Protective sheet

Abstract

This protective sheet is provided with: a protective layer that is affixed to an adherend; and a release liner disposed on the surface of the protective layer, the protective layer containing a water-soluble polymer, the release liner having an inner surface facing the protective layer and an outer surface opposite the inner surface, the light transmittance from the outer surface of the release liner to the transmission of the protective layer is 15% or more lower than the light transmittance of the release liner at at least one wavelength.

Description

[0001] Cross-references between related applications

[0002] This application claims the benefit of priority from Japanese Patent Application No. 2022-110748, the disclosure of which is incorporated herein by reference. Technical Field

[0003] The present invention relates to a protective sheet. Background Art

[0004] Conventionally, in the manufacture of semiconductor elements such as semiconductor chips and electronic components such as liquid crystal display devices, it is known to use adhesive protective sheets to prevent foreign matter from adhering to the electronic components (for example, Patent Document 1 below).

[0005] Patent Document 1 listed below discloses a protective sheet including a protective layer formed from a resin composition containing an oxyalkylene group-containing polyvinyl alcohol-based resin and two release sheets disposed on both sides of the protective layer.

[0006] In the production of the above-mentioned electronic components, semiconductor chips are generally produced by dividing (slicing) a single semiconductor wafer (for example, see Patent Document 2 below).

[0007] For example, Patent Document 2 listed below discloses that semiconductor chips are manufactured as follows.

[0008] (1) A plurality of planned dividing lines are formed in a grid pattern on one surface side of a silicon wafer.

[0009] (2) Circuit patterns are formed and electrodes are arranged in each of the regions divided into a grid pattern by the plurality of planned dividing lines (hereinafter also referred to as grid-shaped divided regions). In this way, a semiconductor wafer for obtaining semiconductor chips is manufactured.

[0010] (3) The semiconductor wafer is divided (cut) along the plurality of planned dividing lines, in other words, the semiconductor wafer is divided (cut) according to the grid-shaped divided areas to obtain a plurality of semiconductor chips.

[0011] Prior art literature

[0012] Patent Literature

[0013] Patent Document 1: Japanese Patent Application Laid-Open No. 2021-161735

[0014] Patent Document 2: Japanese Patent Application Laid-Open No. 2012-119670 Summary of the Invention

[0015] Problems to be solved by the invention

[0016] As described above, when a single semiconductor wafer is divided (cut) to obtain a plurality of semiconductor chips, a portion of the semiconductor wafer near the divided portion (cut portion) may be pulverized, thereby generating a small amount of dust.

[0017] Furthermore, if such dust adheres to one surface side (the side where the circuit pattern is formed) of the semiconductor chip, the operational reliability of the circuit included in the circuit pattern formed on the one surface side may be reduced, which is not preferable.

[0018] Therefore, it is considered that the protective sheet is attached to one surface side (the side where the circuit pattern is formed) of the semiconductor wafer to protect the semiconductor chip when manufacturing the semiconductor chip.

[0019] As such a protective sheet, it is considered useful to have a water-soluble protective layer that can be easily removed from an adherend such as a semiconductor wafer after use.

[0020] When attaching a protective sheet to an adherend such as a semiconductor wafer, the following methods are possible: placing the protective sheet cut into a predetermined shape in a laminating device and attaching it to the adherend; or directly attaching the protective sheet cut into a predetermined shape to the adherend.

[0021] Furthermore, it is believed that providing a gripping portion on the release liner is effective in aligning the protective layer when placed in a laminating apparatus or directly attached to an adherend, and in facilitating the removal of the release liner from the protective layer.

[0022] However, this will cause the release liner to protrude outward from the outer periphery of the protective layer, and the outer periphery of the release liner and the outer periphery of the protective layer will no longer be aligned. Therefore, it may be difficult to accurately determine the position of the protective layer from the release liner side, making it difficult to align the protective layer.

[0023] Therefore, a technical problem of the present invention is to provide a protective sheet in which the protective layer can be easily aligned with respect to a transfer device, an adherend, and the like.

[0024] Solutions for solving problems

[0025] The protective sheet of the present invention comprises: a protective layer to be adhered to an adherend; and a release liner disposed on a surface of the protective layer, wherein the protective layer comprises a water-soluble polymer, the release liner comprises an inner surface opposing the protective layer and an outer surface opposite the inner surface, and the light transmittance of the release liner from the outer surface to the point of passing through the protective layer is lower than the light transmittance of the release liner by at least 15% at at least one wavelength.

[0026] Furthermore, the protective sheet of the present invention comprises: a protective layer adhered to an adherend; a first release liner disposed on one surface of the protective layer; and a second release liner disposed on the other surface of the protective layer, wherein the protective layer comprises a water-soluble polymer compound, the first release liner and the second release liner each comprising an inner surface opposing the protective layer and an outer surface opposite to the inner surface, and the light transmittance from the outer surface of the second release liner to the outer surface of the first release liner is lower than the light transmittance of the second release liner at at least one wavelength by 15% or more. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1A This is a schematic cross-sectional view showing the structure of a protective sheet according to one embodiment of the present invention.

[0028] Figure 1B This is a schematic cross-sectional view showing the structure of a protective sheet according to another embodiment of the present invention.

[0029] Figure 2A This is a schematic cross-sectional view showing one mode of cutting the protective layer in the protective sheet according to one embodiment of the present invention.

[0030] Figure 2B This is a schematic cross-sectional view showing one mode of cutting the protective layer when obtaining a protective sheet according to another embodiment of the present invention.

[0031] Figure 2C This is a schematic cross-sectional view showing an example in which a first release liner is bonded to the exposed surface of the protective layer to obtain a protective sheet according to another embodiment.

[0032] Figure 3A This is a schematic cross-sectional view showing a state in which a sensing device is used to detect the position of a protective layer obtained by post-precutting.

[0033] Figure 3B This is a schematic cross-sectional view showing a state in which a protective layer obtained by post-cutting is attached to a surface to be protected of a semiconductor wafer using a mounting device.

[0034] Figure 3C It is a schematic cross-sectional view showing a state where a protective layer is bonded to the surface to be protected of a semiconductor wafer.

[0035] Figure 4A This is a schematic cross-sectional view showing a state in which a sensing device is used to detect the position of a protective layer obtained by pre-cutting.

[0036] Figure 4B This is a schematic cross-sectional view showing a state in which a protective layer obtained by pre-cutting is bonded to a surface to be protected of a semiconductor wafer using a laminating device.

[0037] Figure 4C It is a schematic cross-sectional view showing a state where a protective layer is bonded to the surface to be protected of a semiconductor wafer. DETAILED DESCRIPTION

[0038] Hereinafter, one embodiment of the present invention will be described.

[0039] [Protective sheet according to the first embodiment]

[0040] like Figure 1A and Figure 1B As shown, a protective sheet 10 according to a first embodiment of the present invention includes: a protective layer 1 ; a first release liner 2 disposed on one surface of the protective layer 1 ; and a second release liner 3 disposed on the other surface of the protective layer 1 .

[0041] In the protective sheet 10 of the first embodiment, the protective layer 1 contains a water-soluble polymer compound.

[0042] That is, the protective layer 1 is water-soluble.

[0043] On the other hand, the first release liner 2 and the second release liner 3 are water-insoluble.

[0044] The protective layer 1 of the present embodiment has adhesiveness sufficient to be attached to an adherend.

[0045] The protective layer 1 of this embodiment preferably has adhesiveness (pressure-sensitive adhesiveness).

[0046] The protective sheet 10 of the present embodiment is used to prevent foreign matter from adhering to the surface of an adherend while the adherend is subjected to various treatments by attaching the protective layer 1 to the adherend.

[0047] It should be noted that, in this embodiment, the adherend is a semiconductor wafer.

[0048] The first release liner 2 and the second release liner 3 are each attached to the protective layer 1 in order to prevent foreign matter from adhering to the protective layer 1 before being attached to the semiconductor wafer.

[0049] Each of the first release liner 2 and the second release liner 3 includes an inner surface facing the protective layer 1 and an outer surface opposite to the inner surface.

[0050] The protective sheet 10 of the present embodiment is used by peeling off the second release liner 3 and affixing the other surface of the protective layer 1 to a semiconductor wafer.

[0051] In this embodiment, as described below, the protection target surface of the adherend and the protective layer 1 are accurately positioned, and then the protective layer 1 is attached to the protection target surface.

[0052] Positioning can be indirect rather than direct.

[0053] For example, when protective layer 1 is placed in a laminating device or the like that is intended to place an adherend at a predetermined position and is bonded to the adherend using the laminating device, positioning of protective layer 1 relative to the adherend can be achieved by positioning protective layer 1 in the laminating device.

[0054] In the present embodiment, at the time of positioning, the protective layer 1 is not bonded to the entire surface of the second release liner 3 but partially covers the inner surface of the second release liner 3 .

[0055] Furthermore, the protective sheet 10 during positioning in this embodiment includes: a laminated region where the second release liner 3 and the protective layer 1 are laminated; and a single layer region where the second release liner 3 is not laminated with the protective layer 1 but only with the second release liner 3, and the single layer region is provided to surround the laminated region.

[0056] In the protective sheet 10 of the first embodiment, the light transmittance of the second release liner 3 is higher than the transmittance of the protective layer 1 , the first release liner 2 , or the laminate of the protective layer 1 and the first release liner 2 .

[0057] More specifically, in this embodiment, the transmittance of light from the outer surface of the second release liner to the light passing through the protective layer 1 is lower than the transmittance of the second release liner 3 by more than 15% at at least one wavelength, or the transmittance of light from the outer surface of the second release liner 3 to the outer surface of the first release liner 2 is lower than the transmittance of the second release liner 3 by more than 15% at at least one wavelength.

[0058] In the protective sheet 10 of the first embodiment, the transmittance T of the second release liner 3 measured at one wavelength included in the near-infrared region is A and the transmittance T of the protective layer 1 measured at the one wavelength B The difference is set as ΔT AB , the transmittance T A The transmittance T of the first release liner 2 measured at the one wavelength is C The difference is set as ΔT AC , the transmittance T A The transmittance T of the laminate of the protective layer 1 and the first release liner 2 measured at the one wavelength is D The difference is set as ΔT AD When the ΔT AB , the ΔT AC or the ΔT AD More than 15%.

