Substrate film for semiconductor manufacturing tape

Abstract

To provide a base film for a semiconductor manufacturing tape, which is excellent in uniform elongation, rigidity, and processing stability.SOLUTION: Provided is a base film 1 for a semiconductor manufacturing tape, which comprises a laminate of an intermediate layer 2 and a surface layer 3 laminated on both sides of the intermediate layer 2 and has a three layer structure in which the surface layer, the intermediate layer, and the surface layer are laminated in the order. The base film contains at least a homopolymer of 1-butene, does not have a yield point when the extension ratio thereof is increased from 0% to 100% under the condition of a tensile speed of 300 mm / min, and has a stress of 5 MPa or more and 20 MPa or less (at 25% extension).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a substrate film for a tape for semiconductor manufacturing (hereinafter, sometimes simply referred to as "substrate film"). [Background technology]

[0002] A widely used method for manufacturing semiconductor devices such as IC chips involves, for example, dicing a wafer circuit formed on a substantially circular semiconductor wafer onto a semiconductor manufacturing tape (dicing tape) for wafers to obtain individual semiconductor devices. After dicing, the dicing tape is stretched to form gaps between the semiconductor devices (i.e., expanded), and then each semiconductor device is picked up by a robot or the like.

[0003] In addition, dicing die attach film (DDAF), which has an adhesive layer laminated on the adhesive layer of the above-mentioned dicing tape, is used as a semiconductor manufacturing tape for wafers.After the wafer circuit is divided by dicing on the dicing die attach film, the dicing die attach film is stretched to form gaps between the semiconductor devices, and the adhesive layer is then photo-cured, and the semiconductor devices are peeled off from the adhesive layer with the adhesive layer still attached and picked up.

[0004] Dicing tape and dicing die attach films are generally composed of an adhesive layer that secures the wafer and a base film that contains a polyolefin or the like. For example, a dicing tape has been proposed that includes a base film that is a laminate of a polyolefin layer (intermediate layer) that contains 30 to 100 wt % of an amorphous polyolefin with a propylene and / or 1-butene content of 50 wt % or more, 0 to 70 wt % of a crystalline polypropylene-based resin, and 0 to 70 wt % of a polyethylene-based resin, and polyethylene-based resin layers (surface layers) that are laminated on both sides of the polyolefin layer and are composed of a polyethylene-based resin such as low-density polyethylene (see, for example, Patent Document 1).

[0005] In addition, a substrate film has been proposed that is composed of a laminate of an intermediate layer containing an amorphous polyolefin containing 40% by mass or more of at least one component selected from the group consisting of ethylene, propylene, and 1-butene, and surface layers laminated on both sides of the intermediate layer and containing crystalline polyethylene as a main component (see, for example, Patent Document 2).

[0006] Also, a random copolymer of propylene and ethylene and / or an α-olefin having 4 to 8 carbon atoms, in which the content of ethylene and / or an α-olefin having 4 to 8 carbon atoms is 6% by weight or more, and the density measured in accordance with ASTM D1505 is 885 kg / m 3 A substrate film has been proposed that is composed of a laminate of an intermediate layer containing the following propylene-based random copolymer (β) as a main component, and surface layers laminated on both sides of the intermediate layer and containing a propylene-based random copolymer (α) as a main component, which has a lower content of ethylene and / or an α-olefin having 4 to 8 carbon atoms than the propylene-based random copolymer (β) and a higher density (see, for example, Patent Document 3). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 11-323273 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-232683 [Patent Document 3] Japanese Patent Application Publication No. 2018-65327 Summary of the Invention [Problem to be solved by the invention]

[0008] However, in the base film described in Patent Document 1, because the same amount or more of crystalline random polypropylene is added to the amorphous butene copolymer, necking occurs when the base film is stretched, resulting in insufficient uniform stretchability (uniform expandability) of the base film.In addition, because a low-viscosity butene copolymer is used, thickness fluctuations due to discharge fluctuations such as draw resonance during molding of the base film increase, resulting in insufficient processing stability of the base film.

[0009] Furthermore, the substrate film described in Patent Document 2 has insufficient rigidity, which causes a problem of unstable unwinding of the substrate in the manufacturing process of the substrate film.

[0010] Furthermore, the base film described in Patent Document 3 uses a semi-crystalline resin instead of an amorphous resin, which causes necking during molding of the base film, resulting in insufficient uniform stretchability of the base film. Furthermore, the rigidity of the base film is insufficient, which causes unstable unwinding of the base film during the base film manufacturing process. Furthermore, the surface of the base film is highly adhesive, which causes the base film to stick to the transport roll during transport, making it difficult to transport and wind the base film, and which causes blocking during winding of the base film, resulting in insufficient processing stability.

