Process release film, method for manufacturing the same, and applications.

Abstract

By possessing high degassing properties, resin-encapsulated semiconductors and the like can be produced with productivity exceeding the limits of conventional technology. At the same time, it maintains the excellent release properties, appearance of molded products, and mold conformability that have been required of process release films, and provides a process release film that balances these at a high level that surpasses the limits of conventional technology. [Solution] A release film for processes, wherein at least one of its two surfaces has irregularities formed on it, and the Sdr (unfolded surface area ratio) of the surface on which the irregularities are formed, measured with a laser microscope, is 4.0 to 50.0%.

Description

Technical Field

[0001] The present invention relates to a release film for a process, preferably a release film for a process used in a semiconductor encapsulation process or the like. In particular, the present invention relates to a release film for a process, a method for manufacturing the same, and a method for manufacturing a resin-encapsulated semiconductor using the same, which have a short time required for air bleeding during vacuum adsorption in a semiconductor encapsulation process or the like and can produce a resin-encapsulated semiconductor or the like with high production efficiency.

Background Art

[0002] In recent years, with the miniaturization and weight reduction of semiconductor packages and the like, reducing the amount of encapsulation resin used has been under consideration. And in order to be able to firmly adhere the interface between a semiconductor chip or the like and the resin even when the amount of encapsulation resin used is reduced, it has been desired to reduce the amount of release agent contained in the encapsulation resin. For this reason, as a method for obtaining the releasability between the encapsulation resin after curing and the mold, a method of disposing a release film between the inner surface of the mold and a semiconductor chip or the like has been adopted.

[0003] At the time of encapsulation, the release film is usually stretched along the inner surface of the mold by vacuum suction and brought into a state of being in close contact with the inner surface. At this time, if the air is not completely exhausted during the stretching process and the release film adheres to the inner surface, an air pocket may be partially formed between the release film and the inner surface of the mold, and wrinkles may occur in the release film at that portion. If there are wrinkles in the release film, the shape of the wrinkles on the surface of the release film is transferred to the surface of the resin-encapsulated portion, resulting in poor appearance and problems such as a decrease in yield. Therefore, good degassing and suppression of wrinkles thereby have been required. Also, if pinholes or the like occur in the release film at this time, the mold will be contaminated, so it has also been necessary to effectively suppress pinholes or the like. In order to solve such problems, it has been proposed to provide irregularities on the surface of the release film that satisfy specific conditions. More specifically, for example, a release film having a specific surface roughness (Rz) (see, for example, Patent Document 1), a release film having a specific arithmetic mean roughness (Ra) and a specific peak count (RPc) (see, for example, Patent Document 2), etc. have been proposed. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2002-359259 [Patent Document 2] International Publication No. 2015 / 068808 A1 Pamphlet [Overview of the project] [Problems that the invention aims to solve]

[0005] However, with the development of this technological field, the requirements for process release films, such as release films for semiconductor encapsulation processes, are increasing year by year. In particular, from the perspective of higher productivity, there is a growing demand for high degassing performance that can complete the removal of air between the release film and the inner surface of the mold in a shorter amount of time. This invention has been made in view of these circumstances, and aims to provide a process release film that has high degassing properties, enabling the production of resin-encapsulated semiconductors and the like with productivity exceeding the limits of conventional technology, while maintaining the excellent release properties, appearance of molded products, and mold conformability that have been required of process release films, and balancing these at a high level that exceeds the limits of conventional technology. [Means for solving the problem]

[0006] As a result of diligent research to solve the above problems, the inventors of the present invention have found that setting the Sdr (Surface Area Ratio) of the surface of the process release film to an appropriate value is important for achieving high degassing performance without impairing other properties of the process release film, and have completed the present invention. In other words, the present invention and its embodiments are as described below in [1] to [9].

[0007] [1] A release film for processes, wherein at least one of its two surfaces has irregularities formed on it, and the Sdr (surface area ratio) of the surface with the irregularities, measured with a laser microscope, is 4.0 to 50.0%. [2] The process release film according to [1], wherein the surface having the irregularities and an Sdr (developed surface area ratio) of 4.0 to 50.0% has an RPc (peak count) of 30 to 87. [3] A process release film according to [1] or [2], wherein the water contact angle on the opposite side of the surface having the irregularities and having an Sdr (unfolded surface area ratio) of 4.0 to 50.0% is 90 to 130°. [4] A release film for the process described in any one of items [1] to [3], having a thickness of 10 to 100 μm. [5] A release film for processes according to any one of items [1] to [4], wherein the tensile modulus at 120°C is 30 to 500 MPa. [6] A release film for processes according to any one of [1] to [5], wherein the tensile modulus of elasticity at 170°C is 20 to 400 MPa. [7] A process for manufacturing a metal embossed roll by blasting the surface of a metal roll with particles of 40 to 100 mesh size, and A process of passing a film between the metal embossing roll and another roll to form irregularities on the surface of the film, A method for manufacturing a process release film according to any one of [1] to [6], comprising the above. [8] A process release film used in a semiconductor encapsulation process, as described in any one of items [1] to [6]. [9] A method for manufacturing a resin-encapsulated semiconductor, A step of placing a semiconductor device to be resin-sealed in a predetermined position within a molding die, A step of placing a process release film according to any one of [1] to [6] on the inner surface of the molding die such that the surface having the irregularities and having an Sdr (unfolded surface area ratio) of 4.0 to 50.0% faces the inner surface of the molding die, A step of degassing the space between the release film for the process and the inner surface of the mold, After clamping the molding die, the process involves curing the sealing resin placed between the semiconductor device and the release film for the semiconductor encapsulation process. A method for manufacturing the resin-encapsulated semiconductor having the above-mentioned characteristics. [Effects of the Invention]

[0008] The process release film of the present invention has high degassing properties, allowing for quick removal of air between the release film and the inner surface of the mold, and also possesses excellent release properties, wrinkle suppression, and mold conformability. By using this film, molded products obtained by resin encapsulation of semiconductor chips, etc., can be manufactured with productivity and quality that exceeds the limitations of conventional technology. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram showing an example of a method for manufacturing a resin-encapsulated semiconductor using the process release film of the present invention. [Modes for carrying out the invention]

[0010] The present invention relates to a process release film having irregularities formed on at least one of its two surfaces, wherein the Sdr (unfolded surface area ratio) of the surface on which the irregularities are formed, as measured by a laser microscope, is 4.0 to 50.0%. In the release film for the process of the present invention, concavities and convexities are formed on at least one of its surfaces, and by having the Sdr (developed interface area ratio) of the concavo-convex surface within a predetermined numerical range, high degassing property in the lateral direction is realized. For example, when used as a release film for the process in a molding process using a mold, air bleeding between the release film for the process and the inner surface of the mold can be completed in a short time, etc., which can contribute to the improvement of the productivity of the molding process.