[0059] In addition, in this specification, the near-infrared region refers to a region with a wavelength of 800 nm to 2500 nm.

[0060] Furthermore, in the first embodiment of the present invention, it is preferable to use a wavelength of 1060 nm as one of the wavelengths included in the near-infrared region.

[0061] The protective layer 1 is bonded to the surface to be protected of the electronic component.

[0062] Examples of the electronic components include semiconductor wafers and the like.

[0063] Examples of the semiconductor wafer include one having a surface side formed with regions divided into a grid (hereinafter also referred to as grid-shaped divided regions), each of which has a circuit pattern formed therein and an electrode portion arranged therein.

[0064] When the electronic component is a semiconductor wafer as described above, the protective layer 1 is bonded to one surface of the semiconductor wafer for use.

[0065] In this way, by adhering the protective layer 1 to one surface of the semiconductor wafer, when the semiconductor wafer is divided (cut) to obtain a plurality of semiconductor chips, it is possible to prevent a part of the semiconductor wafer near the dividing portion (cutting portion) from being pulverized, etc., and thereby preventing fine foreign matter from adhering to the circuit patterns formed on the one surface and the electrode portions arranged on the one surface.

[0066] It should be noted that the circuit patterns are circuit patterns formed for each of the grid-shaped partitioned regions, and the electrode portions are electrode portions arranged for each of the grid-shaped partitioned regions.

[0067] exist Figure 1A In the protective sheet 10 shown, the protective layer 1 , the first release liner 2 , and the second release liner 3 have substantially the same size in a plan view.

[0068] Furthermore, the protective layer 1 generally has a size larger than the surface to be protected of the electronic component in a plan view.

[0069] The protection sheet 10 of the present embodiment is used for protecting a semiconductor wafer, for example, as follows.

[0070] (a) After laminating one and the other release liners (2, 3) on both sides of the protective layer 1 to obtain the protective sheet, the laminate is cut in such a manner that the planar size of the laminate of one release liner (first release liner 2) and the protective layer 1 is approximately the same as the planar size of the one semiconductor wafer (post-pre-cutting method).

[0071] That is, in the post-precut method, the protective sheet 10 is constructed such that the protective layer 1 is sandwiched between a release liner (the second release liner 3) having a larger planar dimension than the protective layer 1 and a release liner (the first release liner 2) having approximately the same planar dimension as the protective layer 1.

[0072] The protective sheet 10 of this embodiment is also used for protecting a semiconductor wafer as follows.

[0073] (b) After laminating one release liner (first release liner 2) on one surface of the protective layer 1, only the protective layer 1 is cut so that its planar dimensions are substantially the same as those of the semiconductor wafer (pre-cut method). Then, another release liner having a planar dimension larger than that of the protective layer 1 (e.g., a release liner having a planar dimension substantially the same as that of the first release liner (second release liner 3)) is laminated on the other surface of the cut protective layer 1.

[0074] That is, in the pre-cut method, the protective sheet 10 is configured such that the protective layer 1 is sandwiched between two release liners (one and the other release liners) having a larger planar dimension than the protective layer 1 .

[0075] As described in (a) above, in one aspect of this embodiment, when the protective layer 1 is attached to the surface to be protected of the electronic component, the protective layer 1 is cut from the first release liner 2 side so as to have a planar dimension substantially the same as that of the surface to be protected of the electronic component while forming a laminate with the first release liner 2 (see Figure 2A ).

[0076] That is, in Figure 1A In the protective sheet 10 shown, the protective layer 1 is formed by a post-cutting method to have substantially the same size as the surface to be protected of the electronic component.

[0077] exist Figure 1A In the protective sheet 10 shown, the first release liner 2 and the second release liner 3 have substantially the same size in a plan view, and the planar size thereof is larger than the surface to be protected of the electronic component.

[0078] In contrast, in Figure 1B In the protective sheet 10 shown, the protective layer 1 has substantially the same size as the surface to be protected of the electronic component in a plan view.

[0079] Specifically, the protective layer 1 is cut after forming a laminate with one release liner, for example, the first release liner 2 (see Figure 2B ) and made into a plane size roughly the same as the protected surface of the electronic component.

[0080] That is, in Figure 1BIn the protective sheet 10 shown, the protective layer 1 is pre-cut to have substantially the same size as the surface of the electronic component to be protected.

[0081] It should be noted that the other release liner, for example, the second release liner 3, is attached to the exposed surface of the protective layer 1 after the protective layer 1 is cut (see Figure 2C ).

[0082] The second release liner 3 may be in the form of an elongated tape having a long dimension and a short dimension.

[0083] The protective sheet 10 includes a strip-shaped second release liner 3 and a plurality of protective layers 1 having the same shape as the protected surface. The plurality of protective layers 1 may be arranged in the longitudinal direction of the second release liner 3 or a certain distance may be provided between adjacent protective layers 1 in the longitudinal direction.

[0084] In this case, the first release liner 2 may be in a tape shape like the second release liner 3 , and may have the same shape as the surface to be protected like the protective layer 1 .

[0085] The second release liner 3 may be larger than the protective layer 1 in both the longitudinal direction and the transverse direction.

[0086] That is, in the protective sheet 10 , the second release liner 3 may protrude outward from the outer peripheral edge of the protective layer 1 , and the second release liner 3 may protrude over the entire circumference of the protective layer 1 .

[0087] The protection sheet 10 can be produced, for example, as follows.

[0088] (1) Using an applicator or the like, a water-soluble resin composition containing a water-soluble polymer compound together with the remaining liquid component is applied to the first release liner 2 to a predetermined thickness (eg, 10 μm).

[0089] (2) The applied water-soluble resin composition is dried at a predetermined temperature for a predetermined time (eg, 110° C. for 2 minutes). Thus, a protective layer 1 containing a water-soluble polymer compound is formed on the first release liner 2 .

[0090] (3) The second release liner 3 is bonded to the surface of the protective layer 1 opposite to the surface on which the first release liner 2 is arranged (the exposed surface of the protective layer 1 ).

[0091] It should be noted that in Figure 1B In the production of the protective sheet 10 shown in FIG. 1 , between the above steps (2) and (3), a step of cutting the protective layer 1 so as to have a planar dimension substantially the same as that of the surface to be protected of the electronic component is performed (step (2'), see FIG. Figure 2B ).

[0092] In the protective sheet 10 of the first embodiment, the protective layer 1 is preferably produced using a composition obtained by dispersing the water-soluble polymer compound in water (hereinafter referred to as a protective layer-forming composition) as a water-soluble resin composition containing the water-soluble polymer compound and the remaining liquid component.

[0093] The protective layer-forming composition preferably contains 5 parts by mass or more and 80 parts by mass or less of the water-soluble polymer compound, more preferably 10 parts by mass or more and 70 parts by mass or less of the water-soluble polymer compound, and further preferably 15 parts by mass or more and 60 parts by mass or less of the water-soluble polymer compound, relative to 100 parts by mass of water.

[0094] Furthermore, in the protective layer-forming composition, it is preferred that the water-soluble polymer compound be dissolved in water.

[0095] In addition, in the protective layer-forming composition, the water-soluble polymer compound can be dissolved in water by treating the composition at a temperature of 20° C. to 90° C.

[0096] Furthermore, the viscosity of the protective layer-forming composition at 25° C. is preferably 0.03 Pa·s or more, more preferably 0.05 Pa·s or more, and even more preferably 0.1 Pa·s or more.

[0097] By setting the viscosity at 25° C. to be equal to or higher than the above lower limit, when the protective layer-forming composition is applied onto the first release liner 2 to form the protective layer 1 on the first release liner 2 , the thickness of the protective layer 1 can be prevented from easily fluctuating.

[0098] Furthermore, the viscosity of the protective layer-forming composition at 25° C. is preferably 15 Pa·s or less, more preferably 10 Pa·s or less, and even more preferably 5 Pa·s or less.

[0099] By setting the viscosity at 25° C. to be below the above upper limit, the coating properties when the protective layer-forming composition is applied onto the first release liner 2 can be improved.

[0100] The viscosity of the protective layer-forming composition at 25° C. can be measured using a digital viscometer (product name “DV-IPrime”) manufactured by Eiko Seiki Co., Ltd., using an LV-3 spindle at a rotation speed of 50 rpm.

[0101] Examples of the water-soluble polymer compound include polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP), water-soluble polyester (PES), and polyethylene oxide (PEO).

[0102] As the water-soluble polymer compound, polyvinyl alcohol, polyvinyl pyrrolidone, water-soluble polyester, polyethylene oxide, etc. may be used alone or in combination of two or more thereof.

[0103] As the water-soluble polymer compound, at least one selected from the group consisting of polyvinyl alcohol, water-soluble polyester, and polyethylene oxide is preferably used, and polyvinyl alcohol is more preferably used.

[0104] The saponification degree of the polyvinyl alcohol is preferably 50 or more and 98 or less, and more preferably 60 or more and 90 or less.

[0105] When the saponification degree is within the above numerical range, the polyvinyl alcohol can exhibit sufficient water solubility. In addition, when the protective layer-forming composition contains the polyvinyl alcohol, the protective layer-forming composition can be applied to the first release liner 2 with good workability.

[0106] The saponification degree of the polyvinyl alcohol can be determined by proton nuclear magnetic resonance spectroscopy ( 1 H-NMR determination method).

[0107] When the measurement sample contains an additive and a peak derived from the additive overlaps with a peak used for calculating the saponification degree, the saponification degree of the polyvinyl alcohol is measured after the additive is separated by subjecting the measurement sample to methanol extraction or the like.

[0108] The saponification degree of the polyvinyl alcohol can be measured under the following conditions.

[0109] <Measurement conditions>

[0110] Analytical instrument FT-NMR: Bruker Biospin, AVANCE III-400.

[0111] Observation frequency 400MHz (1H).

[0112] The measurement solvent is heavy water or deuterated dimethyl sulfoxide (DMSO).

[0113] ·Measurement temperature: 80℃.

[0114] Chemical shift reference external standard TSP-d4 (0.00 ppm) (for heavy water determination);

[0115] Measurement solvent (2.50 ppm) (in the case of deuterated DMSO measurement).

