is preferably 1 ten thousand or more, particularly preferably 15 ten thousand or more, and further preferably 20 ten thousand or more. The weight average molecular weight is preferably 150 ten thousand or less, and particularly preferably 100 ten thousand or less. The weight average molecular weight (Mw) in the present specification is a value in terms of standard polystyrene measured by Gel Permeation Chromatography (GPC).

The acrylic polymer before being reacted with the unsaturated group-containing compound can be used as the non-active energy ray-curable polymer component.

The weight average molecular weight of the acrylic polymer as the active energy ray-curable polymer component is preferably 1 ten thousand or more, particularly preferably 15 ten thousand or more, and further preferably 20 ten thousand or more. The weight average molecular weight is preferably 150 ten thousand or less, and particularly preferably 100 ten thousand or less.

Examples of the monomer and/or oligomer having at least one or more active energy ray-curable groups include esters of a polyhydric alcohol and (meth) acrylic acid.

When ultraviolet rays are used as the active energy rays for curing the active energy ray-curable adhesive, a photopolymerization initiator is preferably added to the adhesive. Further, an inactive energy ray-curable polymer component or oligomer component, a crosslinking agent, and the like may be added to the adhesive.

The thickness of the adhesive agent layer 12 of the present embodiment is preferably 1 μm or more, particularly preferably 3 μm or more, and more preferably 5 μm or more. The thickness of the adhesive layer 12 is preferably 70 μm or less, particularly preferably 30 μm or less, and more preferably 15 μm or less. By setting the thickness of the adhesive layer 12 to the above range, the work processing sheet 1 of the present embodiment easily exhibits desired adhesiveness.

(3) Stripping sheet

In the work processing sheet 1 of the present embodiment, for the purpose of protecting the surface of the adhesive layer 12 opposite to the substrate 11 (hereinafter, sometimes referred to as "adhesive surface"), a release sheet may be laminated on the surface before the surface is attached to a work.

The above-mentioned release sheet may be of any configuration, and examples thereof include a release sheet obtained by subjecting a plastic film to a release treatment with a release agent or the like. Specific examples of the plastic film include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; and polyolefin films such as polypropylene and polyethylene. As the release agent, silicones, fluorine-based ones, long-chain alkyl-based ones, and the like can be used, and among them, silicones which are inexpensive and can obtain stable performance are preferable.

The thickness of the release sheet is not particularly limited, and may be, for example, 16 μm or more and 250 μm or less.

(4) Others

In the work processing sheet 1 of the present embodiment, a pressure-sensitive adhesive layer may be laminated on the surface of the pressure-sensitive adhesive layer 12 opposite to the substrate 11. In this case, the work processing sheet 1 of the present embodiment can be used as a dicing die bonding sheet. A work is attached to the surface of the adhesive layer of the sheet opposite to the adhesive layer 12, and the adhesive layer and the work are cut together, whereby a chip having a singulated (single) adhesive layer laminated thereon can be obtained. The singulated adhesive layer can be used to easily fix the chip to an object on which the chip is mounted. As a material constituting the pressure-sensitive adhesive layer, a material containing a thermoplastic resin and a low-molecular-weight thermosetting pressure-sensitive adhesive component, a material containing a B-stage (semi-cured) thermosetting pressure-sensitive adhesive component, or the like is preferably used.

In the work processing sheet 1 of the present embodiment, a protective film forming layer may be laminated on the pressure-sensitive adhesive surface of the adhesive agent layer 12. In this case, the work processing sheet 1 of the present embodiment can be used as a protective film forming and cutting sheet. A work is attached to the surface of the protective film forming layer of the sheet opposite to the adhesive layer 12, and the protective film forming layer is cut together with the work, whereby a chip in which the protective film forming layer is individually laminated can be obtained. In this case, a protective film forming layer is generally laminated on the surface opposite to the surface on which the circuit is formed. By curing the singulated protective film forming layer at a predetermined timing, a protective film having sufficient durability can be formed on the chip. Preferably, the protective film forming layer is formed of an uncured curable adhesive.

