JP2020036007A - Film, and method of manufacturing film - Google Patents

Abstract

To provide a film suitable as a base material for a semiconductor manufacturing process, having: such a degree of heat resistance that the film heated to high temperature in a heating step can be handled without being closely adhered to an apparatus surface; and flexibility and uniform stretchability enough to be used as a tacky adhesive film for dicing.SOLUTION: The film is provided that has a maximum value Taof a 5% elongation stress at 25°C of 1.0 MPa or more and 20.0 MPa or less and has at least one α plane when the α plane denotes a surface having a skewness (Ssk) of -1.0 or more and 10.0 or less.SELECTED DRAWING: None

Description

  The present invention relates to a film and a method for producing the film.

  Highly flexible films that can be stretched under low loads at room temperature have been applied to various products such as substrates such as adhesive tapes, transfer substrates for molding, and cushioning materials at the time of pressing. In addition, they are used in a wide range of fields such as circuit and semiconductor manufacturing process applications and decorative applications.

  For example, in the process of manufacturing a semiconductor, a process of attaching an adhesive tape for processing a semiconductor wafer to a pattern surface of a semiconductor wafer, and polishing the back surface of a semiconductor wafer vacuum-adsorbed through a porous chuck made of ceramics or stainless steel to reduce the thickness. Back grinding step of thinning, a step of mounting a semiconductor wafer having a reduced thickness in the step on a dicing tape, a step of peeling the adhesive tape for processing a semiconductor wafer from the semiconductor wafer, and a step of dividing the semiconductor wafer by dicing, Various processes exist.

  In recent years, semiconductor wafers have become thinner along with the miniaturization of electronic devices, and the strength of the semiconductor wafers has been reduced. For example, after the dicing step, a pressure-sensitive adhesive film having excellent flexibility is required to reduce a load on a semiconductor wafer generated in a step of radially expanding the dicing adhesive film and picking up individual chips. In addition, the lack of uniform stretchability at the time of expansion together with the flexibility greatly affects the yield, and therefore, further improvement in uniform stretchability is also required. As a method for improving the flexibility and uniform stretchability of the pressure-sensitive adhesive film, for example, a film mainly composed of a resin having excellent flexibility such as a polypropylene-based resin or an olefin-based elastomer, and a styrene-based elastomer may be used as a base material of the pressure-sensitive adhesive film. A method of using a film is known (Patent Document 1).

JP 2011-119548 A

  On the other hand, a step of attaching a dicing adhesive film to the semiconductor wafer surface polished in the back grinding step and peeling the back grinding sheet by thermal peeling may be used. If the heat resistance of the adhesive film for dicing, which is heated at the same time, is insufficient, the adhesive film may adhere to the surface of a device such as a porous chuck which is in direct contact with the film to adsorb and fix the film, which may make handling difficult. In such a problem, since the adhesion of the film becomes stronger as the film becomes more flexible, the above-mentioned flexibility requirement is in a trade-off relationship, and it is compatible with the conventionally known films including the film described in Patent Document 1. It was very difficult.

  The present invention solves the above-mentioned problems of the prior art, and is used as a heat-resistant film which can be handled without a film heated to a high temperature in a heating step without being in close contact with an apparatus surface or the like, and an adhesive film for dicing. It is an object of the present invention to provide a film having sufficient flexibility and uniform stretchability and suitable as a substrate for a semiconductor manufacturing process.

In order to solve such a problem, the present invention has the following configuration.
(1) When a plane having a skewness (Ssk) of −1.0 or more and 10.0 or less is defined as an α plane, a maximum value Ta _max of 5% elongation stress at 25 ° C. is 1.0 MPa or more and 20.0 MPa or less. And a film having at least one α-plane.
(2) The film according to (1), wherein a polar force component of surface energy is 0.0 mN / m or more and 0.9 mN / m or less on the α plane.
(3) The film according to (1) or (2), wherein the skewness Ssk of the α plane is more than 3.0 and not more than 7.0.
(4) The film according to any one of (1) to (3), wherein the α-plane has a surface roughness (SRa) of 200 nm or more and 1,500 nm or less.
(5) The film according to any one of (1) to (4), wherein a 10% endothermic temperature at a maximum melting peak measured by DSC is from 145 ° C to 180 ° C.
(6) When the temperature is raised from 25 ° C. to 160 ° C. at a rate of 10 ° C./min, the maximum dimensional change rate at 100 ° C. or less is Dm, the direction in which Dm is the maximum is the X direction, and the Dm in the X direction is Dmx. The film according to any one of (1) to (5), wherein Dmx is from -5.0% to 2.0%.
(7) The film according to (6), wherein Dm in all directions is -10.0% or more and 2.0% or less.
(8) When the two layers having different thermoplastic elastomer contents are the A layer and the B layer, and the resin component in the A layer is 100% by mass, the content of the thermoplastic elastomer in the A layer is M _A (% by mass). ), when the 100% by mass of the resin component in the layer B, the content of the thermoplastic elastomer in the layer B is taken as M _{B (wt%),} an a layer and B layer, a layer of at least one located in the outermost layer, and characterized in that it is a M _{a <M B,} the film according to any one of (1) to (7).
(9) The film according to (8), wherein the A layer, the B layer, and the A layer are located in this order.
(10) The film according to any one of (1) to (9), wherein the thickness unevenness is 10.0% or less.
(11) Any of (1) to (10), wherein the in-plane variation of stress in the range of elongation of 50 to 500% in an atmosphere at 25 ° C. is 0.0 MPa or more and 5.0 MPa or less. A film as described in Crab.
(12) The method according to any one of (1) to (11), wherein the variation of the stress increase rate in the elongation range of 50 to 500% at 25 ° C. is 0.0% or more and 2.0% or less. The film as described.
(13) The film according to any one of (1) to (12), wherein a rate of change in thickness after heat treatment at 90 ° C. for 10 minutes is 0.5% or more and 10.0% or less.
(14) The dimensional change at 90 ° C. when the temperature was raised from 25 ° C. to 160 ° C. at a rate of 10 ° C./min under a load of 5 g / mm ² was calculated as the dimensional change at 90 ° C. Is the X direction, the direction orthogonal to the X direction in the film plane is the Y direction, the 90 ° C. dimensional change rate in the X direction is Tx (%), and the 90 ° C. dimensional change rate in the Y direction is Ty (%). The film according to any one of (1) to (13), wherein | Tx−Ty | is more than 3.00 and less than 10.00.
(15) The method for producing a film according to any one of (1) to (14), comprising a step of stretching the non-oriented sheet in at least one direction at a magnification of 1.01 or more and 2.00 or less. A method for producing a film, comprising:
(16) The method for producing a film according to (15), comprising a step of stretching the non-oriented sheet in two directions orthogonal to each other at a magnification of 1.01 or more and 2.00 or less. .
(17) The method for producing a film according to any one of (1) to (14), further comprising a rolling step of rolling the non-oriented sheet at a roll linear pressure of 30 kg / cm or more and 500 kg / cm or less. Characterized by a method for producing a film.

  According to the present invention, a film having heat resistance, flexibility, and uniform stretchability and a method for producing the same can be provided, and the film of the present invention can be suitably used as a substrate for a semiconductor production process. In addition, the film of the present invention may be used as an electrically insulating material such as a copper-clad laminate, a back sheet for a solar cell, an adhesive tape, a flexible printed circuit board, a membrane switch, a sheet heating element, or a flat cable, a material for a capacitor, and a case material. Applications where vibration control and heat resistance are important, such as automotive materials and building materials, and applications where flexibility and puncture resistance are important, such as pouches for pharmaceuticals and food packaging, etc. Can also be suitably used.

It is an example of the roughness curve used for the measurement of Ssk.

In the film of the present invention, when a plane having a skewness (Ssk) of −1.0 or more and 10.0 or less is defined as an α plane, the maximum value of the 5% elongation stress Ta _max at 25 ° C. is 1.0 MPa or more and 20 MPa or more. 0.0 MPa or less and at least one α-plane.

In the film of the present invention, from the viewpoint of reducing chip damage in the semiconductor manufacturing process, it is important that the maximum value Ta _max of the 5% elongation stress at 25 ° C. is 1.0 MPa or more and 20.0 MPa or less. When Ta _max is less than 1.0 MPa, the film may be deformed during heating due to the mass of the semiconductor wafer, or may be deformed unevenly when the film is expanded. On the other hand, when Ta _max is larger than 20.0 MPa, the load at the time of picking up the chip is large, and the chip may be damaged. From the above viewpoint, Ta _max is more preferably from 1.5 MPa to 15.0 MPa, and still more preferably from 2.0 MPa to 10.0 MPa. The method for setting Ta _max to the above range is not particularly limited. For example, at least a film having a glass transition temperature of at least one layer having a glass transition temperature of −100 ° C. or more and less than 0 ° C. at a magnification of 2.00 times or less. Examples include a method of forming an oriented film stretched in one direction.

The term “stress at 5% elongation at 25 ° C.” refers to a stress at 5% elongation at 25 ° C. measured at a test speed of 300 mm / min according to JIS K 7127 (1999, specimen type 2). The “maximum value of 5% elongation stress at 25 ° C. Ta _max ” is defined as 0 ° in any direction parallel to the film surface, and 175 ° clockwise rotated from the 0 ° direction parallel to the film surface. Assuming that the direction is 175 °, in the range from 0 ° to 175 ° at 5 ° intervals at 25 ° C at a test speed of 300 mm / min according to JIS K 7127 (1999, specimen type 2). The 5% elongation stress was measured, and it means the maximum value of the 36 measured values obtained. For measuring the stress at 5% elongation, a rectangular sample of 150 mm (measurement direction) × 10 mm (direction perpendicular to the measurement direction) is used.