[0011] In the release film for the process of the present invention, it is only necessary that concavities and convexities are formed on at least one of the two surfaces, that is, concavities and convexities may be formed only on one surface, or concavities and convexities may be formed on both surfaces. In many usage forms of the release film for the process, since the degassing property of one surface arranged on the mold side is important, it is sufficient if concavities and convexities are formed on one surface. In that case, forming concavities and convexities only on one surface is advantageous in terms of manufacturing simplicity, cost, etc. Also, there are cases where smoothness is required on the surface of a resin such as a sealing resin. From this perspective, a release film with concavities and convexities formed only on one surface may be preferably used. When concavities and convexities are formed on both surfaces, it is advantageous in that excellent degassing property, release property, etc. can be imparted to both surfaces. Also, since a little concavity and convexity are imparted to the surface of the sealing resin, it is also possible to make it difficult to see flow marks of the resin, etc.

[0012] There is no particular limitation on the shape of the concavities and convexities. For example, they may be formed into various shapes such as satin finish, hairline, lattice shape, round shape, square shape, star shape, etc. When forming concavities and convexities using a metal embossing roll manufactured by performing a blasting process using particles with a particle size of 40 to 100 mesh described later, from the perspective of ease of manufacture, etc., it is preferable to have a shape such as satin finish.

[0013] If irregularities are formed on both surfaces, it is acceptable if only the irregularities on one of the surfaces satisfy the condition that the Sdr is between 4.0% and 50.0%, or if the irregularities on both surfaces satisfy the condition that the Sdr is between 4.0% and 50.0%. As mentioned above, in many usage configurations, the degassing ability of one surface that is placed on the mold side is important, so in that case, it is sufficient if only the irregularities on one surface satisfy the condition that the Sdr is between 4.0% and 50.0%, and this is also advantageous in terms of ease of manufacturing and cost. When providing excellent degassing properties to both surfaces depending on the usage, it is preferable that the surface irregularities on both surfaces satisfy the condition that the Sdr is between 4.0% and 50.0%.

[0014] The unfolded surface area ratio (Sdr) of an uneven surface indicates how much the actual surface area increases relative to the area of ​​the defined region. More specifically, the unfolded area ratio Sdr is defined by the following formula, where Sdr is 0 for a perfect plane and 0.414 (41.4%) for a surface inclined at 45°.

number

[0015] The mechanism by which the effects of the present invention, such as high lateral degassing, are obtained when Sdr is within the above range is not entirely clear, but it is presumed that there is some relationship between the surface irregularities specified by Sdr being within a predetermined range, which ensures a sufficient airflow path between the mold and the surface. From the viewpoint of achieving even better degassing performance, Sdr is preferably 6% or more, and particularly preferably 8% or more. From the viewpoint of degassability and other factors, a higher Sdr is preferable, and there is no particular upper limit in relation to the objectives of the present invention. However, when using ordinary polymer materials and manufacturing at ordinary costs, it is generally 40% or less, and more commonly 30% or less. Sdr can be adjusted as appropriate by adjusting the manufacturing conditions of the process release film and the surface condition through surface treatment, etc. More specifically, for example, it can be adjusted as appropriate by setting the particle size in the process of manufacturing a metal embossing roll by blasting the surface of the metal roll described later with particles of particle size 40 to 100 mesh, and the embossing roll temperature in the process of passing the film described later between the metal embossing roll and other rolls to form irregularities on the film surface, etc., to suitable values.

[0016] In the release film of the present invention, it is preferable that the RPc (peak count) of at least one of the surfaces on which the irregularities are formed is 30 to 87. By having the RPc of the irregular surface within a predetermined numerical range, even higher lateral degassing performance can be achieved, and when used as a process release film in a molding process using a mold, for example, air can be removed between the process release film and the inner surface of the mold in a shorter time, thereby contributing to a further improvement in the productivity of the molding process. In this embodiment, if irregularities are formed on both surfaces, only the irregularities on one of the surfaces may satisfy the condition that the RPc (peak count) is between 30 and 87, or the irregularities on both surfaces may satisfy the condition that the RPc (peak count) is between 30 and 87. In this embodiment, the surface with an RPc (peak count) of 30 to 87 is preferably the same surface as the surface with an Sdr (developed interface area ratio) of 4.0 to 50.0%.

[0017] In this invention, RPc (peak count) is the number of peak counts based on the roughness curve, measured according to JIS B0601 2013 (ISO 4287:1997, Amd.1:2009), and is defined by the following formula (I). RPc = L / RSm ... (I) In equation (I), L represents the reference length, which is 10 mm. RSm represents the average length of the roughness curve elements and is measured according to JIS B0601:2013 (ISO 4287:1997, Amd.1:2009). The measurement can be performed using a surface roughness measuring instrument, and more specifically, by the method described in the embodiment of this application.

[0018] The mechanism by which RPc being within the above range leads to even higher lateral degassing performance is not entirely clear. However, it is presumed that when the peak density specified by RPc is within a predetermined range, the number and size of the airflow channels become more appropriate, and this, combined with the specified Sdr, ensures sufficient airflow between the mold and the other components. Furthermore, from the viewpoint of achieving even better degassing performance, RPc is preferably 40 to 80, and particularly preferably 50 to 80. RPc can be adjusted as appropriate by adjusting the surface condition through manufacturing conditions for the process release film and surface treatment described later. More specifically, for example, it can be adjusted as appropriate by setting the particle size in the process of manufacturing a metal embossing roll by blasting the surface of the metal roll described later with particles of particle size 40 to 100 mesh, and the embossing roll temperature in the process of forming irregularities on the film surface by passing the film described later between the metal embossing roll and other rolls to suitable values.

