JP7784294B2 - Workpiece processing sheet, workpiece processing method, and use of workpiece processing sheet - Google Patents

Description

The present invention relates to a workpiece processing sheet used in processing workpieces such as semiconductor wafers, a workpiece processing method, and the use of the workpiece processing sheet.

Semiconductor wafers, such as silicon and gallium arsenide, and various packages are manufactured in large diameters, cut into chips (diced), peeled off (picked up), and then moved to the next process, the mounting process. During this process, the semiconductor wafer or other workpiece is stacked on an adhesive sheet (hereinafter sometimes referred to as the "workpiece processing sheet") that has a base material and an adhesive layer, and undergoes processing such as backgrinding, dicing, cleaning, drying, expanding, picking up, and mounting.

During the above pickup process, to facilitate chip pickup, the chips may be pushed up individually from the side of the workpiece processing sheet opposite the side on which the chips are stacked. In particular, to prevent chips from colliding with each other during pickup and to facilitate pickup, the workpiece processing sheet is usually stretched (expanded) to separate the chips. Therefore, the workpiece processing sheet is required to have excellent flexibility to enable good expansion.

Patent Document 1 discloses a dicing substrate film that includes a base layer and a surface layer, with the aim of providing a workpiece processing sheet with excellent expandability. The surface layer contains a specified polystyrene resin and a specified vinyl aromatic hydrocarbon-conjugated diene hydrocarbon copolymer or a hydrogenated product thereof.

Patent No. 6146616

Workpiece processing sheets are generally manufactured in a long length and wound around a core to form a roll. When winding the workpiece processing sheet onto such a roll or when unwinding the workpiece processing sheet from the roll, the workpiece processing sheet is transported using multiple guide rolls. At this time, the workpiece processing sheet may stick to the guide rolls, preventing smooth transport, and such sticking may cause wrinkles or sagging in the workpiece processing sheet.

Furthermore, when using a workpiece processing sheet, the workpiece processing sheet may stick to the tape mounter, etc., making it impossible to perform the desired operation.

For this reason, workpiece processing sheets are also required to have low friction to prevent them from sticking to guide rolls, tape mounters, etc.

The present invention was made in light of these circumstances, and aims to provide a workpiece processing sheet that has excellent expandability and low friction.

To achieve the above-mentioned objectives, the present invention first provides a workpiece processing sheet comprising a substrate and an adhesive layer laminated on one side of the substrate, wherein the fluorine atomic ratio on the side of the substrate opposite the adhesive layer, as measured by X-ray photoelectron spectroscopy (XPS), is 0.01 atm% or more and 2.5 atm% or less (Invention 1).

The workpiece processing sheet according to the above invention (Invention 1) has a substrate exhibiting the above-mentioned fluorine atomic ratio, thereby achieving excellent expandability while also exhibiting excellent low friction, which can prevent sticking to guide rolls, tape mounters, etc.

In the above invention (Invention 1), the fluorine atomic ratio is preferably 0.35 atm% or more (Invention 2).

In the above inventions (Inventions 1 and 2), the substrate preferably contains at least one of polytetrafluoroethylene (PTFE), ethylene tetrafluoroethylene copolymer (ETFE), polyvinylidene fluoride (PVDF), perfluoroalkoxyalkane (PFA), perfluoroethylene propene copolymer (FEP), polychlorotrifluoroethylene (PCTFE), and ethylene chlorotrifluoroethylene copolymer (ECTFE) (Invention 3).

In the above inventions (Inventions 1 to 3), it is preferable that the base material primarily comprises at least one resin selected from the group consisting of thermoplastic polyurethane and ethylene-(meth)acrylic acid copolymer (Invention 4).

In the above inventions (Inventions 1 to 4), the static friction force measured between the substrate side surface of the workpiece processing sheet and the aluminum plate at a load of 1.96 N and a tensile speed of 100 mm/min in accordance with JIS K7125:1999 is preferably 0.001 N or more and 4.0 N or less (Invention 5).

In the above inventions (Inventions 1 to 5), it is preferable that the substrate have a breaking elongation of 400% or more and 1000% or less in a tensile test conducted at 23°C (Invention 6).

In the above inventions (Inventions 1 to 6), it is preferable that the substrate has a breaking strength of 20 N/15 mm or more and 90 N/15 mm or less in a tensile test carried out at 23° C. (Invention 7).

Secondly, the present invention provides a workpiece processing method characterized by comprising a laminating step of laminating multiple workpieces on the adhesive layer side of the workpiece processing sheet (Inventions 1 to 7), and an expanding step of stretching the workpiece processing sheet on which the multiple workpieces are stacked, thereby separating the multiple workpieces from one another (Invention 8).