[0116] The saponification degree of the polyvinyl alcohol was calculated based on the following formula using the peak of the methylene group derived from the vinyl alcohol unit (VOH) (heavy water; 2.0 to 1.0 ppm, deuterated DMSO; 1.9 to 1.0 ppm) and the peak of the acetyl group derived from the vinyl acetate unit (VAc) (heavy water; around 2.1 ppm, deuterated DMSO; around 2.0 ppm).

[0117] In the following formula, [VOH(-CH2)-] refers to the intensity of the peak derived from -CH2- in the vinyl alcohol unit, and [VAc(CH3CO-)] refers to the intensity of the peak derived from CH3CO- in the vinyl acetate unit.

[0118]

[0119] The average degree of polymerization of the polyvinyl alcohol is preferably 100 or more and 1000 or less, and more preferably 100 or more and 800 or less.

[0120] When the average degree of polymerization is within the above numerical range, the polyvinyl alcohol can exhibit sufficient water solubility. In addition, when the protective layer-forming composition contains the polyvinyl alcohol, the protective layer-forming composition can be applied to the first release liner 2 with good workability.

[0121] The average degree of polymerization of the polyvinyl alcohol can be measured by aqueous GPC (Gel Permeation Chromatography).

[0122] The average degree of polymerization of the polyvinyl alcohol can be measured under the following conditions.

[0123] <Measurement conditions>

[0124] Analytical instrument: Agilent, 1260 Infinity.

[0125] Chromatography columns: TSKgel G6000PWXL (manufactured by TOSOH Corporation) and TSKgel G3000PWXL (manufactured by TOSOH Corporation).

[0126] The two chromatographic columns are connected in series.

[0127] Column temperature: 40°C.

[0128] · Eluent: 0.2 M sodium nitrate aqueous solution.

[0129] Injection volume: 100 μL.

[0130] · Detector Differential Refractometer (RI).

[0131] Standard samples: PEG standard sample and PVA standard sample.

[0132] The specific measurement was performed as follows.

[0133] (1) The mass average molecular weight Mw of the sample to be measured (PVA) and the PVA standard sample are calculated by GPC measurement using a PEG standard sample. The average degree of polymerization of the PVA standard sample is known.

[0134] (2) A calibration curve is prepared using the average degree of polymerization of the PVA standard sample and the calculated mass average molecular weight Mw of the PVA standard sample.

[0135] (3) Using the prepared calibration curve, the average degree of polymerization of the sample (PVA) to be measured is determined from the mass average molecular weight Mw of the sample (PVA) to be measured.

[0136] When the polyvinyl alcohol is used as the water-soluble polymer, a plurality of polyvinyl alcohols having different saponification degrees may be used in combination, or a plurality of polyvinyl alcohols having different average polymerization degrees may be used in combination.

[0137] The water-soluble polyester has a residue of a polycarboxylic acid and a residue of a polyol.

[0138] The water-soluble polyester is, for example, a polymerization product of monomer components including a polycarboxylic acid component and a polyol component.

[0139] It should be noted that the water-soluble polyester is water-soluble based on common technical knowledge.

[0140] The water-soluble polyester preferably satisfies at least one of the following (1) to (4).

[0141] (1) When water at room temperature (23±2° C.) was sprayed in a mist form on the entire surface of a 20 μm thick film made of the water-soluble polyester at a spray pressure of 0.005 MPa for 20 minutes, the film was completely dissolved in the water.

[0142] (2) When water at 50° C. was sprayed in a mist form at a spray pressure of 0.005 MPa for 10 minutes onto the entire surface of a film having a thickness of 20 μm formed of the water-soluble polyester, the film was completely dissolved in the water.

[0143] (3) When the water-soluble polyester and water at room temperature are mixed at a mass ratio of water-soluble polyester:water at room temperature=1:5 to obtain a mixed solution, and the mixed solution is irradiated with ultrasonic waves for 20 minutes, the water-soluble polyester is completely dissolved in the water.

[0144] (4) When the water-soluble polyester and 50°C water are mixed at a mass ratio of water-soluble polyester:50°C water=1:5 to obtain a mixed solution, and the mixed solution is irradiated with ultrasonic waves for 10 minutes, the water-soluble polyester is completely dissolved in the water.

[0145] The thickness of the protective layer 1 is preferably 2 μm or more and 70 μm or less, more preferably 3 μm or more and 50 μm or less, and even more preferably 5 μm or more and 40 μm or less.

[0146] The thickness of the protective layer 1 can be determined, for example, by measuring the thickness at five randomly selected points using a micrometer (manufactured by PEACOCK, Model R-205) and calculating the arithmetic average of these thicknesses.

[0147] As the first release liner 2 , for example, a resin sheet produced using a resin such as polyethylene terephthalate (PET) can be mentioned.

[0148] The resin sheet may be a resin sheet in which at least the surface to be bonded to the protective layer 1 is subjected to a release treatment.

[0149] Examples of the mold release treatment include silicone mold release treatment.

[0150] Furthermore, the same release liner as the first release liner 2 can be used as the second release liner 3 .

[0151] The thickness of the first release liner 2 and the second release liner 3 is preferably 15 μm or more and 75 μm or less, and more preferably 20 μm or more and 60 μm or less.

[0152] The thicknesses of the first release liner 2 and the second release liner 3 may be the same or different.

[0153] The thickness of the first release liner 2 and the second release liner 3 can be determined in the same manner as the thickness of the protective layer 1 .

[0154] As described above, in the protective sheet 10 of the first embodiment, the transmittance of the second release liner 3 is higher than the transmittance of the protective layer 1 , the first release liner 2 , or the laminate of the protective layer 1 and the first release liner 2 .

[0155] In the protective sheet 10 of the first embodiment, the transmittance T of the second release liner 3 measured at one wavelength included in the near-infrared region is A and the transmittance T of the protective layer 1 measured at the one wavelength B The difference is set as ΔT AB , the transmittance T A The transmittance T of the first release liner 2 measured at the one wavelength is C The difference is set as ΔTAC , the transmittance T A The transmittance T of the laminate of the protective layer 1 and the first release liner 2 measured at the one wavelength is D The difference is set as ΔT AD When the ΔT AB , the ΔT AC or the ΔT AD More than 15%.

[0156] It should be noted that the transmittance T A The transmittance T is the ratio of the light of one wavelength passing through the second release liner 3 in parallel with the thickness direction. B It refers to the ratio of the light of one wavelength passing through the protective layer 1 in parallel with the thickness direction. The transmittance T C The transmittance T is the ratio of the light of one wavelength passing through the first release liner 2 in parallel with the thickness direction. D It refers to the ratio of light of the one wavelength that transmits the laminate of the protective layer 1 and the first release liner 2 parallel to the thickness direction.

[0157] That is, the transmittance T A ~T D Refers to the transmittance of parallel light.

[0158] Light included in the near-infrared region, that is, near-infrared light, has an extremely long wavelength and therefore easily passes through an object in parallel with the thickness direction when irradiated thereon.

[0159] Therefore, in order to make the ΔT AB 15% or more, it is necessary to prevent light of one wavelength included in the near-infrared region from passing through the protective layer 1 in parallel with the thickness direction. In order to make the ΔT AC 15% or more, it is necessary to prevent the light of the one wavelength from passing through the first release liner 2 in parallel with the thickness direction. In order to make the ΔT AD The ratio is 15% or more, and it is necessary to prevent the light of the one wavelength from transmitting through the laminate of the protective layer 1 and the first release liner 2 in parallel with the thickness direction.

[0160] Specifically, the protective layer 1 and the first release liner 2 need to partially absorb or diffusely reflect the light of the one wavelength that is transmitted parallel to the thickness direction.

[0161] As a treatment for preventing the light of the one wavelength from transmitting through the protective layer 1 in parallel with the thickness direction, there can be mentioned the inclusion of a pigment in the protective layer-forming composition for forming the protective layer 1 .

[0162] Since the protective layer 1 contains the pigment, even if it is near-infrared light such as the light of the one wavelength, part of the light of the one wavelength can be absorbed by the pigment.

[0163] Furthermore, the pigment can be used to diffusely reflect a portion of the light of the one wavelength.

[0164] As the pigment, conventionally known pigments can be used.

[0165] Examples of the pigments include inorganic pigments such as zinc carbonate, zinc oxide, zinc sulfide, talc, kaolin, calcium carbonate, titanium oxide, silicon dioxide, lithium fluoride, calcium fluoride, barium sulfate, aluminum oxide, zirconium oxide, iron oxide, iron hydroxide, chromium oxide, spinel-type calcined pigments, chromic acid pigments, molybdate red pigments, Prussian blue pigments, aluminum powder pigments, bronze powder pigments, and calcium phosphate pigments; and organic pigments such as phthalocyanine pigments, azo pigments, condensed azo pigments, azo lake pigments, anthraquinone pigments, perylene-pyrene ketone pigments, indigo-thioindigo pigments, isoindolinone pigments, azomethane pigments, and carbon black pigments.

[0166] The protective layer 1 preferably contains 0.1 parts by mass or more of the pigment, more preferably 0.5 parts by mass or more, and even more preferably 1.0 parts by mass or more, based on 100 parts by mass of the water-soluble polymer compound.

[0167] Furthermore, the protective layer 1 preferably contains 30 parts by mass or less of the pigment, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less, based on 100 parts by mass of the water-soluble polymer compound.

[0168] Note that the pigment refers to a colorant that is insoluble in organic solvents such as water and alcohol.

[0169] Furthermore, as a treatment for preventing the light of the one wavelength from transmitting through the protective layer 1 in parallel with the thickness direction, foaming treatment of the protective layer-forming composition for forming the protective layer 1 can also be mentioned.

[0170] The protective layer 1 formed from the protective layer-forming composition subjected to such a foaming treatment contains a large number of bubbles.

[0171] This allows diffuse reflection to occur in the plurality of bubbles included in the protective layer 1 , and therefore reduces the ratio of near-infrared light having a single wavelength as described above that transmits the protective layer 1 in parallel with the thickness direction.

[0172] As described above, when the first release liner 2 is a resin sheet made of a resin such as polyethylene terephthalate (PET), an example of a treatment for preventing light of the one wavelength from passing through the first release liner 2 in parallel with the thickness direction is to foam the resin composition used to make the resin sheet.

[0173] The resin sheet (resin foam sheet) obtained by foaming the resin composition contains a large number of cells, and thus diffuse reflection can occur in the large number of cells.

