Polyolefin film, adhesive film, dicing tape, semiconductor chip manufacturing method, manufacturing equipment

Abstract

The present invention provides a polyolefin film that, when used as a dicing tape, exhibits excellent processability in the expansion process, superior pickup of semiconductor chips, and excellent uniform stretchability. [Solution] A polyolefin film that satisfies equations (1) to (4), where LA1, FA1, and FB1 are the yield point elongation (%), yield point stress (MPa), and stress at 300% elongation (MPa) in the longitudinal direction, respectively, and LA2, FA2, and FB2 are the yield point elongation (%), yield point stress (MPa), and stress at 300% elongation (MPa) in the width direction, respectively. 0.8≦(FB1 / FA1)≦1.2 ··· Formula (1) 0.8≦(FB2 / FA2)≦1.2 ··· Formula (2) |FA1-FA2|≦1.0MPa ··· Formula (3) |LA1-LA2|≦20% ··· Formula (4)

Description

[Technical Field]

[0001] This invention relates to polyolefin films. [Background technology]

[0002] In the semiconductor chip manufacturing process, a known method involves dicing (cutting) semiconductor wafers such as silicon wafers, sapphire wafers, and SiC wafers into chip shapes, then expanding (stretching) them to create a constant spacing between chips, and finally picking up individual chips. Dicing tape is used to fix the semiconductor wafer (hereinafter sometimes simply referred to as a wafer) in the dicing and expanding processes.

[0003] A dicing tape consists of an adhesive layer for attaching wafers and a base film that supports it. In the dicing and expanding processes, after the wafer attached to the adhesive surface of the dicing tape is diced into chips, a circular stage is used to push up the dicing tape from the side opposite to the chip attachment surface (hereinafter sometimes referred to as the back surface), thereby stretching the film on the top surface of the stage in all directions and widening the chip spacing.

[0004] Until now, polyvinyl chloride (PVC), which has excellent stretchability, has been used as the base film for this application. However, PVC contains regulated substances such as dioctyl phthalate as plasticizers, and is flame-retardant, resulting in high CO2 emissions during disposal, which poses environmental problems. As an alternative material, dicing tapes using olefin resins as the base film have been proposed (Patent Documents 1 and 2). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2008-311671 [Patent Document 2] Japanese Patent Publication No. 2023-66585 [Overview of the project] [Problems that the invention aims to solve]

[0006] Patent documents 1 and 2 propose dicing tapes based on polybutene resins, ethylene-ethyl (meth)acrylate copolymers, and ethylene-methyl (meth)acrylate copolymers. However, these dicing tapes exhibit a gradual yielding behavior when stretched and lack a yield point, making it difficult to relieve residual stress after stretching the dicing tape in the expanding process. This raises concerns about problems occurring when picking up chips after dicing and expanding.

[0007] Furthermore, the elongation rate of the film after expansion is generally greater on the sides of the expansion stage than on the top surface, and in some cases the sides can be stretched to several hundred percent. Dicing tapes such as those proposed in Patent Documents 1 and 2 have a large increase in tensile stress due to stretching, that is, the tension on the dicing tape on the sides is large after expansion, which raises concerns that the dicing tape may come off the gripping part or tear near the boundary with the gripping part, resulting in poor processing stability.

[0008] The present invention aims to provide a polyolefin film that, when used as a dicing tape, exhibits excellent processability in the expansion process, superior pickability for semiconductor chips, and excellent uniform stretchability. [Means for solving the problem]

[0009] A preferred embodiment of the present invention is as follows: 1. A polyolefin film that satisfies equations (1) to (4), where LA1, FA1, and FB1 are the longitudinal yield strength elongation (%), yield strength stress (MPa), and stress at 300% elongation (MPa), respectively, and LA2, FA2, and FB2 are the widthwise yield strength elongation (%), yield strength stress (MPa), and stress at 300% elongation (MPa), respectively. 0.8≦(FB1 / FA1)≦1.2 ··· Formula (1) 0.8≦(FB2 / FA2)≦1.2 ··· Formula (2) |FA1-FA2|≦1.0MPa ··· Formula (3) |LA1-LA2|≦20% ··· Formula (4) 2. The polyolefin film described in 1., which satisfies equations (5) and (6) when FC1 is the minimum stress (MPa) in the elongation range from yield point elongation LA1 (%) to 300% in the longitudinal direction, and FC2 is the minimum stress (MPa) in the elongation range from yield point elongation LA2 (%) to 300% in the width direction. (FA1-FC1)≦0.8MPa ··· Formula (5) (FA2-FC2)≦0.8MPa ··· Formula (6) 3. A polyolefin film as described in 1. or 2., wherein FA1 and FA2 are 7 MPa or more and 15 MPa or less. 4. A polyolefin film according to any of 1. to 3., having a melting point of 150℃ or higher and 250℃ or lower. A polyolefin film according to any of 1 to 4, wherein, when the surface resistivity of the film at 5.23℃ and 65%RH is ρs1 (Ω / sq), at least one surface satisfies formula (7).

[0010] 1.0 × 10 7 Ω / sq ≤ ρs1 ≤ 1.0 × 10 13 Ω / sq··· Formula (7) A polyolefin film according to any of 1 to 5, wherein, when the surface resistivity of the film at 6.23℃ and 65%RH is ρs1 (Ω / sq), the above formula (7) is satisfied on both surfaces. A polyolefin film according to any of 1 to 6, wherein, when the surface resistivity of the film at 7.23°C and 65%RH is ρs1 (Ω / sq), and the surface resistivity of the film measured at 23°C and 65%RH after heating at 80°C for 10 minutes is ρs2 (Ω / sq), at least one surface satisfies equation (8).

[0011] 0.5 ≦ (ρs2 / ρs1) ≦ 1.5 ··· Equation (8) 8. The polyolefin film according to any one of 1. to 7., wherein on at least one surface, the arithmetic mean waviness Wa measured at a cut-off value of 2.0 mm is 1.5 μm or less. 9. The polyolefin film according to any one of 1. to 8., containing homopolypropylene and linear low density polyethylene. 10. The polyolefin film according to 9., wherein linear low density polyethylene is the main component. 11. The polyolefin film according to any one of 1. to 10., containing a propylene-based elastomer. 12. The polyolefin film according to any one of 1. to 11., containing an ethylene-based elastomer. 13. The polyolefin film according to any one of 1. to 12., wherein the arithmetic mean height Sa of at least one surface is 0.5 μm or more. 14. The polyolefin film according to any one of 1. to 13., composed of at least two layers or more, and at least one surface layer contains polyethylene particles. 15. The polyolefin film according to any one of 1. to 14., composed of at least two layers or more, at least one surface layer contains linear low density polyethylene as the main component, and contains polyethylene particles. 16. The polyolefin film according to any one of 1. to 15., wherein the content of volatile organic compounds is 10 ppm or less. 17. An adhesive film having an adhesive layer on at least one surface of the polyolefin film according to any one of 1. to 16. 18. The adhesive film according to 17., substantially free of perfluoroalkyl compounds and polyfluoroalkyl compounds. 19. A dicing tape comprising the polyolefin film according to any one of 1. to 16. or a dicing tape made of the adhesive film according to 17. or 18. 20. A method for manufacturing a semiconductor chip using the dicing tape according to 19. 21. A manufacturing apparatus having a mechanism for manufacturing semiconductor chips using the dicing tape described in 19. [Effects of the Invention]

[0012] According to the present invention, when used as a dicing tape, it is possible to provide a polyolefin film that exhibits excellent processability in the expansion process, excellent pickability for semiconductor chips, and excellent uniform stretchability. [Brief explanation of the drawing]

[0013] [Figure 1] A schematic diagram illustrating the dicing method. [Modes for carrying out the invention]

[0014] Embodiments of the present invention will be described below.

[0015] A preferred embodiment of the present invention is a polyolefin film that satisfies equations (1) to (4), where the yield point elongation (%), yield point stress (MPa), and stress at 300% elongation (MPa) in the longitudinal direction are LA1, FA1, and FB1, respectively, and the yield point elongation (%), yield point stress (MPa), and stress at 300% elongation (MPa) in the width direction are LA2, FA2, and FB2, respectively. 0.8≦(FB1 / FA1)≦1.2 ··· Formula (1) 0.8≦(FB2 / FA2)≦1.2 ··· Formula (2) |FA1-FA2|≦1.0MPa ··· Formula (3) |LA1-LA2|≦20% ··· Formula (4) From an environmental perspective, the polyolefin film of the present invention preferably contains 50% by mass or more of polyolefin resin in at least one layer constituting the film, with the total mass of that layer being 100% by mass, more preferably 70% by mass or more, and even more preferably 80% by mass or more. In the present invention, polyolefin resins may preferably be one or more selected from polyethylene resins such as high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), low-crystalline or amorphous ethylene-α-olefin copolymers, styrene-ethylene-butylene-ethylene block copolymer (SEBC), and ethylene-ethylene-butylene-ethylene block copolymer (CEBC); polypropylene resins such as homopolypropylene, random copolymers of propylene and ethylene and / or butene-1 (random polypropylene), block polypropylene, propylene-α-olefin copolymer, and propylene-ethylene-α-olefin copolymer; polybutene resins such as polybutene-1, polybutene-1-ethylene copolymer, and polybutene-1-propylene copolymer; and 4-methyl-1-pentene-α-olefin copolymer, ethylene-ethyl (meth)acrylate copolymer, ethylene-methyl (meth)acrylate copolymer, ethylene-n-butyl (meth)acrylate copolymer, and ethylene-vinyl acetate copolymer. Examples of the α-olefins include propylene, ethylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-pentene, and 1-heptene.