Third, the present invention provides a use of the workpiece processing sheet (Inventions 1 to 7) in a workpiece processing method, characterized in that the workpiece processing method comprises a laminating step of laminating multiple workpieces on the adhesive layer side of the workpiece processing sheet, and an expanding step of stretching the workpiece processing sheet on which the multiple workpieces are stacked, thereby separating the multiple workpieces from one another (Invention 9).

The workpiece processing sheet of the present invention has excellent expandability and low friction.

1 is a cross-sectional view of a workpiece processing sheet according to one embodiment of the present invention. FIG. 1 is a diagram for explaining a test for evaluating low friction properties.

Hereinafter, an embodiment of the present invention will be described.
A cross-sectional view of a workpiece processing sheet according to one embodiment is shown in Fig. 1. The workpiece processing sheet 1 shown in Fig. 1 includes a substrate 11 and an adhesive layer 12 laminated on one side of the substrate 11.

In the workpiece processing sheet 1 according to this embodiment, the fluorine atomic ratio measured by X-ray photoelectron spectroscopy (XPS) on the surface of the substrate 11 opposite the adhesive layer 12 is 0.01 atm% or more and 2.5 atm% or less.

The workpiece processing sheet 1 according to this embodiment has excellent low friction because the fluorine atomic ratio is 0.01 atm% or higher. This effectively reduces the frictional force generated between the substrate 11 side of the workpiece processing sheet 1 and guide rolls, tape mounters, etc., making it less likely to stick to the guide rolls, tape mounters, etc. As a result, the workpiece processing sheet 1 according to this embodiment can be easily transported and used, and the occurrence of wrinkles and sagging in the workpiece processing sheet 1 due to sticking can be effectively suppressed. From the perspective of making it easier to achieve even better low friction, the fluorine atomic ratio is preferably 0.35 atm% or higher, and more preferably 1.0 atm% or higher.

Furthermore, the workpiece processing sheet 1 according to this embodiment exhibits excellent expandability due to the fluorine atomic ratio being 2.5 atm% or less. Generally, when a specific additive is added to the substrate 11 to impart desired performance, the flexibility of the substrate 11 is impaired, which can reduce expandability. As described below, the workpiece processing sheet 1 according to this embodiment can achieve a fluorine atomic ratio of 0.01 atm% or more by adding specific components to the substrate. However, by keeping the fluorine atomic ratio at 2.5 atm% or less, it is possible to achieve both the excellent low friction and excellent expandability described above. From the perspective of making it easier to achieve both excellent low friction and excellent expandability at a higher level, the fluorine atomic ratio is preferably 2.3 atm% or less, and more preferably 1.8 atm% or less.

Details of the method for measuring the above-mentioned fluorine atom ratio are as described in the test examples below.

1. Structure of the Workpiece Processing Sheet (1) Substrate The structure and composition of the substrate 11 in this embodiment are not particularly limited as long as it exhibits the above-mentioned fluorine atomic ratio. An example of a suitable composition of the substrate 11 is one in which a predetermined amount of a fluorine-containing compound is added to a resin as the main component.

(1-1) Resin as Main Component While examples of the resin as the main component mentioned above are not particularly limited, it is preferable to use at least one resin selected from the group consisting of thermoplastic polyurethane and ethylene-(meth)acrylic acid copolymer. Substrates composed of these resins generally tend to have high frictional forces with guide rolls, etc. Therefore, substrates composed of these resins can effectively benefit from the low friction effect achieved by the workpiece processing sheet 1 according to this embodiment. Note that, in this specification, "(meth)acrylic acid" refers to both acrylic acid and methacrylic acid. The same applies to other similar terms. Furthermore, "copolymer" also includes the concept of a "polymer" composed of a single monomer.

The thermoplastic polyurethane is not particularly limited, and examples thereof include resins obtained by reacting an isocyanate with a polyol. Examples of diisocyanates include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, and hexamethylene diisocyanate. Examples of polyols include polyester polyols such as lactone-based polyester polyols and adipate-based polyester polyols; polyether polyols such as polypropylene (ethylene) polyols and polytetramethylene ether glycol; and polycarbonate polyols.

As the thermoplastic polyurethane according to this embodiment, it is preferable to use an ether-type thermoplastic polyurethane obtained using a polyol containing an ether bond. By using this ether-type thermoplastic polyurethane, it becomes easier to achieve both low friction and expandability.

Examples of the ethylene-(meth)acrylic acid copolymer include ethylene-acrylic acid copolymer and ethylene-methacrylic acid copolymer, with ethylene-methacrylic acid copolymer being preferred.