[0011] The present invention has been made in view of the above problems, and has as its object to provide a substrate film for a tape for semiconductor manufacturing that has excellent uniform elongation, rigidity, and processing stability. [Means for solving the problem]

[0012] In order to achieve the above object, the substrate film for a semiconductor manufacturing tape of the present invention is characterized by containing at least a 1-butene homopolymer, having no yield point during elongation from 0% to 100% at a tensile speed of 300 mm / min, and having a stress (at 25% elongation) of 5 MPa or more and 20 MPa or less. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a substrate film for a tape for semiconductor manufacturing that has excellent uniform elongation, rigidity, and processing stability. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 3 is a cross-sectional view showing a substrate film for a semiconductor manufacturing tape according to a second embodiment of the present invention. [Figure 2] 1 shows an SS curve (stress-strain curve) in the MD of the substrate film of Example 1. [Figure 3] 1 shows the TD SS curve (stress-strain curve) of the base film of Example 1. [Figure 4] 1 shows an SS curve (stress-strain curve) in the MD of the substrate film of Example 10. [Figure 5] 1 shows the TD SS curve (stress-strain curve) of the substrate film of Example 10. DETAILED DESCRIPTION OF THE INVENTION

[0015] The substrate film for a semiconductor manufacturing tape of the present invention will be specifically described below. Note that the present invention is not limited to the following embodiments, and appropriate modifications can be made within the scope of the present invention.

[0016] (First embodiment) The substrate film of this embodiment is a film formed from a polyolefin resin, and contains at least a homopolymer of 1-butene.

[0017] <1-butene homopolymer> In this embodiment, a homopolymer obtained by polymerizing 1-butene alone is used as the polybutene. This 1-butene homopolymer has a high molecular weight and bulky side chains. The strong intermolecular forces caused by these bulky side chains enable the homopolymer to improve the uniform stretchability of the substrate film, similar to that of an amorphous polymer, despite being a crystalline polymer.

[0018] The 1-butene homopolymer used in this embodiment has a weight average molecular weight (Mw) of about 500,000 to 1,500,000.

[0019] The "weight average molecular weight" is calculated in accordance with JIS K 7252-1:2016.

[0020] The 1-butene homopolymer used in this embodiment has a high molecular weight, and therefore has low surface adhesion, making it possible to use it as a surface layer. In addition, since it has higher rigidity than amorphous polyolefins, it is possible to provide a substrate film having high rigidity that allows the substrate to be unwound in the substrate film manufacturing process.

[0021] Furthermore, the 1-butene homopolymer used in this embodiment can be molded using a general-purpose extruder despite its high molecular weight, and the high molecular weight component gives the film low surface adhesion. This makes it possible to suppress adhesion to transport rolls when transporting the base film, as well as suppress blocking when winding the base film and draw resonance when molding the base film, thereby improving the processing stability of the base film.

[0022] As described above, by using a 1-butene homopolymer as the resin forming the substrate film, the uniform extensibility, rigidity, and processing stability of the substrate film can be improved.

[0023] <Low-density polyethylene> The base film of this embodiment has a density of 0.930 g / cm 3 It contains low density polyethylene with a density of 0.930 g / cm 3 In the following cases, an excessive increase in crystallinity is suppressed and flexibility is improved, thereby improving the isotropy of the base film. 3 If it is larger than this, the crystallinity increases excessively, which may result in a decrease in isotropy, and the rigidity may become too large, which may result in a decrease in the pick-up ability of the semiconductor device and damage to the semiconductor device.

[0024] In addition, from the viewpoint of improving processing stability, the density of low-density polyethylene is 0.860 g / cm 3 It is preferable that the concentration is 0.880 g / cm or more. 3 More preferably, it is equal to or greater than this.

[0025] Furthermore, since linear low-density polyethylene has side-chain branches in the linear structure of high-density polyethylene, the degree of crystallinity is not too high compared to high-density polyethylene, and it has excellent flexibility.

[0026] From the viewpoint of strength, linear low-density polyethylene produced using a metallocene catalyst or a Ziegler catalyst may also be used.