[0016] As the polyolefin resin used in the polyolefin film of the present invention, from the viewpoint of controlling the content of volatile organic compounds (VOCs), which will be described later, to a preferred range, polyethylene resins such as high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), low-crystalline or amorphous ethylene-α-olefin copolymer, styrene-ethylene-butylene-ethylene block copolymer (SEBC), and ethylene-ethylene-butylene-ethylene block copolymer (CEBC) are more preferably used among the above-mentioned polyolefin resins; polypropylene resins such as homopolypropylene, random copolymer of propylene and ethylene and / or butene-1 (random polypropylene), block polypropylene, propylene-α-olefin copolymer, and propylene-ethylene-α-olefin copolymer are more preferably used; polybutene resins such as polybutene-1, polybutene-1-ethylene copolymer, and polybutene-1-propylene copolymer are more preferably used. In other words, it is more preferable that the polyolefin film of the present invention does not contain ethylene-ethyl (meth)acrylate copolymer, ethylene-methyl (meth)acrylate copolymer, ethylene-n-butyl (meth)acrylate copolymer, or ethylene-vinyl acetate copolymer.

[0017] Furthermore, the melt flow rate of the polyolefin resin used in the polyolefin film of the present invention, measured at 230°C and a load of 21.18 N, is preferably 1 g / 10 min or more, more preferably 2 g / 10 min or more, and particularly preferably 3 g / 10 min or more, from the viewpoint of setting the melt extrusion temperature during the production of the polyolefin film, as described later, within a favorable range. In addition, if the polyolefin film of the present invention contains a polyolefin resin of 1 g / 10 min or more and less than 3 g / 10 min, the content of the polyolefin resin of 1 g / 10 min or more and less than 3 g / 10 min is preferably 40% by mass or less, and more preferably 30% by mass or less, when the entire polyolefin film is considered as 100% by mass.

[0018] In the polyolefin film of the present invention, the yield point elongation LA1 (%), yield point stress FA1 (MPa), stress FB1 (MPa) at 300% elongation in the longitudinal direction, minimum stress FC1 (MPa) in the elongation range from yield point elongation LA1 (%) to 300% in the longitudinal direction, yield point elongation LA2 (%), yield point stress FA2 (MPa) in the width direction, stress FB2 (MPa) at 300% elongation, and minimum stress FC2 (MPa) in the elongation range from yield point elongation LA2 (%) to 300% in the width direction shall be calculated by performing a tensile test at 23°C and 300 mm / min using the method described in the examples. If the longitudinal direction (machine direction during film manufacturing) and width direction of the polyolefin film are unknown, the longitudinal direction and width direction shall be determined by the following method, and LA1, FA1, FB1, FC1, LA2, FA2, FB2, and FC2 shall be determined. First, tensile tests are performed five times each in six directions at 30° intervals, starting from any direction within the film surface, using the method described in the examples. Then, the arithmetic mean of the stress at 5% elongation in each direction is calculated, and the direction with the highest value is defined as the longitudinal direction, with the direction 90° from this direction defined as the width direction. In each evaluation of the polyolefin film of the present invention, the longitudinal and width directions are determined using the method described above, even when they are unknown.

[0019] Furthermore, in this invention, the yield point refers to the point of maximum stress that occurs in the tensile test described above, between 5% and 200% elongation, and specifically refers to the point that satisfies all of the following conditions (a), (b), and (c).

[0020] Condition (a) The point at which the difference F of tensile stress, calculated for every 1% elongation, changes from a positive value (0.01 MPa or more) to 0.00 MPa or a negative value (-0.01 MPa or less). For example, if the difference F (49%) obtained by subtracting the stress at 48% elongation from the stress at 49% elongation is 0.01 MPa, and the difference F (50%) obtained by subtracting the stress at 49% elongation from the stress at 50% elongation is -0.01 MPa, then 50% elongation is considered the point that meets condition (a).

[0021] Condition (b) Using the point that satisfies condition (a) as a reference, the point where the F values ​​at three consecutive points on the high-elongation side are 0.00 MPa or a negative value (-0.01 MPa or less). For example, if condition (a) is satisfied at the point of 50% elongation, condition (b) can be satisfied when the difference F(51%), difference F(52%), and difference F(53%) calculated in the same manner as above are all 0.00 MPa or less.

[0022] Condition (c) The difference obtained by subtracting the minimum stress in the elongation range from the maximum point to 300% elongation from the stress at the maximum point that satisfies both conditions (a) and (b) is 0.05 MPa or more.

[0023] If the polyolefin film of the present invention has two or more maximum points within the elongation range of 5% to 200%, the point with the highest yield stress among these maximum points is defined as the yield point of the polyolefin film of the present invention.

[0024] The polyolefin film of the present invention preferably satisfies formulas (1) and (2) above. That is, it is preferable that FB1 / FA1 and FB2 / FA2 are between 0.8 and 1.2. Generally, the yield point in a tensile test of a polyolefin film is said to be due to deformation of higher-order structures such as spherulites, or, in the case of a film made of two or more incompatible resins, due to interfacial delamination of the resins. Furthermore, after the yield point, the stress may increase with stretching due to crystal rearrangement, etc., after passing through a necking region (a region exhibiting constant stress), or the stress may increase with stretching without showing a necking region after the yield point. The preference for FB1 / FA1 and FB2 / FA2 of the polyolefin film of the present invention being between 0.8 and 1.2 means that the structural change of the film from the yield point to 300% elongation is relatively small. Therefore, when the polyolefin film of the present invention is used in processes involving localized stretching of the film, such as expanding, drawing, and press molding, the variation in film quality due to structural differences in the processed film is small, and a good product can be obtained. Furthermore, when the polyolefin film is used as a dicing tape, from the viewpoint of improving the aforementioned film quality and expandability (stretchability), FB1 / FA1 and FB2 / FA2 are preferably 0.8 or higher, and more preferably 0.9 or higher. If FB1 / FA1 and FB2 / FA2 are too small, it is thought that there will be insufficient tension to stretch the film on the upper surface of the stage during expansion, and sufficient expandability (elongation) cannot be obtained. Furthermore, from the viewpoint of improving the aforementioned film quality, suppressing detachment of the gripping portion due to increased stretching tension during expansion, and suppressing tearing of the dicing tape, FB1 / FA1 and FB2 / FA2 are preferably 1.2 or lower, and more preferably 1.1 or lower. Regarding the tearing of the dicing tape, it is particularly likely to occur near the boundary between the gripping portion and the extended portion on the side of the expand stage. However, by setting FB1 / FA1 and FB2 / FA2 to 1.2 or less, it is believed that localized stress concentration caused by structural differences near the boundary will be suppressed, making it less prone to tearing.

[0025] The yield stresses FA1 and FA2, and the stresses FB1 and FB2 at 300% elongation can be controlled by the composition and crystallization conditions of the polyolefin film, as described later. Methods for controlling FB1 / FA1 and FB2 / FA2 to between 0.8 and 1.2 include, for example, controlling the crystallinity of the polyolefin film to between 20% and 40%, reducing the spherulite size, and improving dispersibility if the film contains layers made of at least two immiscible resins.

[0026] Furthermore, the polyolefin film of the present invention preferably satisfies formula (3) above, that is, |FA1-FA2| is preferably 1.0 MPa or less. |FA1-FA2| is preferably 1.0 MPa or less, more preferably 0.9 MPa or less, and even more preferably 0.8 MPa or less, from the viewpoint of improving uniform stretchability when the polyolefin film of the present invention is used as a dicing tape. |FA1-FA2| can be controlled to the above-mentioned preferred range by the composition, dispersion state, and manufacturing conditions of the polyolefin film described later.

[0027] The polyolefin film of the present invention preferably satisfies formula (4), that is, |LA1-LA2| is preferably 20% or less. From the viewpoint of improving uniform stretchability when the polyolefin film of the present invention is used as a dicing tape, |LA1-LA2| is preferably 20% or less, more preferably 15% or less, and even more preferably 10% or less. |LA1-LA2| can be controlled to the above-mentioned preferred range by the composition, dispersion state, and manufacturing conditions of the polyolefin film described later.

[0028] The polyolefin film of the present invention preferably satisfies the following formulas (5) and (6). (FA1-FC1)≦0.8MPa ··· Formula (5) (FA2-FC2)≦0.8MPa ··· Formula (6) In other words, it is preferable that FA1-FC1 and FA2-FC2 are 0.8 MPa or less. From the viewpoint of improving expandability (elongation), FA1-FC1 and FA2-FC2 are preferably 0.8 MPa or less, and more preferably 0.5 MPa or less. If FA1-FC1 or FA2-FC2 are too large, there may not be enough tension to stretch the film on the top surface of the stage during expansion, and sufficient expandability (elongation) may not be obtained. Furthermore, from the viewpoint of improving pick-up performance after expansion, FA1-FC1 and FA2-FC2 are preferably 0.2 MPa or more, and more preferably 0.4 MPa or more. This is because if FA1-FC1 or FA2-FC2 are too small, residual stress between chips after expansion tends to be high, and problems such as chips unintentionally peeling off the dicing tape when the film is pushed up from the back during pickup are likely to occur.

[0029] FA1-FC1 and FA2-FC2 can be controlled to the preferred range described above by the composition, dispersion state, and manufacturing conditions of the polyolefin film, as described later. Methods for controlling FA1-FC1 and FA2-FC2 to the preferred range include, for example, controlling the crystallinity of the polyolefin film to 20% or more and 40% or less, reducing the spherulite size, and improving dispersibility if the film contains layers made of at least two immiscible resins.

[0030] The yield strength FA1 in the longitudinal direction and the yield strength FA2 in the width direction of the polyolefin film of the present invention are preferably 7 MPa or higher from the viewpoint of ensuring the rigidity of the polyolefin film and improving process stability during manufacturing, processing, and use. Furthermore, FA1 and FA2 are preferably 15 MPa or lower, and more preferably 12 MPa or lower, from the viewpoint of improving the expandability (elongation) of the polyolefin film. FA1 and FA2 can be controlled to the above-mentioned preferred ranges by the composition of the polyolefin film and manufacturing conditions described later.

[0031] The polyolefin film of the present invention preferably has a melting point of 150°C or higher from the viewpoint of improving heat resistance during use, preferably has a melting point of 250°C or lower from the viewpoint of improving melt extrudeability during manufacturing, more preferably has a melting point of 200°C or lower, and even more preferably has a melting point of 170°C or lower. As a method for controlling the melting point of the polyolefin film, a method using a thermoplastic resin having a melting point in the above temperature range is mentioned, preferably using a polyolefin resin, more preferably using a polypropylene resin, and even more preferably using homopolypropylene.