[0019] In the process release film of the present invention, it is preferable that the water contact angle of the surface opposite to the surface on which irregularities having at least an Sdr of 4.0 to 50% are formed is 90 to 130°. By having the water contact angle of the surface within the above numerical range, even better release properties can be achieved between the process release film of this embodiment and the molded object. In the process release film of this embodiment, the water contact angle of only one surface, i.e., the surface opposite to the surface where the Sdr is 4.0 to 50% and irregularities are formed, may be in the range of 90 to 130°, or the water contact angles of both surfaces may be in the range of 90 to 130°. For example, when used in a molding process using a mold, it is preferable that the water contact angles of both surfaces are in the range of 90 to 130° in order to improve both the release properties from the mold and the release properties from the molded workpiece.

[0020] The water contact angle of the film surface in this embodiment can be measured using a contact angle measuring instrument in accordance with JIS R3257, and more specifically, it can be measured by the method described in the embodiment of this application. The water contact angle of the release film surface is more preferably 95° to 120°, even more preferably 98° to 115°, and particularly preferably 100° to 110°.

[0021] The water contact angle of the release film surface can be increased or decreased as appropriate by means conventionally used in the industry, but for example, by appropriately selecting the material of the film surface, the water contact angle of the surface can be brought within the above preferred numerical range. From this viewpoint, it is preferable that the surface of the process release film of the present invention contains a resin selected from the group consisting of fluororesin, 4-methyl-1-pentene (co)polymer, and polystyrene resin. Furthermore, additives (release agents) that can improve release properties may be used, or surface treatment may be performed. There are no particular restrictions on the type of release agent that can be used. At least one selected from the group consisting of silicone-based release agents, melamine-based release agents, polyolefin-based release agents, epoxy-based release agents, acrylic-based release agents, fluorine-based release agents, cellulose-based release agents, paraffin-based release agents, epoxy-melamine-based release agents, long-chain alkyl-based release agents, and combinations thereof can be used as appropriate. In particular, the use of fluorine-based release agents, long-chain alkyl-based release agents, etc., is preferred. These release agents may be added to the resin that constitutes the surface of the process release film, or they may be applied to the surface of the process release film. Furthermore, the water contact angle can be appropriately adjusted by adjusting the shape, density, size, etc., of the irregularities formed on the surface of the film in this invention.

[0022] There are no particular limitations on the total thickness of the process release film of the present invention. An appropriate thickness can be selected depending on the application and usage of the process release film, but for example, 10 to 300 μm is preferred, and 30 to 150 μm is more preferred. When the total thickness of the release film is within the above range, it is preferable because it provides good handling when used as a roll and reduces the amount of release film waste. The thickness of the process release film of the present invention can be adjusted as appropriate by adjusting the film manufacturing conditions. For example, when manufacturing the film by extrusion molding, the thickness can be adjusted by adjusting the spacing of the lips during the process. When stretching the film, the thickness can be adjusted by appropriately setting the stretching ratio.

[0023] From the viewpoint of suppressing wrinkles during molding, it is preferable that the process release film of the present invention has a tensile modulus of elasticity that exhibits a specific value. In other words, the process release film of the present invention preferably has a tensile modulus of 30 MPa to 500 MPa at 120°C, or preferably has a tensile modulus of 20 MPa to 400 MPa at 170°C. Furthermore, the process release film of the present invention preferably has a tensile modulus of 30 MPa to 500 MPa at 120°C and a tensile modulus of 20 MPa to 400 MPa at 170°C. If the tensile modulus of the laminated film is 30 MPa to 500 MPa at 120°C, or 20 MPa to 400 MPa at 170°C, then the occurrence of wrinkles when used in processes such as resin encapsulation can be suppressed even more effectively. The mechanism by which the tensile modulus of process release films exhibits the above-mentioned specific value at a particular temperature suppresses wrinkle formation is not entirely clear. However, it is presumed that having a tensile modulus above a certain value when heated during the process suppresses deformation that leads to wrinkle formation, while having a tensile modulus below a certain value allows for strain to be dispersed, and this is somehow related to this mechanism. Furthermore, from the viewpoint of mold conformability and other factors, the tensile modulus at 120°C is preferably 300 MPa or less, and the tensile modulus at 170°C is more preferably 200 MPa or less.

[0024] The process release film of this embodiment has a tensile modulus of elasticity at 120°C. The pressure is preferably between 30 MPa and 500 MPa. It is more preferable that the pressure be between 40 MPa and 450 MPa. It is more preferable that the pressure be between 50 MPa and 400 MPa. It is more preferably 200 MPa to 350 MPa. A pressure of 250 MPa to 300 MPa is particularly preferable. The process release film of this embodiment has a tensile modulus of elasticity at 170°C. The pressure is preferably between 20 MPa and 400 MPa. It is more preferable that the pressure be between 25 MPa and 300 MPa. A pressure of 30 MPa to 250 MPa is more preferable. It is more preferably 100 MPa to 200 MPa. A pressure of 120 MPa to 160 MPa is particularly preferable. The laminated film constituting the process release film of the present invention is particularly preferable if its tensile modulus at 120°C and its tensile modulus at 170°C are both within the above preferred range, as this expands the degree of freedom and applications during processing.

[0025] The tensile modulus of the process release film of this embodiment can be measured at 120°C or 170°C using a tensile testing machine in accordance with JIS K7127, and more specifically, it can be measured by the method described in the embodiment of this application. There are no particular restrictions on the method for adjusting the tensile modulus of process release films; it can be adjusted as appropriate using methods conventionally employed in this industry. For example, it can be adjusted by appropriately selecting materials such as polymers that make up the film. More specifically, it becomes easier to achieve the above-mentioned tensile modulus by appropriately using polymer materials with relatively good heat resistance, such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyamide-6, polyamide-66, polypropylene, ethylene-tetrafluoroethylene copolymer, syndiotactic polystyrene, and 4-methylpentene-1(co)polymer. Furthermore, since stretching the film (uniaxial or biaxial stretching) generally improves the tensile modulus of process release films, this can be used to adjust the tensile modulus as needed.

[0026] The release film for the process of the present invention may be a single-layer film or a laminated film of two or more layers. From the standpoint of simplicity in composition and manufacturing, as well as cost, a single-layer film is preferable. On the other hand, from the viewpoint of simultaneously and efficiently achieving both desirable or preferred properties of the film surface, such as surface properties and release properties, and preferred properties of the entire film, such as tensile elasticity, it is preferable to have a laminated film of two or more layers. In particular, it is especially preferable that the laminated film includes a release layer A that has release properties for molded products and molds, and a heat-resistant resin layer B that supports the release layer. Furthermore, if it is desired that both surfaces have release properties, it is preferable to include an additional release layer A', resulting in a layer configuration of release layer A / heat-resistant resin layer B / release layer A'.