[0027] The linear low-density polyethylene preferably has a melt mass flow rate (MFR) of 0.5 to 7.5 g / 10 min, more preferably 1.0 to 6.0 g / 10 min, and even more preferably 2.0 to 5.0 g / 10 min. When the melt mass flow rate (MFR) is 0.5 g / 10 min or higher, the molecular weight is not too large, allowing for improved flexibility and processability, while when the MFR is 7.5 g / 10 min or lower, the molecular weight is not too small, allowing for improved processing stability.

[0028] The melt mass flow rate can be obtained by measuring in accordance with the standard of JIS K7210:1999.

[0029] From the above, the resin forming the base film is selected to have a density of 0.93 g / cm 3 By using a low density polyethylene having a density of 1000 or less, the flexibility and isotropy of the base film can be improved.

[0030] <Base film> In the base film of this embodiment, the stress (at 25% elongation) in the mechanical axis (longitudinal) direction (hereinafter referred to as "MD") of the base film and the direction perpendicular thereto (hereinafter referred to as "TD") is 5 MPa to 20 MPa. If the stress is greater than 20 MPa, the rigidity will be too high, which may reduce the pickup ability of the semiconductor device and cause damage to the semiconductor device. If the stress is less than 5 MPa, the rigidity will be low, which may make it difficult to unwind the base during the base film manufacturing process and may reduce the coatability of the adhesive.

[0031] That is, since the stress in MD and TD (at 25% elongation) is 5 MPa or more and 20 MPa or less, a substrate film with excellent rigidity that allows the substrate to be unwound in the substrate film manufacturing process can be provided.

[0032] The stress in MD and TD (at 25% elongation) is preferably 6 MPa or more and 15 MPa or less, and more preferably 7 MPa or more and 13 MPa or less.

[0033] Furthermore, the substrate film of this embodiment does not have a yield point when stretched from 0% to 100% at a tensile speed of 300 mm / min, and therefore can provide a substrate film with excellent uniform stretchability.

[0034] The mass ratio of the 1-butene homopolymer to the low-density polyethylene in the base film of this embodiment is preferably in the range of 1-butene homopolymer:low-density polyethylene=10:90 to 70:30. Setting the mass ratio of the 1-butene homopolymer to the low-density polyethylene within this range prevents necking during the formation of the base film, resulting in more uniform expansion and making the base easier to unwind during the base film production process. Furthermore, it is possible to prevent blocking during winding of the base film and thickness fluctuations due to draw resonance during formation of the base film. Therefore, it is possible to provide a base film with even more uniform elongation, rigidity, and processing stability.

[0035] Furthermore, in the base film of this embodiment, from the viewpoint of further improving the uniform extensibility of the base film, the ratio of stress (at 40% elongation) to stress (at 20% elongation) in MD and TD (i.e., the elongation of the base film) is preferably from 1 to 2, more preferably from 1.05 to 1.8, and even more preferably from 1.1 to 1.7. If the elongation of the base film is greater than 2, excessive stress may increase, making it difficult to hold the expanding ring, and if the elongation of the base film is less than 1, necking may occur, making uniform expansion difficult.

[0036] Furthermore, from the viewpoint of achieving excellent isotropy of the base film during expansion and suppressing the occurrence of sagging, the ratio of the stress in MD (at 25% elongation) to the stress in TD (at 25% elongation) (i.e., the stress ratio of the base film at 25% elongation) is preferably 0.8 or more and 1.3 or less, more preferably 0.85 or more and 1.15 or less, and even more preferably 0.9 or more and 1.1 or less.

[0037] The above "stress" refers to the stress measured in accordance with JIS K7161-2:2014.

[0038] The thickness of the substrate film is preferably 50 to 300 μm, more preferably 80 to 150 μm. If the thickness of the substrate film is 50 μm or more, the handleability is improved, and if the thickness is 300 μm or less, the flexibility (expandability) can be improved. In the case of a substrate film for wafers, the thickness of the substrate film is preferably 50 to 150 μm, more preferably 70 to 100 μm.

[0039] <Manufacturing method> The base film of this embodiment is a mixture of the above-mentioned 1-butene homopolymer and a cellulose acylate copolymer having a density of 0.93 g / cm 3 The base film of this embodiment may also be produced by a known calendar method or inflation method, using a resin material containing the following low-density polyethylene and extruding the resin material at a predetermined temperature, for example, using an extruder equipped with a T-die.

[0040] (Second embodiment) The substrate film of this embodiment is a substrate film constituted by a laminate of at least one intermediate layer containing the above-mentioned 1-butene homopolymer and surface layers laminated on both sides of the intermediate layer.