[0174] Thereby, even near-infrared light having a single wavelength as described above can reduce the ratio of light transmitted through the first release liner 2 in parallel with the thickness direction.

[0175] Furthermore, when the first release liner 2 is a resin sheet made of a resin such as polyethylene terephthalate (PET), the resin sheet may be foamed in its prepared state.

[0176] For example, the resin sheet may be stretched to form a foaming treatment to generate voids during the stretching.

[0177] Furthermore, as a treatment for preventing light of the one wavelength from transmitting through the first release liner 2 in parallel with the thickness direction, there is mentioned coating ink containing a pigment such as titanium oxide on at least one surface of the first release liner 2 .

[0178] By forming a coating layer containing a pigment on at least one surface (inner surface, outer surface, or both surfaces) of the first release liner 2, even near-infrared light of the aforementioned single wavelength can be partially absorbed by the pigment contained in the coating layer.

[0179] Furthermore, the pigment can be used to diffusely reflect a portion of the light of the one wavelength.

[0180] Furthermore, the first release liner 2 may be constructed using a resin containing a pigment, and the pigment may absorb a portion of the light of the one wavelength, or diffusely reflect a portion of the light of the one wavelength using the pigment, thereby reducing the ratio of the light of the one wavelength passing through the first release liner 2 parallel to the thickness direction.

[0181] Furthermore, as a treatment for preventing the light of the one wavelength from transmitting through the first release liner 2 in parallel with the thickness direction, matte processing or embossing processing may be applied to at least one surface of the first release liner 2 .

[0182] By subjecting at least one surface of the first release liner 2 to matte processing or embossing, diffuse reflection can be generated on the concave and convex portions of the surface of the first release liner 2 .

[0183] Thereby, even near-infrared light having a single wavelength as described above can reduce the ratio of light transmitted through the first release liner 2 in parallel with the thickness direction.

[0184] The first release liner 2 may be a laminated film having a light-shielding layer, a laminated film having a resin layer and a metal vapor-deposited layer, or a film such as an aluminum laminated film.

[0185] In order to prevent the light of the one wavelength from passing through the laminate of the protective layer 1 and the first release liner 2 in parallel with the thickness direction and to make the transmittance T of the second release liner 3 A Transmittance T of the laminate of the protective layer 1 and the first release liner 2 D The difference ΔT AD The transmittance T of the second release liner 3 is 15% or more. A The transmittance T of the protective layer 1 B The difference ΔT AB and the transmittance T of the second release liner 3 A The transmittance T of the first release liner 2 C The difference ΔT AC The total value of may be 15% or more.

[0186] For example, when ΔT AB 5% or more based on making ΔT AC is 10% or more, or when ΔT AB 10% or more based on making ΔT AC It may be 5% or more.

[0187] Transmittance T of protective layer 1 B and the transmittance T of the first release liner C Adjustments can be made in the same manner as described above.

[0188] It should be noted that, of course, as described above, by making ΔT AB and ΔT AC At least one of them is 15% or more, and the ΔT AD More than 15%.

[0189] The difference in transmittance for detecting the presence of the protective layer 1 and the first release liner 2 through the second release liner 3 is preferably 20% or more, more preferably 25% or more. The difference in transmittance may be 30% or more, 40% or more, or 50% or more.

[0190] It should be noted that it is preferable to have such a difference in transmittance also in another embodiment described later.

[0191] By increasing the transmittance T of the protective layer 1 measured at the one wavelength as much as possible B , the transmittance T of the first release liner 2 measured at the one wavelength C and the transmittance T of the laminate of the protective layer 1 and the first release liner 2 measured at the one wavelength. D The transmittance T of the second release liner 3 measured at the one wavelength is considered from the perspective of the difference between A It is preferable that the transmittance of the light of the one wavelength is high.

[0192] The transmittance T of the second release liner 3 measured at the one wavelength is A It is preferably 65% ​​or more, more preferably 75% or more, and even more preferably 85% or more.

[0193] The transmittance T of the second release liner 3 measured at the one wavelength is A It may be 100% or less, or 95% or less.

[0194] The transmittance T of the second release liner 3 at the one wavelength A , the transmittance T of the protective layer 1 at the wavelength B , the transmittance T of the first release liner 2 at the one wavelength C and the transmittance T of the laminate of the protective layer 1 and the first release liner 2 at the one wavelength D The parallel light transmittance at the aforementioned one wavelength can be determined by measuring the parallel light transmittance at the aforementioned one wavelength using a spectrophotometer (manufactured by JASCO Corporation, trade name "V-670").

[0195] In the measurement of parallel light transmittance using a spectrophotometer, the measurement wavelength can be set to a range of 190 nm to 3000 nm.

[0196] The second release liner 3 may be a 50 μm thick release liner, the protective layer 1 may be a 10 μm thick release liner, and the first release liner 2 may be a 40 μm thick release liner.

[0197] In addition, the measurement of the parallel light transmittance using a spectrophotometer was performed without using an integrating sphere.

[0198] [Protective sheet according to the second embodiment]

[0199] In the protective sheet 10 of the second embodiment of the present invention, the transmittance T of the second release liner 3 measured at one wavelength included in the ultraviolet region is A’ and the transmittance T of the protective layer 1 measured at the one wavelengthB’ The difference is set as ΔT A’B’ , the transmittance T A’ The transmittance T of the first release liner 2 measured at the one wavelength is C’ The difference is set as ΔT A’C’ , the transmittance T A’ The transmittance T of the laminate of the protective layer 1 and the first release liner 2 measured at the one wavelength is D’ The difference is set as ΔT A’D’ When the ΔT A’B’ , the ΔT A’C’ or the ΔT A’D’ The protective sheet 10 of the first embodiment described above is configured similarly to the protective sheet 10 of the first embodiment except that the ratio is 15% or more.

[0200] In this specification, the ultraviolet region refers to a region with a wavelength of 200 nm or more and less than 380 nm.

[0201] Furthermore, in the second embodiment of the present invention, it is preferable to use a wavelength of 330 nm as one of the wavelengths included in the ultraviolet region.

[0202] The transmittance T A’ ~T D’ With the transmittance T A ~T D It also refers to the transmittance of parallel light.

[0203] Furthermore, the transmittance T of the second release liner 3 at one wavelength included in the ultraviolet region is A’ , the transmittance T of the protective layer 1 at the wavelength B’ , the transmittance T of the first release liner 2 at the one wavelength C’ and the transmittance T of the laminate of the protective layer 1 and the first release liner 2 at the one wavelength D’ It can also be measured in the same manner as described above.

[0204] Ultraviolet light (UV light) in the ultraviolet region has an extremely short wavelength and therefore, when irradiated onto an object, is less likely to pass through the object than the aforementioned light having an extremely long wavelength, namely, near-infrared light.

[0205] Therefore, by subjecting the protective layer 1 to the same treatment as described in the first embodiment, the above-mentioned ΔT A’B’ By subjecting the first release liner 2 to the same treatment as described in the first embodiment, the above-mentioned ΔT can be increased to 15% or more. A’C’ 15% or more, the above-mentioned ΔT can be made to be 15% or more by subjecting the laminate of the protective layer 1 and the first release liner 2 to the same treatment as described in the first embodiment.A’D’ More than 15%.

[0206] Furthermore, the above-mentioned ΔT can also be adjusted by performing other processing than the above-mentioned A’B’ , ΔT A’C ' and ΔT A’D’ More than 15%.

[0207] For example, by forming the protective layer 1 from the protective layer-forming composition containing an ultraviolet absorber, or forming the first release liner 2 from a resin containing an ultraviolet absorber, the ΔT can be made A’B’ , the ΔT A’C’ and ΔT A’D’ More than 15%.

[0208] Examples of the ultraviolet absorber include triazine ultraviolet absorbers, benzotriazole ultraviolet absorbers, benzophenone ultraviolet absorbers, oxybenzophenone ultraviolet absorbers, salicylate ultraviolet absorbers, and cyanoacrylate ultraviolet absorbers.

[0209] These various ultraviolet absorbers may be used alone or in combination of two or more.

[0210] When the protective layer 1 contains the ultraviolet absorber, the protective layer 1 preferably contains 0.1 parts by mass or more of the ultraviolet absorber relative to 100 parts by mass of the water-soluble polymer compound, more preferably 0.5 parts by mass or more of the ultraviolet absorber, and even more preferably 1.0 parts by mass or more of the ultraviolet absorber.

[0211] Furthermore, when the protective layer 1 contains the ultraviolet absorber, the protective layer 1 preferably contains 20 parts by mass or less of the ultraviolet absorber relative to 100 parts by mass of the water-soluble polymer compound, more preferably 15 parts by mass or less of the ultraviolet absorber, and even more preferably 10 parts by mass or less of the ultraviolet absorber.

[0212] Furthermore, the ΔT can be increased by forming the protective layer 1 with the protective layer-forming composition containing the azo dye described later instead of the ultraviolet absorber, or forming the first release liner 2 with a resin containing the azo dye instead of the ultraviolet absorber. A’B’ , the ΔT A’C’ and ΔT A’D’ More than 15%.

[0213] In addition, as said azo dye, the yellow dye etc. which show yellow are mentioned, for example.

[0214] When the protective layer 1 contains the azo dye, the content thereof can be the same as the content of the ultraviolet absorber described above.

[0215] Furthermore, the ΔT can be made smaller by forming the protective layer 1 from the protective layer-forming composition containing the azo dye in addition to the ultraviolet absorber, or forming the first release liner 2 from a resin containing the azo dye in addition to the ultraviolet absorber. A’B’ , the ΔT A’C’ and ΔT A’D’ More than 15%.

[0216] [Protective sheet according to the third embodiment]

[0217] In the protective sheet 10 of the third embodiment of the present invention, the transmittance T of the second release liner 3 measured at one wavelength included in the visible region is A” and the transmittance T of the protective layer 1 measured at the one wavelength B” The difference is set as ΔT A”B” , the transmittance T A” The transmittance T of the first release liner 2 measured at the one wavelength is C” The difference is set as ΔT A”C” , the transmittance T A” The transmittance T of the laminate of the protective layer 1 and the first release liner 2 measured at the one wavelength is D” The difference is set as ΔT A”D” When the ΔT A”B” , the ΔT A”C” or the ΔT A”D” The protective sheet 10 of the first embodiment described above is configured similarly to the protective sheet 10 of the first embodiment except that the ratio is 15% or more.