  It is important that the film of the present invention has at least one α plane when a plane having a skewness (Ssk) of −1.0 or more and 10.0 or less is an α plane. The skewness (Ssk) here is obtained according to JIS B 0601 (2001), and represents the shape of the uneven portion on the surface. Ssk having a positive value indicates that the surface is composed of a sharp projection and a rounded concave portion, and Ssk having a negative value indicates that the surface has a rounded convex portion. It represents that it is composed of sharp recesses. In both cases where Ssk is positive and negative, Ssk becomes a sharper shape as its absolute value increases.

  When the Ssk of the film surface is less than -1.0, the roundness of the convex portion on the surface becomes excessively large, and the contact area between the surface and another member when the other members are overlapped becomes large. It tends to be too strong. On the other hand, when the Ssk of the film surface is larger than 10.0, the projections on the surface are excessively sharp, and scratches and shavings are apt to occur during film transport, making it difficult to obtain a film with good appearance. Ssk is preferably 1.0 or more and 8.0 or less, and more preferably more than 3.0 and 7.0 or less, from the viewpoint of improving the appearance while suppressing the increase in adhesion during heating.

  The method for setting Ssk to −1.0 or more and 10.0 or less or the preferred range described above is not particularly limited. For example, a layer in which the outermost layer contains 80% by mass or more of a polypropylene resin with respect to 100% by mass of all components or Examples include a method of finely stretching a laminated film which is a layer containing particles having an average particle size of 0.5 μm or more and 15 μm or less (preferably 5 μm or more and 15 μm or less) at a low magnification of 1.01 or more and 2.00 or less. Can be

  The method of measuring Ssk will be specifically described with reference to FIG. FIG. 1 is an example of a roughness curve used for Ssk measurement. In the reference length (Lr) 1 in FIG. 1, when the height 4 of the roughness curve 2 from the base line 3 is represented by z and z = Z (x), Z (x ) Is obtained by dividing the value obtained by integrating the cube of x) in the range of x = 0 to Lr by the cube of Rq. Here, Rq is a parameter of the surface roughness determined according to JIS B 0601 (2001), and is a value determined as an average value of the square of Z (x). That is, when the range from x = 0 to Lr is measured, the value obtained by integrating the square of Z (x) in the range from x = 0 to Lr is divided by Lr as shown in the following equation 2. Is Rq. Note that the reference length 1 (Lr) can be appropriately determined according to the specifications of the measuring device and the like. The base line 3 corresponds to the area of the peak formed by the roughness curve 2 in the range of the reference length 1 (Lr). It is a line drawn so that the areas of the valleys are equal. In addition, an Ssk measuring device that can perform measurement can be appropriately selected. For example, “VertScan” (registered trademark) manufactured by Ryoka Systems Inc. can be used.

  In the film of the present invention, it is preferable that the polar force component of the surface energy on the α-plane is 0.0 mN / m or more and 0.9 mN / m or less. The polar force component in the present invention refers to a value calculated by a measuring method described later. By setting the polar force component of the α-plane to 0.9 mN / m or less, the adhesive force between the α-plane and the metal member of the manufacturing apparatus at the time of heating can be suppressed low, so that the elongation of the film when the semiconductor wafer moves can be reduced. Separation in the case of close contact with the metal member is also facilitated. The polar force component of the α plane is more preferably 0.0 mN / m or more and 0.6 mN / m or less, and further preferably 0.0 mN / m or more and 0.4 mN / m or less. The method for setting the polar force component on the film surface to the above specific range is not particularly limited, and examples thereof include a method in which a layer mainly composed of an α-olefin-based resin is disposed on the outermost layer of the film. As used herein, the term “mainly composed of an α-olefin resin” means that the layer contains 50% by mass or more of the α-olefin-based resin when all components constituting the layer are 100% by mass. As another method, the polar force component on the film surface can be increased by performing a corona discharge treatment on the film surface.

  The film of the present invention has a surface roughness (SRa) of 200 nm or more and 1 from the viewpoint of reducing air entrapment when another member and the α surface are brought into close contact with each other and maintaining the thickness accuracy. , 500 nm or less. When the SRa of the α plane is 1,500 nm or less, the accuracy of the film thickness can be kept high. On the other hand, by setting the SRa of the α-plane to 200 nm or more, a sufficient air passage can be secured when another member is disposed on the α-plane. ) Can be reduced when air is fixed. Further, by setting the SRa of the α-plane to 200 nm or more, the contact area with the member is reduced, so that the increase in the adhesion when heated can be reduced. In view of the above, the SRa of the α plane is more preferably 250 nm or more and 1,300 nm or less, and still more preferably 300 nm or more and 1,100 nm or less. Note that SRa is measured in accordance with JIS B 0601 (1994).

  There is no particular limitation on the method for setting SRa to 200 nm or more and 1,500 nm or less, or the above-mentioned preferred range. In such a case, a method in which inorganic particles or organic particles are contained in the outermost layer) and a method in which inorganic particles or organic particles are coated with a binder resin to form a surface are exemplified.

  The film of the present invention preferably has a 10% endothermic temperature at the maximum melting peak measured by DSC of from 145 ° C to 180 ° C. The 10% endothermic temperature (hereinafter, sometimes simply referred to as 10% endothermic temperature) at the maximum melting peak measured by DSC is measured under a nitrogen atmosphere according to JIS-K-7121 (2012) using a differential calorimeter. The temperature of the measurement sample is raised at a rate of 20 ° C./min from 25 ° C. to 280 ° C., and the temperature can be calculated from the measurement result by a method described later. When the 10% endothermic temperature of the film is 145 ° C. or higher, it is possible to reduce an increase in adhesion when heated. On the other hand, when the 10% endothermic temperature of the film is 180 ° C. or lower, sufficient flexibility can be secured. From the above viewpoint, the 10% endothermic temperature is more preferably from 152 ° C. to 165 ° C. The differential calorimeter used for the measurement is not particularly limited as long as it can be measured, and can be appropriately selected from known ones. As an apparatus used for the measurement, EXTRA DSC6220 (manufactured by Hitachi High-Tech Science Co., Ltd. (formerly SII Nanotechnology Co., Ltd.)) and the like can be mentioned.

  The film of the present invention has a maximum dimensional change rate Dm at 100 ° C. or lower when the temperature is raised from 25 ° C. to 160 ° C. at a temperature rising rate of 10 ° C./min, a direction in which Dm is maximum in the X direction, and a Dm in the X direction. Is Dmx, it is preferable that Dmx is −5.0% or more and 2.0% or less. By setting Dmx within the above range, it is easy to reduce deformation such as expansion when the film becomes high temperature. In particular, a known tape base material used in a semiconductor manufacturing process has a large expansion deformation even in a medium temperature region of about 100 ° C. Therefore, reducing the dimensional change in this temperature range is a great advantage in terms of improving the yield when the film is used in the above applications.

Dm (%) can be measured by the following method, and Dmx (%) can be determined by the following procedure. First, a film sample cut into a size of 15 mm (measurement direction) × 4 mm (a direction perpendicular to the measurement direction) in a room temperature environment was allowed to stand for 24 hours in an atmosphere at a temperature of 25 ° C. and a relative humidity of 65%. The length (L0) in the measurement direction is measured. Next, using TMA / SS6000 (manufactured by Seiko Instruments Inc.), the film sample was heated from 25 ° C. to 160 ° C. under a load of 5 g / mm ² and a heating rate of 10 ° C./min. Measure the length in the measurement direction in the range of ° C. From the obtained measurement data, the timing at which the difference between the length in the measurement direction and L0 is the largest is specified, and the length in the measurement direction at this time is defined as L1. After that, the dimensional change rate (%) is obtained from L0 and L1 according to the following equation 3, and the obtained value is defined as Dm (%) in the measurement direction. Further, the measurement direction is rotated clockwise by 5 ° in parallel with the film surface, and similarly, the value of Dm (%) in each direction until the rotation angle reaches 175 ° is determined. The maximum value is specified as Dmx (%) from Dm (%) in all measurement directions thus obtained, and the direction in which Dmx (%) is obtained is defined as the X direction.
Formula 3: dimensional change (%) = (L1−L0) × 100 / L0.

  By setting the Dmx of the film to 2.0% or less, displacement of the semiconductor wafer due to expansion when used in a semiconductor manufacturing process can be reduced. On the other hand, by setting the Dmx of the film to -5.0% or more, generation of wrinkles can be reduced. From the above viewpoint, Dmx of the film is more preferably -4.0% or more and 1.5% or less, and still more preferably -3.0% or more and 1.0% or less. The method for setting the Dmx of the film to the above range is not particularly limited. For example, the film is stretched in at least one direction at a magnification of 1.01 times or more and 2.00 times or less, and then stretched at a temperature of 60 ° C or more and a stretching temperature of −10 ° C. or less. A method of adopting a step of transporting in a room temperature environment after cooling for at least two seconds.