[0041] An example of a substrate film having this multilayer structure is substrate film 1, which has a three-layer structure consisting of a laminate of an intermediate layer 2 and surface layers 3 laminated on both sides of the intermediate layer 2, laminated in the order surface layer / intermediate layer / surface layer, as shown in Figure 1.

[0042] Examples of the surface layer include those containing a 1-butene homopolymer as described in the first embodiment above, and those containing a polypropylene homopolymer.

[0043] <Polypropylene homopolymer> Polypropylene homopolymer is a homopolypropylene obtained by polymerizing propylene alone, and this polypropylene homopolymer has high stereoregularity and a high degree of crystallinity that contributes to the melting point, resulting in excellent heat resistance. Furthermore, due to its high degree of crystallinity, it has high rigidity, but by mixing it with the linear low-density polyethylene described above, flexibility that contributes to the expandability of the base film can be obtained.

[0044] The intermediate layer may contain, for example, the above-mentioned 1-butene homopolymer and an olefin-based elastomer.

[0045] <Olefin elastomer> Olefin-based elastomers are composed of olefin-based materials that conform to the definition of the term elastomer in JIS K 6200. More specifically, materials composed of copolymers of amorphous or low-crystalline α-olefins fall under the category of olefin-based elastomers, those primarily composed of polyethylene are called ethylene-based elastomers, and those primarily composed of polypropylene are called propylene-based elastomers. For example, an ethylene-based elastomer is called "Tafmer (registered trademark)" manufactured by Mitsui Chemicals, Inc., and an propylene-based elastomer is called "Vistamax (registered trademark)" manufactured by ExxonMobil Corporation.

[0046] The density of olefin elastomers is 0.850 to 0.900 g / cm 3 It is preferable that the density is 0.860 to 0.890 g / cm 3 It is more preferable that:

[0047] From the viewpoint of processability and cost efficiency, the mass ratio of the 1-butene homopolymer to the olefin elastomer in the intermediate layer is preferably in the range of 1-butene homopolymer:olefin elastomer=60:40 to 90:10.

[0048] <Base film> In the substrate film of this embodiment, the stress in MD and TD (at 25% elongation) is 5 MPa or more and 20 MPa or less. If the stress is more than 20 MPa, the rigidity becomes too high, which may reduce the pickup ability of the semiconductor device and cause damage to the semiconductor device. If the stress is less than 5 MPa, the rigidity becomes low, which may make it difficult to unwind the substrate and reduce the coatability of the adhesive in the substrate film manufacturing process.

[0049] That is, since the stress in MD and TD (at 25% elongation) is 5 MPa or more and 20 MPa or less, a substrate film with excellent rigidity that allows the substrate to be unwound in the substrate film manufacturing process can be provided.

[0050] Furthermore, the substrate film of this embodiment does not have a yield point when stretched from 0% to 100% at a tensile speed of 300 mm / min, and therefore can provide a substrate film with excellent uniform stretchability.

[0051] Furthermore, similarly to the base film in the first embodiment described above, from the viewpoint of further improving the uniform elongation of the base film, the ratio of the stress (at 40% elongation) to the stress (at 20% elongation) in MD and TD (i.e., the elongation rate of the base film) is preferably 1 or more and 2 or less, more preferably 1.05 or more and 1.8 or less, and even more preferably 1.1 or more and 1.7 or less.

[0052] Furthermore, similarly to the base film in the first embodiment described above, from the viewpoint of suppressing the occurrence of sagging due to the isotropy of the base film when expanded, the ratio of the stress in MD (at 25% elongation) to the stress in TD (at 25% elongation) (i.e., the stress ratio of the base film at 25% elongation) is preferably 0.8 or more and 1.3 or less, more preferably 0.85 or more and 1.15 or less, and even more preferably 0.9 or more and 1.1 or less.

[0053] Furthermore, similarly to the base film in the first embodiment described above, the mass ratio of 1-butene homopolymer to low-density polyethylene in the base film constituting the surface layer is preferably in the range of 1-butene homopolymer:low-density polyethylene=10:90 to 70:30.

[0054] The thickness of the base film having a multilayer structure in this embodiment is preferably 50 to 300 μm, more preferably 80 to 150 μm, as in the case of the first embodiment described above. In the case of a base film for a wafer, the thickness of the base film is preferably 50 to 150 μm, more preferably 70 to 100 μm.

[0055] For example, in the case of a substrate film having a three-layer structure in which a surface layer / an intermediate layer / a surface layer are laminated in this order, the thickness of the surface layer is not particularly limited, but is preferably 5 to 15 μm, more preferably 8 to 10 μm, and the thickness of the intermediate layer is not particularly limited, but is preferably 40 to 120 μm, more preferably 50 to 80 μm.