[0032] In this invention, the melting point refers to the value measured by the DSC (Differential Scanning Calorimetry) method described in the examples. If the polyolefin film of this invention has two or more melting points, it is preferable that the highest temperature melting point falls within the above preferred range.

[0033] The polyolefin film of the present invention preferably has an arithmetic mean waviness Wa measured at a cutoff value of 2.0 mm on at least one surface of 1.5 μm or less, more preferably 1.0 μm or less, and even more preferably 0.5 μm or less, from the viewpoint of improving processability and yield when laminating an adhesive layer to a polyolefin film by a coating method, suppressing the transfer of uneven shapes when polyolefin films and adhesive films are laminated in roll form or sheet form, and improving inspection accuracy in the inspection process of polyolefin films and adhesive films. Similarly, the polyolefin film of the present invention preferably has an arithmetic mean waviness Wa of 1.5 μm or less on both surfaces of 1.5 μm or less, even more preferably 1.0 μm or less, and especially preferably 0.5 μm or less. The arithmetic mean waviness Wa of the polyolefin film of the present invention can be measured by the method described in the examples. The arithmetic mean waviness Wa can be controlled to the above-mentioned preferred range by the composition and manufacturing conditions of the polyolefin film described later.

[0034] The polyolefin film of the present invention, when used in semiconductor chip manufacturing processes and the like, preferably has a volatile organic compound (VOC) content of 10 ppm or less, more preferably 5 ppm or less, and particularly preferably 3 ppm or less, as measured by the method described in the examples below, in order to suppress contamination of semiconductor components and to suppress a decrease in production efficiency in the semiconductor wafer dicing process. The volatile organic compound (VOC) content in the polyolefin film of the present invention can be controlled to the above-mentioned preferred range by the composition of the polyolefin film and the manufacturing conditions.

[0035] The polyolefin film of the present invention preferably contains at least one polyethylene resin X selected from the group consisting of high-density polyethylene (HDPE), low-density polyethylene (LDPE), and linear low-density polyethylene (LLDPE), in order to control the parameters of formulas (1) to (6) within a preferred range and improve the balance between flexibility and rigidity. In this invention, the density is 0.93 g / cm³. 3 The above polyethylene is high-density polyethylene, with a density of 0.90 g / cm³. 3 More than 0.93g / cm 3 Polyethylene with a density of less than 1 is defined as low-density polyethylene or linear low-density polyethylene.

[0036] The polyethylene resin X described above may be used alone or in combination, but in the polyolefin film of the present invention, it is preferable to contain at least low-density polyethylene and / or linear low-density polyethylene, in order to control the parameters of formulas (1), (2), (5), and (6) within the preferred ranges described above. Furthermore, in order to reduce the in-plane anisotropy of the polyolefin film of the present invention and to control the parameters of formulas (3) and (4) within the preferred ranges described above, it is more preferable that the polyolefin film of the present invention contains linear low-density polyethylene.

[0037] The total content of low-density polyethylene and linear low-density polyethylene in the polyolefin film of the present invention is preferably 30% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more, when the entire polyolefin film is considered to be 100% by mass, in order to control the parameters of formulas (1), (2), (5), and (6) to the preferred ranges described above.

[0038] Furthermore, in terms of controlling the parameters of formulas (1) to (6) to the preferred range described above, the content of linear low-density polyethylene in the polyolefin film of the present invention is preferably 30% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more. In other words, it is a more preferable embodiment that the polyolefin film of the present invention has linear low-density polyethylene as its main component. Herein, "having linear low-density polyethylene as its main component" means that linear low-density polyethylene has the highest content among the materials constituting the polyolefin film.

[0039] Furthermore, the total content of low-density polyethylene and linear low-density polyethylene in the polyolefin film of the present invention is preferably 90% by mass or less, and more preferably 80% by mass or less, from the viewpoint of controlling the yield stress FA1 in the longitudinal direction and the yield stress FA2 in the width direction to 7 MPa or more.

[0040] The polyolefin film of the present invention preferably contains at least one polypropylene resin Y selected from the group consisting of homopolypropylene, random copolymer of propylene and ethylene and / or butene-1 (random polypropylene), and block polypropylene, in order to impart rigidity and heat resistance and to ensure process stability during manufacturing and use. It is even more preferable to contain at least homopolypropylene in order to improve rigidity and to give the polyolefin film of the present invention a melting point of 150°C or higher, thereby further improving heat resistance.

[0041] From the viewpoint of improving rigidity and heat resistance, the content of polypropylene resin Y in the polyolefin film of the present invention is preferably 10% by mass or more, and more preferably 15% by mass or more, when the total polyolefin film is considered as 100% by mass. Furthermore, from the viewpoint of controlling the parameters of formulas (1) and (2) to 0.8 or more, controlling the parameters of formulas (5) and (6) to 0.8 MPa or less, and controlling FA1 and FA2 to 15 MPa or less, the content of polypropylene resin Y in the polyolefin film is more preferably 50% by mass or less, and even more preferably 40% by mass or less.

[0042] The polyolefin film of the present invention preferably contains low-density polyethylene and / or linear low-density polyethylene and the polypropylene resin X described above, from the viewpoint of controlling the parameters of formulas (1), (2), (5), and (6) to the preferred range described above. It is even more preferable to contain linear low-density polyethylene and a polypropylene resin from the viewpoint of controlling the parameters of formulas (3) and (4) to the preferred range described above and controlling the content of volatile organic compounds (VOCs) in the polyolefin film to the preferred range described above. Furthermore, it is particularly preferable to contain linear low-density polyethylene and homopolypropylene from the viewpoint of controlling the parameter of formula (4) to the preferred range described above and providing rigidity and heat resistance. When the polyolefin film of the present invention contains linear low-density polyethylene and homopolypropylene, when the entire polyolefin film of the present invention is considered as 100% by mass, the lower limit of the linear low-density polyethylene content in the polyolefin film is preferably 30% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more, and the upper limit of the linear low-density polyethylene content is preferably 80% by mass or less. The lower limit of the homopolypropylene content in the polyolefin film is preferably 10% by mass or more, more preferably 15% by mass or more, and the upper limit of the homopolypropylene content is preferably 40% by mass or less, and even more preferably 30% by mass or less.

[0043] The polyolefin film of the present invention preferably contains an ethylene-based elastomer or a propylene-based elastomer in addition to the polyethylene-based resin X and polypropylene-based resin Y, from the viewpoint of controlling the parameters of formulas (1) and (2) to 0.8 or higher, and controlling the parameters of formulas (5) and (6) to 0.8 MPa or lower. Known ethylene-based elastomers and propylene-based elastomers can be used. Examples of ethylene-based elastomers include ethylene-α-olefin copolymers with a density of less than 0.90, styrene-ethylene-butylene-ethylene block copolymers (SEBC), and ethylene-ethylene-butylene-ethylene block copolymers (CEBC). Examples of propylene-based elastomers include low-crystallinity or amorphous propylene polymers, propylene-α-olefin copolymers, and propylene-ethylene-α-olefin copolymers. Examples of the α-olefins include propylene, ethylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-pentene, and 1-heptene.

[0044] The aforementioned ethylene-based elastomers and propylene-based elastomers can be appropriately selected according to the desired effect, and one or more may be used in the polyolefin film of the present invention. When the polyolefin film of the present invention contains a polypropylene resin Y, it is preferable to use a propylene-based elastomer in combination from the viewpoint of controlling the parameters of formulas (1) and (2) to 0.8 or higher, and controlling the parameters of formulas (5) and (6) to 0.8 MPa or lower, and it is more preferable to use a propylene-based elastomer having a melting point of 120°C or higher from the viewpoint of suppressing a decrease in heat resistance. When the polyolefin film of the present invention contains at least a polypropylene resin Y and a propylene-based elastomer, the content of the propylene-based elastomer in the polyolefin film is preferably 5% by mass or more, and more preferably 10% by mass or more, when the total polyolefin film is considered as 100% by mass, from the viewpoint of controlling the parameters of formulas (1) and (2) to 0.8 or higher, and controlling the parameters of formulas (5) and (6) to 0.8 MPa or lower. Furthermore, when the polyolefin film of the present invention contains at least a polypropylene resin Y and a propylene elastomer, the content of the propylene elastomer in the polyolefin film is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less, from the viewpoint of controlling the parameters of formulas (1) and (2) to less than 1.2, controlling the yield stresses FA1 and FA2 to 7 MPa or more, and ensuring process stability, processability, and heat resistance during manufacturing and use.

[0045] Furthermore, even when the polyolefin film of the present invention contains the polyethylene resin X and the polypropylene resin Y, it is preferable to include a propylene elastomer from the same viewpoint as described above. The more preferable propylene elastomer and the preferred range of the propylene elastomer content in the polyolefin film are as described above.

[0046] Furthermore, when the polyolefin film of the present invention contains the polyethylene resin X and the polypropylene resin Y, it is preferable to add the propylene elastomer, ethylene elastomer, or other compatibilizer from the viewpoint of improving the compatibility of the polyethylene resin X and the polypropylene resin Y and controlling the arithmetic mean waviness Wa to a desirable range. Other known compatibilizers other than the propylene elastomer and ethylene elastomer can be used, but styrene-ethylene-butylene-styrene block copolymer (SEBS) is preferred from the viewpoint of melt extrusion characteristics and recyclability. In a similar view, the polyolefin film of the present invention more preferably uses at least one of the following in addition to polyethylene resin X and polypropylene resin Y: ethylene-α-olefin copolymer with a density of less than 0.90, styrene-ethylene-butylene-ethylene block copolymer (SEBC), ethylene-ethylene-butylene-ethylene block copolymer (CEBC), and styrene-ethylene-butylene-styrene block copolymer (SEBS). Furthermore, from the viewpoint of improving processing stability and thermal stability, it is even more preferable to use ethylene-α-olefin copolymer and / or ethylene-ethylene-butylene-ethylene block copolymer (CEBC) with a density of less than 0.90.