[0027] Release layer A The release layer A constituting the process release film of this embodiment is a layer that comes into contact with the mold surface when used in a molding process using a mold, and has irregularities formed on it with an Sdr (unfolded interface area ratio) of 4.0 to 50.0% from the viewpoint of smooth degassing and release from the mold. The details of the irregularities and their preferred form are as described above. There are no particular restrictions on the water contact angle of the release layer A, but from the viewpoint of further improving release properties from the mold, the contact angle with water is preferably 90° to 130°, more preferably 95° to 120°, particularly preferably 98° to 115°, and even more preferably 100° to 110°. It is preferable to include a resin selected from the group consisting of fluororesin, 4-methyl-1-pentene (co)polymer, and polystyrene resin, due to its excellent release properties for molded products and ease of availability.

[0028] The fluororesin that can be used for release layer A may be a resin containing constituent units derived from tetrafluoroethylene. It may be a homopolymer of tetrafluoroethylene, or a copolymer with other olefins. Examples of other olefins include ethylene. A copolymer containing tetrafluoroethylene and ethylene as monomer constituent units is a preferred example, in which the proportion of constituent units derived from tetrafluoroethylene is preferably 55 to 100% by mass, and the proportion of constituent units derived from ethylene is preferably 0 to 45% by mass.

[0029] The 4-methyl-1-pentene(co)polymer that can be used in release layer A may be a homopolymer of 4-methyl-1-pentene, or it may be a copolymer of 4-methyl-1-pentene and other olefins having 2 to 20 carbon atoms (hereinafter referred to as "olefins having 2 to 20 carbon atoms").

[0030] In the case of copolymers of 4-methyl-1-pentene and olefins having 2 to 20 carbon atoms, the olefin copolymerized with 4-methyl-1-pentene can impart flexibility to 4-methyl-1-pentene. Examples of olefins having 2 to 20 carbon atoms include ethylene, propylene, 1-butene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-tetradecene, 1-hexadecene, 1-heptadecene, 1-octadecene, and 1-eicosene. These olefins may be used individually or in combination of two or more.

[0031] In the case of a copolymer of 4-methyl-1-pentene and an olefin having 2 to 20 carbon atoms, it is preferable that the proportion of constituent units derived from 4-methyl-1-pentene is 96 to 99% by mass, and the proportion of other constituent units derived from the olefin having 2 to 20 carbon atoms is 1 to 4% by mass. By reducing the content of constituent units derived from the olefin having 2 to 20 carbon atoms, the copolymer can be made harder, i.e., the storage modulus E' can be increased, which is advantageous in suppressing the occurrence of wrinkles in the sealing process, etc. On the other hand, by increasing the content of constituent units derived from the olefin having 2 to 20 carbon atoms, the copolymer can be made softer, i.e., the storage modulus E' can be lowered, which is advantageous in improving mold conformability.

[0032] 4-methyl-1-pentene(co)polymers can be produced by methods known to those skilled in the art. For example, they can be produced by methods using known catalysts such as Ziegra-Natta catalysts or metallocene catalysts. It is preferable that the 4-methyl-1-pentene(co)polymer is a highly crystalline (co)polymer. The crystalline copolymer may be either an isotactic copolymer or a syndiotactic copolymer, but an isotactic copolymer is particularly preferable from the standpoint of physical properties and is also readily available. Furthermore, the stereoregularity and molecular weight of the 4-methyl-1-pentene(co)polymer are not particularly limited, as long as it can be molded into a film and has sufficient strength to withstand the temperature and pressure during mold molding. The 4-methyl-1-pentene copolymer may be a commercially available copolymer, such as TPX® manufactured by Mitsui Chemicals, Inc.

[0033] The polystyrene resin that can be used for the release layer A includes styrene homopolymers and copolymers, and preferably contains at least 60% by weight of styrene-derived structural units in the polymer, and more preferably 80% by weight or more. The polystyrene resin may be isotactic polystyrene or syndiotactic polystyrene, but isotactic polystyrene is preferred from the viewpoint of transparency and availability, while syndiotactic polystyrene is preferred from the viewpoint of release properties and heat resistance. One type of polystyrene may be used alone, or two or more types may be used in combination.

[0034] The release layer A preferably has heat resistance that can withstand the mold temperature during molding (typically 120 to 180°C). From this viewpoint, the release layer A preferably contains a crystalline resin having crystalline components, and the melting point of the crystalline resin is preferably 190°C or higher, and more preferably 200°C to 300°C. To provide crystallinity to the release layer A, for example, in the case of fluororesins, it is preferable to include at least a constituent unit derived from tetrafluoroethylene; in the case of 4-methyl-1-pentene(co)polymer, it is preferable to include at least a constituent unit derived from 4-methyl-1-pentene; and in the case of polystyrene-based resins, it is preferable to include at least syndiotactic polystyrene. The inclusion of crystalline components in the resin constituting the release layer A makes it less likely for wrinkles to occur during resin encapsulation processes, and is suitable for suppressing the transfer of wrinkles to the molded product, which would otherwise result in appearance defects.

[0035] The resin containing the above-mentioned crystalline components that constitute the release layer A preferably has a heat of fusion of crystals in the first heating step measured by differential scanning calorimetry (DSC) in accordance with JIS K7221 of 15 J / g or more and 60 J / g or less, and more preferably 20 J / g or more and 50 J / g or less. If it is 15 J / g or more, it is possible to more effectively exhibit heat resistance and release properties that can withstand hot press molding in resin encapsulation processes, etc., and the rate of dimensional change can also be suppressed, so the occurrence of wrinkles can be prevented. On the other hand, if the heat of fusion of crystals is 60 J / g or less, the release layer A will have an appropriate hardness, so sufficient conformability of the film to the mold can be obtained in resin encapsulation processes, etc., and film damage is effectively suppressed.

[0036] The release layer A may contain other resins in addition to the fluororesin, 4-methyl-1-pentene copolymer, and / or polystyrene resin. In this case, it is preferable that the other resin has relatively high hardness. Examples of other resins include polyamide-6, polyamide-66, polybutylene terephthalate, and polyethylene terephthalate. Even if the release layer A contains a large amount of a soft resin (for example, a large amount of olefins with 2 to 20 carbon atoms in the 4-methyl-1-pentene copolymer), the release layer A can be hardened by further including a resin with relatively high hardness, which is advantageous in suppressing the occurrence of wrinkles in the sealing process and the like.