[0056] Furthermore, for example, in the case of a substrate film having a three-layer structure in which a surface layer / an intermediate layer / a surface layer are laminated in this order, from the viewpoints of processability and low cost, the ratio of the intermediate layer to the entire substrate film is preferably 40 to 95%, and more preferably 50 to 90%.

[0057] <Manufacturing method> For example, when producing a substrate film having a three-layer structure in which a surface layer / an intermediate layer / a surface layer are laminated in this order, first, a resin material for forming the surface layer and a resin material for forming the intermediate layer are prepared.

[0058] Next, the resin material for forming the surface layer and the resin material for forming the intermediate layer are simultaneously extruded and molded at a predetermined temperature using an extruder equipped with a T-die, thereby producing the base film having the multilayer structure of this embodiment, which is composed of a laminate of the intermediate layer and the surface layers laminated on both sides of the intermediate layer. Note that the base film of this embodiment may also be produced by a known calendar method or inflation method.

[0059] <Other forms> The substrate film of the present invention may contain various additives. Examples of the additives include known additives commonly used in semiconductor manufacturing tapes, such as crosslinking aids, antistatic agents, heat stabilizers, antioxidants, ultraviolet absorbers, lubricants, antiblocking agents, and colorants. These additives may be used alone or in combination of two or more.

[0060] Furthermore, examples of crosslinking aids include triallyl isocyanurate, and when the base film contains a crosslinking aid, the content of the crosslinking aid in the base film is preferably 0.05 to 5 parts by mass, and more preferably 1 to 3 parts by mass, per 100 parts by mass of the resin forming the base film.

[0061] Furthermore, in the second embodiment described above, an example has been given of a substrate film having a three-layer structure in which surface layer / intermediate layer / surface layer are laminated in this order. However, the substrate film having a multilayer structure of the present invention is not limited to a three-layer structure, and may be, for example, a substrate film having a five-layer structure in which surface layer / intermediate layer / intermediate layer / intermediate layer / surface layer are laminated in this order. [Example]

[0062] The present invention will be described below based on examples. However, the present invention is not limited to these examples, and these examples can be modified or changed based on the spirit of the present invention, and such modifications are not excluded from the scope of the present invention.

[0063] The materials used to prepare the substrate film are shown below. (1) LLDPE-1: Linear low-density polyethylene, melting point: 120°C, density: 0.913 g / cm 3 , MFR: 2.0g / 10min (2) LLDPE-2: Linear low-density polyethylene, melting point: 108°C, density: 0.921 g / cm 3 , MFR: 2.5g / 10min (3) LLDPE-3: Linear low-density polyethylene, melting point: 93°C, density: 0.903 g / cm 3 , MFR: 2.0g / 10min (4) LLDPE-4: Linear low-density polyethylene, melting point: 124°C, density: 0.936 g / cm 3 , MFR: 2.0g / 10min (5) LLDPE-5: Linear low-density polyethylene, density: 0.923 g / cm 3 MFR: 0.5 g / 10 min (manufactured by Prim Polymer Co., Ltd., trade name: Ultzex ​​(registered trademark) 2005HC) (6) LDPE-1: Low-density polyethylene, melting point: 108°C, density: 0.918 g / cm 3 MFR: 7.5 g / 10 min (manufactured by Ube Maruzen PE Co., Ltd., product name: UBE Polyethylene L719) (7) LDPE-2: Low-density polyethylene, melting point: 110°C, density: 0.922 g / cm 3 MFR: 5.0 g / 10 min (manufactured by Ube Maruzen PE Co., Ltd., product name: UBE Polyethylene F522N) (8) PP elastomer 1: propylene-based elastomer, density: 0.889 g / cm 3 , MFR: 8.0 g / 10 min (230°C), polyethylene content: 4% (manufactured by Exxon Corporation, trade name: Vistamax (registered trademark) 3588FL) (9) PP elastomer 2: propylene-based elastomer, density: 0.862 g / cm 3 , MFR: 3.0 g / 10 min (230°C), polyethylene content: 16% (manufactured by Exxon, trade name: Vistamax (registered trademark) 6102FL) (10) PP elastomer 3: propylene-based elastomer, melting point: 160°C, density: 0.868g / cm 3 MFR: 6.0g / 10min (230℃) (11) Amorphous polyolefin + crystalline polypropylene (1-butene-propylene copolymer: crystalline polypropylene = 50:50): Density: 0.880 g / cm 3 MFR: 11.7g / 10min (manufactured by Dainichi Seika Chemicals Co., Ltd., product name: Perricone CAP350S) (12) 1-Bu: homopolymer of 1-butene, melting point: 128°C, density: 0.920 g / cm 3 , MFR: 0.5g / 10min (13) PE elastomer: ethylene-based elastomer, melting point: less than 50°C, density: 0.864 g / cm 3 MFR: 6.7g / 10min (230℃) (14) h-PP: Polypropylene homopolymer, melting point: 163°C, density: 0.900 g / cm 3 , MFR: 0.5g / 10min