  In the film of the present invention, Dm in all directions is preferably -10% or more and 2.0% or less. When the amount of dimensional change is within a specific range within the film plane, it is possible to reduce non-uniform deformation particularly when the film area is large. Dm is more preferably -9.0% or more and 1.5% or less, and even more preferably -8.0% or more and 1.0% or less, in all directions of the film. The method of setting Dm to the above specific range is not particularly limited, and examples thereof include a method of stretching in two directions orthogonal to each other at a magnification of 1.01 or more and 2.00 or less. "The Dm in all directions is -10% or more and 2.0% or less" means that an arbitrary direction parallel to the film surface is rotated by 175 ° clockwise from the 0 ° direction and from the 0 ° direction parallel to the film surface. When the Dm is measured at 5 ° intervals in a range from the 0 ° direction to the 175 ° direction, all values are -10% to 2.0%. Means

The film of the present invention has two layers having different thermoplastic elastomer contents in the A layer and the B layer, in terms of suppressing the deterioration of the handleability due to the close contact with a manufacturing apparatus when heated, the A layer and the B layer. when the resin component is 100 mass%, M _{a (wt%)} the content of the thermoplastic elastomer in the layer a, when taken as 100% by mass of the resin component in the layer B, containing the thermoplastic elastomer in the B layer the amount is taken as M _{B (wt%),} an a layer and B layer is preferably a layer is positioned as the outermost layer of at least one, and an M _{a <M B.} By reducing the content of the thermoplastic elastomer in the A layer, which is the outermost layer, the adhesion to the manufacturing apparatus when heated is suppressed, and by having the B layer containing a large amount of the thermoplastic elastomer, for the semiconductor manufacturing process, It is possible to ensure the flexibility required for the film. Note that the content of the thermoplastic elastomer in each layer is calculated assuming that all components constituting the layer are 100% by mass. Incidentally, as long as they do not impair the effects of the present invention, embodiments A layer does not contain a thermoplastic elastomer, i.e., may be aspects M _A is zero.

  The thermoplastic elastomer refers to a high molecular weight material which is softened by heating and has rubber elasticity at 25 ° C. Examples of the thermoplastic elastomer used in the present invention include hydrocarbon elastomers such as polyester elastomers, polystyrene elastomers and polyolefin elastomers, and polyamide elastomers.

  Examples of the polyester-based elastomer include a block copolymer of an aromatic polyester and an aliphatic polyester, and a block copolymer of an aromatic polyester and an aliphatic polyether. In view of the above, a block copolymer of an aromatic polyester and an aliphatic polyether is preferable.

  The aromatic polyester in the polyester elastomer is preferably at least one of a polybutylene terephthalate resin and a polyethylene terephthalate resin. Here, the polybutylene terephthalate resin refers to a polyester obtained by using terephthalic acid or a combination of terephthalic acid and isophthalic acid as a dicarboxylic acid component, and using 1,4-butanediol as a diol component. Part of the acid component (less than 50 mol%) is replaced with another dicarboxylic acid component or oxycarboxylic acid component, or part of the diol component (less than 50 mol%) is replaced with a low molecular weight diol component other than the butanediol component. The polyester may be used. The polyethylene terephthalate resin refers to a polyester obtained by using terephthalic acid as a dicarboxylic acid component or a dicarboxylic acid component obtained by combining terephthalic acid and isophthalic acid, and using ethylene glycol as a diol component. Part (less than 50 mol%) of the polyester is replaced with another dicarboxylic acid component or oxycarboxylic acid component, or a part of the diol component (less than 50 mol%) is replaced with a low molecular weight diol component other than the ethylene glycol component. There may be.

  The aliphatic polyether in the polyester-based elastomer is preferably a polyalkylene glycol-based resin, and the type thereof is not particularly limited as long as the effects of the present invention are not impaired. Resin, polybutylene glycol resin, polytetramethylene glycol resin, polyhexylene glycol, polyheptylene glycol resin, polyoctylene glycol resin, polydodecylene glycol resin, and copolymers thereof And the like. Among them, at least one of a polytetramethylene glycol-based resin and a polyethylene glycol-based resin is preferable. Here, the polyalkylene glycol-based resin refers to an aliphatic polyether having polyalkylene glycol as a main component, and a part (less than 50% by mass) of a polyether portion is replaced with a dioxy component other than the alkylene glycol component. Or an aliphatic polyether. In addition, polyethylene glycol resin, polypropylene glycol resin, polybutylene glycol resin, polytetramethylene glycol resin, polyhexylene glycol, polyheptylene glycol resin, polyoctylene glycol resin, polydodecylene glycol The same applies to aliphatic polyether resins such as resin.

  Examples of commercially available polyester elastomers that can be used in the film of the present invention include “Hytrel” (registered trademark) manufactured by Dupont Toray, “Perprene” (registered trademark) manufactured by Toyobo, and "Primalloy" (registered trademark) and the like.

  Examples of the polystyrene-based elastomer include, for example, a block copolymer of polystyrene and polybutadiene, a block copolymer of polystyrene and hydrogenated polybutadiene, a block copolymer of polystyrene and polyisoprene, and a block of polystyrene and hydrogenated polyisoprene. Copolymers and block copolymers of polystyrene and polyisobutylene can be exemplified. More specifically, SBS (styrene-butadiene-styrene copolymer), SEBS (styrene-ethylene / butylene-styrene copolymer), SIS (styrene-isoprene-styrene copolymer), and SEPS (styrene-ethylene / propylene-styrene copolymer) And the like. In addition, the polystyrene-based elastomer of the present invention includes an acid anhydride group, a carboxyl group, an amino group, an imino group, an alkoxysilyl group, a silanol group, a silyl ether group, a hydroxyl group, and an epoxy group, as long as the effects of the present invention are not impaired. And those modified with at least one functional group selected from the group consisting of

  Examples of commercially available polystyrene-based elastomers that can be used for the film of the present invention include, for example, “Clayton” (registered trademark) manufactured by Clayton Polymer Japan, “Dynaron” (registered trademark) manufactured by JSR, and “Claton” manufactured by Asahi Kasei. "TUFTEC" (registered trademark), "SOE" (registered trademark), "Tafprene" (registered trademark), "Asaprene" (registered trademark), "Septon" (registered trademark) manufactured by Kuraray, manufactured by Aron Kasei AR-FL series.

  The first embodiment of the polyolefin elastomer is one selected from the group consisting of polyethylene and polypropylene, and one selected from the group consisting of polybutadiene, hydrogenated polybutadiene, polyisoprene, hydrogenated polyisoprene, polyisobutylene, and α-olefin. And a copolymer. The form of the copolymerization may be any of block copolymerization and graft copolymerization, and is limited to the case of a copolymer consisting of one selected from the group consisting of polyethylene and polypropylene and an α-olefin, and is a random copolymerization. Is also good. The α-olefin is an olefin having a double bond at one terminal of a molecular chain, and for example, 1-octene is preferably used.

  A second embodiment of the polyolefin elastomer is one selected from the group consisting of polyethylene and polypropylene, and an ethylene-propylene copolymer, an ethylene-propylene-diene copolymer, an ethylene-butene copolymer, and an ethylene-octene copolymer. It is a blend with one selected from the group consisting of coalesced and hydrogenated styrene-butadiene copolymers. At this time, the ethylene-propylene copolymer, ethylene-propylene-diene copolymer, ethylene-butene copolymer, and ethylene-octene copolymer may be partially or completely crosslinked.

  The polyolefin-based elastomer is selected from the group consisting of an acid anhydride group, a carboxyl group, an amino group, an imino group, an alkoxysilyl group, a silanol group, a silyl ether group, a hydroxyl group and an epoxy group, as long as the effects of the present invention are not impaired. It may be modified with at least one selected functional group.

  Commercially available polyolefin-based elastomers that can be used in the film of the present invention include, for example, “Mirastomer” (registered trademark) manufactured by Mitsui Chemicals, “Esporex” (registered trademark) manufactured by Sumitomo Chemical, and Mitsubishi Chemical "Thermolan" (registered trademark), "Zeras" (registered trademark), "Engage" (registered trademark) manufactured by Dow Chemical, and the like.

  Examples of the polyamide-based elastomer include a block copolymer of a polyamide and an aliphatic polyester, and a block copolymer of a polyamide and an aliphatic polyether. Commercially available polyamide elastomers that can be used in the film of the present invention include “UBESTA” (registered trademark) manufactured by Ube Industries, “Daiamide” (registered trademark), and “Vestamide E” (manufactured by Daicel Evonik). (Registered trademark) and "PEBAX" (registered trademark) manufactured by Arkema.

  The thermoplastic elastomer may be used alone or in combination of two or more, as long as the effects of the present invention are not impaired. However, in the latter case, the content is calculated by adding all the thermoplastic elastomers.

  In the film of the present invention, it is preferable that the layer A, the layer B, and the layer A are located in this order from the viewpoint of curling during heating. At this time, the composition of the layer A may be the same or different as long as the relationship between the amounts of the thermoplastic elastomers in the layer A and the layer B is maintained, as long as the effects of the present invention are not impaired. Further, another layer may be included between the A layer and the B layer as long as the effects of the present invention are not impaired.