2. Method for manufacturing sheet for processing workpiece

The method for producing the workpiece-processing sheet 1 of the present embodiment is not particularly limited. For example, it is preferable to obtain the work processing sheet 1 by forming the adhesive layer 12 on a release sheet and then laminating one surface of the base material 11 on the surface of the adhesive layer 12 opposite to the release sheet.

The adhesive layer 12 can be formed by a known method. For example, a coating liquid containing an adhesive composition for forming the adhesive layer 12 and further containing a solvent or a dispersion medium as necessary is prepared. Then, the coating liquid is applied to a releasable surface (hereinafter, sometimes referred to as a "releasable surface") of a release sheet. Next, the obtained coating film is dried, whereby the adhesive layer 12 can be formed.

The coating liquid can be applied by a known method, and for example, can be applied by a bar coating method, a blade coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method, or the like. The properties of the coating liquid are not particularly limited as long as the coating liquid can be applied, and a component for forming the adhesive agent layer 12 may be contained as a solute or a component for forming the adhesive agent layer 12 may be contained as a dispersion. The release sheet may be released as a process material, or may protect the adhesive layer 12 until it is attached to an adherend.

When the adhesive composition for forming the adhesive agent layer 12 contains the crosslinking agent, it is preferable to form a crosslinked structure in the adhesive agent layer 12 at a desired existing density by causing a crosslinking reaction between the polymer component in the coating film and the crosslinking agent by changing the drying conditions (temperature, time, etc.) described above or by separately providing a heat treatment. Further, in order to sufficiently progress the crosslinking reaction, after the adhesive agent layer 12 and the substrate 11 are bonded, for example, aging may be performed by leaving them to stand for several days in an environment of 23 ℃ and a relative humidity of 50%.

3. Method for using sheet for processing workpiece

The workpiece-processing sheet 1 of the present embodiment can be used for processing a workpiece such as a semiconductor wafer. That is, the adhesive surface of the workpiece processing sheet 1 of the present embodiment can be attached to a workpiece, and then the workpiece can be processed on the workpiece processing sheet 1. The work processing sheet 1 of the present embodiment can be used as a back grinding sheet, a dicing sheet, an expanding sheet, a picking sheet, and the like according to this processing. Here, as examples of the work, a semiconductor member such as a semiconductor wafer or a semiconductor package; glass members such as glass plates.

As described above, the sheet 1 for workpiece processing of the present embodiment exhibits excellent expandability. Therefore, the work processing sheet 1 of the present embodiment is particularly suitable for use as a dicing sheet, an expanding sheet, or a pickup sheet among the work processing sheets.

In addition, when the work processing sheet 1 of the present embodiment includes the above-described adhesive layer, the work processing sheet 1 can be used as a dicing-bonding wafer. Further, when the work processing sheet 1 of the present embodiment includes the above-described protective film forming layer, the work processing sheet 1 can be used as a protective film forming and cutting sheet.

When the adhesive layer 12 of the work processing sheet 1 of the present embodiment is formed of the active energy ray-curable adhesive, it is also preferable to irradiate the active energy ray as described below when used. That is, when the processing of the workpiece is completed on the workpiece processing sheet 1 and the processed workpiece is separated from the workpiece processing sheet 1, it is preferable to irradiate the adhesive layer 12 with the active energy ray before the separation. This cures the adhesive layer 12, thereby reducing the adhesive force of the adhesive sheet to the processed work satisfactorily, and facilitating separation of the processed work.

The embodiments described above are described for easy understanding of the present invention, and are not described for limiting the present invention. Therefore, each element disclosed in the above embodiments also covers all design changes and equivalents that fall within the technical scope of the present invention.