Resins other than those mentioned above may also be used as the main component of the substrate 11. Examples of such resins include polyester-based resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; ethylene-vinyl acetate copolymers; ethylene-methyl (meth)acrylate copolymers; and other ethylene-(meth)acrylate ester copolymers; polyolefin-based resins such as polyethylene, polypropylene, polybutene, polybutadiene, polymethylpentene, ethylene-norbornene copolymers, and norbornene resins; polyvinyl chloride-based resins such as polyvinyl chloride and vinyl chloride copolymers; (meth)acrylate ester copolymers; polyimides; polystyrenes; polycarbonates; and fluororesins.

The above resins may be used alone or in combination of two or more.

In this specification, the term "main component" in relation to the substrate refers to a component that accounts for more than 50% by mass of all components constituting the substrate, particularly a component that accounts for 60% by mass or more, and even more particularly a component that accounts for 70% by mass or more.

(1-2) Fluorine-containing compound Examples of the above-mentioned fluorine-containing compound are not particularly limited, but it is preferable to use at least one of polytetrafluoroethylene (PTFE), ethylene tetrafluoroethylene copolymer (ETFE), polyvinylidene fluoride (PVDF), perfluoroalkoxyalkane (PFA), perfluoroethylene propene copolymer (FEP), polychlorotrifluoroethylene (PCTFE), and ethylene chlorotrifluoroethylene copolymer (ECTFE). By using these, it becomes easier to achieve both excellent low friction and excellent expandability.

The polytetrafluoroethylene may be in powder form, for example. In this case, the substrate 11 can be produced using a mixture in which powdered polytetrafluoroethylene is added to a resin that serves as the main component. Note that the polytetrafluoroethylene may remain in powder form in the substrate 11 thus obtained.

The polytetrafluoroethylene preferably has a number average molecular weight of 10,000 or more, particularly preferably 100,000 or more, and even more preferably 1,000,000 or more. The number average molecular weight is also preferably 10,000,000 or less, particularly preferably 7,000,000 or less, and even more preferably 5,000,000 or less. Using polytetrafluoroethylene with a number average molecular weight within the above range makes it easier to achieve both excellent low friction and excellent expandability.

The polytetrafluoroethylene content in substrate 11 is preferably 0.001% by mass or more, particularly preferably 0.03% by mass or more, and even more preferably 0.1% by mass or more. Furthermore, this content is preferably 80% by mass or less, particularly preferably 60% by mass or less, and even more preferably 50% by mass or less. By containing polytetrafluoroethylene in substrate 11 within these ranges, it becomes easier to achieve the fluorine atom ratio described above.

(1-3) Other Compositions and Components The substrate 11 may be composed of a resin whose main component is a resin that itself contains fluorine atoms. That is, the substrate 11 may be composed of a resin in which functional groups containing fluorine atoms have been introduced into the resin that is the main component. In this case, the substrate 11 does not need to contain a compound containing fluorine.

The substrate 11 may also contain components other than those described above. 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 it is preferable to set it within a range that allows the substrate to exhibit the desired functions.

(1-4) Surface Treatment of Substrate The surface of the substrate 11 on which the pressure-sensitive adhesive layer 12 is laminated may be subjected to surface treatment such as primer treatment, corona treatment, plasma treatment, roughening treatment (matt processing), etc. in order to improve adhesion to the pressure-sensitive adhesive layer 12. Examples of roughening treatment include embossing and sandblasting.

(1-5) Method for Producing Substrate The method for producing the substrate 11 in this embodiment is not particularly limited, and for example, melt extrusion methods such as inflation, T-die, and round die methods; calendaring methods; solution methods such as dry and wet methods, etc. Among these, from the viewpoint of efficiently producing the substrate, it is preferable to employ the melt extrusion method, and it is particularly preferable to employ the inflation method.

When the above-mentioned fluorine-containing compound is used as the material for the substrate 11, the main component resin and the compound can be melt-kneaded and then extruded using a known extruder to form a film.

(1-6) Physical Properties of the Substrate The substrate 11 in this embodiment preferably has a breaking elongation of 400% or more, particularly preferably 450% or more, and even more preferably 520% or more, in a tensile test performed at 23°C. The substrate 11 according to this embodiment is easily able to achieve such a relatively high breaking elongation when the fluorine atom ratio is within the above-mentioned range. Furthermore, a breaking elongation of 500% or more makes it easy to exhibit excellent expandability. The upper limit of the breaking elongation is not particularly limited, and may be, for example, 1000% or less, particularly 950% or less, or even 900% or less. Details of the method for measuring the breaking elongation are as described in the test examples below.