[0037] The content of these other resins is preferably, for example, 3 to 30% by mass relative to the resin components constituting the release layer A. By setting the content of the other resins to 3% by mass or more, the effect of the addition can be made substantial, and by setting it to 30% by mass or less, the release properties from the mold and molded product can be maintained.

[0038] Furthermore, in addition to the fluororesin, 4-methyl-1-pentene(co)polymer, and / or polystyrene resin, the release layer A may also contain known additives commonly used in film resins, such as heat stabilizers, weather stabilizers, rust inhibitors, copper-damaging stabilizers, and antistatic agents, to the extent that it does not impair the purpose of this embodiment. The content of these additives can be, for example, 0.0001 to 10 parts by mass per 100 parts by weight of the fluororesin, 4-methyl-1-pentene copolymer, and / or polystyrene resin.

[0039] The thickness of the release layer A is not particularly limited as long as it provides sufficient release properties for the molded product, but it is usually 1 to 50 μm, and preferably 5 to 30 μm.

[0040] Release layer A' As described above, the process release film of this embodiment may have a release layer A' in addition to the release layer A and the heat-resistant resin layer B. That is, the process release film of this embodiment may be a laminated film containing a release layer A, a heat-resistant resin layer B, and a release layer A' in that order. In this case, from the viewpoint of maintaining good peelability with respect to the molded product, the contact angle of the release layer A' with respect to water is preferably 90° to 130°, more preferably 95° to 120°, particularly preferably 98° to 115°, and even more preferably 100° to 110°. Details regarding the preferred material of release layer A' are the same as those described above for release layer A. The surface of the release layer A' may or may not have irregularities with an Sdr (unfolded surface area ratio) of 4.0 to 50.0%, but it is preferable that no irregularities are formed when smoothness of the resin surface, such as that of the sealing resin, is required. On the other hand, if excellent degassing properties are required on both surfaces, the surface may have irregularities.

[0041] In the case where the process release film of this embodiment is a laminated film containing a release layer A, a heat-resistant resin layer B, and a release layer A' in that order, the release layer A and the release layer A' may be layers with the same configuration or layers with different configurations. From the viewpoint of preventing warping and ensuring ease of handling by having similar release properties on all sides, it is preferable that release layer A and release layer A' have the same or substantially the same configuration. From the viewpoint of designing release layer A and release layer A' optimally in relation to the process in which they are used, for example, making release layer A excellent at releasing from the mold and release layer A' excellent at releasing from the molded product, it is preferable that release layer A and release layer A' have different configurations. If release layer A and release layer A' have different configurations, they may be made of the same material but differ in thickness and other components, or they may be made of different materials and other components.

[0042] Heat-resistant resin layer B The heat-resistant resin layer B constituting the process release film of this embodiment supports the release layer A (and optionally the release layer A') and has the function of suppressing wrinkle formation due to mold temperature, etc. Any resin layer, including an unstretched film, can be used for the heat-resistant resin layer B, but it is particularly preferable that it includes a stretched film.

[0043] The stretched film described above may be a uniaxially oriented film or a biaxially oriented film. If it is a uniaxially oriented film, it may be stretched longitudinally or transversely, but it is desirable that it be stretched in at least the transverse (TD) direction. There are no particular limitations on the method or apparatus for obtaining the stretched film described above; stretching can be performed using methods known in this industry. For example, it can be stretched using heated rolls or a tenter-type stretcher.

[0044] As the stretched film mentioned above, it is preferable to use a stretched film selected from the group consisting of stretched polyester film, stretched polyamide film, and stretched polypropylene film. These stretched films are particularly suitable as stretched films for the heat-resistant resin layer B because stretching makes it relatively easy to reduce or make negative the coefficient of thermal expansion in the transverse (TD) direction, their mechanical properties are suitable for the application of this embodiment, and they are relatively easy to obtain at low cost.

[0045] As the stretched polyester film, stretched polyethylene terephthalate (PET) film and stretched polybutylene terephthalate (PBT) film are preferred, and biaxially stretched polyethylene terephthalate (PET) film is particularly preferred. There are no particular limitations on the polyamide that makes up the stretched polyamide film, but polyamide-6, polyamide-66, etc., can be preferably used. As the stretched polypropylene film, uniaxially oriented polypropylene film, biaxially oriented polypropylene film, and the like can be preferably used. There are no particular limitations on the stretching ratio; an appropriate value should be set as needed to appropriately control the thermal dimensional change rate and achieve suitable mechanical properties. For example, in the case of stretched polyester film, it is preferable that the stretching ratio be in the range of 2.7 to 8.0 times in both the longitudinal and transverse directions; in the case of stretched polyamide film, it is preferable that the stretching ratio be in the range of 2.7 to 5.0 times in both the longitudinal and transverse directions; in the case of stretched polypropylene film, it is preferable that the stretching ratio be in the range of 5.0 to 10.0 times in both the longitudinal and transverse directions; and in the case of uniaxially oriented polypropylene film, it is preferable that the stretching ratio be in the range of 1.5 to 10.0 times in the longitudinal direction.

[0046] From the viewpoint of controlling the strength of the film and its thermal dimensional change rate within an appropriate range, it is preferable that the heat-resistant resin layer B has heat resistance that can withstand the mold temperature during molding (typically 120 to 180°C). From this viewpoint, it is preferable that the heat-resistant resin layer B contains a crystalline resin having crystalline components, and that the melting point of the crystalline resin is preferably 125°C or higher, more preferably 155°C to 300°C, even more preferably 185°C to 210°C, and particularly preferably 185°C to 205°C.

[0047] As described above, it is preferable that the heat-resistant resin layer B contains a crystalline resin having crystalline components. As the crystalline resin to be contained in the heat-resistant resin layer B, for example, crystalline resins such as polyester resin, polyamide resin, and polypropylene resin can be used in part or in whole. Specifically, it is preferable to use polyethylene terephthalate or polybutylene terephthalate for polyester resin, polyamide 6 or polyamide 66 for polyamide resin, and isotactic polypropylene for polypropylene resin.