For example, another layer may be laminated between the base material 11 and the adhesive agent layer 12 of the work processing sheet 1 of the present embodiment, or on the surface of the base material 11 opposite to the adhesive agent layer 12. Further, other layers may be laminated on the surface of the front surface layer 111 opposite to the intermediate layer 112, between the front surface layer 111 and the intermediate layer 112, between the intermediate layer 112 and the back surface layer 113, and on the surface of the back surface layer 113 opposite to the intermediate layer 112.

Examples

The present invention will be described in more detail with reference to examples and the like, but the scope of the present invention is not limited to these examples and the like.

[ example 1]

(1) Production of the substrate

45 parts by mass of a random Polypropylene resin (manufactured by Japan Polypropylene Corporation, product name "NOVATEC FX 3B"), 16 parts by mass of an olefin thermoplastic elastomer (manufactured by Japan Polypropylene Corporation, product name "WELNEX RFX 4V"), 15 parts by mass of an acid-modified resin (manufactured by SK functional Polymer Corporation, product name "BONDINE LX4110", ethyl acrylate content: 5% by mass, acid component amount: 3% by mass), and 25 parts by mass of an antistatic agent (manufactured by SANYO CHEMICAL INDUSTRIES, LTD., product name "PELECTRON PVH") were dried and kneaded by a biaxial kneader, thereby obtaining particles for a surface layer.

Further, 28 parts by mass of a random Polypropylene resin (manufactured by Japan Polypropylene Corporation, product name "NOVATEC FX 3B"), 39 parts by mass of an olefin-based thermoplastic elastomer (manufactured by Japan Polypropylene Corporation, product name "WELNEX RFX 4V"), and 33 parts by mass of a styrene-based thermoplastic elastomer (manufactured by Asahi Kasei Corporation, product name "Tuftec H1041", styrene-ethylene/butylene-styrene copolymer, styrene ratio: 30 wt%) were dried and kneaded by a biaxial kneader, thereby obtaining pellets for an intermediate layer.

Further, 70 parts by mass of an olefinic thermoplastic elastomer (manufactured by Japan Polypropylene Corporation, product name "WELNEX RFX 4V") and 30 parts by mass of an antistatic agent (manufactured by SANYO CHEMICAL INDUSTRIES, LTD., product name

"PELECTRON PVH") were dried and kneaded using a twin-screw kneader, thereby obtaining pellets for the back surface layer.

Using the three kinds of pellets obtained as described above, a three-layer substrate was obtained by coextrusion molding using a small T die extruder (product name "LABO PLASTOMILL", manufactured by Toyo Seiki Seisaku-sho, ltd.) to obtain a three-layer substrate in which a surface layer having a thickness of 4 μm, a middle layer having a thickness of 64 μm, and a back layer having a thickness of 12 μm were sequentially laminated.

(2) Preparation of adhesive composition

A (meth) acrylate polymer was obtained by polymerizing 62 parts by mass of n-butyl acrylate, 10 parts by mass of methyl methacrylate, and 28 parts by mass of 2-hydroxyethyl acrylate by a solution polymerization method. Next, 2-methacryloyloxyethyl isocyanate (MOI) was added in an amount corresponding to 80 mol% relative to 2-hydroxyethyl acrylate constituting the (meth) acrylate polymer, and dibutyltin dilaurate (DBTDL) as a tin-containing catalyst was added in an amount of 0.13 parts by mass relative to 100 parts by mass of the (meth) acrylate polymer. Then, the reaction was carried out at 50 ℃ for 24 hours, whereby a (meth) acrylate polymer having an active energy ray-curable group introduced into a side chain was obtained. The weight average molecular weight of the active energy ray-curable polymer was measured by the method described below, and was 50 ten thousand.

To a solvent were mixed 100 parts by mass (in terms of solid content, the same applies hereinafter) of the (meth) acrylate polymer having an active energy ray-curable group introduced into a side chain obtained above, 2 parts by mass of 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl ] phenyl } -2-methylpropan-1-one (manufactured by basf CORPORATION, product name "Omnirad 127") as a photopolymerization initiator, and 1 part by mass of trimethylolpropane-modified toluene diisocyanate (manufactured by TOSOH CORPORATION, product name "CORONATE L") as a crosslinking agent to obtain a coating solution of an adhesive composition.