[0064] Example 1 <Preparation of base film> First, the materials shown in Table 1 were blended to prepare a resin material of Example 1 having the composition (parts by mass) shown in Table 1. Next, this resin material was extruded using a three-kind, three-layer co-extruder through a T-die at a die temperature of 180 to 200°C and a chill roll temperature of 40°C to obtain a substrate film having the thickness shown in Table 1.

[0065] <Evaluation of the presence or absence of a yield point> Using the prepared substrate film, a measurement sample was obtained in accordance with JIS K7161-2: 2014. Next, the obtained measurement sample was set in a tensile tester (manufactured by Shimadzu Corporation, product name: AG-5000A) so that the distance between the grippers was 40 mm, and a tensile test was performed in accordance with JIS K7161-2: 2014 at a temperature of 23°C and a relative humidity of 40% at a tension rate of 300 mm / min.

[0066] In the SS curves (stress-strain curves) of MD and TD, those for which no yield point was confirmed during the elongation rate from 0% to 100% (no necking occurred and uniform expansion was possible) were marked with a circle, and those for which a yield point was confirmed (necking occurred and uniform expansion was not possible) were marked with an X. The results are shown in Table 1.

[0067] In addition, the S-S curves (stress-strain curves) in the MD and TD directions of the base film of this embodiment are shown in FIGS. 2 to 3. As shown in FIGS. 2 to 3, it can be seen that in the S-S curves (stress-strain curves) in the MD and TD directions, there is no yield point while the elongation ratio extends from 0% to 100%.

[0068] <Measurement of Stress in MD and TD> Using the produced base film, a sample for measurement was obtained in accordance with JIS K7161-2:2014. Next, the obtained sample for measurement was set in a tensile testing machine (manufactured by Shimadzu Corporation, product name: AG-5000A) such that the distance between the grips was 40 mm, and a tensile test was conducted at a tensile speed of 300 mm / min in an environment where the temperature was 23°C and the relative humidity was 40% in accordance with JIS K7161-2:2014.

[0069] Then, the stress at 25% elongation (25% stress) in the MD and TD directions of the base film was measured, and the ratio of the stress in the MD direction (at 25% elongation) to the stress in the TD direction (at 25% elongation) (that is, the stress ratio of the base film at 25% elongation) was calculated. The above results are shown in Table 1.

[0070] Similarly, the stress at 20% elongation (20% stress) and the stress at 40% elongation (40% stress) in the MD and TD directions of the base film were measured, and the ratio of the stress at 40% elongation to the stress at 20% elongation in the MD direction (that is, the elongation rate of the base film in the MD direction) and the ratio of the stress at 40% elongation to the stress at 20% elongation in the TD direction (that is, the elongation rate of the base film in the TD direction) were calculated. The above results are shown in Table 1.

[0071] <Rigidity Evaluation> Using the produced base film, the rigidity was evaluated. More specifically, in the manufacturing process of the base film, when the unwinding of the base material was possible, it was marked as ○ (the rigidity of the base film is excellent), and when the unwinding of the base material was unstable in the manufacturing process of the base film, it was marked as × (the rigidity of the base film is poor). The above results are shown in Table 1.

[0072] <Processing stability evaluation> The fabricated substrate films were used to evaluate processing stability. More specifically, a rating of ◯ (excellent processing stability of the substrate film) was given if adhesion to the transport roll during transport of the substrate film was suppressed, blocking during winding of the substrate film, and thickness fluctuations due to draw resonance during molding of the substrate film were prevented. A rating of × (poor processing stability of the substrate film) was given if the substrate film adhered to the transport roll during transport, making transport and winding of the substrate film difficult, or if thickness fluctuations due to draw resonance during molding of the substrate film were significant. The results are shown in Table 1.

[0073] (Examples 2 to 9, Comparative Examples 1 to 3) Substrate films having the thicknesses shown in Tables 1 and 3 were produced in the same manner as in Example 1 above, except that the composition of the resin component was changed to the composition (parts by mass) shown in Tables 1 and 3.