Furthermore, the base material 11 in this embodiment preferably has a breaking strength of 90 N/15 mm or less, and particularly preferably 85 N/15 mm or less, in a tensile test conducted at 23°C. By ensuring that the fluorine atom ratio of the base material 11 in this embodiment is within the aforementioned range, the strength (stress) at break can be kept within this range. Furthermore, a breaking strength of 90 N/15 mm or less facilitates the exhibiting of excellent expandability. The lower limit of the breaking strength is not particularly limited, and may be, for example, 20 N/15 mm or more, particularly 40 N/15 mm or more, or even 60 N/15 mm or more. Details of the method for measuring the breaking strength are as described in the test examples below.

In this embodiment, the thickness of the substrate 11 is preferably 50 μm or more, particularly preferably 60 μm or more, and even more preferably 80 μm or more. Having a thickness of the substrate 11 of 50 μm or more ensures excellent handleability of the workpiece processing sheet 1 according to this embodiment. Furthermore, the thickness of the substrate 11 is preferably 200 μm or less, particularly preferably 180 μm or less, and even more preferably 150 μm or less. Having a thickness of the substrate 11 of 200 μm or less makes it easier to achieve excellent expandability.

(2) Pressure-sensitive adhesive layer In this embodiment, the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 12 is not particularly limited as long as it can exert sufficient adhesive strength to the adherend (particularly, adhesive strength to the workpiece sufficient for processing the workpiece). Examples of pressure-sensitive adhesives constituting the pressure-sensitive adhesive layer 12 include acrylic pressure-sensitive adhesives, rubber pressure-sensitive adhesives, silicone pressure-sensitive adhesives, urethane pressure-sensitive adhesives, polyester pressure-sensitive adhesives, polyvinyl ether pressure-sensitive adhesives, etc. Among these, it is preferable to use acrylic pressure-sensitive adhesives because they can easily exert the desired adhesive strength.

The adhesive constituting the adhesive layer 12 in this embodiment may be an adhesive that is not active energy ray curable, or it may be an adhesive that is active energy ray curable (hereinafter, sometimes referred to as an "active energy ray curable adhesive"). When the adhesive layer 12 is composed of an active energy ray curable adhesive, the adhesive layer 12 can be cured by irradiation with active energy rays, easily reducing the adhesive strength of the workpiece processing sheet 1 to the adherend. In particular, irradiation with active energy rays makes it possible to easily separate the processed workpiece from the workpiece processing sheet 1.

The above-mentioned non-active energy ray-curable adhesives and active energy ray-curable adhesives can be any known adhesives.

In this embodiment, the thickness of the adhesive layer 12 is preferably 1 μm or more, particularly preferably 3 μm or more, and even more preferably 5 μm or more. Furthermore, the thickness of the adhesive layer 12 is preferably 70 μm or less, particularly preferably 30 μm or less, and even more preferably 15 μm or less. By ensuring that the thickness of the adhesive layer 12 is within the above-mentioned range, the workpiece processing sheet 1 according to this embodiment is more likely to exhibit the desired adhesiveness.

(3) Release sheet In the workpiece processing sheet 1 according to this embodiment, a release sheet may be laminated on the side of the adhesive layer 12 opposite the substrate 11 (hereinafter sometimes referred to as the "adhesive side") in order to protect that side until it is attached to the workpiece.

The release sheet may be made of any material, including plastic films that have been treated with a release agent. Specific examples of such plastic films include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, and polyolefin films such as polypropylene and polyethylene. Silicone-based, fluorine-based, and long-chain alkyl-based release agents can be used, with silicone-based release agents being preferred due to their low cost and stable performance.

There are no particular restrictions on the thickness of the release sheet, and it may be, for example, 16 μm or more and 250 μm or less.

(4) Others: In the workpiece processing sheet 1 according to this embodiment, an adhesive layer may be laminated on the surface of the adhesive layer 12 opposite the substrate 11. In this case, the workpiece processing sheet 1 according to this embodiment can be used as a dicing/die bonding sheet. By attaching a workpiece to the adhesive layer on the surface opposite the adhesive layer 12 and dicing the adhesive layer together with the workpiece, a chip can be obtained in which the individual adhesive layers are laminated. The individual adhesive layers allow the chip to be easily fixed to the target on which it is to be mounted. Materials constituting the adhesive layer described above are preferably those containing a thermoplastic resin and a low-molecular-weight thermosetting adhesive component, or those containing a B-stage (semi-cured) thermosetting adhesive component.