  The film of the present invention, from the viewpoint of improving the handleability by imparting the slipperiness, in the case where the film has a single-layer configuration, in the film, when the film has a laminated configuration, it may also contain particles in at least one outermost layer of one side. preferable. The particles are not particularly limited as long as the effects of the present invention are not impaired, and inorganic particles and organic particles can be used, or both can be used in combination. Examples of the inorganic particles include metal oxides such as silica, alumina, titania, and zirconia, barium sulfate, calcium carbonate, aluminum silicate, calcium phosphate, mica, kaolin, clay, and zeolite. Among these, metal oxides such as silica, alumina, titania and zirconia, zeolites and calcium carbonate are preferred. As the organic particles, crosslinked particles of a polymethoxysilane compound, crosslinked particles of a polyethylene compound, crosslinked particles of a polystyrene compound, crosslinked particles of an acrylic compound, crosslinked particles of a polyurethane compound, crosslinked particles of a polyester compound, fluorine Examples include crosslinked particles of a system compound, or a mixture thereof.

  The average particle size of the above particles is not particularly limited as long as the effects of the present invention are not impaired, but is preferably 0.5 μm or more and 15.0 μm or less from the viewpoint of improving the handleability by imparting slipperiness. Here, the average particle diameter of the particles can be determined by calculating a weight average diameter using a circle equivalent diameter obtained by image processing from a transmission electron micrograph of the particles. Further, the content of the particles is preferably 1% by mass or more and 50% by mass or less when the whole layer containing the particles is 100% by mass.

  The film of the present invention preferably has a thickness unevenness of 10.0% or less, more preferably 6.0% or less, from the viewpoint of reducing the reduction in the yield in semiconductor wafer dicing. When the thickness unevenness is 10.0% or less, the frequency of occurrence of chipping due to rattling at the time of dicing the semiconductor wafer is reduced, so that the yield is reduced, and the uniformity at the time of expanding is also improved. The thickness unevenness can be calculated as a percentage obtained by measuring the thickness at 5 points in the longitudinal direction, 5 points in the width direction, and a total of 10 points, and dividing the difference between the maximum value and the minimum value by the average value. .

  The method for controlling the thickness unevenness to 10.0% or less or the above preferable range is not particularly limited as long as the effects of the present invention are not impaired. For example, the sheet is stretched at a stretching ratio of 1.10 times or more and 2.00 times or less, preferably A method of stretching at a stretching ratio of 1.10 times or more and 1.50 times or less, and the like can be given. By stretching under such conditions, thickness unevenness can be reduced while suppressing a decrease in flexibility. In the stretching, it is also preferable to reduce the stretching tension by setting the stretching temperature to 90 ° C. or higher and the melting point of the film or lower. The smaller the thickness unevenness, the better, and the lower limit is most preferably 0.0%.

  In the film of the present invention, from the viewpoint of further improving the uniformity at the time of expansion, the in-plane variation of stress in the elongation range of 50 to 500% is from 0.0 MPa to 5.0 MPa in an atmosphere at 25 ° C. Is preferred. By setting the physical properties in the above range, the elongation of the film at the time of expansion can be uniformed in the plane, and the positional accuracy when picking up the semiconductor wafer can be improved. More preferably, the in-plane variation of stress in the range of 50 to 500% elongation at 25 ° C. is 0.0 MPa or more and 2.5 MPa or less. Hereinafter, the in-plane variation of the stress in the elongation range of 50 to 500% measured in an atmosphere at 25 ° C. may be simply referred to as the in-plane variation of the stress.

  The in-plane variation of stress can be measured by the following method. First, a rectangular sample of 150 mm (measurement direction) × 10 mm (a direction perpendicular to the measurement direction) was prepared, and “JIS” was measured by a film strength / elongation measuring device (AMF / RTA-100) manufactured by Orientec Co., Ltd. The stress at the time of extension of the measurement sample is measured at a temperature of 25 ° C., a relative humidity of 65%, and a test speed of 300 mm / min according to K 7127 (1999, specimen type 2). Then, the same measurement is performed by rotating clockwise by 5 °, and the same measurement is repeated until the measurement direction becomes a direction rotated 175 ° clockwise from the initial measurement direction. In the elongation range of ~ 500%, the difference between the maximum value and the minimum value of the 36 measured values at each elongation point is calculated, and the maximum value of the obtained values is defined as the in-plane variation of stress (MPa). Do .

  The method for making the in-plane variation of the stress 0.0 MPa or more and 5.0 MPa or less in the above preferred range is not particularly limited as long as the effects of the present invention are not impaired, but, for example, the casting direction of the cast film (corresponding to the longitudinal direction). In order to reduce the orientation of the film, there is a method of reducing the dispersion diameter of the elastomer component added to the film. By uniformly dispersing the flexible elastomer component in the matrix resin, it is possible to suppress the formation of alignment due to tension generated between the die and the cast drum. From the above viewpoint, the dispersion diameter of the elastomer component is preferably 1 nm or more and 180 nm or less.

  In the film of the present invention, from the viewpoint of suppressing stress concentration on the semiconductor wafer at the time of expansion and reducing breakage, the change in the rate of stress increase in the elongation range of 50 to 500% in a 25 ° C. atmosphere is 0. It is preferably 0% or more and 2.0% or less. By adopting such an embodiment, stress concentration on the semiconductor wafer due to a sudden change in stress of the film during expansion is suppressed, and as a result, damage to the semiconductor wafer is reduced. In addition, the fluctuation | variation of the stress increase rate in the 50-500% elongation range measured under the atmosphere of 25 degreeC below may only be called the fluctuation | variation of a stress increase rate.

  The fluctuation of the stress increase rate can be measured by the following method. First, a rectangular sample of 150 mm (measurement direction) × 10 mm (a direction perpendicular to the measurement direction) is prepared, and a temperature of 25 ° C. and a relative humidity of 65% according to “JIS K 7127 (1999, specimen type 2)”. Then, the stress at 5% elongation of the measurement sample is measured at a test speed of 300 mm / min, and at each elongation point, the stress change rate in the elongation range from -10% (the change value of the stress is referred to as the elongation amount). The value is extracted in the range of elongation of 50 to 500%. Thereafter, the maximum value and the minimum value are specified from the obtained values, the difference between them is obtained, and the obtained value is calculated. The same measurement was performed by rotating the measurement direction clockwise 5 ° in parallel with the film surface, and the measurement direction was rotated 175 ° right from the initial measurement direction. Same measurement until direction Is repeated, and the maximum value is specified from the 36 measured values obtained, and this is defined as the fluctuation (%) of the stress increase rate of the film. The film can be appropriately selected from those, and for example, a film strength / elongation measuring device (AMF / RTA-100) manufactured by Orientec Co., Ltd. can be used.

  The method for setting the variation of the stress increase rate to 0.0% or more and 2.0% or less or the above preferred range is not particularly limited. For example, the dispersion diameter of the elastomer component to be added to the film is 100 nm or less, and the stretching ratio is 1 Rolling is performed by a method of stretching by 10 times or more and 2.00 times or less, or by setting the dispersion diameter of the elastomer component to the above range and setting the roll linear pressure to 30 kg / cm to 500 kg / cm by the method described later. Method and the like. That is, by dispersing the elastomer component more uniformly and forming a fine orientation under heating, local orientation crystallization accompanying elongation is reduced, and the expandability becomes more uniform.

  From the viewpoint of further improving the heat resistance, the film of the present invention preferably has a thickness change rate after heating at 90 ° C. for 10 minutes of 0.5% or more and 10.0% or less. When the rate of change in thickness, that is, the rate of expansion in the thickness direction due to heating is within a certain range, expansion in the surface direction (direction perpendicular to the thickness direction) during heating can be reduced. More specifically, when the rate of change in thickness after heat treatment at 90 ° C. for 10 minutes is 0.5% or more, deterioration in film flatness during heating can be reduced. When the rate of change in thickness after that is 10.0% or less, expansion in the surface direction during heating can be suppressed to an extent that does not become excessive. From the above viewpoint, the rate of change in thickness after heat treatment at 90 ° C. for 10 minutes is more preferably 1.0% or more and 8.0% or less, and still more preferably 2.3% or more and 8.0% or less.

  The thickness change rate (%) after heat treatment at 90 ° C. for 10 minutes can be measured by the following procedure. First, on a straight line (hereinafter, sometimes referred to as a center line) connecting two midpoints of opposing sides of a 100 mm × 100 mm square film cut arbitrarily, a 10 mm interval excluding each end. 9 points (a total of 17 points due to overlapping centers) are taken as measurement points. Next, the thickness at each measurement point is measured with an electronic micrometer, and the average value is defined as the thickness before heat treatment. Thereafter, heat treatment is performed for 10 minutes in an oven heated to 90 ° C., the film is taken out of the oven, the film thickness at each measurement point is measured in the same manner, and the average value is defined as the thickness after the heat treatment. The value obtained by dividing the thus obtained thickness after the heat treatment by the thickness before the heat treatment is defined as the thickness change rate (%) of the film after the heat treatment at 90 ° C. for 10 minutes. The electronic micrometer used for thickness measurement is not particularly limited as long as it can be measured. For example, an electronic micrometer (K-312A type) manufactured by Anritsu Corporation can be used.

  The method for setting the rate of change in thickness after heat treatment at 90 ° C. for 10 minutes to 0.5% or more and 10.0% or less is not particularly limited as long as the effects of the present invention are not impaired. A method of rolling at a linear pressure of 30 kg / cm or more and 500 kg / cm or less may be used.