(3) Formation of adhesive layer

The coating liquid of the adhesive composition obtained in the step (2) was applied to the release surface of a release sheet (product name "SP-PET381031" manufactured by linec Corporation) having a thickness of 38 μm and having a silicone-based release agent layer formed on one surface of a polyethylene terephthalate film, and dried by heating, thereby obtaining a laminate having an adhesive agent layer having a thickness of 5 μm formed on the release sheet.

(4) Production of adhesive sheet

The surface on the surface layer side of the base material obtained in the step (1) is subjected to corona treatment, and then the corona-treated surface is bonded to the surface on the adhesive layer side of the laminate obtained in the step (3), thereby obtaining a sheet for processing a workpiece.

Here, the weight average molecular weight (Mw) is a weight average molecular weight in terms of standard polystyrene measured by Gel Permeation Chromatography (GPC) under the following conditions (GPC measurement).

< measurement Condition >

The measurement device: HLC-8320, manufactured by TOSOH CORPORATION

GPC column (passage in the following order): TOSOH CORPORATION, inc

TSK gel superH-H

TSK gel superHM-H

TSK gel superH2000

Determination of the solvent: tetrahydrofuran (THF)

Measurement temperature: 40 deg.C

[ example 2]

A substrate having a three-layer structure was obtained by co-extrusion molding of a low-density polyethylene (UBE INDUSTRIES, manufactured by LTD., product name "F244N", melt flow rate: 2g/10 min) as a resin for the surface layer and the back layer and a low-density polyethylene (UBE INDUSTRIES, manufactured by LTD., product name "F522A", low-density polyethylene, melt flow rate: 5g/10 min) as a resin for the intermediate layer using a small T-die extruder (Toyo Seiki Seisaku-sho, manufactured by Ltd.), and a surface layer having a thickness of 21 μm, an intermediate layer having a thickness of 28 μm, and a back layer having a thickness of 21 μm were sequentially laminated. A sheet for workpiece processing was obtained in the same manner as in example 1, except that this base material was used.

[ example 3]

After 28 parts by mass of a random Polypropylene resin (manufactured by Japan Polypropylene Corporation, product name "NOVATEC FX 3B"), 45 parts by mass of an olefin thermoplastic elastomer (manufactured by Japan Polypropylene Corporation, product name "WELNEX RFX 4V") and 30 parts by mass of an antistatic agent (SANYO CHEMICAL INDUSTRIES, ltd., product name "polyethylene PVH") were dried, respectively, they were kneaded by a biaxial kneader, thereby obtaining particles for a surface layer.

Further, 38 parts by mass of a random Polypropylene resin (product name "NOVATEC FX3B" manufactured by Japan Polypropylene Corporation) and 62 parts by mass of an olefin-based thermoplastic elastomer (product name "WELNEX RFX4V" manufactured by Japan Polypropylene Corporation) were dried and kneaded by a biaxial kneader to obtain pellets for an intermediate layer.

Further, 65 parts by mass of an olefin-based thermoplastic elastomer (manufactured by Japan Polypropylene Corporation, product name "WELNEX RFX 4V") and 35 parts by mass of an antistatic agent (manufactured by SANYO CHEMICAL INDUSTRIES, ltd., product name "PELECTRON PVH") were dried and kneaded by a biaxial kneader, thereby obtaining pellets for a back surface layer.

Using the three kinds of pellets obtained as described above, co-extrusion molding was carried out using a small T die extruder (manufactured by Toyo Seiki Seisaku-sho, ltd., product name "LABO PLASTOMILL") to obtain a substrate having a three-layer structure in which a surface layer having a thickness of 4 μm, a middle layer having a thickness of 68 μm, and a back layer having a thickness of 8 μm were sequentially laminated. A sheet for workpiece processing was obtained in the same manner as in example 1, except that this base material was used.