[0047] The content of the propylene-based elastomer, ethylene-based elastomer, and other compatibilizers in the polyolefin film is preferably 2% by mass or more, and more preferably 5% by mass or more, when the total mass of each layer containing polyethylene resin X and polypropylene resin Y is taken as 100% by mass. Furthermore, from the viewpoint of controlling the parameters of formulas (1) and (2) to less than 1.2, controlling the yield stresses FA1 and FA2 to 7 MPa or higher, and ensuring process stability, processability, and heat resistance during manufacturing and use, it is preferable to blend the polyolefin film so that the total amount of the propylene-based elastomer, ethylene-based elastomer, and other compatibilizers in the polyolefin film is 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. From the viewpoint of controlling the parameters of formulas (1) and (2) to 0.8 or higher, and controlling the parameters of formulas (5) and (6) to 0.8 MPa or lower, it is preferable to blend it to 5% by mass or more, and more preferably 10% by mass or more.

[0048] The polyolefin film of the present invention preferably has an arithmetic mean height Sa of at least one surface of 0.5 μm or more, and more preferably 0.7 μm or more, from the viewpoint of improving transportability during manufacturing and use, improving winding performance when winding the polyolefin film into a roll, and improving unwinding performance from the roll during processing and use. Furthermore, the upper limit of the arithmetic mean height Sa of the surface may be as long as it does not impair the effects of the present invention, but from the viewpoint of suppressing transfer to the opposite surface and reducing costs, it is preferably 2.0 μm or less, and more preferably 1.5 μm or less.

[0049] Methods for controlling the arithmetic mean height Sa of at least one surface of the polyolefin film of the present invention to 0.5 μm or more include, for example, a method of embossing the surface of the polyolefin film during or after the film manufacturing process, a method of using two or more immiscible resins in a layer placed on the surface of the polyolefin film, or a method of including inorganic particles or organic particles. Examples of inorganic particles include inorganic oxide particles (silica particles, alumina particles, titanium oxide particles, etc.), inorganic carbonate particles (calcium carbonate particles, barium carbonate particles, etc.), inorganic silicate particles (aluminum silicate particles, talc particles, kaolin particles, etc.), and examples of organic particles include acrylic particles, polyolefin particles (polyethylene particles, polypropylene particles), polystyrene particles, etc.

[0050] As a method for controlling the arithmetic mean height Sa to 0.5 μm or more, from the viewpoint of improving productivity and reducing environmental impact, it is more preferable to use two or more incompatible resins or to include inorganic or organic particles in the layer disposed on the surface of the polyolefin film. The polyolefin film of the present invention may consist of a single layer or two or more layers, but from the viewpoint of achieving both the arithmetic mean roughness Sa and other properties of the polyolefin film, it is more preferable to have two or more layers, and to use two or more incompatible resins or to include inorganic or organic particles in the layer disposed on at least one surface. From a similar viewpoint, it is even more preferable to include organic particles in the layer disposed on at least one surface, and it is particularly preferable to include polyethylene particles in the layer disposed on at least one surface.

[0051] When expanding a dicing tape using the polyolefin film of the present invention, in terms of reducing the friction between the film and the processing apparatus to obtain high stretchability, and improving the process stability during manufacturing and processing, it is preferable that the static friction coefficient between at least one pair of surfaces is 0.6 or less, and more preferably 0.4 or less. Further, from the viewpoint of preventing displacement when winding the polyolefin film of the present invention in a roll shape or during storage, it is preferable that the static friction coefficient between at least the surfaces is 0.1 or more.

[0052] The static friction coefficient in the present invention refers to the static friction coefficient evaluated by the method described in the examples. As a method for controlling the static friction coefficient, there are a method of controlling the arithmetic mean roughness Sa to 0.5 or more, and a method of adding lubricants such as fatty acid amides, metal soaps, fluorine-based polymers, silicone-based lubricants, fatty acids, and vegetable oils, and these can be appropriately selected according to the desired characteristics.

[0053] The polyolefin film of the present invention preferably has antistatic properties from the viewpoint of suppressing the adhesion of dust etc. due to charging, or suppressing the destruction and product deterioration due to the charging of semiconductor chips and devices manufactured using the polyolefin film of the present invention, and improving the product yield rate. Specifically, when the surface resistivity of the film at 23°C and 65% RH is ρs1 (Ω / sq), it is preferable that at least one surface satisfies the following formula (7).

[0054] 1.0×10 7 Ω / sq≦ρs1≦1.0×10 13 Ω / sq ··· Formula (7) That is, it is preferable that ρs1 is 1.0×10 7 Ω / sq or more and 1.0×10 13 Ω / sq or less. Further, from the same viewpoint, it is preferable that ρs1 satisfies the above formula (7) on both surfaces of the polyolefin film of the present invention. ρs1 can be measured by the method described in the examples. From the viewpoint of improving the antistatic properties, ρs1 is 1.0×10 12Ω / sq or less is more preferable, and 1.0 × 10 11 A ratio of Ω / sq or less is even more preferable, and 1.0 × 10 10 A value of Ω / sq or less is particularly preferred. Furthermore, from the viewpoint of balancing antistatic properties with other film properties and film quality, ρs1 should be 1.0 × 10⁻⁶. 8 A density of Ω / sq or higher is more preferable.

[0055] One method for controlling the ρs1 of the polyolefin film of the present invention to the preferred range described above is to include an antistatic agent in the polyolefin film. Examples of antistatic agents used in the polyolefin film of the present invention include low molecular weight antistatic agents such as surfactants, conductive particles such as carbon black, and polymer antistatic agents. However, polymer antistatic agents are more preferable from the viewpoint of being less prone to bleeding out onto the film surface, having excellent non-contamination properties, and controlling the content of volatile organic compounds (VOCs) in the polyolefin film to a preferred range. While known polymeric antistatic agents can be used, from the above viewpoint, it is particularly preferable that the polymer be at least one selected from the group consisting of polyether-polyolefin block copolymers, polyether ester amides, polyetheramides, polyetheramide-imides, polyethylene glycol (meth)acrylate copolymers, ionomers, and polymers with ionic compounds (e.g., metal salts such as lithium salts). From the viewpoint of excellent compatibility with the polyolefin resin used in the polyolefin film in the present invention, polyether-polyolefin block copolymers, ionomers, and polymers with ionic compounds (e.g., metal salts such as lithium salts) are more preferable, and polyether-polyolefin block copolymers are even more preferable.

[0056] When an antistatic agent is included in the polyolefin film of the present invention, the antistatic agent may be included in any layer of the polyolefin film. However, from the viewpoint of suppressing peeling charge when unwinding the polyolefin film of the present invention wound into a roll or a dicing tape comprising the polyolefin film of the present invention, and charging due to friction during the usage process, as well as from the viewpoint of balancing antistatic properties with other film properties, film quality, productivity, and cost, it is more preferable to include the antistatic agent in the layer with the smaller thickness of a polyolefin film consisting of two or more layers, or to include the antistatic agent in at least one surface layer or both surface layers of a polyolefin film consisting of three or more layers.

[0057] The content of the antistatic agent described above can be appropriately adjusted according to the desired surface resistivity. However, when the entire layer containing the antistatic agent is considered to be 100% by mass, the content of the antistatic agent in the layer is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more. Similarly, from the viewpoint of productivity, reducing the content of volatile organic compounds (VOCs) in the polyolefin film, and achieving compatibility with film properties other than antistatic properties and film quality, the content of the antistatic agent in the layer is preferably 40% by mass or less, and even more preferably 30% by mass or less. Furthermore, from the viewpoint of reducing the content of volatile organic compounds (VOCs) in the polyolefin film, when the entire polyolefin film is considered to be 100% by mass, the total content of the antistatic agent in the polyolefin film is preferably 20% by mass or less, more preferably 15% by mass or less, and especially preferably 10% by mass or less.

[0058] In order to exhibit stable antistatic properties regardless of the manufacturing method or usage environment, it is preferable that the polyolefin film of the present invention satisfies the following formula (8) when the surface resistivity of the film, measured at 23°C and 65% RH after heating at 80°C for 10 minutes, is denoted as ρs² (Ω / sq).

[0059] 0.5≦(ρs2 / ρs1)≦1.5 Equation (8) In other words, it is preferable that the ratio of ρs2 to ρs1, (ρs2 / ρs1), is between 0.5 and 1.5. ρs2 can be measured by the method described in the examples.

[0060] One method for setting (ρs2 / ρs1) to between 0.5 and 1.5 involves performing thermal melt extrusion with a specific amount of high-molecular-weight antistatic agent having a higher MFR (i.e., low viscosity) than the most abundant resin in the polyethylene film, and then, when cooling and solidifying the resin with a cooling roll, pressing it with a rubber roll set to 40°C to 90°C at a pressure of 0.1 MPa to 0.5 MPa, and after obtaining the resulting sheet, setting the winding speed to 100.5% to 125% of the rotation speed of the cooling roll. By performing such pressing and winding, the flattening and relaxation of the high-molecular-weight antistatic agent in the film progresses, making it possible to reduce the changes in fine shape during the subsequent heating process and the resulting changes in the antistatic effect at high temperatures.

[0061] The polyolefin film of the present invention preferably has a tensile elongation at break of 400% or more. The tensile elongation at break is determined by performing tensile tests five times each in the longitudinal and width directions of the polyolefin film at 23°C and 300 mm / min using the method described in the examples, and the arithmetic mean of the tensile elongation at break (the arithmetic mean of a total of 10 points) is taken as the tensile elongation at break of the polyolefin film.

[0062] Because the tensile elongation at break is 400% or more, when the polyolefin film of the present invention is used for wafer dicing or wafer expanding applications, it can be used smoothly without tearing the film when expanding chips or picking up chips. From a similar viewpoint, a tensile elongation at break of 600% or more is more preferable. There is no particular upper limit set for the tensile elongation at break, but in practice it is about 1,500% or less.