[0074] Then, the presence or absence of a yield point was evaluated, stresses in MD and TD were measured, and rigidity and processing stability were evaluated in the same manner as in Example 1. The results are shown in Tables 1 and 3.

[0075] (Examples 10 to 15, Comparative Examples 4 to 8) First, in each example and each comparative example, the materials shown in Tables 2 and 4 were blended to prepare a resin material for forming a surface layer and a resin material for forming an intermediate layer having the composition (parts by mass) shown in Tables 2 and 4.

[0076] Next, using a three-type, three-layer co-extruder equipped with a T-die, the resin material for forming the surface layer and the resin material for forming the intermediate layer were simultaneously extruded and molded under conditions of 180-200°C and a chill roll temperature of 40°C, thereby obtaining a substrate film having the thickness shown in Tables 2 and 4 (i.e., the ratio of the intermediate layer to the entire substrate film was 80%) and a three-layer structure laminated in the order of surface layer / intermediate layer / surface layer.

[0077] Then, the presence or absence of a yield point was evaluated, stresses in MD and TD were measured, and rigidity and processing stability were evaluated in the same manner as in Example 1. The results are shown in Tables 2 and 4.

[0078] 4 and 5 show the SS curves (stress-strain curves) in MD and TD for the substrate film of Example 10. As shown in Fig. 4 and Fig. 5, the SS curves (stress-strain curves) in MD and TD show that there is no yield point between the elongation percentages of 0% and 100%.

[0079] [Table 1]

[0080] [Table 2]

[0081] [Table 3]

[0082] [Table 4]

[0083] As shown in Tables 1 and 2, the base films of Examples 1 to 15 contain at least a 1-butene homopolymer, and when stretched at a tensile speed of 300 mm / min, do not have a yield point during stretching from 0% to 100%, and have a stress (at 25% stretch) of 5 MPa or more and 20 MPa or less. As a result, they have excellent uniform stretchability, rigidity, and processing stability.

[0084] On the other hand, as shown in Table 3, in the base film of Comparative Example 1, an excessive amount of crystalline 1-butene homopolymer was added, and therefore a yield point was confirmed, and in TD, the ratio of stress (at 40% elongation) to stress (at 20% elongation) was less than 1, indicating poor uniform elongation.

[0085] Furthermore, as shown in Table 3, the base film of Comparative Example 2 does not contain a 1-butene homopolymer, and therefore a yield point is confirmed, and it is clear that the film has poor uniform elongation and poor processing stability.

[0086] Furthermore, as shown in Table 3, the base film of Comparative Example 3 uses a linear low-density polyethylene with high density and crystallinity, so a yield point was confirmed, and in TD, the ratio of stress (at 40% elongation) to stress (at 20% elongation) was less than 1, indicating poor uniform elongation.

[0087] As shown in Table 4, the substrate film of Comparative Example 4 does not contain a 1-butene homopolymer, and therefore a yield point was confirmed, indicating poor uniform elongation. Furthermore, the ratio of the stress in MD (at 25% elongation) to the stress in TD (at 25% elongation) was greater than 1.3, indicating poor isotropy. Furthermore, because a low-viscosity butene copolymer was used, thickness fluctuations due to draw resonance increased when the substrate film was molded, indicating poor processing stability.

[0088] Furthermore, as shown in Table 4, the substrate film of Comparative Example 5 does not contain a 1-butene homopolymer, and the stress in TD (at 25% elongation) is less than 5 MPa. Therefore, the unwinding of the substrate becomes unstable during the substrate film manufacturing process, and the rigidity is poor.

[0089] Furthermore, as shown in Table 4, the substrate film of Comparative Example 6 does not contain a 1-butene homopolymer, and the ratio of stress (at 40% elongation) to stress (at 20% elongation) in both MD and TD is less than 1, indicating a confirmed yield point and poor uniform elongation. Furthermore, the stress (at 25% elongation) in both MD and TD is less than 5 MPa, indicating that the unwinding of the substrate becomes unstable during the substrate film production process and that rigidity is poor. Furthermore, because the film surface is highly adhesive, the substrate film adheres to the transport roll when transported, making transport and winding of the substrate film difficult, indicating poor processing stability.

[0090] Furthermore, as shown in Table 4, the substrate film of Comparative Example 7 had a TD stress (at 25% elongation) of less than 5 MPa, which resulted in unstable unwinding of the substrate during the substrate film manufacturing process and poor rigidity.