[0218] In this specification, the visible region refers to a region with a wavelength of 380 nm or more and less than 800 nm.

[0219] Furthermore, in the third embodiment of the present invention, it is preferable to use one wavelength within the range of 550 nm to 650 nm as one wavelength included in the visible region.

[0220] Transmittance T A” ~T D” and transmittance T A ~T D It also refers to the transmittance of parallel light.

[0221] Furthermore, the transmittance T of the second release liner 3 at one wavelength included in the visible region is A” , the transmittance T of the protective layer 1 at the wavelength B”, the transmittance T of the first release liner 2 at the one wavelength C” and the transmittance T of the laminate of the protective layer 1 and the first release liner 2 at the one wavelength D” It can also be measured in the same manner as described above.

[0222] Light included in the visible region, that is, visible light (visible rays), has a shorter wavelength than near-infrared light. Therefore, when irradiated onto an object, it is less likely to pass through the object than near-infrared light.

[0223] Therefore, by subjecting the protective layer 1 to the same treatment as described in the first embodiment, the above-mentioned ΔT A”B” By subjecting the first release liner 2 to the same treatment as described in the first embodiment, the above-mentioned ΔT can be increased to 15% or more. A”C” 15% or more, the above-mentioned ΔT can be made to be 15% or more by subjecting the laminate of the protective layer 1 and the first release liner 2 to the same treatment as described in the first embodiment. A”D” More than 15%.

[0224] Furthermore, the ΔT can be made smaller by forming the protective layer 1 from the protective layer-forming composition containing a component that absorbs visible light, or forming the first release liner 2 from a resin containing a component that absorbs visible light. A”B” , the ΔT A”C” and ΔT A”D” More than 15%.

[0225] Examples of the component that absorbs visible light include dyes.

[0226] In addition, a dye refers to a colorant having a property of being soluble in water, an organic solvent, or the like.

[0227] Examples of the dye include azo dyes, anthraquinone, quinophthalone, styryl, diphenylmethane, triphenylmethane, oxazine, triazine, xanthene, methane, azomethine, acridine, and dioxazine.

[0228] When the protective layer 1 contains the dye, the protective layer 1 preferably contains 0.1 parts by mass or more of the dye relative to 100 parts by mass of the water-soluble polymer compound, more preferably 0.5 parts by mass or more of the dye, and even more preferably 1.0 parts by mass or more of the dye.

[0229] When the protective layer 1 contains the dye, the protective layer 1 preferably contains 30 parts by mass or less, more preferably 20 parts by mass or less, and further preferably 10 parts by mass or less, based on 100 parts by mass of the water-soluble polymer compound.

[0230] In the protective sheets 10 of the first to third embodiments, examples are described in which the second release liner 3 and the protective layer 1, the second release liner 3 and the first release liner 2, or the second release liner 3 and the laminate of the protective layer 1 and the first release liner 2 are distinguished by using a transmittance difference.

[0231] On the other hand, the second release liner 3 and the protective layer 1, the second release liner 3 and the first release liner 2, and the second release liner 3 and the laminate of the protective layer 1 and the first release liner 2 can be distinguished not only by the difference in transmittance but also by the difference in haze or the difference in lightness (L value).

[0232] When distinguishing the first release liner 2 and the second release liner 3 based on the difference in haze, the haze of the first release liner 2 is preferably as high as possible, and the haze of the second release liner 3 is preferably as low as possible.

[0233] The lower limit of the haze of the first release liner 2 is preferably 70% or more, more preferably 80% or more, further preferably 90% or more, further preferably 93% or more, and particularly preferably 98% or more.

[0234] Furthermore, the upper limit of the haze of the second release liner 3 is preferably 10% or less, more preferably 7% or less, further preferably 5% or less, and particularly preferably 3% or less.

[0235] The haze of the first release liner 2 and the haze of the second release liner 3 refer to haze in the thickness direction, and the haze in the thickness direction is a value measured in accordance with JIS K 7136.

[0236] The haze in the thickness direction can be measured using a turbidimeter (manufactured by Nippon Denshoku Co., Ltd., trade name "NDH2000").

[0237] Furthermore, when distinguishing the protective layer 1 and the second release liner 3 based on the difference in haze, the haze of the protective layer 1 is preferably as high as possible, and the haze of the second release liner 3 is preferably as low as possible.

[0238] The lower limit of the haze of the protective layer 1 is preferably 15% or more, more preferably 25% or more, and even more preferably 35% or more.

[0239] In addition, the upper limit of the haze of the second release liner 3 is preferably set as described above.

[0240] The haze of the protective layer 1 also refers to the haze in the thickness direction, and the haze in the thickness direction can be measured in the same manner as for the first release liner 2 and the second release liner 3 .

[0241] When distinguishing the first release liner 2 and the second release liner 3 based on the difference in lightness (L value), the lightness (L value) of the first release liner 2 is preferably as low as possible, and the lightness (L value) of the second release liner 3 is preferably as high as possible.

[0242] The upper limit of the lightness (L value) of the first release liner 2 is preferably 10 or less, more preferably 7 or less, and even more preferably 5 or less.

[0243] The lower limit of the lightness (L value) of the second release liner 3 is preferably 70 or more, more preferably 80 or more, and even more preferably 90 or more.

[0244] The lightness (L value) of the first release liner 2 and the lightness (L value) of the second release liner 3 can be measured using a color temperature meter (manufactured by SugaTest Instruments, trade name “SM-T”).

[0245] In the measurement using the color temperature meter, the chromaticity (a value and b value) of the first release liner 2 and the chromaticity (a value and b value) of the second release liner 3 may be measured simultaneously.

[0246] When distinguishing the protective layer 1 and the second release liner 3 based on the difference in lightness (L value), the lightness (L value) of the protective layer 1 is preferably as low as possible, and the lightness (L value) of the second release liner 3 is preferably as high as possible.

[0247] The upper limit of the lightness (L value) of the protective layer 1 is preferably 70 or less, more preferably 65 or less.

[0248] Furthermore, the lower limit of the lightness (L value) of the second release liner 3 is preferably 80 or more, more preferably 90 or more.

[0249] The lightness (L value) of the protective layer 1 can also be measured using the color temperature meter in the same manner as the lightness (L value) of the first release liner 2 and the lightness (L value) of the second release liner 3 .

[0250] In addition, in the measurement using the color temperature table, the chromaticity (a value and b value) of the protective layer 1 may be measured simultaneously.

[0251] Furthermore, the protective layer 1 and the first and second release liners 2 and 3 can also be distinguished by the difference in gloss (hereinafter referred to as gloss difference).

[0252] For example, the gloss difference can be determined by measuring the gloss of a laminate having a first release liner 2 laminated on one surface of a protective layer 1 and a second release liner 3 laminated on the other surface thereof when light is incident at an angle of 60° (gloss at an incident angle of 60°).

[0253] As the light incident at an angle of 60°, white light can be used.

[0254] The gloss at an incident angle of 60° can be measured using a spectrophotometer CM-26dG manufactured by Konica Minolta.

[0255] The gloss difference of the laminate is preferably 20 GU or more, more preferably 30 GU or more, more preferably 50 GU or more, and more preferably 90 GU or more.

[0256] By setting the gloss difference of the laminate to be within the above-mentioned range, the protective layer 1 , the first release liner 2 , and the second release liner 3 can be sufficiently distinguished from each other.

[0257] Next, a semiconductor wafer is taken as an example of an electronic component, and a protective layer 1 (see Figure 2A ) is bonded to the protection target surface of the semiconductor wafer, and an example of bonding the protection layer 1 (see 2B) obtained by the pre-cut method to the protection target surface of the semiconductor wafer is described.

[0258] First, an example will be described below in which a protective sheet 10 including a protective layer 1 obtained by a post-cutting method is used and the protective layer 1 is bonded to a surface to be protected of a semiconductor wafer.

[0259] The bonding of the protective layer 1 to the protection target surface of the semiconductor wafer using a protective sheet 10 having a protective layer 1 obtained by a post-pre-cutting method is implemented using a sensing device 100 and an installation device 200, wherein the sensing device 100 detects the position of the protective layer 1 in the protective sheet 10, and the installation device 200 bonds the protective layer 1 to the protection target surface of the semiconductor wafer based on the position of the protective layer 1 detected by the sensing device 100.

[0260] like Figure 3A As shown, the sensing device 100 comprises: a holding platform 101 having a holding surface 1011 for holding the protective sheet 10 from the first peeling liner 2 side; and a position detection unit 102, which is arranged at a distance from the holding surface 1011 of the holding platform 101 to detect the position of the protective layer 1 in the protective sheet 10.

[0261] The position detection unit 102 includes a camera 1021 for capturing an image of the protective sheet 10 from the second release liner 3 side, and a lens 1022 for expanding the imaging field of the camera 1021 .

[0262] That is, in the sensing device 100 , the position of the protective layer 1 in the protective sheet 10 is detected using an image captured by the camera 1021 from the second release liner 3 side.

[0263] It should be noted that if Figure 3A As shown by the middle dotted line, the imaging field of the camera 1021 is expanded to the entire protective sheet 10 by the lens 1022 .

[0264] That is, in the sensing device 100 , the camera 1021 can capture the entire protective sheet 10 from the second release liner 3 side.

[0265] Here, as described above, in the protective sheet 10 of the first embodiment, the transmittance T of the second release liner 3 at one wavelength included in the near-infrared region is A The transmittance T of the protective layer 1 at the wavelength B The difference ΔT AB is 15% or more, or as the transmittance T A The transmittance T of the first release liner 2 at the one wavelength C The difference ΔT AC is 15% or more, or, as the transmittance T A The transmittance T of the laminate of the protective layer 1 and the first release liner 2 at the one wavelength D The difference ΔT AD More than 15%.

[0266] The protective sheet 10 of the first embodiment includes a region having a single-layer structure (single-layer region) consisting of only the second release liner 3 and a region having a laminated structure (laminated region) consisting of the first release liner 2 and the protective layer 1 .

[0267] The intensity of light transmitted through the protective sheet 10 from the side provided with the protective layer 1 differs between light transmitted through the single-layer region and light transmitted through the laminated region.