[0048] By incorporating the crystalline components of the crystalline resin into the heat-resistant resin layer B, wrinkles are less likely to occur during the resin encapsulation process, and it is more advantageous to suppress the transfer of wrinkles to the molded product, which would otherwise result in an appearance defect. The resin constituting the heat-resistant resin layer B preferably has a heat of fusion value of 20 J / g or more and 100 J / g or less in the first heating step, measured by differential scanning calorimetry (DSC) in accordance with JIS K7221, more preferably 25 J / g or more and 65 J / g or less, more preferably 25 J / g or more and 55 J / g or less, more preferably 28 J / g or more and 50 J / g or less, more preferably 28 J / g or more and 40 J / g or less, and even more preferably 28 J / g or more and 35 J / g or less. If it is 20 J / g or more, it is possible to effectively exhibit heat resistance and release properties that can withstand hot press molding in resin sealing steps, etc., and the rate of dimensional change can also be suppressed to a minimum, so the occurrence of wrinkles can be prevented. On the other hand, because the heat of fusion of crystals is 100 J / g or less, the heat-resistant resin layer B can be given appropriate hardness, which ensures sufficient conformability of the film to the mold in resin sealing processes and the like, and effectively suppresses damage to the film. In this embodiment, the heat of fusion of crystals refers to the value obtained by summing the peak areas that have a peak at 120°C or higher in a chart showing the relationship between the heat quantity on the vertical axis (J / g) and the temperature on the horizontal axis obtained in the first heating step by differential scanning calorimetry (DSC) measurement in accordance with JIS K7221. The heat of fusion required for the heat-resistant resin layer B can be adjusted by appropriately setting the heating and cooling conditions and stretching conditions during film manufacturing.

[0049] The thickness of the heat-resistant resin layer B is not particularly limited as long as the film strength is ensured, but it is usually 1 to 100 μm, preferably 5 to 50 μm.

[0050] Other layers The process release film of this embodiment may have layers other than the release layer A, the heat-resistant resin layer B, and the release layer A', as long as it does not contradict the objectives of the present invention. For example, an adhesive layer may be provided between the release layer A (or release layer A') and the heat-resistant resin layer B as needed. The material used for the adhesive layer is not particularly limited, as long as it can firmly bond the release layer A and the heat-resistant resin layer B and does not peel off during the resin sealing process or the release process.

[0051] For example, if the release layer A (or release layer A') contains a 4-methyl-1-pentene copolymer, the adhesive layer is preferably a modified 4-methyl-1-pentene copolymer resin graft-modified with an unsaturated carboxylic acid, or an olefin-based adhesive resin composed of a 4-methyl-1-pentene copolymer and an α-olefin copolymer. If the release layer A (or release layer A') contains a fluororesin, the adhesive layer is preferably an adhesive such as a polyester-based, acrylic-based, or fluororubber-based adhesive. The thickness of the adhesive layer is not particularly limited as long as it improves the adhesion between the release layer A (or release layer A') and the heat-resistant resin layer B, but is, for example, 0.5 to 10 μm.

[0052] Method for manufacturing release film for process applications There are no particular limitations on the method for manufacturing the process release film of the present invention, but it is preferable to manufacture it by a manufacturing method having the following steps. • A process for manufacturing metal embossed rolls by blasting the surface of a metal roll with particles of 40-100 mesh size. - A process of passing the film between the metal embossing roll and another roll (which may also be an embossing roll) to form irregularities on the surface of the film. By using the manufacturing method comprising the above steps, the process release film of the present invention can be manufactured with high productivity, having irregularities formed on at least one of the two surfaces, and the Sdr (unfolded surface area ratio) measured by a laser microscope on at least one of the surfaces on which the irregularities are formed being 4.0 to 50.0%. Furthermore, the Sdr can be controlled to a desired value with high precision. In addition, desirable characteristics such as the predetermined RPc (peak count) mentioned above can be easily imparted. When creating a textured surface on both sides, the film may be passed between the embossing roll and another roll twice, or between the embossing rolls once. The former method is usually used.

[0053] The process of manufacturing metal embossing rolls The method for manufacturing a release film for processes according to this embodiment includes the step of manufacturing a metal embossing roll by blasting the surface of a metal roll with particles having a particle size of 40 to 100 mesh. The process for manufacturing the above-mentioned metal embossed roll may include a blast treatment operation using particles with a particle size of 40 to 100 mesh on the surface of the metal roll, or it may include other process operations, or it may consist only of a blast treatment operation using particles with a particle size of 40 to 100 mesh on the surface of the metal roll without any other process operations. Other process operations include a blast treatment operation using particles outside the particle size range of 40 to 100 mesh on the surface of the metal roll, or a process operation to form an uneven pattern using a mill roll method or a resist corrosion method.

[0054] In the method for manufacturing a process release film of this embodiment, a metal embossing roll having an appropriate uneven shape can be efficiently manufactured by blasting the surface of a metal roll with particles of 40 to 100 mesh size. In a subsequent step, the film is passed between the metal embossing roll and another roll to form irregularities on the film surface, so that at least one of the two surfaces has irregularities formed on it, and the Sdr (unfolded surface area ratio) measured by a laser microscope on at least one of the surfaces on which the irregularities are formed is 4.0 to 50.0%. The process release film of the present invention can be manufactured with high productivity and controllability.

[0055] For the metal roll used in the above process, a metal substrate is preferably provided on the entire surface of an iron core. The metal substrate is not particularly limited as long as it is a material commonly used in embossing rolls; examples include zinc, copper, brass, aluminum, iron, stainless steel, and chromium. Among these, copper is preferred due to its excellent stability in forming uneven patterns during the etching process. The thickness of the metal substrate should be set considering factors such as being able to cover the maximum height difference of the embossed pattern. When designing a release film for semiconductor encapsulation processes, a thickness of 1000 to 1500 μm is generally preferred. There are no particular restrictions on the type of embossed pattern; for example, it may be formed in various shapes such as pearlescent or hairline.

[0056] (Blast treatment) In the manufacturing method of the present invention, a metal embossing roll is manufactured by performing a blast treatment on the surface of a metal roll at least once using particles with a particle size of 40 to 100 mesh. The blast treatment may be performed two or more times, in which case particles with a particle size of 40 to 100 mesh may be used in all of the two or more blast treatments, or particles with a particle size outside the 40 to 100 mesh range may be used in at least one of the treatments. Furthermore, when performing two or more blast treatments, particles with the same particle size may be used in all of them, or particles with different particle sizes may be used.