From the viewpoint of suppressing wrinkles and loosening during heating and deformation of the film, the film of the present invention is obtained by applying a load of 5 g / mm ² and increasing the temperature from 25 ° C. to 160 ° C. at a rate of 10 ° C./min. The dimensional change rate at 90 ° C is defined as the 90 ° C dimensional change rate, the direction in which the 90 ° C dimensional change rate is the maximum is the X direction, the X direction is orthogonal to the Y direction in the film plane, and the 90 ° C dimensional change rate in the X direction is the When Tx (%) and 90 ° C. dimensional change in the Y direction are Ty (%), it is preferable that | Tx−Ty | is more than 3.00 and less than 10.00. By adopting such an embodiment, the film becomes non-uniform to the extent that the film is not excessively deformed at the time of heating, and the effect of maintaining the flatness of the film due to a dimensional change is likely to appear. Further, as a result, the film has a direction with high flexibility in the plane, and the expandability is improved particularly when the film has a large thickness.

  More specifically, when | Tx-Ty | is 10.00 or less, the deformation of the film during heating does not become excessively uneven depending on the direction, and the appearance of wrinkles and looseness can be reduced. When | Tx−Ty | is 3.00 or more, a decrease in tension near the center of the fixed sample is reduced, and deformation of the film due to the weight of the semiconductor wafer itself is suppressed. From the above viewpoint, | Tx−Ty | is more preferably 3.50 or more and 8.00 or less.

  The method of setting | Tx-Ty | to be more than 3.00 and less than 10.00 or the above preferable range is not particularly limited. For example, the roll linear pressure is set to 30 kg / cm or more and 500 kg / cm or less, and the tension is set to 0. A method of rolling a cast film having the above-mentioned layer constitution at a pressure of 1 MPa or more and 1.5 MPa or less, etc. may be mentioned. By adjusting the rolling conditions in this manner, the decrease in the amount of shrinkage in the film transport direction (longitudinal direction) is reduced, the deterioration in the balance of the dimensional change rate is suppressed, and the value of | Tx−Ty | can be controlled. In general, by increasing the roll linear pressure and increasing the transport tension, the orientation in the film transport direction becomes stronger, and | Tx−Ty | increases. However, by further increasing the linear pressure, the efficiency of heat transfer to the film is increased and the degree of in-plane orientation is less likely to increase, so that | Tx−Ty | may exhibit a behavior of decreasing.

Tx and Ty can be measured by the following procedure. First, the measurement direction is arbitrarily selected, and a film sample cut into a size of 15 mm (measurement direction) × 4 mm (direction orthogonal to the measurement direction) in a room temperature environment is placed in an atmosphere at a temperature of 25 ° C. and a relative humidity of 65%. For 24 hours, and the length (L2) in the measurement direction is measured. Next, the film sample is heated from 25 ° C. to 160 ° C. at a load of 5 g / mm ² at a rate of 10 ° C./min, and the length (L3) in the measurement direction at 90 ° C. is measured. From the obtained values of L2 and L3, the dimensional change rate of the film sample at 90 ° C. is determined by the following equation 4. The above procedure is repeated five times in total, and the average value of the obtained measured values is defined as a dimensional change rate (%) at 90 ° C. in the direction. Next, the measurement direction is rotated 5 ° clockwise, and the same measurement is performed. Similarly, the value of the dimensional change (%) at 90 ° C. in each direction until the rotation angle reaches 175 ° is obtained. The maximum value is extracted from the thus obtained values of the dimensional change (%) at 90 ° C. in the 36 directions, and this is extracted as Tx (%), the measurement direction at this time is the X direction, the direction orthogonal to the X direction is the Y direction, The value of the 90 ° C. dimensional change rate (%) in the Y direction is defined as Ty (%).
Formula 4: 90 ° C. dimensional change (%) = (L3−L2) × 100 / L2.

  Further, the value of the dimensional change rate at 90 ° C. in directions other than the X direction and the Y direction is not particularly limited as long as the effects of the present invention are not impaired. However, from the viewpoint of reducing the dimensional change when heated by applying a load, the dimensional change rate at 90 ° C. in all directions is preferably −25.00% or more and 10.00% or less. By adopting such an aspect, when the semiconductor wafer is laminated and heated in a state where an elongation load is applied to the film, excessive deformation of the film is suppressed, so that the dimensional stability required in the semiconductor manufacturing process can be easily achieved. realizable.

  The method of setting the dimensional change rate at 90 ° C. in all directions to −25.00% or more and 10.00% or less or the above preferable range is not particularly limited as long as the effects of the present invention are not impaired. For example, | Tx−Ty | More than 3.00 and less than 10.00 or the same method as described above.

  Next, the method for producing the film of the present invention will be described. One embodiment of the method for producing a film of the present invention includes a step of stretching a non-oriented sheet in at least one direction at a magnification of 1.01 to 2.00. Here, the non-oriented sheet refers to a sheet cooled and solidified on a cast drum, that is, a sheet that has not been stretched in a specific direction. By adopting such an embodiment, dimensional stability during heating is improved. The stretching direction can be appropriately determined as long as the effects of the present invention are not impaired. For example, it is preferable to set one direction or two directions orthogonal to each other in the film plane.

  The stretching ratio in the case of stretching in one direction is preferably from 1.10 times to 1.80 times, more preferably from 1.20 times to 1.70 times. When the film is stretched in two directions orthogonal to each other in the plane of the film, the stretch ratio in at least one direction may be within the above range, but the stretch ratio in each direction is more preferably within the above range. That is, it is more preferable to have a step of stretching the non-oriented sheet in two directions orthogonal to each other at a magnification of 1.01 or more and 2.00 or less, and the magnification at this time is preferably 1.10 or more. It is 1.80 times or less, more preferably 1.20 times or more and 1.70 times or less. In addition, `` stretching the non-oriented sheet in two directions orthogonal to each other in the plane '' means not only stretching the non-oriented sheet in two directions at the same time, but also stretching the non-oriented sheet in one direction and then in another direction. It also includes stretching.

  Further, as another embodiment of the method for producing a film of the present invention, there is also an embodiment having a rolling step of rolling a non-oriented sheet at a roll linear pressure of 30 kg / cm or more and 500 kg / cm or less. By adopting such an embodiment, the dimensional stability during heating is improved. Note that this rolling step can be combined with the above-described mode of performing stretching. At this time, if the rolling step is upstream of the stretching, the object of rolling is a non-oriented sheet, and the object of stretching is a film after rolling. On the other hand, when the rolling step is downstream of the stretching, the object of stretching is a non-oriented sheet, and the object of rolling is a film after stretching.

  The temperature control in the rolling step can be performed at an arbitrary temperature equal to or higher than room temperature. When the film is mainly composed of a polypropylene-based resin, the temperature is preferably from 40 ° C to 150 ° C. The roll tension is not particularly limited as long as the effects of the present invention are not impaired, but is preferably 0.1 MPa or more and 1.5 MPa or less from the viewpoint of suppressing wrinkles and loosening during heating and deformation of the film. More preferably, it is 2 MPa or more and 1.4 MPa or less. Further, in the case of rolling, from the viewpoint of applying a linear pressure evenly, it is preferable that the roll material has a difference in hardness between upper and lower sides. As a specific example of a preferred embodiment, there is an embodiment in which the upper roll is a hard chrome steel plating roll having a surface roughness of 0.1 S, and the lower roll is an ultra-hard rubber roll having a lower hardness than the upper roll. The means for adjusting the linear pressure is not particularly limited as long as the effect of the present invention is not impaired, but can be adjusted by, for example, a hydraulic method. Further, the clearance between the upper and lower rolls affects the thickness of the product film, and can be appropriately set according to the thickness of the film to be obtained.

  Hereinafter, the method for producing a film of the present invention will be described with reference to a laminated film made of bidirectionally stretched polypropylene as an example, but the present invention is not construed as being limited to such an example.

  The polypropylene resin A and the thermoplastic elastomer B used for the A layer and the B layer are supplied to separate twin-screw extruders in desired blends, respectively, and melt extrusion is performed at 200 to 260 ° C. Then, after removing foreign matter and denatured polymer by a filter provided in the middle of the polymer tube, the non-oriented sheet is obtained by cooling and solidifying on a cast drum. The temperature of the cast drum is preferably from 0 ° C to 50 ° C. As a method of contacting the cast drum, any method such as an electrostatic application method, a contact method using surface tension of water, an air knife method, a press roll method, and an underwater casting method may be used. From the viewpoint, the air knife method is preferable. The air temperature of the air knife is 25 to 100 ° C., preferably 30 to 80 ° C., and the blowing air speed is preferably 130 to 150 m / s. The air knife has a double pipe structure to improve the uniformity in the width direction. Is preferred. It is also preferable to appropriately adjust the position of the air knife so that air flows downstream of the film formation so as not to cause vibration of the film.

  Thereafter, the non-oriented sheet is stretched in at least one direction at a magnification of 1.01 or more and 2.00 or less for the purpose of improving dimensional stability during heating. The stretching ratio in the case of stretching in one direction is preferably from 1.10 times to 1.80 times, more preferably from 1.20 times to 1.70 times. In addition, it is also preferable that the film is stretched in two directions orthogonal to each other in the plane. In this case, it is preferable that the stretch ratio in at least one direction is within the above range, and the stretch ratio in each direction is more preferably within the above range. It is. Further, the stretching speed is preferably from 10% / min to 200,000% / min.