In addition, in the workpiece processing sheet 1 according to this embodiment, a protective film forming layer may be laminated on the adhesive surface of the adhesive layer 12. In this case, the workpiece processing sheet 1 according to this embodiment can be used as a sheet for both protective film formation and dicing. With such a sheet, a workpiece is attached to the surface of the protective film forming layer opposite the adhesive layer 12, and the protective film forming layer is diced together with the workpiece to obtain a chip on which an individual protective film forming layer is laminated. It is preferable that the workpiece has a circuit formed on one side. In this case, the protective film forming layer is typically laminated on the surface opposite the surface on which the circuit is formed. By curing the individual protective film forming layer at a predetermined time, a protective film with sufficient durability can be formed on the chip. The protective film forming layer is preferably made of an uncured curable adhesive.

2. Physical Properties of the Workpiece Processing Sheet In the workpiece processing sheet 1 according to this embodiment, the static friction force measured between the surface of the substrate 11 and the aluminum plate in accordance with JIS K7125:1999 at a load of 1.96 N and a tensile speed of 100 mm/min is preferably 4.0 N or less, particularly preferably 3.5 N or less, and even more preferably 3.0 N or less. The substrate 11 according to this embodiment, having a fluorine atom ratio within the aforementioned range, easily achieves such a relatively low static friction force. Furthermore, a static friction force of 4.0 N or less easily exhibits excellent low friction properties. The lower limit of the static friction force is not particularly limited, and may be, for example, 0.001 N or more, particularly 0.005 N or more, or even 0.01 N or more. Details of the method for measuring the static friction force are as described in the test examples below.

3. Manufacturing Method of Workpiece Processing Sheet There are no particular limitations on the manufacturing method of the workpiece processing sheet 1 according to this embodiment. For example, it is preferable to obtain the workpiece processing sheet 1 by forming the adhesive layer 12 on a release sheet, and then laminating one side of the substrate 11 on the surface of the adhesive layer 12 opposite the release sheet.

The pressure-sensitive adhesive layer 12 can be formed by a known method. For example, a coating liquid containing a pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer 12 and, if desired, a solvent or dispersion medium is prepared. The coating liquid is then applied to the releasable surface of a release sheet (hereinafter sometimes referred to as the "release surface"). The resulting coating film is then dried to form the pressure-sensitive adhesive layer 12.

The coating liquid described above can be applied by known methods, such as bar coating, knife coating, roll coating, blade coating, die coating, and gravure coating. The nature of the coating liquid is not particularly limited as long as it allows application, and it may contain the components for forming the adhesive layer 12 as a solute or as a dispersoid. The release sheet may be peeled off as a processing material, or it may protect the adhesive layer 12 until it is attached to the adherend.

When the adhesive composition used to form the adhesive layer 12 contains the crosslinking agent described above, it is preferable to change the drying conditions (temperature, time, etc.) or to perform a separate heat treatment to promote the crosslinking reaction between the polymer component in the coating film and the crosslinking agent, thereby forming a crosslinked structure with the desired density within the adhesive layer 12. Furthermore, to promote the above-mentioned crosslinking reaction sufficiently, after bonding the adhesive layer 12 and the substrate 11 together, the resulting product may be cured by, for example, leaving it to stand for several days in an environment of 23°C and a relative humidity of 50%.

4. How to Use the Workpiece Processing Sheet The workpiece processing sheet 1 according to this embodiment can be used to process workpieces such as semiconductor wafers. That is, after the adhesive surface of the workpiece processing sheet 1 according to this embodiment is attached to the workpiece, the workpiece can be processed on the workpiece processing sheet 1. Depending on the processing, the workpiece processing sheet 1 according to this embodiment can be used as a transfer sheet, back-grinding sheet, dicing sheet, expanding sheet, pickup sheet, etc. Examples of workpieces include semiconductor components such as semiconductor wafers and semiconductor packages, and glass components such as glass plates.

As mentioned above, the workpiece processing sheet 1 according to this embodiment has excellent low-friction properties on the substrate side, which effectively prevents sticking to guide rolls, tape mounters, etc., and the resulting problems. From this perspective, the workpiece processing sheet 1 according to this embodiment is suitable for use as a sheet transported by guide rolls or as a sheet handled using a tape mounter. More specifically, it is suitable for use as a transfer sheet, backgrinding sheet, dicing sheet, expanding sheet, or pickup sheet.

Furthermore, as mentioned above, the workpiece processing sheet 1 according to this embodiment also exhibits excellent expandability. From this perspective, the workpiece processing sheet 1 according to this embodiment is suitable for use as a sheet on which expansion takes place, and specifically, is suitable for use as a dicing sheet, expansion sheet, or pickup sheet.