[0057] By performing blasting with particles of 40 to 100 mesh size, it becomes easy to control the surface area of ​​the irregularities and keep the Sdr of the film surface onto which the irregularities are transferred within the range of 4.0 to 50. Furthermore, it becomes easy to control the spacing of the irregularities and keep the Rpc of the film surface onto which the irregularities are transferred within the range of 30 to 87. Therefore, this method is preferable from these viewpoints. The particle size of the particles used for blasting is preferably 80 to 100 mesh. There are no particular restrictions on the material of the particles used in the blast treatment. The material can be appropriately selected in consideration of the depth and shape of the irregularities to be formed, as well as the material of the metal roll. However, materials conventionally used in blast treatment can be preferably used. For example, inorganic particles such as alumina, iron, silicon carbide, chromium oxide, and iron oxide can be preferably used.

[0058] Blasting can be performed, for example, by blowing particles like those described above from the tip of a nozzle using compressed air. The pressure of the compressed air is preferably in the range of 200 to 500 kPa. If it is 200 kPa or higher, it is possible to form irregularities of a depth that can fully achieve the effects of the present invention, and if it is 500 kPa or lower, it is possible to prevent the irregularities from being destroyed and thus hindering the above effects. From the above viewpoint, it is even more preferable that the pressure range of the compressed air is in the range of 300 to 400 kPa. The blasting process is preferably carried out at room temperature, and the particle blasting time is preferably about 0.01 to 0.5 seconds. The nozzle may also be scanned to satisfy the above blasting time conditions, depending on the area of ​​the particles projected from the nozzle.

[0059] In this embodiment, it is preferable to laminate a chromium layer from the viewpoint of providing a protective layer. The chromium layer may be applied before or after the blast treatment. Alternatively, the chromium layer may be laminated both before and after the blast treatment.

[0060] There are various types of chromium that can be used for laminating chromium layers, ranging from those that are smooth enough to have a glossy finish to those that are completely matte. The appropriate type should be selected considering factors such as whether the chromium layer is laminated before or after the blasting process. When laminating a chrome layer before blasting, it is preferable to use a chrome layer with high gloss. The higher the gloss, the smoother the chrome layer, and therefore the more durable it is, making it an excellent protective layer. It also results in better reproducibility as an embossed plate. Furthermore, when a chromium layer is laminated before blasting, it is preferable to make the chromium layer at least 30 μm thick to prevent damage to the chromium layer during blasting. Even more preferable, considering economic factors, is a thickness of 30 to 50 μm.

[0061] When a chromium layer is laminated after blasting, there are no particular restrictions on the thickness of the chromium layer as long as it can provide a protective layer function and control gloss, but a range of 10 to 25 μm is preferred. There are no particular restrictions on the method of laminating the chromium layer; for example, it can be easily applied by plating. The Mohs hardness of the chromium layer is preferably around 7 (6-8).

[0062] A process for forming irregularities on the film surface. The method for manufacturing a release film for a process according to this embodiment includes, in addition to the step of manufacturing the metal embossing roll described above, a step of passing the film between the metal embossing roll and other rolls to form irregularities on the surface of the film. This process of forming irregularities on the film surface allows for highly efficient formation of irregularities on at least one of the two surfaces of the release film for the process of the present invention, and enables the Sdr (unfolded surface area ratio) measured with a laser microscope on at least one of the surfaces on which the irregularities are formed to be 4.0 to 50.0%.

[0063] In this embodiment, there are no particular restrictions on the specific operations and conditions for the process of forming irregularities on the film surface using the metal embossing roll obtained in the process of manufacturing the metal embossing roll described above. Operations and conditions similar to those of conventional embossing processes in the art can be appropriately adopted. For example, a metal embossing roll with a built-in heater can be heated to 60-200°C, and a single-layer or laminated film, before the formation of the texture, can be passed between the metal embossing roll and other rolls, and pressurized to form the texture. At that time, the film may be preheated in a drying oven or in contact with a heating roll. The pressure is preferably 30 to 150 kgf / cm. After pressurization and shaping, the film is preferably cooled. The above-mentioned metal embossing roll and other rolls are preferably placed in a suitable device, such as a known sheet-fed or rotary embossing machine.

[0064] While there are no particular limitations on the method for manufacturing the process release film when the process release film of the present invention is a laminated film having a release layer A and a heat-resistant resin layer B, for example, 1) Prior to the process of forming irregularities on the film surface, a release layer A and a heat-resistant resin layer B are co-extruded and laminated to produce a film before the formation of irregularities, and this is then subjected to the process of forming irregularities on the film surface to produce a release film for process use. 2) Alternatively, a film before the formation of irregularities may be manufactured by applying and drying molten resin of the release layer A or adhesive layer onto a film that will become the heat-resistant resin layer B, or by applying and drying a resin solution obtained by dissolving the resin of the release layer A or adhesive layer in a solvent. 3) Furthermore, a method can be adopted in which a film to be the release layer A and a film to be the heat-resistant resin layer B are manufactured in advance, and these films are laminated together to produce a process release film. In this case, the surface of the film to be the release layer A may be pre-formed with irregularities. That is, only the film to be the release layer A may be subjected to the process of forming irregularities on the film surface as described above.

[0065] In the method described in 3) above, various known lamination methods can be used to laminate each resin film, such as extrusion lamination, dry lamination, and thermal lamination. In the dry lamination method, each resin film is laminated using an adhesive. As the adhesive, known adhesives for dry lamination can be used. For example, polyvinyl acetate adhesives; polyacrylic ester adhesives consisting of homopolymers or copolymers of acrylic esters (ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, etc.), or copolymers of acrylic esters with other monomers (methyl methacrylate, acrylonitrile, styrene, etc.); cyanoacrylate adhesives; ethylene copolymer adhesives consisting of copolymers of ethylene with other monomers (vinyl acetate, ethyl acrylate, acrylic acid, methacrylic acid, etc.); cellulose adhesives; polyester adhesives; Adhesives such as riamide adhesives, polyimide adhesives, amino resin adhesives made of urea resin or melamine resin, phenol resin adhesives, epoxy adhesives, polyurethane adhesives that crosslink polyols (polyether polyols, polyester polyols, etc.) with isocyanates and / or isocyanurates, reactive (meth)acrylic adhesives, rubber adhesives made of chloroprene rubber, nitrile rubber, styrene-butadiene rubber, etc., silicone adhesives, inorganic adhesives made of alkali metal silicates, low-melting-point glass, etc., and other adhesives can be used. The resin film laminated by method 3) may be a commercially available product or one manufactured by a known manufacturing method. The resin film may be subjected to surface treatments such as corona treatment, atmospheric pressure plasma treatment, vacuum plasma treatment, or primer coating. The method for manufacturing the resin film is not particularly limited, and known manufacturing methods can be used.