[0268] In this embodiment, the light transmittance from the outer surface of the second release liner to the protective layer 1, that is, the transmittance in the laminated region is 15% or more lower than the light transmittance of only the second release liner 3 (transmittance of the single layer region).

[0269] Therefore, in this embodiment, by photographing the protective sheet 10 from the outer surface of the second release liner 3 with the camera 1021 (near infrared camera), the single layer region can be recognized as a bright portion and the laminated region as a dark portion darker than the bright portion.

[0270] In this embodiment, by having a transmittance difference of 15% or more, sufficient contrast is formed between the dark portion and the bright portion, and the outer periphery of the stacked region can be sensed with high accuracy.

[0271] Therefore, the position of the protective layer 1 can be discerned in the protective sheet 10 of the first embodiment.

[0272] This makes it possible to detect the position of the protective layer 1 in the protective sheet 10 of the first embodiment, and to detect at which position on the holding surface 1011 of the holding table 101 the protective layer 1 is disposed.

[0273] As described above, in the protective sheet 10 of the second embodiment, the transmittance T of the second release liner 3 at one wavelength included in the ultraviolet region is A’ The transmittance T of the protective layer 1 at the wavelength B’ The difference ΔT A’B’ is 15% or more, or as the transmittance T A’ The transmittance T of the first release liner 2 at the one wavelength C’ The difference ΔT A’C’ is 15% or more, or, as the transmittance T A’ The transmittance T of the laminate of the protective layer 1 and the first release liner 2 at the one wavelength D’ The difference ΔT A’D’ More than 15%.

[0274] That is, in the protective sheet 10 of the second embodiment, the intensity of ultraviolet rays passing through the laminated region and the single layer region are different.

[0275] Therefore, similarly to the first embodiment, by photographing the protective sheet 10 from the outer surface of the second release liner 3 with the camera 1021 (ultraviolet camera), the single layer region can be recognized as a bright portion and the laminated region as a dark portion darker than the bright portion.

[0276] Therefore, by distinguishing the portion having light and dark in the image, the position of the protective layer 1 can be distinguished even in the protective sheet 10 of the second embodiment.

[0277] This makes it possible to detect the position of the protective layer 1 in the protective sheet 10 of the second embodiment, and to detect at which position on the holding surface 1011 of the holding table 101 the protective layer 1 is disposed.

[0278] Furthermore, as described above, in the protective sheet 10 of the third embodiment, the transmittance T of the second release liner 3 at one wavelength included in the visible region is A” The transmittance T of the protective layer 1 at the wavelength B” The difference ΔT A”B” is 15% or more, or as the transmittance T A” The transmittance T of the first release liner 2 at the one wavelength C” The difference ΔT A”C” is 15% or more, or, as the transmittance T A”The transmittance T of the laminate of the protective layer 1 and the first release liner 2 at the one wavelength D” The difference ΔT A”D” More than 15%.

[0279] That is, in the protective sheet 10 of the third embodiment, the intensities of visible light passing through the laminated region and the single layer region are different.

[0280] Therefore, similarly to the first embodiment, by photographing the protective sheet 10 from the outer surface of the second release liner 3 with the camera 1021 (visible light camera), the single layer region can be recognized as a bright portion and the laminated region as a dark portion darker than the bright portion.

[0281] Therefore, by distinguishing the portion having light and dark, the position of the protective layer 1 can be distinguished even in the protective sheet 10 of the third embodiment.

[0282] This makes it possible to detect the position of the protective layer 1 in the protective sheet 10 of the third embodiment, and to detect at which position on the holding surface 1011 of the holding table 101 the protective layer 1 is disposed.

[0283] In this embodiment, in order to improve the sensitivity of the camera 1021 , a backlight may be provided to irradiate the inner surface of the second release liner 3 with light including near infrared rays, ultraviolet rays, and visible rays.

[0284] After detecting the position of the protective layer 1 in the protective sheet 10 and detecting where the protective layer 1 is disposed on the holding surface 1011 of the holding table 101 , the second release liner 3 is peeled off to expose one surface of the protective layer 1 .

[0285] like Figure 3B As shown, the mounting device 200 includes: a chamber 201; an electrostatic chuck table 202, which is arranged at the bottom of the chamber 201; a head 203, which is arranged above the electrostatic chuck table 202 and inside the chamber 201; and a pump P for decompressing the interior of the chamber 201.

[0286] It should be noted that, hereinafter, the vertical direction (vertical direction) is referred to as the Z-axis direction, and the horizontal direction ( Figure 3B The horizontal direction along the paper) is set as the X-axis direction, and the direction perpendicular to both the Z-axis and the X-axis ( Figure 3B The direction perpendicular to the paper surface) is set as the Y-axis direction for explanation.

[0287] like Figure 3BAs shown, in the mounting apparatus 200 , an electrostatic chuck stage 202 holds a dicing die bond film D on which a semiconductor wafer W is mounted by electrostatic force.

[0288] The dicing die bonding film D includes: a die bonding film having an adhesive layer laminated on a base material; and a die bonding layer disposed on the adhesive layer of the die bonding film.

[0289] Then, the semiconductor wafer W is bonded to the die bonding layer of the dicing die bonding film D.

[0290] Furthermore, a dicing ring R is attached to an edge side of the dicing die-bonding film D.

[0291] Furthermore, if Figure 3B As shown, in the mounting device 200 , the head 203 holds the holding table 101 holding the laminate of the protective layer 1 and the first release liner 2 from the first release liner 2 side by suction or the like.

[0292] Furthermore, in the mounting device 200 , the head 203 is configured to be movable in the chamber 201 along the X-axis direction, the Y-axis direction, and the Z-axis direction.

[0293] Note that, in the mounting apparatus 200 , the interior of the chamber 201 is maintained at atmospheric pressure before the head 203 holds the holding table 101 , and is depressurized by the pump P after the head 203 holds the holding table 101 .

[0294] That is, the holding stage 101 is held by the head 203 under atmospheric pressure, and the protection layer 1 is attached to the protection target surface of the semiconductor wafer W under reduced pressure.

[0295] In the mounting device 200 constructed as described above, the protective layer 1 is bonded to the protected surface of the semiconductor wafer W based on the information on the position of the protective layer 1 detected by the sensing device 100, or more specifically, the information on the position of the holding surface 1011 of the holding table 101 on which the protective layer 1 is arranged (hereinafter also referred to as the position information of the protective layer on the holding table).

[0296] Specifically, based on the position information of the protective layer on the holding table, the head 203 is moved in the X-axis direction and the Y-axis direction so that the periphery of the semiconductor wafer W is roughly consistent with the periphery of the protective layer 1, and then the head 203 is moved downward in the Z-axis direction so that the exposed surface of the protective layer 1 is attached to the protected surface of the semiconductor wafer W.

[0297] The bonding of the exposed surface of the protective layer 1 is preferably performed while applying a pressure of about 0.3 MPa.

[0298] This allows the exposed surface of the protective layer 1 to be sufficiently adhered to the surface of the semiconductor wafer W to be protected.

[0299] Then, the exposed surface of the protective layer 1 is sufficiently brought into contact with the surface to be protected of the semiconductor wafer W, and then the head 203 is moved upward in the Z-axis direction to peel the first release liner 2 from the protective layer 1 .

[0300] Therefore, if Figure 3C As shown, the surface to be protected of the semiconductor wafer W can be provided with the protection layer 1 .

[0301] It should be noted that when the exposed surface of the protective layer 1 is bonded to the surface to be protected of the semiconductor wafer W, at least one of the holding table 101 and the electrostatic chuck table 202 may be heated in advance.

[0302] Next, an example will be described in which a protective sheet including the protective layer 1 obtained by the pre-cutting method is used and the protective layer 1 is bonded to the surface to be protected of a semiconductor wafer.

[0303] In implementing the use Figure 1B When the protective sheet 10 shown, which includes the protective layer 1 obtained by the pre-cutting method, is attached to the surface to be protected of the semiconductor wafer, either the first release liner 2 or the second release liner 3 is peeled off, and the position of the protective layer 1 relative to the attached release liner is detected while the surface of the protective layer 1 is exposed.

[0304] Therefore, in this embodiment, it is necessary to generate a transmittance difference between the release liner bonded to one surface of the protective layer 1 and the protective layer 1 .

[0305] For example, when the first release liner 2 is peeled off from the protective layer 1 and the second release liner 3 is attached to the protective layer 1, the transmittance T of the second release liner 3 at one wavelength included in the near infrared region needs to be set to A The transmittance T of the protective layer 1 at the wavelength B The difference ΔT AB It is necessary to make the transmittance T of the second release liner 3 at one wavelength included in the ultraviolet region 15% or more. A’ The transmittance T of the protective layer 1 at the wavelength B’ The difference ΔT A’B’ It is necessary to make the transmittance T of the second release liner 3 at one wavelength included in the visible region 15% or more. A” The transmittance T of the protective layer 1 at the wavelength B” The difference ΔT A”B” More than 15%.

[0306] Hereinafter, an example will be described in which the first release liner 2 is peeled from the protective layer 1 and the second release liner 3 is attached to the protective layer 1 , the position of the protective layer 1 relative to the second release liner 3 is detected, and then the protective layer 1 is attached to the surface to be protected of the semiconductor wafer.

[0307] The bonding of the protective layer 1 to the protected surface of the semiconductor wafer using a protective sheet 10 having a protective layer 1 obtained by a pre-cutting method is implemented using a sensing device 300 and a laminating device 400, wherein the sensing device 300 detects the position of the protective layer 1 relative to the second peeling pad 3 and the position of the semiconductor wafer, and the laminating device 400 bonds the protective layer 1 to the protected surface of the semiconductor wafer based on the position of the protective layer 1 relative to the second peeling pad 3 and the position of the semiconductor wafer detected by the sensing device 300.

[0308] like Figure 4A As shown, the sensing device 300 comprises: a wafer holding table 301 having a holding surface 3011 for holding a semiconductor wafer W; a holding member 302, arranged above the wafer holding table 301, for holding the stack of the protective layer 1 and the second peeling pad 3 from both end edges of the stack; and a position detection unit 303, arranged above the holding member 302, for detecting the position of the protective layer 1 relative to the second peeling pad 3 and the position of the semiconductor wafer W.