  Stretching can be performed at any temperature of room temperature or higher, but is preferably performed at 20 ° C to 170 ° C, more preferably at 100 ° C to 170 ° C. It is also preferable to preheat for 1 second or more before stretching. Further, the stretching method, after stretching the non-oriented sheet in the longitudinal direction, stretching in the width direction, or, after stretching in the width direction, successively biaxial stretching method of stretching in the longitudinal direction, almost in the longitudinal direction and width direction Any of a simultaneous biaxial stretching method in which stretching is performed simultaneously and a uniaxial stretching method in which stretching is performed only in the longitudinal direction or the width direction may be employed. Here, the longitudinal direction refers to the running direction of the film, and the width direction refers to a direction parallel to the film surface and orthogonal to the longitudinal direction. The stretching may be performed in one step or in multiple steps as long as the effects of the present invention are not impaired.

  Further, the film may be subjected to a heat treatment after the stretching. The heat treatment can be performed by any conventionally known method such as in an oven or on a heated roll. This heat treatment is preferably performed at a temperature equal to or higher than the stretching temperature and equal to or lower than the stretching temperature + 50 ° C. The heat treatment temperature here means the highest temperature among the heat treatment temperatures performed after stretching. Further, the heat treatment time can be arbitrarily set within a range that does not deteriorate the characteristics.

  The heat-treated film is cooled and wound up as an intermediate product roll. This cooling step is preferably performed at a temperature of 60 ° C. or higher and a stretching temperature of −10 ° C. or lower for 1 second or longer, and then conveyed in a room temperature environment for the purpose of suppressing a dimensional change during heating. The cooling may be performed in multiple stages as long as the effects of the present invention are not impaired. Further, the film can be unwound from the intermediate product roll and cut in parallel with the longitudinal direction so as to have a desired width to obtain a wound final product roll. Note that the number of final product rolls obtained from one intermediate product roll may be one or more.

  The thus obtained film of the present invention has both heat resistance and flexibility, and can be suitably used as a substrate for a semiconductor manufacturing process.

  Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited thereto.

[Measurement and evaluation methods]
The measurements and evaluations shown in the examples were performed under the following conditions.

(1) Skewness (Ssk)
According to JIS B0601 (2001), the measurement was performed using "VertScan" (registered trademark) 2.0 R5300GL-Lite-AC manufactured by Ryoka Systems Inc. The measurement was performed on both sides of the film. The details of the apparatus and members such as lenses used for the measurement and the measurement conditions are as follows.
Photographing device: CCD camera SONY HR-57 1/2 inch objective lens: 5x
Intermediate lens: 0.5x
Wavelength filter: 530 nm white
Measurement mode: Focus
Measurement software: VS-Measure Version 5.5.1
Analysis software: VS-Viewer Version 5.5.1
Measurement area: 1.252 × 0.939 mm ² .

(2) Maximum value of 5% elongation stress at 25 ° C. Ta _max
According to JIS K 7127 (1999, test piece type 2), it was measured at 25 ° C. and 65% RH using a film strength / elongation measuring device (AMF / RTA-100) manufactured by Orientec Co., Ltd. First, a sample cut into a size of 150 mm in length and 10 mm in width in an arbitrary direction was stretched at an original length of 50 mm and a pulling speed of 300 mm / min to determine a stress Ta (unit: MPa) at 5% extension. . The same measurement was performed five times for each sample, and the average value was calculated. Further, the measurement is performed in the same manner while changing the direction clockwise by 5 °, and the maximum value of the measured values in each direction from 0 ° to 175 ° is determined as the maximum value of the 5% elongation stress at 25 ° C. Ta _max (MPa). And

(3) Surface roughness (SRa)
It was measured in accordance with JIS B 0601 (1994) using a high-definition fine shape measuring instrument (three-dimensional surface roughness meter) of a stylus method. The measurement apparatus and measurement conditions were as follows, and the following analysis system was used for calculating SRa. The measurement was performed on both sides of the film.
Measuring device: 3D micro shape measuring instrument (Model ET-4000A) Analysis system manufactured by Kosaka Laboratory Co., Ltd .: 3D surface roughness analysis system (Model TDA-31)
Stylus: Tip radius 0.5 μmR, diameter 2 μm, diamond needle pressure: 100 μN
Measurement direction: Average X measurement length after measuring once each in film longitudinal direction and film width direction: 1.0 mm
X feed speed: 0.1 mm / s (measuring speed)
Y feed pitch: 5 μm (measurement interval)
Number of Y lines: 81 (number of measurement lines)
Z magnification: 20 times (vertical magnification)
Low frequency cutoff: 0.20mm (undulation cutoff value)
High frequency cutoff: R + W (roughness cutoff value) mm R + W means that cutoff is not performed.
Filter method: Gaussian spatial leveling: Yes (tilt correction)
Reference area: 1 mm ² .

(4) Polar force component of surface energy The polar force component of the surface energy of the film was determined as follows. First, the following equation 7 was derived from the extended Fowkes equation (the following equation 5) and Young's equation (the following equation 6).
[Extended Fowkes expression]
Formula 5: γSL = γS + γL-2 (γsd · γLd) 1 / 2-2 (γsD · γLD) 1 / 2-2 (γsh · γLh) 1/2
[Young's formula]
Equation 6: γS = γSL + γL cos θ
The definitions of γS, γL, γSL, θ, γsd, γLd, γsD, γLD, γsh, and γhL in Expressions 5 and 6 are as follows.
γS: surface energy of the solid γL: surface tension of the liquid γSL: tension at the interface between the solid and liquid θ: contact angle γsd with the liquid, γLd: dispersive force component of γS, γL γsD, γLD: polar force component of γS, γL γsh, γhL: hydrogen bond component of γS, γL Formula 7: (γsd · γLd) 1/2 + (γsD · γLD) 1/2 + (γsh · γLh) 1/2 = γL (1 + cosθ) / 2
Next, the contact angles with the film of four kinds of liquids whose respective components of the surface tension are known are measured, substituted into Equation 6, and the three-dimensional linear simultaneous equations for each liquid are solved to obtain the surface energy of the film. The polar force component of was determined. For solving the simultaneous equations, numerical calculation software “Mathematica 7.0” was used. The contact angle was measured using a measurement solution of water, ethylene glycol, formamide, and methylene iodide, and a contact angle meter CA-D manufactured by Kyowa Interface Chemical Co., Ltd. was used as a measuring instrument. The measurement was performed on both sides of the film.

(5) 10% endothermic temperature at the maximum melting peak Using a differential calorimetry (DSC), the measurement sample is heated at a rate of 20 ° C./min from 25 ° C. to 280 ° C. in a nitrogen atmosphere according to JIS K 7121 (2012). The highest endothermic peak of the DSC curve obtained by the analysis was analyzed. As a specific procedure, first, a base line was drawn from a flat region having a higher temperature than the peak, and a point at which the DSC curve intersected on the lower temperature side was used as a reference point. Thereafter, the difference (Y _max ) from the Y-axis height at the highest temperature peak was calculated from the Y-axis height of this reference point. Further, Y-axis height to explore the temperature on the DSC curve to be 1/10 of _{Y max,} and the temperature was 10% endothermic temperature. The following measurement apparatus and data analysis system were used, and the mass of the measurement sample was 5 mg.
Equipment: EXSTAR DSC6220 manufactured by Hitachi High-Tech Science
Data analysis system: Disk session SSC / 5200
(6) Dm, Dmx
First, a film sample cut into a size of 15 mm (measurement direction) × 4 mm (a direction perpendicular to the measurement direction) in a room temperature environment was allowed to stand for 24 hours in an atmosphere at a temperature of 25 ° C. and a relative humidity of 65%. The length (L0) in the measurement direction was measured. Next, using TMA / SS6000 (manufactured by Seiko Instruments Inc.), the film sample was heated from 25 ° C. to 160 ° C. under a load of 5 g / mm ² and a heating rate of 10 ° C./min. The length in the measurement direction was measured in the range of ° C. From the obtained measurement data, the timing at which the difference between the length in the measurement direction and L0 was the largest was specified, and the length in the measurement direction at this time was defined as L1. Then, the dimensional change rate (%) was obtained from the following equation 3 using L0 and L1.
Formula 3: Dimensional change rate (%) = (L1−L0) × 100 / L0
The initial measurement direction was arbitrarily selected, and the average value of the dimensional change (%) obtained by performing five measurements in the measurement direction was defined as Dm (%) in the direction. Further, the measurement direction was rotated clockwise by 5 °, and similarly, the value of Dm (%) in each direction until the rotation angle reached 175 ° was determined. The maximum value of the obtained values was defined as Dmx (%), and the direction in which Dmx (%) was obtained was defined as the X direction.

(7) Unevenness in Thickness Ten films of 10 cm × 10 cm were cut out from the center of the roll in the width direction and both end positions to obtain samples for evaluation. For each sample, the thickness was measured at 5 points in the longitudinal direction, 5 points in the width direction, and a total of 10 points, and the thickness unevenness was obtained from the average value, the maximum value, and the minimum value according to the following equation 8.
Formula 8: Thickness unevenness (%) = (maximum thickness−minimum thickness) / average thickness Thickness unevenness of each of the obtained three samples in the width direction at three points (both ends and the center) is calculated as follows. The average value was calculated and adopted as thickness unevenness. When the film was a sheet sample, 30 sheets of 10 cm × 10 cm were cut out at an arbitrary position on the sheet, and the average value of the thickness unevenness of each sample was calculated and adopted as the thickness unevenness.