[0063] From the viewpoint of controlling the tensile elongation at break to 400% or more, it is preferable to use a resin suitable for each layer as the material constituting each layer described later. Furthermore, from the viewpoint of controlling the tensile elongation at break to 400% or more, it is preferable that the polyolefin film of the present invention be manufactured by a melt extrusion method using a T-die, and it is even more preferable that the process does not include a heat stretching step such as sequential biaxial stretching or simultaneous biaxial stretching.

[0064] The polyolefin film of the present invention may be a single-layer film or a film consisting of two or more layers, but from the viewpoint of improving the balance of various properties, it is preferable to have two or more layers.

[0065] Specific examples of the polyolefin film of the present invention consisting of two or more layers include a two-layer structure consisting of a base layer and a back layer, a three-layer structure having a dicing layer, a base layer, and a back layer in that order, and a three-layer structure having an adhesive layer, a base layer, and a back layer in that order, but it is not limited to these and can be designed as appropriate according to the desired properties. Specific examples of each layer will be described later.

[0066] The thickness of the polyolefin film of the present invention can be adjusted as appropriate according to the application and desired properties, but is preferably 10 to 200 μm, more preferably 20 to 150 μm, and particularly preferably 40 to 120 μm. If it is thinner than 10 μm, the strength will be insufficient, making it difficult to transport during the manufacturing process, or it may tear during processing or use. If it is thicker than 200 μm, the cutability may decrease.

[0067] <Base material layer> The following describes a base layer that constitutes an example of a preferred configuration of the polyolefin film of the present invention. The base layer contains at least a resin and is the thickest layer in the polyolefin film of the present invention. When the polyolefin film of the present invention is used as a dicing tape, the base layer is preferably a layer that improves processing stability, expandability (elongation), and pickability after expansion during the expansion process. In the case of a single-layer polyolefin film of the present invention, it consists only of the base layer.

[0068] The thickness of the base layer can be appropriately adjusted according to the required characteristics of the polyolefin film of the present invention, but it is preferable that it be 40% or more and 95% or less when the total thickness of the film layer is taken as 100%. From the viewpoint of improving processing stability in the expansion process, expandability (elongation), and pickability after expansion, the thickness of the base layer is more preferably 50% or more, and even more preferably 60% or more. Furthermore, from the viewpoint of process stability during the manufacture and use of the polyolefin film of the present invention, the thickness of the base layer is more preferably 90% or less.

[0069] In the base layer of the polyolefin film of the present invention, it is preferable to use a polyolefin resin preferred for the polyolefin film described above, and the content of the polyolefin resin in the base layer is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more, when the total mass of the base layer is considered to be 100% by mass.

[0070] Furthermore, as described above, the base layer of the polyolefin film of the present invention is preferably a layer that improves processing stability, expandability (elongation), and pickability after expansion when used as a dicing tape. Therefore, it is preferable to use the preferred resins listed above in terms of controlling the parameters of formulas (1) to (6), yield stress FA1, FA2, and melting point. Similarly, it is preferable to control the preferred content of each resin in the base layer within the ranges described above. Specific examples of preferred embodiments of the base layer of the present invention include an embodiment in which the base layer mainly consists of linear low-density polyethylene, further contains homopolypropylene, and further contains at least one selected from the group consisting of propylene-based elastomers, ethylene-based elastomers, and other compatibilizers. More preferably, when the entire base layer of the present invention is considered as 100% by mass, the base layer mainly consists of linear low-density polyethylene, further contains homopolypropylene, and further contains at least one selected from the group consisting of propylene-based elastomers, ethylene-based elastomers, and other compatibilizers in a total content of 10% or more. Particularly preferred is an embodiment in which the base layer mainly consists of linear low-density polyethylene, further contains 10% by mass or more and 30% by mass or less of homopolypropylene, and further contains at least one selected from the group consisting of propylene-based elastomers, ethylene-based elastomers, and other compatibilizers in a total content of 15% or more. In this context, "primarily composed of linear low-density polyethylene" means that linear low-density polyethylene has the highest content among the materials constituting the base layer.

[0071] <Back layer> Next, the back layer of the polyolefin film of the present invention will be described. The back layer is a layer containing at least a resin and is disposed on at least one surface of the polyolefin film of the present invention. Furthermore, this back layer refers to a layer having a finite thickness, and it is preferable that the polyolefin film of the present invention has excellent slipperiness, release properties, and antistatic properties.

[0072] From the viewpoint of productivity, processability, and recyclability, the back layer is preferably mainly composed of a polyolefin resin suitable for the polyolefin film of the present invention as described above. The main component in the back layer of the present invention means that it accounts for 50% by mass or more when the entire back layer is considered as 100% by mass, and the content of the polyolefin resin in the back layer of the present invention is more preferably 70% by mass or more. Furthermore, from the viewpoint of improving the slipperiness and release properties of the polyolefin film, it is preferable to apply a method to control the arithmetic mean roughness Sa to 0.5 μm or more and a method to control the static friction coefficient to the back layer of the present invention. Preferred embodiments of the composition of the back layer of the polyolefin film of the present invention are exemplified below, but are not limited to these and can be appropriately designed according to the desired properties.

[0073] As one preferred embodiment of the composition of the back layer of the polyolefin film of the present invention, in order to control the parameters of formulas (1) to (6) within a preferred range and to improve slipperiness and release properties, the main component is the total amount of one or more resins selected from the group consisting of low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), homopolypropylene, random copolymer of propylene and ethylene and / or butene-1 (random polypropylene), and block polypropylene, and further includes inorganic particles and organic particles. A more preferred method is to use the total amount of one or more resins selected from the group consisting of linear low-density polyethylene (LLDPE), random copolymer of propylene and ethylene and / or butene-1 (random polypropylene), and block polypropylene as the main component, and further include organic particles. An even more preferred method is to use linear low-density polyethylene (LLDPE) as the main component and further include organic particles. The above-mentioned organic particles can be used, but polyethylene particles are more preferred from the viewpoint of productivity and recyclability. In other words, one particularly preferred embodiment of the back layer of the polyolefin film of the present invention is a method in which linear low-density polyethylene (LLDPE) is the main component and polyethylene particles are also included.

[0074] Furthermore, as another preferred embodiment, a method is used in which the back layer is made by using the polyethylene resin X and the polypropylene resin Y which is incompatible with it, in order to suppress process contamination due to particle shedding during processing and to improve slipperiness and release properties. From the viewpoint of improving slipperiness, a method using high-density polyethylene and the polypropylene resin Y is more preferred, and a method using high-density polyethylene and homopolypropylene is even more preferred.

[0075] Furthermore, in addition to the preferred resins mentioned above, it is preferable that the back layer of the present invention contains the aforementioned antistatic agent in order to reduce the surface resistivity of the back layer surface and suppress charging due to peeling and friction. The antistatic agents suitable for the back layer of the present invention and the amount of antistatic agent in the back layer are as described above.

[0076] The back layer of the present invention may be further improved by adding lubricants such as fatty acid amides, metal soaps, fluorinated polymers, silicone lubricants, fatty acids, and vegetable oils to the preferred embodiment described above to improve lubricity.

[0077] The thickness of the backing layer can be adjusted as appropriate within a range that does not impair the effects of the polyolefin film of the present invention, but it is preferable that it be 5% or more and 25% or less when the total thickness of the film layers of the polyolefin film of the present invention is taken as 100%. If the thickness of the backing layer is less than 5%, the film will be laminated into a thin film when manufacturing the film of the present invention, making production difficult, or the slipperiness that is the effect of the backing layer may not be fully exhibited. Furthermore, if the layer composition of the backing layer exceeds 25%, the processing stability, expandability (elongation), and pickability after expansion of the polyolefin film of the film of the present invention may be insufficient, or the slipperiness effect may be reduced, or the cost may increase depending on the type of material used for the backing layer.

[0078] <Dicing layer> The polyolefin film of the present invention may be provided with a dicing layer. The dicing layer is a layer containing at least a resin and having a finite thickness. The dicing layer is a layer that is placed between the substrate layer of the polyolefin film and the surface to which the wafer is attached, i.e., the adhesive layer, when the polyolefin film of the present invention is used for wafer dicing. The dicing layer is preferably used in particular when dicing using the blade dicing method because it suppresses the generation of cutting debris and exhibits excellent dicing properties, but the dicing layer may also be provided on dicing tapes for other purposes, such as laser dicing, scribe-breaking, or plasma dicing.

[0079] When the polyolefin film of the present invention is used for blade dicing applications, an olefin-based elastomer is preferably used as the resin for the dicing layer. By using an olefin-based elastomer, cutting chips during dicing are suppressed and sufficient stretchability is obtained.

[0080] As the olefin-based elastomer, known olefin-based elastomers can be used, but it is preferable to use one or more α-olefin-based elastomers selected from the group consisting of ethylene-based elastomers, propylene-based elastomers, 1-butene-based elastomers, and 4-methylpentene-1-based elastomers. From the viewpoint of suppressing cutting chips during dicing, propylene-based elastomers and 1-butene-based elastomers are particularly preferred, and propylene-based elastomers are especially preferred. Furthermore, the dicing layer may be made in combination of these α-olefin-based elastomers and one or more resins selected from the group consisting of high-density polyethylene, low-density polyethylene, linear low-density polyethylene, homopolypropylene, random copolymer of propylene and ethylene and / or butene-1 (random polypropylene), block polypropylene, propylene-α-olefin copolymer, and propylene-ethylene-α-olefin copolymer polypropylene.

[0081] When the polyolefin film of the present invention is used for dicing applications other than the blade dicing method, it is preferable to use a polyolefin resin, which is preferably used in the polyolefin film of the present invention as described above, for the dicing layer.

[0082] The dicing layer preferably contains an antistatic agent, similar to the back layer described above, in order to provide antistatic properties. The suitable antistatic agents for the dicing layer and the amount of antistatic agent in the dicing layer are as described above.