[0091] As shown in Table 4, the ratio of the stress in MD (at 25% elongation) to the stress in TD (at 25% elongation) in the base film of Comparative Example 8 was greater than 1.3, indicating poor isotropy. Also, the ratio of the stress in TD (at 40% elongation) to the stress in TD (at 20% elongation) was less than 1, indicating a yield point and poor uniform elongation. [Industrial Applicability]

[0092] As described above, the present invention is suitable for a substrate film for a tape for manufacturing a semiconductor device. [Explanation of symbols]

[0093] 1. Base film 2. Middle class 3 Surface layer

Claims

1. It comprises a homopolymer of 1-butene and a linear low-density polyethylene having a density of 0.930 g / cm 3 or less, a mass ratio of the 1-butene homopolymer to the linear low-density polyethylene (1-butene homopolymer:linear low-density polyethylene) of 10:90 to 70:30; Under the conditions of a thickness of 80 μm and a tensile speed of 300 mm / min, the film does not have a yield point when stretched from 0% to 100%. A substrate film for a tape for semiconductor manufacturing, characterized in that the stress (at 25% elongation) is 5 MPa or more and 20 MPa or less when the thickness is 80 μm.

2. A substrate film for semiconductor manufacturing tape as described in claim 1, characterized in that, under conditions of a thickness of 80 μm, the ratio of stress (at 40% elongation) to stress (at 20% elongation) is 1 or more and 2 or less.

3. A substrate film for semiconductor manufacturing tape as described in claim 1 or claim 2, characterized in that, under conditions of a thickness of 80 μm, the ratio of stress in MD (at 25% elongation) to stress in TD (at 25% elongation) is 0.8 or more and 1.3 or less.

4. An intermediate layer comprising a homopolymer of 1-butene; surface layers laminated on both sides of the intermediate layer, each containing the 1-butene homopolymer and a linear low-density polyethylene having a density of 0.930 g / cm 3 or less, wherein the mass ratio of the 1-butene homopolymer to the linear low-density polyethylene is 1-butene homopolymer:linear low-density polyethylene=40:60; the intermediate layer has a thickness of 64 μm, the surface layer has a thickness of 8 μm, and the stretching rate is 300 mm / min. The stretching rate does not have a yield point during stretching from 0% to 100%; A substrate film for a tape for semiconductor manufacturing, characterized in that the stress (at 25% elongation) is 5 MPa or more and 20 MPa or less under the condition that the thickness of the intermediate layer is 64 μm and the thickness of the surface layer is 8 μm.

5. A substrate film for semiconductor manufacturing tape as described in Claim 4, characterized in that under the conditions that the thickness of the intermediate layer is 64 μm and the thickness of the surface layer is 8 μm, the ratio of stress (at 40% elongation) to stress (at 20% elongation) is 1 or more and 2 or less.

6. A substrate film for semiconductor manufacturing tape as described in claim 4 or claim 5, characterized in that under the conditions that the thickness of the intermediate layer is 64 μm and the thickness of the surface layer is 8 μm, the ratio of the stress in MD (at 25% elongation) to the stress in TD (at 25% elongation) is 0.8 or more and 1.3 or less.

7. An intermediate layer comprising a 1-butene homopolymer and a linear low-density polyethylene having a density of 0.930 g / cm 3 or less, wherein the mass ratio of the 1-butene homopolymer to the linear low-density polyethylene is 1-butene homopolymer:linear low-density polyethylene=40:60; and surface layers laminated on both sides of the intermediate layer, the intermediate layer has a thickness of 64 μm, the surface layer has a thickness of 8 μm, and the stretching rate is 300 mm / min. The stretching rate does not have a yield point during stretching from 0% to 100%; A substrate film for a tape for semiconductor manufacturing, characterized in that the stress (at 25% elongation) is 5 MPa or more and 20 MPa or less under the condition that the thickness of the intermediate layer is 64 μm and the thickness of the surface layer is 8 μm.

8. A substrate film for semiconductor manufacturing tape as described in Claim 7, characterized in that when the thickness of the intermediate layer is 64 μm and the thickness of the surface layer is 8 μm, the ratio of stress (at 40% elongation) to stress (at 20% elongation) is 1 or more and 2 or less.

9. A substrate film for semiconductor manufacturing tape as described in claim 7 or claim 8, characterized in that when the thickness of the intermediate layer is 64 μm and the thickness of the surface layer is 8 μm, the ratio of the stress in MD (at 25% elongation) to the stress in TD (at 25% elongation) is 0.8 or more and 1.3 or less.

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