[0309] It should be noted that, hereinafter, the vertical direction (vertical direction) is referred to as the Z-axis direction, and the horizontal direction ( Figure 4A The horizontal direction along the paper) is set as the X-axis direction, and the direction perpendicular to both the Z-axis and the X-axis ( Figure 4A The direction perpendicular to the paper surface) is set as the Y-axis direction for explanation.

[0310] In addition, in the following Figure 4B In the X-axis direction, the Y-axis direction and the Z-axis direction also refer to Figure 4A The X-axis direction, Y-axis direction and Z-axis direction are the same direction.

[0311] The position detection unit 303 includes a camera 3031 for imaging the laminate of the protective layer 1 and the second release liner 3 and the semiconductor wafer W from the second release liner 3 side, and a lens 3032 for expanding the imaging field of the camera.

[0312] That is, in the sensing device 300 , the position of the protective layer 1 relative to the second release liner 3 and the position of the semiconductor wafer W are detected using an image captured by the camera 3031 from the second release liner 3 side.

[0313] It should be noted that if Figure 4AAs shown by the middle dotted line, the imaging field of the camera 3031 is expanded by the lens 3032 to the vicinity of the area gripped by the grip 302 .

[0314] That is, in the sensing device 300 , the camera 3031 can image the laminate of the protective layer 1 and the first release liner 2 from the second release liner 3 side to the vicinity of the region gripped by the gripper 302 , and can also image the semiconductor wafer W.

[0315] The gripper 302 is attached to an arm (not shown) and is movable in the X-axis direction, the Y-axis direction, and the Z-axis direction by the arm.

[0316] Here, as described above, the semiconductor wafer W has a circuit pattern formed on one surface side and is arranged in the electrode portion.

[0317] Furthermore, the semiconductor wafer W generally has a thickness of approximately several tens of μm (eg, 50 μm).

[0318] Therefore, even near-infrared rays having an extremely long wavelength have difficulty transmitting through the semiconductor wafer W.

[0319] Therefore, even if any one of a near-infrared camera, an ultraviolet camera or a visible light camera is used as the camera 3031 to photograph the stack of the protective layer 1 and the second release liner 3 and the semiconductor wafer W from the side of the second release liner 3, in any of the captured images, the protective layer 1 and the semiconductor wafer W are shown as shaded portions (dark portions).

[0320] Thus, by recognizing the shadowed portion (dark portion) in the image, the position of the protective layer 1 relative to the second release liner 3 and the position of the semiconductor wafer W can be detected.

[0321] Moreover, based on the information about the position of the protective layer 1 relative to the second release liner 3 and the position of the semiconductor wafer W, the holding member 302 is moved in the X-axis direction, the Y-axis direction, the Z-axis direction, etc., so that the outer periphery of the semiconductor wafer W is roughly aligned with the outer periphery of the protective layer 1.

[0322] Next, the gripper 302 is moved downward in the Z-axis direction, so that the protective layer 1 of the laminate of the protective layer 1 and the second release liner 3 is bonded to the surface of the semiconductor wafer W to be protected.

[0323] like Figure 4B As shown, the laminating device 400 includes a roller 401 that presses the laminate of the protective layer 1 and the second release liner 3 while rotating in contact with the second release liner 3 .

[0324] In the laminating apparatus 400, as Figure 4BAs shown, the roller 401 moves in the X-axis direction while rotating and presses the laminate of the protective layer 1 and the second release liner 3 , thereby laminating the protective layer 1 to the surface to be protected of the semiconductor wafer W.

[0325] The pressing is preferably performed while applying a pressure of about 0.3 MPa.

[0326] This allows the exposed surface of the protective layer 1 to be sufficiently adhered to the surface of the semiconductor wafer W to be protected.

[0327] After the exposed surface of the protective layer 1 is sufficiently brought into contact with the surface to be protected of the semiconductor wafer W, the gripper 302 is moved upward in the Z-axis direction to peel the second release liner 3 from the protective layer 1 .

[0328] Therefore, if Figure 4C As shown, the surface to be protected of the semiconductor wafer W can be provided with the protection layer 1 .

[0329] The bonding of the protective layer 1 to the surface to be protected of the semiconductor wafer W can also be performed using a vacuum diaphragm laminator that bonds the protective layer 1 to the surface to be protected of the semiconductor wafer W under vacuum.

[0330] Furthermore, the bonding of the protective layer 1 to the surface to be protected of the semiconductor wafer W may also be performed by applying differential pressure in a pressure-adjustable chamber.

[0331] Matters disclosed in this specification include the following. (1)

[0333] A protective sheet comprising: a protective layer adhered to an adherend; and a release liner disposed on a surface of the protective layer, wherein the protective layer comprises a water-soluble polymer, the release liner comprising an inner surface opposing the protective layer and an outer surface opposite the inner surface, and the light transmittance of the release liner from the outer surface to the point of passing through the protective layer is at least 15% lower than the light transmittance of the release liner at at least one wavelength.

[0334] According to this configuration, the position of the protective layer can be accurately grasped from the release liner side.

[0335] This makes it possible to easily align the protective layer with respect to the transfer device, the adherend, and the like. (2)

[0337] A protective sheet comprising: a protective layer adhered to an adherend; a first release liner disposed on one surface of the protective layer; and a second release liner disposed on the other surface of the protective layer, wherein the protective layer comprises a water-soluble polymer compound, the first release liner and the second release liner each comprising an inner surface opposing the protective layer and an outer surface opposite to the inner surface, and the light transmittance from the outer surface of the second release liner to the outer surface of the first release liner is lower than the light transmittance of the second release liner at at least one wavelength by 15% or more.

[0338] According to this configuration, the positions of the protective layer and the first release liner can be accurately grasped from the second release liner side.

[0339] Therefore, particularly when the protective layer and the first release liner are pre-cut later so as to have substantially the same size in a plan view, the position of the protective layer can be accurately grasped based on the position of the first release liner.

[0340] This makes it possible to easily align the protective layer with respect to the transfer device, the adherend, and the like. (3)

[0342] According to the protective sheet described in (1) or (2) above, the one wavelength is any one of the ultraviolet region, the visible region, and the near-infrared region.

[0343] It should be noted that the protective sheet of the present invention is not limited to the above-described embodiments. Furthermore, the protective sheet of the present invention is not limited to the above-described effects. The protective sheet of the present invention can be modified in various ways without departing from the spirit of the present invention.

[0344] For example, in the protective sheet of the present invention, the adherend is not limited to a semiconductor wafer, and an adherend other than a semiconductor can be used as a protection target.

[0345] In addition, in this embodiment, an example is shown in which a protective layer is provided between two release liners, the first release liner and the second release liner. However, the protective sheet of the present invention may also have a two-layer structure of a single release liner and a protective layer.

[0346] Furthermore, apart from these, the protective sheet of the present invention is not limited to the above examples at all.

[0347] Example

[0348] Next, the present invention will be described in more detail with reference to the following examples. The following examples are provided to further illustrate the present invention in detail, but are not intended to limit the scope of the present invention.

[0349] [Example 1]

[0350] An aqueous dispersion solution was prepared in a container by dispersing polyvinyl alcohol (degree of saponification 65, average degree of polymerization 240) in water.

[0351] In addition, polyvinyl alcohol is also referred to as PVA hereinafter.

[0352] Next, the container containing the aqueous dispersion solution was placed in a water bath at 90° C., and the aqueous dispersion container was stirred to dissolve the PVA in water, thereby obtaining a PVA dissolved composition.

[0353] Next, the PVA dissolved composition was applied to a release-treated surface of a second release liner (MRA50 manufactured by MITSUBISHI CHEMICAL Co., Ltd., thickness 50 μm) having a silicone release-treated surface using an applicator to a thickness of 10 μm.

[0354] Next, the second release liner coated with the PVA dissolved composition was dried at 110° C. for 2 minutes to form a protective layer on the second release liner. That is, a laminate of the second release liner and the protective layer was obtained.

[0355] Next, a foamed first release liner (manufactured by Toyobo Co., Ltd., trade name "CRISPER (registered trademark) K1211", thickness 38 μm) was bonded to the protective layer to obtain a protective sheet of Example 1.

[0356] The first release sheet is a release sheet that has been foamed to generate voids during stretching, and has no release treatment applied to its surface.

[0357] The protective sheet of Example 1 described above is a protective sheet produced by reducing the transmittance of the first release liner.

[0358] The saponification degree and average polymerization degree of the polyvinyl alcohol are measured according to the method described in the above embodiment.

[0359] [Example 2]

[0360] A protective sheet of Example 2 was obtained in the same manner as in Example 1 except that a PET film (manufactured by FUJICO CORPORATION, trade name “PET38-SCA1”, thickness 38 μm) having a coating layer containing titanium oxide on one surface was used as the first release liner.

[0361] The other surface of the first release liner (the surface opposite to the surface having the coating layer) is a release-treated surface.

[0362] The protective sheet of Example 2 was produced by forming a protective layer on a second release liner and then laminating the release-treated surface (the surface without the coating layer) of a first release liner to the protective layer.

[0363] As in the above-mentioned Example 2, the protective sheet was also produced by reducing the transmittance of the first release liner.

[0364] [Example 3]

[0365] A protective sheet of Example 3 was obtained in the same manner as in Example 1 except that a silica-containing layer was used as the protective layer and a release liner having a silicone release-treated surface (MRA38, manufactured by MITSUBISHI CHEMICAL Co., Ltd., thickness 38 μm) was used as the first release liner.

[0366] In the protective sheet of Example 3, the protective layer is formed as follows: a silica-containing composition containing silica in the PVA dissolved composition is applied to the release-treated surface of the second release liner with a thickness of 10 μm using an applicator, and then the second release liner coated with the silica-containing composition is dried at 110° C. for 2 minutes.

[0367] As the silica, “SNOWTEX (registered trademark) MP-2040” (trade name) manufactured by Nissan Chemical Industries, Ltd. was used.

[0368] Furthermore, the concentration of the silica in the silica-containing composition was 30% by mass.

[0369] Furthermore, the first release liner is bonded to the protective layer by bonding the surface subjected to the release treatment.

[0370] The protective sheet of Example 3 described above is a protective sheet produced by reducing the transmittance of the protective layer.

[0371] [Reference Example 1]

[0372] A protective sheet of Reference Example 1 was obtained in the same manner as in Example 3 except that a layer containing a dye was used as the protective layer.