[0083] The thickness of the dicing layer can be adjusted as appropriate according to the desired properties, but it is preferably 10% to 30% when the total thickness of the polyolefin film is considered 100%. If the thickness of the dicing layer is less than 10%, the film of the present invention will be laminated into thin films, making production difficult, and the cutting properties that are the effect of the dicing layer may not be fully exhibited. On the other hand, if the thickness of the dicing layer exceeds 30%, the processing stability, expandability (elongation), and pickability after expansion of the polyolefin film of the present invention may be insufficient, and the cost may increase depending on the type of material used for the dicing layer.

[0084] <Adhesive layer> The polyolefin film of the present invention can be used as an adhesive film by arranging an adhesive layer having adhesive properties as the outermost layer, in addition to the base layer, back layer, and dicing layer described above.

[0085] The adhesive layer may be made from any of the following materials: crosslinked materials such as acrylic or silicone, non-crosslinked materials such as natural rubber or synthetic rubber, or pseudo-crosslinked materials (thermoplastics). For example, when producing a polyolefin film containing an adhesive layer by co-extrusion, it is preferable to use a thermoplastic resin as the main component from the viewpoint of recyclability. Here, using a thermoplastic resin as the main component means that the proportion of thermoplastic resin in the composition is 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more.

[0086] Suitable resins for the adhesive layer when producing a polyolefin film containing an adhesive layer by co-extrusion include styrene-diene copolymers such as styrene-butadiene copolymer (SBR), styrene-isoprene-styrene copolymer (SIS), styrene-butadiene-styrene copolymer (SBS), and their hydrogenated products (e.g., styrene-ethylene-butadiene-styrene copolymer (SEBS), etc.), and styrene-isobutylene copolymers (e.g., styrene-isobutylene-styrene triblock copolymer (SIBS), styrene-isobutylene diblock copolymer (SIB), or styrene-isobutylene block copolymers such as mixtures thereof), polyethylene resins such as high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and ethylene-α-olefin copolymer, polypropylene resins such as propylene-α-olefin copolymer and propylene-ethylene-α-olefin copolymer, and polybutene resins such as polybutene-1-ethylene copolymer and polybutene-1-propylene copolymer. Furthermore, in addition to the resin suitable for the adhesive layer described above, it is more preferable to further include tackifiers such as aliphatic copolymers, aromatic copolymers, aliphatic-aromatic copolymers, alicyclic copolymers, petroleum resins, terpene resins, terpene phenol resins, rosin resins, alkylphenol resins, xylene resins, or hydrogenated versions thereof, in order to enhance the tackiness of the adhesive layer.

[0087] The adhesive film of the present invention, having an adhesive layer on at least one surface of the polyolefin film, is preferably substantially free of perfluoroalkyl compounds and polyfluoroalkyl compounds, regardless of the manufacturing method, from the viewpoint of suppressing environmental pollution. The content of perfluoroalkyl compounds and polyfluoroalkyl compounds in the adhesive film can be measured by high-performance liquid chromatography-mass spectrometry (LC-MS). In the present invention, "substantially free of perfluoroalkyl compounds and polyfluoroalkyl compounds" means that if the adhesive film contains only either a perfluoroalkyl compound or a polyfluoroalkyl compound, the content is less than 5 ng / g (5 ppb), and if the adhesive film contains both a perfluoroalkyl compound and a polyfluoroalkyl compound, the total content is less than 5 ng / g (5 ppb).

[0088] The thickness of the adhesive layer can be adjusted as appropriate according to the desired properties, but it is preferably 5% or more and 25% or less when the total thickness of the polyolefin film is considered as 100%. If the thickness of the adhesive layer is less than 5%, sufficient adhesiveness may not be achieved, or the film may become thin-film laminated when manufacturing the film of the present invention, making production difficult. On the other hand, if the thickness of the adhesive layer exceeds 25%, the flexibility may become too high, making it difficult to handle the polyolefin film of the present invention during manufacturing, processing, and use.

[0089] Each layer of the polyolefin film of the present invention may optionally contain particles other than those described above, lubricants, nucleating agents, antioxidants, heat-resistant agents, weather-resistant agents, antistatic agents, etc. The amount of these components added is preferably 5% by mass or less, and more preferably 3% by mass or less, when the total mass of each layer is considered to be 100% by mass.

[0090] Next, the method for producing the polyolefin film of the present invention will be described. The method for producing the polyolefin film of the present invention is not particularly limited. For example, in the case of a two-layer structure of "base layer, back layer", a three-layer structure of "dicing layer, base layer, back layer", or a three-layer structure of "adhesive layer, base layer, back layer", examples include a so-called co-extrusion method in which the resins constituting each layer are melt-extruded from separate extruders and laminated together in a die, or a method in which each of the above-mentioned layers is melt-extruded individually and then laminated by a lamination method. However, from the viewpoint of productivity, production by co-extrusion is more preferable. For co-extrusion, known methods such as the inflation method and the T-die method are used, but from the viewpoint of excellent thickness accuracy and controlling the arithmetic mean roughness Sa and arithmetic mean waviness Wa to a preferred range, the hot-melt co-extrusion method using the T-die method is even more preferable. Furthermore, from the viewpoint of controlling the tensile elongation at break of the present invention to the preferred range and from the viewpoint of reducing the environmental burden during production, it is particularly preferable that the method does not include a heating stretching process such as sequential biaxial stretching or simultaneous biaxial stretching.

[0091] As an alternative manufacturing method, the "base layer and back layer" or "dicing layer, base layer, and back layer" can be manufactured by a hot-melt co-extrusion method, and then an adhesive layer can be provided by a coating method or a lamination method.

[0092] When producing the polyolefin film of the present invention by co-extrusion, in order to suppress thermal degradation of the polyolefin resin, antistatic agent, and other additives used in each layer and to reduce the content of volatile organic compounds (VOCs) in the polyolefin film, the melt extrusion temperature is preferably 280°C or lower, more preferably 260°C or lower, and even more preferably 245°C or lower.

[0093] In the polyolefin film of the present invention, if there is a layer containing two or more immiscible resins, in order to improve the dispersion state of the resins in the layer and to control the parameters of formula (3) and formula (4) to preferred values, and to control the arithmetic mean waviness Wa to a preferred range, some or all of the resins used in the layer may be melt-kneaded in advance using a twin-screw extruder or the like. In this case, the melt extrusion temperature is preferably 280°C or lower, more preferably 260°C or lower, and even more preferably 245°C or lower, in order to suppress thermal degradation and reduce the volatile organic compound (VOC) content of the polyolefin resin.

[0094] Furthermore, when the polyolefin film of the present invention is manufactured by a T-die method of hot-melt co-extrusion, it is preferable to rapidly cool and solidify the resin after melt extrusion on a cooling roll controlled to a temperature of 20°C to 80°C, in order to control the parameters of formulas (1), (2), (5), and (6) within a preferred range. From the viewpoint of controlling the parameters of formulas (1) and (2) to 1.2 or less, and controlling the parameters of formulas (5) and (6) to 0.15 MPa or more, the temperature of the cooling roll is more preferably 25°C or higher. Furthermore, from the viewpoint of controlling the parameters of formulas (1) and (2) to 0.8 or more, and controlling the parameters of formulas (5) and (6) to 0.8 MPa or less, the temperature of the cast drum is more preferably 50°C or lower. Furthermore, from the viewpoint of controlling the arithmetic mean waviness Wa of the polyolefin film within the preferred range, when cooling and solidifying the molten resin on the cooling roll, the molten resin on the cooling roll may be pressed with a predetermined pressure using a nip roll made of rubber or the like to cool and solidify it.

[0095] The polyolefin film of the present invention can be preferably used as an industrial film such as a protective film or an in-process film, or as a packaging film. However, because it has excellent stretchability and processing stability in stretching processes such as the expanding process, it can be more preferably used as a protective film when drawing metals, an in-process film when dicing and expanding semiconductor wafers, or as a component of pouch-type or cup-type aluminum laminate packaging films. In particular, because it has excellent processing stability in the stretching process and excellent pick-up after expansion, it can be even more preferably used for dicing and expanding semiconductor wafers. Furthermore, it can also be suitably used as a film for other semiconductor manufacturing processes, such as transferring semiconductor wafers after dicing or expanding onto an in-process film containing the polyolefin film of the present invention for storage and transport. [Examples]

[0096] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples. The measurement and evaluation of various physical properties were carried out by the following methods, and unless otherwise specified, the measurements were carried out in a room at 23°C and 65%RH.

[0097] (1) Thickness of each layer Using a microtome, cross-sectional sections with cross-sections in the width-thickness direction were prepared from the polyolefin film, and these sections were coated with platinum to create observation samples. Next, the film cross-sections were observed at arbitrary magnifications using a Hitachi S-4800 field emission scanning electron microscope, and the thickness of each layer of the polyolefin film was measured.

[0098] (2) Melt Flow Rate (MFR) Using a melt indexer manufactured by Toyo Seiki Seisakusho, the MFR of the resins used in the examples or comparative examples was measured in accordance with JIS K7210-1997, at 230°C and a load of 21.18N unless otherwise specified.

[0099] (3) Melting point In accordance with JIS K-7121 (2012), the resins used in the examples and comparative examples, and the resulting polyolefin films, were measured using a differential scanning calorimeter (Seiko Instruments EXSTAR DSC6220) under the following conditions. The melting point of the resin was determined from the differential scanning calorimeter curve obtained in step (v), and the melting point of the film was determined from the differential scanning calorimeter curve obtained in step (i). If there were two or more melting points, the peak temperature on the higher side was used as the melting point of the resin or film. Sample quantity: 3 mg Heating rate, cooling rate: 20℃ / min Temperature program: Process (i) Heating from 30°C to 250°C, Step (ii) Hold at 250°C for 5 minutes. Process (iii) Cooling from 250°C to -30°C. Step (iv) Hold at -30°C for 5 minutes. Process (v) Heating from -30°C to 250°C.