More specifically, the workpiece processing sheet 1 according to this embodiment is suitable for use in a workpiece processing method or semiconductor device manufacturing method that includes a lamination step in which multiple workpieces are stacked on the surface of the workpiece processing sheet facing the adhesive layer 12, and an expansion step in which the workpieces are stretched to separate the multiple workpieces from one another. These methods may further include a pick-up step in which, after the expansion step, the multiple workpieces are individually picked up while they are spaced apart.

In the above-described method, the multiple workpieces are preferably chips obtained by dividing the aforementioned semiconductor material, glass material, or the like. In this case, multiple chips obtained by dividing in advance may be stacked on the workpiece processing sheet 1 according to this embodiment. Alternatively, multiple chips may be obtained by dividing the semiconductor material, glass material, or the like on the workpiece processing sheet 1 according to this embodiment. In the latter case, in the above-described method, instead of the above-described stacking step, a dicing step may be performed to divide the workpieces on the surface of the adhesive layer 12 opposite the substrate 11.

The above-mentioned stacking, dicing, expanding, and pick-up processes can each be performed using conventional techniques.

When the workpiece processing sheet 1 according to this embodiment is provided with the adhesive layer described above, the workpiece processing sheet 1 can be used as a dicing/die bonding sheet. Furthermore, when the workpiece processing sheet 1 according to this embodiment is provided with the protective film forming layer described above, the workpiece processing sheet 1 can be used as a protective film forming/dicing sheet.

Furthermore, when the adhesive layer 12 in the workpiece processing sheet 1 according to this embodiment is composed of the aforementioned active energy ray-curable adhesive, it is also preferable to irradiate it with active energy rays as follows during use. That is, when processing of a workpiece on the workpiece processing sheet 1 is completed and the processed workpiece is to be separated from the workpiece processing sheet 1, it is preferable to irradiate the adhesive layer 12 with active energy rays before the separation. This hardens the adhesive layer 12, effectively reducing the adhesive strength of the adhesive sheet to the processed workpiece, making it easier to separate the processed workpiece.

The above-described embodiments have been described to facilitate understanding of the present invention, and are not intended to limit the scope of the present invention. Therefore, each element disclosed in the above embodiments is intended to include all design modifications and equivalents that fall within the technical scope of the present invention.

For example, in the workpiece processing sheet 1 according to this embodiment, another layer may be laminated between the substrate 11 and the adhesive layer 12, or on the surface of the substrate 11 opposite the adhesive layer 12.

The present invention will be explained in more detail below using examples, but the scope of the present invention is not limited to these examples.

Example 1
(1) Preparation of substrate A mixture of ether-based thermoplastic polyurethane (Shore A hardness (measured according to JIS K 6253): 95, density: 1.12 g/cm ³ ) and polytetrafluoroethylene (PTFE) powder (manufactured by MC Yamasan Polymers Co., Ltd., product name “Ace Flon”) was fed into a single-layer inflation film-forming apparatus equipped with an extruder having a diameter of 100 mm.

The mixture was then melt-kneaded and extruded through a single-layer die at a temperature of 205°C to produce a 100 μm thick substrate film containing thermoplastic polyurethane as the main component.

The fluorine atomic ratio on one side of the substrate (the side opposite the side on which the adhesive layer will be laminated) was measured as described in Test Example 1 below and was found to be 0.37 atm%. Furthermore, the arithmetic mean roughness Ra of both sides of the substrate was measured (three measurements were taken and the average value was calculated) using a contact roughness meter (manufactured by Mitutoyo Corporation, product name "SV-3000") and was found to be 0.32 μm on one side (the side opposite the side on which the adhesive layer will be laminated) and 0.25 μm on the other side (the side on which the adhesive layer will be laminated).

(2) Preparation of Pressure-Sensitive Adhesive Composition 80 parts by mass of 2-ethylhexyl acrylate (2EHA), 10 parts by mass of methyl methacrylate (MMA), and 10 parts by mass of 2-hydroxyethyl acrylate (HEA) were polymerized by solution polymerization to obtain a (meth)acrylic acid ester polymer. The weight-average molecular weight (Mw) of the polymer was measured by the method described below and was found to be 580,000.

100 parts by mass (solids equivalent, same below) of the resulting (meth)acrylic acid ester polymer was mixed with 5 parts by mass of trimethylolpropane-modified tolylene diisocyanate (manufactured by Toyo Ink Co., Ltd., product name "BHS-8518") as a crosslinking agent in a solvent to obtain a coating liquid of an adhesive composition.