(8) Flexibility / Uniform stretchability Nine straight lines are drawn on a randomly cut 300 mm × 300 mm square film at intervals of 30 mm parallel to one set of sides, and further 30 mm parallel to another set of sides. Then, nine straight lines were drawn to obtain a measurement sample. Using a simultaneous biaxial stretching device (KARO IV Lab Stretcher (manufactured by BRUCKNER)), the obtained measurement sample is stretched in the direction parallel to one set of sides and the direction parallel to the other set of sides under the following conditions. And evaluated according to the following criteria based on the interval between the straight lines. The interval between the straight lines is determined by measuring the average value of the two outermost intervals among the eight intervals formed by the nine straight lines in two directions, and determining the value farthest from 39 mm as the measured value (straight line). Interval). Using this linear interval, the flexibility / uniform stretchability was evaluated based on the following criteria.
<Stretching conditions>
Stretching temperature: 25 ° C
Stretching speed: 10 mm / min Stretching ratio: 1.30 times <Evaluation criteria>
S: The linear interval in the stretched film was 39 ± 1 mm.
A: Not applicable to S, and the distance between straight lines in the stretched film was 39 ± 3 mm.
B: It did not correspond to S and A, and the linear interval in the film after stretching was 39 ± 6 mm.
C: Not applicable to any of S, A, and B.

(9) Non-adhesive (heat resistance)
A 200 mm × 200 mm square film cut out arbitrarily was used as double-sided tape No. No. manufactured by Nitto Denko Corporation. It was attached to a stainless steel metal frame (outside: 200 mm × 200 mm, inside: 180 mm × 180 mm) at 500 AB to obtain a measurement sample. Next, a tin-free steel plate (200 μm thick) was placed on a hot plate heated to 130 ° C., and the measurement sample was allowed to stand so that the film attached to the metal frame was in contact with the SUS plate, and a load of 2 kg was applied. (Contact area: 100 mm x 100 mm) It was left for 240 minutes. Thereafter, the sample and the SUS plate were taken out and cut into a size of 100 mm in length and 25 mm in width in a state where the film and the SUS plate were in close contact with each other to obtain a sample for a peel test. Using a tensile tester (“Tensilon” (registered trademark) UCT-100 manufactured by Orientec), an initial peeling chuck distance of 40 mm and a tensile speed of 20 mm / min were used to perform a 180 ° peel test on the obtained sample. And the peeling force of the SUS plate were evaluated. Peeling force evaluation was performed at N = 3, and non-adhesion was evaluated based on the average value according to the following criteria. In addition, the non-adhesion property was evaluated as B or more.
S: The peeling force was 0.03 N / 50 mm or less (including the case where no close contact was made).
A: It did not correspond to S, and the peeling force was 0.07 N / 50 mm or less.
B: It did not correspond to S and A, and the peeling force was 0.10 N / 50 mm or less.
C: Not applicable to any of S, A, and B.

(10) Dimensional stability (heat resistance)
A 200 mm × 200 mm square film cut out arbitrarily was used as double-sided tape No. No. manufactured by Nitto Denko Corporation. It was attached to a stainless steel frame (outside: 200 mm x 200 mm, inside: 180 mm x 180 mm, thickness 1 mm) at 500 AB to obtain a measurement sample. Next, the sample was placed on a hot plate heated to 130 ° C. and allowed to stand for 1 minute. During that time, the time during which the film was expanded and deformed by visual observation was measured, and the dimensional stability was evaluated according to the following criteria. Confirmation of the expansion deformation of the film by visual observation was made by observing the sample from a horizontal position and judging whether or not the film expanded and expanded rather than the thickness of the metal frame. As for the dimensional stability, B or more was regarded as acceptable.
S: The time of expansion was within 2 seconds.
A: It did not correspond to S, and the time of expansion was within 4 seconds.
B: It did not correspond to S and A, and the time of expansion was within 8 seconds.
C: Not applicable to any of S, A, and B.

(11) Appearance The film cut into A4 size was placed on a black flat plate, the appearance was visually checked, and evaluated according to the following criteria. In addition, the appearance was B or more.
S: The surface state was uniform without streaks or spots.
A: It did not correspond to S, the number of streaks was 2 or less, and the spots where spots occurred were within 2 points.
B: It did not correspond to S and A, the number of streaks was 4 or less, and the number of spots was 4 or less.
C: Not applicable to any of S, A, and B.

(12) Dispersion Diameter of Elastomer The film is cut along a plane parallel to the longitudinal direction and perpendicular to the film surface, and the cross section is photographed with a Leica DMLM manufactured by Leica Microsystems Co., Ltd. at a magnification of 100 times. did. Next, the major axes of all the elastomers in the photographed image were measured, and the average value was calculated. The measurement was performed five times, and the average value was adopted as the dispersion diameter of the elastomer.

(13) In-plane variation of stress in the elongation range of 50 to 500% (in-plane variation of stress)
First, a rectangular sample of 150 mm (measurement direction) × 10 mm (a direction perpendicular to the measurement direction) was prepared, and “JIS” was measured by a film strength / elongation measuring device (AMF / RTA-100) manufactured by Orientec Co., Ltd. According to K 7127 (1999, test piece type 2), the stress at the time of extension of the measurement sample was measured at a temperature of 25 ° C., a relative humidity of 65%, and a test speed of 300 mm / min. The same measurement was performed by rotating clockwise by 5 ° clockwise, and the same measurement was repeated until the measurement direction turned 175 ° clockwise from the first measurement direction. From the elongation range of 50 to 500%, the difference between the maximum value and the minimum value of the above 36 measurements at each elongation point is calculated, and the maximum value of the obtained values is determined by the in-plane variation of stress (MPa). ) It was.

(14) Fluctuation of stress increase rate in the elongation range of 50 to 500% (fluctuation of stress increase rate)
First, a rectangular sample of 150 mm (measurement direction) × 10 mm (a direction perpendicular to the measurement direction) was prepared, and “JIS” was measured by a film strength / elongation measuring device (AMF / RTA-100) manufactured by Orientec Co., Ltd. The stress at 5% elongation of the measurement sample was measured at a temperature of 25 ° C., a relative humidity of 65%, and a test speed of 300 mm / min according to K 7127 (1999, test piece type 2). , A stress change rate (a value obtained by dividing a stress change value by an elongation amount) in an elongation range from −10% was calculated, and the above value was extracted in an elongation range of 50 to 500%. The maximum value and the minimum value are specified based on the measured values, the difference between them is determined, and the obtained value is defined as the fluctuation of the stress increase rate in the measurement direction, and the measurement direction is rotated clockwise by 5 ° in parallel with the film surface. Let the same measurement The same measurement is repeated until the measurement direction becomes a direction rotated 175 ° right from the first measurement direction, and the maximum value is specified from the 36 measured values obtained, and the maximum value is defined as the stress increase rate of the film. (%).

(15) Thickness change rate after heat treatment at 90 ° C. for 10 minutes First, two straight lines (hereinafter referred to as a center line) connecting midpoints of opposing sides of a 100 mm × 100 mm square film cut out arbitrarily. Except for each end, 9 points were taken at intervals of 10 mm (a total of 17 points due to overlapping centers), and these were taken as measurement points. Next, the thickness at each measurement point was measured with an electronic micrometer, and the average value was taken as the thickness before heat treatment. Thereafter, heat treatment was performed for 10 minutes in an oven heated to 90 ° C., the film was taken out of the oven, the film thickness at each measurement point was measured in the same manner, and the average value was taken as the thickness after the heat treatment. The value obtained by dividing the thus obtained thickness after the heat treatment by the thickness before the heat treatment was defined as the thickness change rate (%) of the film after the heat treatment at 90 ° C. for 10 minutes. In addition, as an electronic micrometer used for thickness measurement, an electronic micrometer (K-312A type) manufactured by Anritsu Corporation was used.

(16) Tx, Ty
First, the measurement direction is arbitrarily selected, and a film sample cut into a size of 15 mm (measurement direction) × 4 mm (direction orthogonal to the measurement direction) in a room temperature environment is placed in an atmosphere at a temperature of 25 ° C. and a relative humidity of 65%. For 24 hours, and the length (L2) in the measurement direction was measured. Next, this film sample was heated from 25 ° C. to 160 ° C. at a load of 5 g / mm ² at a rate of 10 ° C./min, and the length (L3) in the measurement direction at 90 ° C. was measured. From the obtained values of L2 and L3, the dimensional change of the film sample at 90 ° C. was determined by the following equation 4. The above procedure was repeated five times in total, and the average value of the measured values obtained was defined as a dimensional change (%) at 90 ° C. in the direction. Next, the measurement direction was rotated clockwise by 5 °, and the same measurement was performed. Similarly, the value of the dimensional change (%) at 90 ° C. in each direction until the rotation angle reached 175 ° was obtained. The maximum value is extracted from the thus obtained values of the dimensional change (%) at 90 ° C. in the 36 directions, and this is extracted as Tx (%), the measurement direction at this time is the X direction, the direction orthogonal to the X direction is the Y direction, The value of the dimensional change (%) at 90 ° C. in the Y direction was defined as Ty (%).
Formula 4: 90 ° C. dimensional change (%) = (L3−L2) × 100 / L2.