Comparative example 1

An ethylene-methacrylic acid copolymer (EMAA) (Dow-Mitsui Polychemicals Co., ltd., product name "NUCREL N0903 HC") was extrusion-molded using a small T-die extruder (manufactured by Toyo Seiki Seisaku-sho, ltd., product name "LABO PLASTOMILL"), thereby obtaining an EMAA film having a thickness of 80 μm. A workpiece-processing sheet was obtained in the same manner as in example 1, except that this EMAA film was used as a base material.

Comparative example 2

One side of the EMAA film produced in the same manner as in comparative example 1 was subjected to electron beam irradiation under the following conditions. A workpiece-processing sheet was obtained in the same manner as in example 1, except that the EMAA film after the electron beam irradiation was used as a base material, and an adhesive layer was laminated on the surface of the base material subjected to the electron beam irradiation.

Irradiation conditions of electron beam irradiation

Irradiation amount: 110kGy

The number of irradiation times: 1 time of

Cumulative exposure: 110kGy

[ test example 1] (measurement of elongation at break)

The substrates prepared in examples and comparative examples were cut into test pieces of 15mm × 150 mm. At this time, the test piece was cut so that the 150mm side was parallel to the MD direction of the base material (the flow direction in the case of manufacturing the base material) and the 15mm side was parallel to the CD direction of the base material (the direction perpendicular to the MD direction) (hereinafter, this test piece may be referred to as "MD direction test piece"). The elongation at break of the test piece in the MD direction was measured in accordance with JIS K7127: 1999.

Specifically, a tensile tester (manufactured by Shimadzu Corporation, product name) was used

"Autograph AG-Xplus 100N"), a tensile test was performed at a speed of 200 mm/min at 23 ℃ on a tensile test piece in the longitudinal direction (MD direction) of the base material with the collet pitch set at 100mm, and the elongation at break (%) was measured. The results are shown in table 2 as the elongation at break in the MD direction.

The substrate was cut in the same manner as described above except that the MD direction and the CD direction were changed to obtain a test piece (hereinafter, this test piece may be referred to as a "CD direction test piece"). The breaking elongation (%) of the CD-direction test piece was also measured in the same manner as described above. The results are shown in Table 2 as the elongation at break in the CD direction.

[ test example 2] (measurement of tensile stress and its ratio)

The MD direction test piece produced in the same manner as in test example 1 was subjected to a tensile test at a speed of 200 mm/min at an environment of 23 ℃ with a collet pitch of 100mm using a tensile tester (manufactured by Shimadzu Corporation, product name "Autograph AG-Xplus 100N") in accordance with JIS K7127:1999, and the variation of tensile stress (MPa) when the tensile elongation (%) was increased from 0% to 150% was measured. And, the tensile stress (MPa) at the time of elongation to tensile elongation (%) of 10%, 25% and 50% was recorded. These tensile stresses are shown in table 2 as the tensile stress in the MD direction.

Further, a tensile test in which the test piece in the CD direction prepared in the same manner as in test example 1 was stretched in the longitudinal direction (CD direction) was performed in the same manner as described above, and the variation in tensile stress (MPa) was measured when the tensile elongation (%) was increased from 0% to 150%. And, the tensile stress (MPa) at the time of elongation to tensile elongation (%) of 10%, 25% and 50% was recorded. These tensile stresses are shown in table 2 as tensile stresses in the CD direction.

Then, the ratio (R) of the tensile stress in the MD direction at 10% elongation to the tensile stress in the CD direction at 10% elongation was calculated _10％ ). Similarly, the ratio of tensile stress at 25% elongation (R) was calculated _25％ ) And the ratio of tensile stress at 50% elongation (R) _50％ ). These results are also shown in Table 2.

[ test example 3] (evaluation of expandability)

One surface of a 6-inch silicon wafer was ground using a grinder (product name "DFG8540" manufactured by DISCO Corporation) until the thickness became 350 μm. The exposed surface of the adhesive layer exposed by peeling the release sheet from the work processing sheets produced in examples and comparative examples was attached to the polished surface using a laminator (laminator).