[0100] (4) Tensile test Using a tensile testing machine (Orientec's universal testing machine "Tensilon®"), polyolefin films were subjected to tensile tests five times each in the longitudinal and widthwise directions at a temperature of 23°C and a speed of 300 mm / min, in accordance with JIS K 7113 (1995). The test specimens used for measurement were strip-shaped with a width of 10 mm and a length of 100 mm, and the distance between the chucks was 30 mm. Furthermore, the arithmetic mean values ​​were calculated five times for the longitudinal yield point elongation LA1, yield point stress FA1, stress FB1 at 300% elongation, minimum stress FC1 in the elongation range from yield point elongation LA1 to 300% in the longitudinal direction, yield point elongation LA2, yield point stress FA2, stress FB2 at 300% elongation in the width direction, and minimum stress FC2 in the elongation range from yield point elongation LA2 to 300% in the width direction. The results were then evaluated for FA1, FA2, FB1 / FA1, FB2 / FA2, FA1-FA2, LA1-LA2, FA1-FC1, and FA2-FC2. The arithmetic mean values ​​were calculated five times for the longitudinal and width direction tensile fracture elongation of each sample in the examples and comparative examples, and all samples showed a tensile fracture elongation of 400% or more.

[0101] (5) Arithmetic mean height Sa The back layer of polyolefin films was measured using a scanning white light interference microscope (VS1540) manufactured by Hitachi High-Tech Science Corporation, in accordance with ISO 25178-2 (2012), under the following conditions and equipment configuration. The captured images were then interpolated (fully interpolated) using the accompanying analysis software, and after surface correction using a fourth-order polynomial approximation, the arithmetic mean height Sa (μm) was obtained by processing with a median filter (3×3 pixels). Five measurements were performed for each type of film, and the arithmetic mean of these five points was taken as the Sa (μm) of the polyolefin film.

[0102] <Measurement conditions and equipment configuration> Objective lens: 10x Telescope tube: 1x Zoom lens: 1x Wavelength filter: 530nm white Measurement mode: Wave Measurement software: VS-Measure 10.0.4.0 Analysis software: VS-Viewer 10.0.3.0 Measurement range: 1009.7 μm × 1010.5 μm (The above range was measured by connecting a total of four fields of view, two fields of view x two fields of view.) Pixel count: 1842 x 1844.

[0103] (6) Arithmetic mean swell Wa The surface of the back layer and the surface opposite the back layer of the polyolefin film (the substrate layer side in the case of a two-layer polyolefin film, and the dicing layer side in the case of a three-layer film) were measured using a scanning white light interference microscope (VS1540) manufactured by Hitachi High-Tech Science Corporation, under the same measurement conditions and apparatus configuration as in (5), except for the measurement range and number of pixels. The captured images were interpolated (fully interpolated) using analysis software, and after surface correction using a fourth-order polynomial approximation, the surface shape was obtained by processing with a median filter (3×3 pixels). The obtained surface shape was processed with a Gaussian filter with a cutoff value of 2.0 mm to remove short-wavelength components and output a waviness image, and the arithmetic mean waviness Wa (μm) was calculated. Five measurements were performed on each surface of each type of film, and the arithmetic mean of the five points was taken as the Wa (μm) for each surface of the polyolefin film.

[0104] <Measurement conditions> Measurement range: 9.1mm x 9.1mm (The above range was measured by stitching together 400 fields of view, each consisting of 20 fields of view x 20 fields of view.) Pixel count: 480 x 480.

[0105] (7) Static friction coefficient After conditioning the polyolefin film at 23°C and 65%RH, it was cut into strips 75mm wide and 100mm long, with the film formation line direction as the longitudinal side, to prepare the samples. The slip coefficient was measured using a slip coefficient measuring device (model ST-200, manufactured by TechnoNeeds Co., Ltd.) under a 23°C, 65%RH atmosphere.

[0106] Specifically, the sample cut into strips was placed on the measuring sample stage of the apparatus so that the length of the tension direction was in the longitudinal direction and the back surfaces of the materials to be evaluated overlapped and in contact with each other, and the ends of the samples were fixed to the load detection U gauge of the apparatus. The film was then left to stand, and a 200g weight with a 6.5cm x 6.5cm "Teflon®" sheet attached to the sample contact surface was placed on top of it to bring the samples into close contact. Then, the static friction coefficient was measured 10 times when the upper film was pulled under the following conditions, and the average of the 6 measured values ​​excluding the top 2 and bottom 2 was taken as the static friction coefficient of the polyolefin film. Measurement distance: 15mm Measurement speed: 300mm / min.

[0107] (8) Dicing test An adhesive layer was prepared on the surface of the polyolefin film opposite to the back layer (the substrate layer side in the case of a two-layer polyolefin film, and the dicing layer side in the case of a three-layer film) using the following method. First, 30% by weight of 2-ethylhexyl acrylate, 70% by weight of vinyl acetate, and 1% by weight of 2-hydroxyethyl methacrylate were mixed in toluene solvent to obtain a base resin with a weight-average molecular weight of 150,000. Then, 100 parts by weight of this base resin and 10 parts by weight of a polyhydric alcohol adduct of tolylene diisocyanate (product name "Coronate L", manufactured by Nippon Polyurethane Co., Ltd.) as a crosslinking agent were dissolved in ethyl acetate. After dissolving, a barcode was applied to the surface layer of the dicing substrate film so that the thickness after drying was 8 μm, and then dried at 80°C for 5 minutes to obtain a dicing tape. Next, a silicon wafer with a diameter of 150 mm was attached to the adhesive side of the dicing tape, and then diced as shown in Figure 1 using a semi-automatic dicing saw (DAD-3350) manufactured by DISCO Corporation under the following conditions so that the chip size was 10 mm square. Subsequently, setting any direction in the longitudinal direction as 0 degrees, the width of the second dicing line intersecting the reference line drawn from the center point in the 0-degree direction was measured and defined as L1(0)(μm). The width of the dicing lines was measured in the same manner for the 90-degree, 180-degree, and 270-degree directions from the center point to obtain L1(90)(μm), L1(180)(μm), and L1(270)(μm), and the chip-to-chip distance L1(μm) before expansion was calculated from the arithmetic mean of these values. Blade: ZH05-SD4000-N1-70 ED Blade rotation speed: 25,000 rpm Cutting speed: 50mm / sec.

[0108] (9) Expand test The silicon wafer and dicing tape diced in (8) were placed in a Hugle expander so that the center of the stage and the center of the silicon wafer were in the same position, and expansion was performed at a stage temperature of 23°C, a stage push-up height of 50 mm, and a stage push-up speed of 6 mm / s. After that, an outer ring with an inner diameter of 178 mm was placed on the expanded dicing tape, the outer circumference was cut, and it was removed from the apparatus. The width of the expanded dicing line was evaluated in the same manner as in (8), and L2(0)(μm), L2(90)(μm), L2(180)(μm), and L2(270)(μm) were determined, and the chip-to-chip distance L2(μm) after expansion was calculated from the arithmetic mean of these values. The expansion test was performed five times for each type of dicing tape.

[0109] (10) Growth rate Using the inter-tip distances L1 (μm) and L2 (μm) obtained in (8) and (9), the elongation rate was evaluated according to the following criteria. <Growth Rate Evaluation Criteria> A: The arithmetic mean of L2 / L1 over 5 trials is 1.20 or higher. B: The arithmetic mean of the five L2 / L1 values ​​is between 1.10 and 1.20. The arithmetic mean of C:L2 / L1 over 5 trials is less than 1.10.

[0110] (11) Uniform stretchability The arithmetic mean, maximum, and minimum values ​​were calculated from the 20 chip-to-chip distances obtained from the five expansion tests conducted in (9), and uniform stretchability was evaluated according to the following criteria. <Evaluation Criteria for Uniform Stretchability> A: ((Maximum value - Minimum value) / Average value)) is less than or equal to 0.10 B + The value of ((maximum value - minimum value) / mean value) is greater than 0.10 and less than or equal to 0.12. B: ((Maximum value - Minimum value) / Average value)) is greater than 0.12 and less than or equal to 0.15 C: ((Maximum value - Minimum value) / Average value)) is greater than 0.15.

[0111] (12) Processing stability In the expansion test conducted in (9), the processing stability was evaluated according to the following criteria. A: In five expansion tests, no film tearing occurred. C: Film tearing occurred at least once during five expansion tests.

[0112] (13) Evaluation of pickup ability After setting the expanded sample prepared in (9) on the stand with the back layer side down, the 16 chips closest to the center point were individually pushed up to a height of 5 mm from the back layer side using a push-up pin with a tip diameter of 0.7 mm, and the pick-up ability was evaluated according to the following criteria. The push-up speed was set to 10 mm / s. <Pickupability Evaluation Criteria> A: Not a single chip was dropped. C: One or more chips have been dropped.

[0113] (14) Surface resistivity ρs1, antistatic properties After storing the polyolefin film in a room at 23°C and 65% RH for 24 hours, the surface resistivity was measured using a digital ultra-high resistance / microcurrent meter R8340A under the same conditions, with an applied voltage of 100V for 10 seconds. The surface on the back layer side and the surface opposite the back layer (the substrate layer side in the case of a two-layer polyolefin film, and the dicing layer side in the case of a three-layer film) were measured, and the antistatic properties were evaluated according to the following criteria. Each measurement was performed five times, and the arithmetic mean of the five measurements was taken as the ρs1 (Ω / sq) for each surface of the polyolefin film. <Antistatic properties> A: ρs1 is 1.0 × 10 7 Ω / sq or more 1.0×10 10 Less than Ω / sq B:ρs1 is 1.0 × 10 10 Ω / sq or more 1.0×10 13 Ω / sq or less C:ρs1 is 1.0×10 7 Less than Ω / sq, or 1.0 × 10⁻⁶ 13 It is greater than Ω / sq.