[0373] In the protective sheet of Reference Example 1, the protective layer is formed by applying a dye-containing composition obtained by dissolving a dye in the PVA dissolving composition to a thickness of 10 μm on the release-treated surface of the second release liner using an applicator, and then drying the second release liner coated with the dye-containing composition at 110° C. for 2 minutes.

[0374] As the dye, "LINA BLUE (registered trademark)" (blue pigment), a trade name, manufactured by DIC Corporation was used.

[0375] Furthermore, the concentration of the dye in the dye-containing composition is 5%.

[0376] The protective sheet of Reference Example 1 described above was also produced by reducing the transmittance of the protective layer.

[0377] [Comparative Example 1]

[0378] A protective sheet of Comparative Example 1 was obtained in the same manner as in Example 1 except that a release liner having a surface subjected to a silicone release treatment (product name MRA38, manufactured by MITSUBISHI CHEMICAL CO., LTD., thickness 38 μm) was used as the first release liner.

[0379] In Comparative Example 1, the first release sheet was attached to the protective layer in the same manner as in Example 3 by attaching the surface to which the release treatment had been applied.

[0380] The protective sheet of Comparative Example 1 described above was produced without reducing the transmittance of both the protective layer and the first release liner.

[0381] Transmittance

[0382] Regarding the protective sheet of each example, the transmittance of the first release liner, the protective layer, and the second release liner was measured.

[0383] The transmittance was measured using light having a wavelength of 1060 nm (near infrared light), light having a wavelength of 330 nm (ultraviolet light), light having a wavelength of 550 nm (visible light), and light having a wavelength of 650 nm (visible light).

[0384] The transmittance of the protective layer was measured by obtaining a laminate of the second release liner and the protective layer and then using the protective layer obtained by peeling the second release liner from the laminate.

[0385] The transmittance is measured by the method described in the above embodiment.

[0386] The results are shown in Table 1 below.

[0387] In the following Table 1, the transmittance of the second release liner measured using light of a wavelength of 1060 nm is expressed as T A The transmittance of the protective layer measured using light of a wavelength of 1060 nm is expressed as T B The transmittance of the first release liner measured using light of a wavelength of 1060 nm is expressed as T C .

[0388] The transmittance of the second release liner measured using light of a wavelength of 330 nm is expressed as TA’ The transmittance of the protective layer measured using light of a wavelength of 330 nm is expressed as T B’ The transmittance of the first release liner measured using light of a wavelength of 330 nm is expressed as T C’ .

[0389] Furthermore, the transmittance of the second release liner measured using light of a wavelength of 550 nm is expressed as T A”1 The transmittance of the protective layer measured using light of a wavelength of 550 nm is expressed as T B”1 The transmittance of the first release liner measured using light of a wavelength of 500 nm is expressed as T C”1 .

[0390] The transmittance of the second release liner measured using light of a wavelength of 650 nm is expressed as T A”2 The transmittance of the protective layer measured using light of a wavelength of 650 nm is expressed as T B”2 The transmittance of the first release liner measured using light of a wavelength of 650 nm is expressed as T C”2 .

[0391] Then, the transmittance T A and transmittance T B The difference (T A -T B ) is expressed as ΔT AB , the transmittance T A and transmittance T C The difference (T A -T C ) is expressed as ΔT AC , the transmittance T A’ and transmittance T B’ The difference (T A’ -T B’ ) is expressed as ΔT A’B’ , the transmittance T A’ and transmittance T C’ The difference (T A’ -T C’ ) is expressed as ΔT A’C’ , the transmittance T A”1 and transmittance T B”1 The difference (T A”1 -T B”1 ) is expressed as ΔT A”1B”1 , the transmittance T A”1 and transmittance T C”1 The difference (T A”1 -T C”1 ) is expressed as ΔT A”1C”1 , the transmittance T A”2 and transmittance TB”2 The difference (T A”2 -T B”2 ) is expressed as ΔT A”2B”2 , the transmittance T A”2 and transmittance T C”2 The difference (T A”2 -T C”2 ) is expressed as ΔT A”2C”2 .

[0392] <Haze>

[0393] Regarding the protective sheet of each example, the haze of the first release liner, the protective layer, and the second release liner was measured.

[0394] The haze is measured by the method described in the above embodiment.

[0395] The results are shown in Table 1 below.

[0396] <Gloss at an incident angle of 60°>

[0397] Regarding the protective sheet of each example, the gloss when light was incident at an angle of 60° on the first release liner, the protective layer, and the second release liner (gloss at an incident angle of 60°) was measured.

[0398] White light was used as the light incident at an angle of 60°.

[0399] The gloss at an incident angle of 60° was measured using a spectrophotometer CM-26dG manufactured by Konica Minolta.

[0400] The results are shown in Table 1 below.

[0401] In addition, in Table 1, "GU" (Gloss Unit) shown in parentheses is the unit of gloss.

[0402] <Lightness (L value)>

[0403] Regarding the protective sheet of each example, the lightness (L value) of the first release liner, the protective layer, and the second release liner was measured.

[0404] The measurement of the lightness (L value) is carried out using a color temperature meter as described in the above embodiment.

[0405] The results are shown in Table 1 below.

[0406] In addition, in the measurement of lightness (L value) using a color temperature table, chromaticity (a value and b value) is also measured simultaneously.

[0407] Therefore, in Table 1 below, the measurement results of the chromaticity (a value and b value) of the first release liner, the protective layer, and the second release liner are also shown for the protective sheet of each example.

[0408] In Table 1 below, the lightness (L value) and chromaticity (a value and b value) of the protective sheet of each example were calculated from the measured values ​​of the first release liner, the protective layer, and the second release liner. 2 +a 2 +b 2 ) 1 / 2 value.

[0409] The results are also shown in Table 1 below.

[0410] <Discrimination>

[0411] The protective sheet of each example was evaluated for the discernibility of the protective layer or the first release liner.

[0412] In the evaluation of the discriminability, the protective layer and the first release liner that had been pre-cut were used as test pieces.

[0413] The evaluation of the discrimination performance was performed using a transmission-type photoelectric sensor (manufactured by KEYENCE, product name “PR-G51N”) including a light projecting section and a light receiving section.

[0414] Specifically, regarding the protective sheet of each example, the light-emitting portion is arranged outside the second release sheet and the light-receiving portion is arranged outside the first release sheet. Then, when laser light is irradiated from the light-emitting portion, the light-receiving portion is evaluated to see whether the protective layer or the first release liner is recognized as a shadow portion (dark portion).

[0415] Furthermore, when the protective layer or the first release liner was recognized as a shadow portion (dark portion), it was evaluated as "good", and when it was not recognized as a shadow portion, it was evaluated as "unacceptable".

[0416] Note that, as the laser light irradiated from the light projecting unit, laser light with a wavelength of 550 nm and laser light with a wavelength of 650 nm were used.

[0417] The results of evaluating the discernibility of the protective layer or the first release liner using a 550 nm laser and a 650 nm laser are shown in Table 1 below.

[0418] [Table 1]

[0419]

[0420] According to Table 1, we can see that: A”2C”2 In Examples 1 and 2 where the difference was 15% or more, the discrimination performance when irradiating the laser beam with a wavelength of 650 nm was evaluated as "excellent".A”2B”2 In Example 3 and Reference Example 1, which were 15% or more, the discrimination performance when irradiated with laser light having a wavelength of 650 nm was evaluated as "excellent".

[0421] In contrast, we know that: ΔT A”2C”2 and ΔT A”2B”2 In Comparative Example 1, in which all the values ​​were less than 15%, the evaluation of the discriminability when irradiated with laser light having a wavelength of 650 nm was "unacceptable".

[0422] In addition, we know that: ΔT A”1C”1 In Examples 1 and 2 where the difference was 15% or more, the discrimination performance when irradiated with a laser beam having a wavelength of 550 nm was evaluated as "excellent". A”1B”1 In Example 3 where the percentage was 15% or more, the evaluation of the discriminability when irradiated with laser light having a wavelength of 550 nm was "excellent".

[0423] On the other hand, it can be seen that in Reference Example 1 and Comparative Example 1, ΔT A”1B”1 The evaluation of the discriminability when irradiated with laser light having a wavelength of 550 nm was less than 15%, and it was deemed "unacceptable".

[0424] From these results, it can be understood that when visible light is irradiated as laser light, if the difference between the transmittance of the second release liner and the transmittance of the protective layer is 15% or more, the second release liner and the protective layer can be sufficiently distinguished, and if the difference between the transmittance of the second release liner and the transmittance of the first release liner is 15% or more, the second release liner and the first release liner can be sufficiently distinguished.

[0425] Furthermore, even when near-infrared light is used as the laser light instead of visible light, or ultraviolet light is used as the laser light instead of visible light, if the difference between the transmittance of the second release liner and the transmittance of the protective layer is 15% or more, the second release liner and the protective layer can be sufficiently distinguished as in the case of visible light, and if the difference between the transmittance of the second release liner and the transmittance of the first release liner is 15% or more, the second release liner and the first release liner can be sufficiently distinguished as in the case of visible light.

[0426] Description of Reference Numerals

[0427] 1: protective layer; 2: first release liner; 3: second release liner; 10: protective sheet.

Claims

1. A protective sheet, wherein: The protective sheet has: A protective layer adhered to an adherend; and A release liner is disposed on the surface of the protective layer. The protective layer comprises a water-soluble polymer. The release liner includes an inner surface facing the protective layer and an outer surface opposite to the inner surface. The light transmittance from the outer surface of the release liner to the point where the light passes through the protective layer is lower than the light transmittance of the release liner by 15% or more at at least one wavelength.

2. A protective sheet, wherein: The protective sheet has: A protective layer is attached to the adherend; A first release liner is disposed on a surface of the protective layer; and A second release liner is disposed on the other surface of the protective layer, The protective layer comprises a water-soluble polymer compound, The first release liner and the second release liner each include an inner surface facing the protective layer and an outer surface opposite to the inner surface. The light transmittance from the outer surface of the second release liner to the outer surface of the first release liner is lower than the light transmittance of the second release liner by 15% or more at at least one wavelength.

3. The protective sheet according to claim 1 or 2, wherein: The one wavelength is any one of the ultraviolet region, the visible region, and the near-infrared region.

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