(3) Formation of adhesive layer The adhesive composition coating solution obtained in step (2) above was applied to the release surface of a release sheet (manufactured by Lintec Corporation, product name "SP-PET381031"), which was made by forming a silicone-based release agent layer on one side of a 38 μm thick polyethylene terephthalate (PET) film, and the resulting coating was dried by heating to form an adhesive layer with a thickness of 10 μm on the release sheet. This gave a laminate consisting of the release sheet and the adhesive layer.

(4) Preparation of workpiece processing sheet One side of the substrate obtained in the above step (1) (the side opposite to the side on which the fluorine atom ratio was measured) was bonded to the adhesive layer side of the laminate obtained in the above step (3), thereby obtaining a workpiece processing sheet.

Here, the weight average molecular weight (Mw) is a weight average molecular weight measured by gel permeation chromatography (GPC) under the following conditions (GPC measurement) and converted into standard polystyrene.
<Measurement conditions>
Measuring device: Tosoh Corporation, HLC-8320
GPC columns (passed in the following order): TSK gel super H-H manufactured by Tosoh Corporation
TSK gel superHM-H
TSK gel superH2000
Measurement solvent: tetrahydrofuran Measurement temperature: 40°C

[Examples 2 to 4 and Comparative Example 2]
A workpiece processing sheet was obtained in the same manner as in Example 1, except that the amount of PTFE powder added was changed so that the fluorine atom ratio of the substrate would be the value shown in Table 1.

Comparative Example 1
An ether-based thermoplastic polyurethane (Shore A hardness (measured according to JIS K 6253): 95, density: 1.12 g/cm ³ ) was supplied to a single-layer inflation film-making device equipped with a 100 mm diameter extruder. The resin was melt-kneaded and then introduced into a single-layer die at a temperature of 205°C and extruded to produce a 100 μm thick substrate containing thermoplastic polyurethane as the main component. A workpiece processing sheet was obtained in the same manner as in Example 1, except that the substrate thus obtained was used.

The fluorine atomic ratio on one side of the obtained substrate (the side opposite to the side on which the pressure-sensitive adhesive layer was laminated) was measured as described in Test Example 1 below, and was found to be 0.00 atm %.

Test Example 1 (Measurement of Fluorine Atom Ratio)
The workpiece processing sheets manufactured in the examples and comparative examples were cut to a size of 5 mm x 5 mm to obtain samples for measurement. Then, elemental analysis was performed on the substrate side of the samples using an X-ray photoelectron spectroscopy (XPS) device (manufactured by ULVAC, product name "PHI Quantera SXM"). Specifically, C1s, N1s, O1s, and F1s were measured, and the ratio of detected F1s was calculated as the fluorine atomic ratio (atm%). The measurement was performed twice for each sample, and the average value was calculated. The results are shown in Table 1.

Test Example 2 (Measurement of static friction force)
The static friction force (N) of the substrate side of the workpiece processing sheets manufactured in the examples and comparative examples against an aluminum plate was measured in accordance with JIS K7125:1999 at a load of 1.96 N and a pulling speed of 100 mm/min. The measurement was performed three times for each sample, and the average value was calculated. The results are shown in Table 1.

Test Example 3 (Measurement of breaking elongation and breaking strength)
The substrates used in the examples and comparative examples were cut to a size of 15 mm wide x 150 mm long to obtain samples for measurement. The samples were placed in a universal tensile tester (Shimadzu Corporation, product name "AG-IS") so that the stretchable portion was 100 mm. The samples were then pulled at 23°C and a pulling rate of 200 mm/min, and the elongation and stress (strength) at which the sample broke were defined as the breaking elongation (%) and breaking strength (N/15 mm), respectively. Measurements were performed three times for each sample in the extrusion direction (MD) during substrate preparation and in the direction perpendicular thereto (CD), and the average of these six measurements was calculated. The results are shown in Table 1.

Test Example 4 (Evaluation of low friction)
The workpiece processing sheets produced in the examples and comparative examples were manufactured into long pieces measuring 20 m in length and 30 cm in width. They were transported using four guide rolls, and the low friction properties of the workpiece processing sheets were evaluated by checking for any transport problems during transport.

Specifically, as shown in Figure 2, workpiece processing sheet 1 was unwound from workpiece processing sheet roll 2 and passed through guide rolls 3a, 3b, 3c, and 3d in this order before being wound onto winding core 30. The roll 2 used here was wound with the substrate side of workpiece processing sheet 1 facing outward. Therefore, during transport, the substrate side of workpiece processing sheet 1 came into contact with guide rolls 3b and 3d. The unwinding speed was 2 m/min.