[0114] (15) Surface resistivity ρs² and stability of antistatic properties For the sample surfaces that received an A or B rating for antistatic properties, the surface resistivity ρs² (Ω / sq) was measured using the following procedure. First, the polyolefin film was stored in a hot air oven at 80°C for 10 minutes, then stored in a room at 23°C and 65% RH for 24 hours. Under the same conditions, the surface resistivity was measured on the back layer side and the substrate layer side using a digital ultra-high resistance / micro-current meter R8340A with an applied voltage of 100V for 10 seconds. Each measurement was performed five times, and the arithmetic mean of these five measurements was taken as the ρs² (Ω / sq) for each surface of the polyolefin film. The stability of the antistatic properties was evaluated according to the following criteria. <Stability of antistatic properties> A: ρs2 / ρs1 is between 0.5 and 1.5 B: ρs2 / ρs1 is less than 0.5 or greater than 1.5.

[0115] (16) Content of volatile organic compounds (VOCs) 600mm 2 Polyolefin film cut into strips was sealed in 20 mL vials and heat-treated in a 60°C oven for 24 hours, after which GC / MS analysis was performed. The detected VOC components were calculated using an absolute calibration curve method based on decane conversion.

[0116] <Measurement conditions> GC / MS instrument: Agilent 6890A GC / 5973N MSD HSS equipment: Agilent 7697A HS oven temperature: 60℃ Column: Slightly polar column Ion acquisition: Scan method.

[0117] The resins used in the examples and comparative examples are shown below. LLDPE; MFR at 190℃: 5g / 10min, melting point: 115℃, density: 922kg / m³ 3 Commercially available linear low-density polyethylene LDPE; MFR at 190℃: 7g / 10min, melting point: 107℃, density: 918kg / m³ 3Commercially available low-density polyethylene HPP; commercially available homopolypropylene with MFR: 8g / 10min at 230℃ and melting point of 165℃. RPP; Commercially available random polypropylene with MFR: 5g / 10min at 230℃, melting point: 128℃ PE-E; MFR at 230℃: 2.5g / 10min, Melting point: 63℃, Density: 880kg / m³ 3 Commercially available ethylene-ethylene-butylene-ethylene block copolymer PP-E; Commercially available polypropylene elastomer with MFR: 6 / 10 min at 230°C and melting point: 161°C. PB; Commercially available homopolybutene with MFR: 1.8g / 10min at 190℃ and melting point: 114℃ PE particles MB: A masterbatch of polyethylene particles is prepared by kneading high molecular weight polyethylene fine particles "Mipelon®" PM200, manufactured by Mitsui Chemicals, Inc., with an average particle diameter of 10 μm, and the aforementioned LLDPE at a mass ratio of 10:90 using a twin-screw extruder at 230°C. AS; MFR: 15g / 10min at 190℃, Sanyo Chemical Industries' antistatic agent "Perectron®" PVL (polyether-polyolefin block copolymer) EVA; a commercially available ethylene-vinyl acetate copolymer with a melting point of 96°C and a MFR of 15g / 10min at 190°C.

[0118] <Example 1> The constituent resins for each layer listed in Table 1 were fed into the extruders of a T-die composite film manufacturing machine with a 2,400 mm die width and a multi-manifold with two extruders, one with a diameter of φ65 mm (for the back layer) and the other with a diameter of φ115 mm (for the base layer). The discharge rate of each extruder was adjusted so that the back layer thickness ratio was 10% and the base layer thickness ratio was 90%. The film was extruded from the composite T-die at a temperature of 230°C, and the surface of the base layer was brought into contact with a cooling roll at 30°C to produce a two-layer polyolefin film with a film thickness of 100 μm, in which the back layer and base layer were laminated. The rotation speed of the polyolefin film winding roll was set to 103% of the rotation speed of the cooling roll.

[0119] <Examples 2-5, Comparative Examples 1-3> A polyolefin film was prepared in the same manner as in Example 1, except that the constituent resins of each layer were as shown in Tables 1 and 2.

[0120] <Examples 6-8> The constituent resins of each layer were as shown in Table 1, and a polyolefin film was manufactured in the same manner as in Example 1, except that when cooling the molten resin with a cooling roll, a rubber roll set to 60°C was pressed at a pressure of 0.35 MPa.

[0121] <Examples 9-12> The constituent resins for each layer listed in Table 2 were fed into each of the three extruders of a T-die composite film-making machine with a die width of 2,400 mm and a multi-manifold having three extruders with diameters of φ65 mm (for the back layer), φ115 mm (for the base layer), and φ65 mm (for the dicing layer). The discharge rate of each extruder was adjusted so that the thickness ratio of the back layer was 10%, the thickness ratio of the base layer was 80%, and the thickness ratio of the dicing layer was 10%, resulting in a three-layer structure with a film thickness of 100 μm, where the back layer, base layer, and dicing layer were laminated. Polyolefin films were then manufactured in the same manner as in Example 1.

[0122] [Table 1]

[0123] [Table 2]

[0124] Examples 1 and 4 exhibited excellent elongation, uniform stretchability, processing stability, and pick-up properties. Examples 2 and 3 showed even better uniform stretchability compared to Examples 1 and 4. Furthermore, Example 3 had a lower Wa and superior surface uniformity compared to Examples 1, 2, and 4, resulting in a better product yield. On the other hand, Comparative Example 1 did not show a yield point and was inferior in uniform stretchability, processing stability, and pick-up properties. Comparative Example 2 had low FB1 / FA1 and FB2 / FA2 values, resulting in inferior elongation and uniform stretchability. Comparative Example 3 had a high |FA1-FA2| value, resulting in inferior uniform stretchability. In addition, Example 5, which used an antistatic agent in the back layer, exhibited excellent elongation, uniform stretchability, processing stability, and pick-up properties, as well as superior antistatic layer protection and stability, resulting in a better product yield compared to Example 2. Example 6 had a lower Wa than Example 5, superior surface uniformity, superior stability, and a better product yield compared to Example 5. Example 7 showed even better antistatic properties and product yield than Example 6. Example 8 also showed superior antistatic properties and stability compared to Example 3, and a good product yield. Examples 9 and 10, in which an antistatic agent was added to the dicing layer, showed superior elongation, uniform stretchability, processing stability, pick-up properties, and antistatic properties, and had a better product yield compared to Example 5. Examples 1-10 suppressed the generation of volatile organic compounds (VOCs) and had a better product yield compared to Examples 11 and 12. [Explanation of symbols]

[0125] 1 Dicing Tape 2 wafers 3 Dicing lines

Claims

1. A polyolefin film that satisfies equations (1) to (4), where LA1, FA1, and FB1 are the yield point elongation (%), yield point stress (MPa), and stress at 300% elongation (MPa) in the longitudinal direction, respectively, and LA2, FA2, and FB2 are the yield point elongation (%), yield point stress (MPa), and stress at 300% elongation (MPa) in the width direction, respectively. 0.8≦(FB1 / FA1)≦1.2... Formula (1) 0.8≦(FB2 / FA2)≦1.2... Formula (2) |FA1-FA2|≦1.0MPa... Formula (3) |LA1-LA2|≦20% ... Formula (4)

2. The polyolefin film according to claim 1, wherein when FC1 is the minimum stress (MPa) in the elongation range from yield point elongation LA1 (%) to 300% in the longitudinal direction, and FC2 is the minimum stress (MPa) in the elongation range from yield point elongation LA2 (%) to 300% in the width direction, the polyolefin film satisfies equations (5) and (6). (FA1-FC1)≦0.8MPa... Formula (5) (FA2-FC2)≦0.8MPa... Formula (6)

3. The polyolefin film according to claim 1 or 2, wherein FA1 and FA2 are 7 MPa or more and 15 MPa or less.

4. A polyolefin film according to claim 1 or 2, having a melting point of 150°C or higher and 250°C or lower.

5. The polyolefin film according to claim 1 or 2, wherein, when the surface resistivity of the film at 23°C and 65% RH is ρs1 (Ω / sq), at least one surface satisfies formula (7). 1.0×10 ７ Ω / sq ≤ ρs1 ≤ 1.0×10 １３ Ω / sq... Equation (7)

6. The polyolefin film according to claim 1 or 2, wherein, when the surface resistivity of the film at 23°C and 65% RH is ρs1 (Ω / sq), both surfaces satisfy formula (7).

7. The polyolefin film according to claim 1 or 2, wherein when the surface resistivity of the film at 23°C and 65% RH is ρs1 (Ω / sq), and the surface resistivity of the film measured at 23°C and 65% RH after heating at 80°C for 10 minutes is ρs2 (Ω / sq), at least one surface satisfies formula (8). 0.5≦(ρs2 / ρs1)≦1.5... Formula (8)

8. The polyolefin film according to claim 1 or 2, wherein the arithmetic mean waviness Wa measured at a cutoff value of 2.0 mm on at least one surface is 1.5 μm or less.

9. A polyolefin film according to claim 1 or 2, comprising homopolypropylene and linear low-density polyethylene.

10. The polyolefin film according to claim 9, wherein linear low-density polyethylene is the main component.

11. A polyolefin film according to claim 1 or 2, containing a propylene-based elastomer.

12. A polyolefin film according to claim 1 or 2, comprising an ethylene-based elastomer.

13. The polyolefin film according to claim 1 or 2, wherein the arithmetic mean height Sa of at least one surface is 0.5 μm or more.

14. The polyolefin film according to claim 1 or 2, comprising at least two layers, wherein at least one surface layer contains polyethylene particles.

15. The polyolefin film according to claim 1 or 2, comprising at least two layers, wherein at least one surface layer is mainly composed of linear low-density polyethylene and contains polyethylene particles.

16. The polyolefin film according to claim 1 or 2, wherein the content of volatile organic compounds is 10 ppm or less.

17. An adhesive film having an adhesive layer on at least one surface of the polyolefin film according to claim 1.

18. The adhesive film according to claim 17, which is substantially free of perfluoroalkyl compounds and polyfluoroalkyl compounds.

19. A dicing tape comprising the polyolefin film described in claim 1, or a dicing tape comprising the adhesive film described in claim 17.

20. A method for manufacturing a semiconductor chip using the dicing tape described in claim 19.

21. A manufacturing apparatus having a mechanism for manufacturing a semiconductor chip using the dicing tape described in claim 19.

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