(resin)
The resins used in the production of the film are as follows. The average particle diameter of each particle was determined by calculating a weight average diameter using a circle equivalent diameter obtained by image processing from a transmission electron micrograph of the particle.
<Resins other than thermoplastic elastomers>
(Polyolefin A)
Crystalline polypropylene "Prime Polypro" (registered trademark) J106 manufactured by Prime Polymer.
(Polyolefin B)
A masterbatch raw material in which 10 parts by mass of zeolite particles (JC-70, manufactured by Mizusawa Chemical Co., average particle size: 6 μm) are mixed with polyolefin A.
(Polyolefin C)
A masterbatch raw material in which polyolefin A is mixed with 10 parts by mass of crosslinked acrylic particles (MZ-10HN, manufactured by Soken Chemical Co., Ltd., average particle size: 10 μm).
<Thermoplastic elastomer>
(Elastomer A-1)
Ethylene-octene-1 copolymer "Engage" (registered trademark) 8411 manufactured by Dow Chemical Company.
(Elastomer A-2)
Hydrogenated styrene-butadiene copolymer (HSBR) "DYNARON" (registered trademark) 1320P manufactured by JSR.
(Elastomer A-3)
Ethylene / α-olefin random copolymer “Tuffmer” (registered trademark) H-1030S manufactured by Mitsui Chemicals, Inc.
(Elastomer A-4)
Styrene-based thermoplastic elastomer (SEBS) "ToughTech" (registered trademark) H-1141 manufactured by Asahi Kasei Corporation.

(Example 1)
Raw materials for obtaining the layers A and B adjusted to the compositions shown in Table 1 were supplied to separate twin-screw extruders each having an oxygen concentration of 0.2% by volume. The cylinder temperature of the extruder that supplied the raw material for obtaining the layer A and the cylinder temperature of the extruder that supplied the raw material for obtaining the layer B were both set to 260 ° C. After passing through the short pipe and the die, the mixture was sent to a T-die and discharged from the T-die into a sheet on a cast drum whose temperature was controlled at 30 ° C to obtain a non-oriented sheet having a thickness of 240 µm. Next, the non-oriented sheet is stretched in the longitudinal direction and the width direction by a sequential biaxial stretching apparatus at a stretching temperature of 120 ° C. and a magnification of 1.25 times, and the total thickness is 160 μm, A layer / B layer / A A laminated film having two layers and three layers was obtained. Table 1 shows the evaluation results of each characteristic.

(Examples 2 to 16, 20 to 25, Comparative Examples 1 to 4)
A film was obtained in the same manner as in Example 1 except that the film configuration, the extrusion temperature, and the stretching conditions were as shown in Tables 1 to 5. Tables 1 to 5 show the evaluation results of the properties of the obtained film.

(Examples 17 to 19)
Raw materials for obtaining the layers A and B adjusted to the compositions shown in Table 3 were supplied to separate twin-screw extruders each having an oxygen concentration of 0.2% by volume. The cylinder temperature of the extruder that supplied the raw material for obtaining the layer A and the cylinder temperature of the extruder that supplied the raw material for obtaining the layer B were both set to 260 ° C. The same procedure as in Example 1 was carried out except that the shape of the roll surface was transferred to a T-die through a short pipe and a die, and then discharged from the T-die onto a cast drum whose temperature was controlled at 30 ° C., and the shape of the roll surface was transferred by an emboss roll. To obtain a film. Table 3 shows the evaluation results of each characteristic.

(Example 26)
Corona discharge treatment was performed on both surfaces of the film obtained in Example 5 at a discharge density of 9.0 × 10 ⁴ W / m ² . Table 5 shows the evaluation results of each characteristic.

(Example 27)
The film configuration was as shown in Table 6, and a non-oriented sheet having a thickness of 250 µm was obtained in the same manner as in Example 5. The obtained non-oriented sheet was prepared by using an upper roll as a hard chrome steel plating roll having a surface roughness of 0.1 S and a lower roll as a heat-resistant rubber roll (hardness: D75) at a linear pressure of 150 kg / cm, a roll temperature of 90 ° C, and a take-up roll. Rolling was performed under the condition of a tension of 0.8 MPa to obtain a laminated film having a total thickness of 160 μm. Table 6 shows the evaluation results of each characteristic.

(Examples 28 to 30)
The film configuration and rolling conditions were as shown in Table 6, and a laminated film having a total thickness of 160 µm was obtained in the same manner as in Example 26. Table 6 shows the evaluation results of each characteristic.

  The resin composition in the film configuration was calculated assuming that the entire resin component constituting each layer was 100% by mass. The skewness Ssk, the polar component of the surface energy, and the surface roughness SRa are measured for both surfaces. When one surface arbitrarily selected is the surface 1 and the opposite surface is the surface 2, the surface 1 The measured value is shown on the left, and the measured value of surface 2 is shown on the right. The same applies to Tables 2 to 6 above.

  According to the present invention, it is possible to provide a film having both flexibility, uniform stretchability at the time of expansion and heat resistance, and a method for producing the film. The film of the present invention can be suitably used as a substrate for a semiconductor production process. In addition, the film of the present invention may be used as an electrically insulating material such as a copper-clad laminate, a back sheet for a solar cell, an adhesive tape, a flexible printed circuit board, a membrane switch, a sheet heating element, or a flat cable, a material for a capacitor, and a case material. Applications where vibration control and heat resistance are important, such as automotive materials and building materials, and applications where flexibility and puncture resistance are important, such as pouches for pharmaceuticals and food packaging, etc. Can also be suitably used.

1: Reference length (Lr)
2: Roughness curve 3: Base line 4: Height from base line (z)

Claims (17)

When a plane having a skewness (Ssk) of −1.0 or more and 10.0 or less is defined as an α plane, a maximum value Ta _max of a 5% elongation stress at 25 ° C. is 1.0 MPa or more and 20.0 MPa or less, A film having at least one α-plane.   2. The film according to claim 1, wherein a polar force component of surface energy on the α-plane is 0.0 mN / m or more and 0.9 mN / m or less.   3. The film according to claim 1, wherein the skewness Ssk of the α plane is more than 3.0 and not more than 7.0. 4.   The film according to any one of claims 1 to 3, wherein a surface roughness (SRa) of the α-plane is 200 nm or more and 1,500 nm or less.   The film according to any one of claims 1 to 4, wherein a 10% endothermic temperature at a maximum melting peak measured by DSC is from 145 ° C to 180 ° C.   When the maximum dimensional change rate at 100 ° C. or lower when the temperature is raised from 25 ° C. to 160 ° C. at a rate of 10 ° C./min is Dm, the direction in which Dm is the maximum is the X direction, and the Dm in the X direction is Dmx. , Dmx is -5.0% or more and 2.0% or less, The film according to any one of claims 1 to 5, characterized in that:   The film according to claim 6, wherein Dm in all directions is -10.0% or more and 2.0% or less. When the two layers having different thermoplastic elastomer contents are the A layer and the B layer, and the resin component in the A layer is 100% by mass, the thermoplastic elastomer content in the A layer is M _A (% by mass), B when taken as 100% by mass of the resin component in the layer, the content of the thermoplastic elastomer in the layer B is taken as M _{B (wt%),}
An A layer and B layer, A layer is positioned as the outermost layer of at least one, and characterized in that it is a M _{A <M B,} the film according to any one of claims 1 to 7.   The film according to claim 8, wherein the A layer, the B layer, and the A layer are located in this order.   The film according to any one of claims 1 to 9, wherein the thickness unevenness is 10.0% or less.   The film according to any one of claims 1 to 10, wherein, in an atmosphere at 25 ° C, in-plane variation of stress in an elongation range of 50 to 500% is 0.0 MPa or more and 5.0 MPa or less. .   12. The method according to claim 1, wherein a change in the rate of stress increase in an elongation range of 50 to 500% in an atmosphere at 25 [deg.] C. is 0.0% or more and 2.0% or less. Film.   The film according to any one of claims 1 to 12, wherein a thickness change rate after heat treatment at 90 ° C for 10 minutes is 0.5% or more and 10.0% or less. When a load of 5 g / mm ² was applied and the temperature was raised from 25 ° C. to 160 ° C. at a rate of 10 ° C./min, the dimensional change at 90 ° C. was 90 ° C. X direction, the direction orthogonal to the X direction in the film plane is the Y direction, the 90 ° C. dimensional change rate in the X direction is Tx (%), and the 90 ° C. dimensional change rate in the Y direction is Ty (%). The film according to any one of claims 1 to 13, wherein | Tx-Ty | is more than 3.00 and less than 10.00.   The method for producing a film according to any one of claims 1 to 14, comprising a step of stretching the non-oriented sheet in at least one direction at a magnification of 1.01 or more and 2.00 or less. , Film manufacturing method.   The method for producing a film according to claim 15, further comprising a step of stretching the non-oriented sheet in two directions perpendicular to each other at a magnification of 1.01 or more and 2.00 or less. The method for producing a film according to any one of claims 1 to 14, further comprising a rolling step of rolling the non-oriented sheet at a roll linear pressure of 30 kg / cm or more and 500 kg / cm or less. Manufacturing method.

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