The four guide rolls were each made of metal and had a diameter of 20 cm and a width of 60 cm. The distance between adjacent guide rolls was 40 cm. The winding core 4 was made of ABS and had a diameter of 3 inches.

The low friction was evaluated based on the following criteria, and the results are shown in Table 1.
◯: The surface on the substrate side did not stick to the guide roll, and all 20 m could be wound onto the winding core 4 satisfactorily.
Δ: Although wrinkles and slack occurred in the workpiece processing sheet 1 when it was wound onto the winding core 4, the entire 20 m could be wound onto the winding core 4 satisfactorily.
×: At least one of the following three problems occurred: the substrate side surface stuck to the guide roll, wrinkles or slack occurred in the work processing sheet 1 when it was wound onto the winding core 4, and the work processing sheet 1 wrapped around the guide roll, and good winding onto the winding core 4 was not possible.

Test Example 5 (Evaluation of Expandability)
The release sheet was peeled from the workpiece processing sheet produced in the Examples and Comparative Examples, and the exposed surface of the adhesive layer exposed was attached to a 6-inch ring frame. The workpiece processing sheet was cut to fit the outer diameter of the ring frame and then placed in an expansion tester (manufactured by JCM Corporation, product name "ME-300B"). The ring frame was then pulled down at a pull-down distance of 50 mm and a pull-down speed of 5 mm/s to expand the workpiece processing sheet. Based on the condition of the workpiece processing sheet at that time, the expandability was evaluated according to the following criteria. The results are shown in Table 1.
⊚: The workpiece processing sheet was able to expand without breaking or whitening due to yielding.
◯: The workpiece processing sheet was able to expand without breaking.
×: The workpiece processing sheet was broken or whitened due to yielding, and could not be expanded.

As is clear from Table 1, the workpiece processing sheets produced in the examples exhibited excellent low friction, allowing for good transportability, while also exhibiting excellent expandability.

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

1... Workpiece processing sheet 11... Substrate 12... Adhesive layer 2: Roll body 3a, 3b, 3c, 3d: Guide roll 4: Winding core

Claims (8)

A workpiece processing sheet comprising a substrate and an adhesive layer laminated on one side of the substrate,
the substrate contains at least one resin selected from thermoplastic polyurethane and ethylene-(meth)acrylic acid copolymer as a main component, and also contains at least one of polytetrafluoroethylene (PTFE), ethylene tetrafluoroethylene copolymer (ETFE), polyvinylidene fluoride (PVDF), perfluoroalkoxyalkane (PFA), perfluoroethylene propene copolymer (FEP), polychlorotrifluoroethylene (PCTFE), and ethylene chlorotrifluoroethylene copolymer (ECTFE);
A workpiece processing sheet characterized in that the fluorine atomic ratio measured by X-ray photoelectron spectroscopy (XPS) on the surface of the substrate opposite the adhesive layer is 0.01 atm% or more and 2.5 atm% or less. The workpiece processing sheet according to claim 1, characterized in that the fluorine atomic ratio is 0.35 atm% or more. 3. The workpiece processing sheet according to claim 1, wherein the base material is mainly composed of ether-based thermoplastic polyurethane and also contains polytetrafluoroethylene powder. The workpiece processing sheet according to any one of claims 1 to 3, characterized in that the static friction force between the substrate side surface of the workpiece processing sheet and an aluminum plate, measured in accordance with JIS K7125:1999 at a load of 1.96 N and a tensile speed of 100 mm/min, is 0.001 N or more and 4.0 N or less. The workpiece processing sheet according to any one of claims 1 to 4 , characterized in that the substrate has a breaking elongation of 400% or more and 1000% or less in a tensile test carried out at 23°C. The workpiece processing sheet according to any one of claims 1 to 5 , characterized in that the base material has a breaking strength of 20 N/15 mm or more and 90 N/15 mm or less in a tensile test conducted at 23°C. a lamination step of laminating a plurality of workpieces on the adhesive layer side of the workpiece processing sheet according to any one of claims 1 to 6 ;
and an expanding step of stretching the workpiece processing sheet on which the plurality of workpieces are stacked to separate the plurality of workpieces from one another. Use of the workpiece processing sheet according to any one of claims 1 to 6 for a workpiece processing method,
The workpiece machining method includes:
a lamination step of laminating a plurality of workpieces on the adhesive layer side of the workpiece processing sheet;
and an expanding step of stretching the workpiece processing sheet on which the plurality of workpieces are stacked to separate the plurality of workpieces from one another.