After 20 minutes of the attachment, a dicing apparatus (manufactured by DISCO Corporation, product name "DFD 6362") was used to perform dicing under the following dicing conditions to singulate the silicon wafer into chips.

Cutting conditions

Chip size: 5mm

Cutting height (cutting height)

Z1：0.135mm

Z2：0.060mm

A blade: both of Z1 and Z2 below were manufactured by DISCO Corporation

Z1: product name "ZH05-SD3000-50DD"

Z2: product name "NBC-SD3000-50BB"

Rotational speed of the blade

Z1：30000rpm

Z2：45000rpm

Cutting speed: 20 mm/sec

Cutting water amount: 1.0L/min

Cutting water temperature: 20 deg.C

Then, the adhesive layer of the sheet for workpiece processing was irradiated with ultraviolet rays (light amount 160 mJ/cm) through the base material in a nitrogen atmosphere using an ultraviolet irradiation apparatus (manufactured by LINTEC Corporation, product name "RAD-2000") ² ) The adhesive layer is cured.

Then, the work piece processing sheet to which the cut chips and the ring frame were attached was set in an expanding apparatus (manufactured by hue Electronics inc., product name "HS-1840"), and the ring frame was pulled down at a speed of 1 mm/sec until the work piece processing sheet was broken. The amount of pull-down at break (draw き and とし amounts) (mm) was recorded. In addition, no fracture even when the pull-down limit of the device (80 mm) was reached was recorded as "> 80mm". The expandability was further evaluated according to the following criteria. The pull-down amount at break and the evaluation results are shown in table 2.

O: the pull-down amount at the time of fracture is 20mm or more.

X: the pull-down at break is less than 20mm.

As can be seen from table 2, the workpiece-processing sheets produced in the examples exhibited excellent expandability.

Industrial applicability

The workpiece processing sheet of the present invention can be suitably used for processing a workpiece such as a semiconductor wafer.

Claims

1. A sheet for processing a workpiece, comprising a base material and an adhesive layer laminated on one surface side of the base material,

the substrate comprises a surface layer close to the adhesive layer, a back layer far from the adhesive layer, and an intermediate layer between the surface layer and the back layer,

the elongation at break measured when a tensile test is performed on a test piece obtained by cutting the base material into a strip shape having a short side of 15mm under conditions of a chuck pitch of 100mm and a tensile rate of 200 mm/min at 23 ℃ is 600% or more in both MD direction stretching and CD direction stretching,

a ratio (R) of a tensile stress at 25% elongation measured when a tensile test is performed in which the substrate is stretched in the MD direction to a tensile stress at 25% elongation measured when a tensile test is performed in which the substrate is stretched in the CD direction _25％ ) The content of the organic acid is less than 1.3,

a ratio (R) of a tensile stress at 50% elongation measured when a tensile test is performed in which the substrate is stretched in the MD direction to a tensile stress at 50% elongation measured when a tensile test is performed in which the substrate is stretched in the CD direction _50％ ) Is 1.3 or less.

2. The sheet for processing a workpiece according to claim 1,

the surface layer, the intermediate layer, and the back layer each contain a polyolefin resin and a thermoplastic elastomer, and the surface layer and the back layer each contain an antistatic agent.

3. The sheet for processing a workpiece according to claim 2,

the intermediate layer is free of the antistatic agent, or

The intermediate layer contains the antistatic agent and is less than the respective contents of the antistatic agent in the surface layer and the back layer, the unit of the content being mass%.

4. The sheet for processing a workpiece according to claim 1,

the face layer, the intermediate layer, and the back layer each contain polyethylene,

the polyethylene contained in the intermediate layer has a Melt Flow Rate (MFR) measured according to JIS K7210-1 that is different from the polyethylene contained in each of the surface layer and the back layer.

5. The sheet for processing a workpiece according to any one of claims 1 to 4, wherein the sheet for processing a workpiece is a dicing sheet.