[0066] 1) The co-extrusion molding method is preferable because it is less likely to cause defects such as foreign matter getting caught between the resin layer that will become the release layer A and the resin layer that will become the heat-resistant resin layer B, and also less likely to cause warping of the release film. 3) The lamination method is a suitable manufacturing method when a stretched film is used for the heat-resistant resin layer B. In this case, it is preferable to form an appropriate adhesive layer at the interface between the films as needed. To improve the adhesion between the films, surface treatment such as corona discharge treatment may be applied to the interface between the films as needed.

[0067] The release film for the process may be uniaxially or biaxially stretched as needed, which can increase the film's strength. Stretching may be performed before or after the process of forming irregularities on the film surface, but from the viewpoint of appropriately controlling the properties of the film surface, such as Sdr (Surface Area Ratio), it is preferable to perform it before the process of forming irregularities on the film surface.

[0068] The coating means in the coating method described in 2) above is not particularly limited, but various types of coaters such as roll coaters, die coaters, and spray coaters can be used. The melt extrusion means is not particularly limited, but extruders having T-type dies or inflation-type dies can be used.

[0069] Usage patterns of release films for process applications (manufacturing process) The process release film of the present invention can be used by placing it between a semiconductor chip or the like and the inner surface of a mold when resin is injected into a mold with the chip or the like placed inside the mold. By using the process release film of the present invention, mold release defects, burr generation, and the like can be effectively prevented. The resin used in the above manufacturing process may be either a thermoplastic resin or a thermosetting resin, but thermosetting resins are widely used in this art, and it is particularly preferable to use an epoxy-based thermosetting resin. While semiconductor chip encapsulation is the most typical manufacturing process described above, the present invention is not limited to this and can also be applied to fiber-reinforced plastic molding processes, plastic lens molding processes, and the like.

[0070] Figure 1 is a schematic diagram showing an example of a method for manufacturing a resin-encapsulated semiconductor using the release film of the present invention. As shown in Figure 1a, the release film 1 of the present invention is supplied into the molding die 8 from a roll-shaped winding by rolls 1-2 and 1-3. Next, the release film 1 is placed on the inner surface of the upper die 2. At this time, the inner surface of the upper die 2 is vacuumed from the suction port 3 to make the release film 1 adhere closely to the inner surface of the upper die 2. The process release film 1 of the present invention has excellent lateral degassing properties, so the degassing time is shortened, and resin-encapsulated semiconductors can be manufactured with high productivity. In addition, it has excellent adhesion to the inner surface of the upper die 2, so the occurrence of wrinkles is suppressed, and resin-encapsulated semiconductors with a good appearance can be manufactured. In order to achieve these remarkable effects, in this embodiment, the surface with irregularities and an Sdr (unfolded surface area ratio) of 4.0 to 50.0% is placed facing the inner surface of the upper die 2. A semiconductor chip 6 placed on a substrate is placed in the lower mold 5 of the molding apparatus. By placing a sealing resin on the semiconductor chip 6, or by injecting a liquid sealing resin to cover the semiconductor chip 6, the sealing resin 4 is contained between the upper mold 2, which has a release film 1 that is exhausted and tightly attached, and the lower mold 5. Next, as shown in Figure 1b, the upper mold 2 and the lower mold 5 are closed via the release film 1 of the present invention, and the sealing resin 4 is cured.

[0071] As the mold closes and hardens, the sealing resin 4 flows into the mold as shown in Figure 1c, and the sealing resin 4 flows into the space and fills the area around the sides of the semiconductor chip 6. The sealed semiconductor chip 6 is then removed by opening the upper mold 2 and the lower mold 5. After opening the mold and removing the molded product, the release film 1 is reused multiple times or a new release film is supplied, and the product is subjected to the next resin molding process.

[0072] By adhering the release film of the present invention to the upper mold and interposing it between the mold and the sealing resin, resin adhesion to the mold is prevented, the resin molded surface of the mold is not contaminated, and the molded product can be easily released. Furthermore, the release film can be supplied anew for each resin molding operation, or it can be supplied anew for each of multiple resin molding operations.

[0073] The encapsulating resin may be a liquid resin or a resin that is solid at room temperature, but any encapsulating material that becomes liquid during encapsulation can be used as appropriate. Specifically, epoxy resins (biphenyl-type epoxy resin, bisphenol epoxy resin, o-cresol novolac-type epoxy resin, etc.) are mainly used as encapsulating resins, and other commonly used encapsulating resins such as polyimide resins (bismaleimide-type) and silicone resins (thermosetting addition-type) can be used. Furthermore, the resin encapsulation conditions vary depending on the encapsulating resin used, but for example, a curing temperature of 120°C to 180°C and a molding pressure of 10 to 50 kg / cm² are used. 2 The curing time can be set as appropriate within the range of 1 to 60 minutes.

[0074] The order in which the release film 1 is placed on the inner surface of the molding die 8 and the order in which the semiconductor chip 6 is placed inside the molding die 8 are not particularly limited and may be performed simultaneously, or the release film 1 may be placed after the semiconductor chip 6 is placed, or the semiconductor chip 6 may be placed after the release film 1 is placed.

[0075] As described above, the process release film 1 of the present invention has high release properties, allowing the semiconductor package 4-2 to be easily released. Furthermore, since the release film 1 has appropriate flexibility, it conforms well to the shape of the mold while being resistant to wrinkling due to the heat of the molding die 8. Therefore, a sealed semiconductor package 4-2 with a good appearance can be obtained without wrinkles being transferred to the resin sealing surface of the sealed semiconductor package 4-2 or areas where the resin is not filled (resin defects) occurring. Furthermore, since the release film 1 has excellent lateral degassing properties, the degassing time when adhering it to the inner surface of the upper mold 2 is shortened, enabling the production of resin-encapsulated semiconductors with high productivity.

[0076] In the method for manufacturing resin-encapsulated semiconductors using the process release film of the present invention, the method is not limited to a compression molding method in which a solid encapsulating resin material 4 is pressurized and heated, as shown in Figure 1, but a transfer molding method in which a fluid encapsulating resin material is injected may also be employed.

[0077] The release film of the present invention can be preferably used not only in the process of resin-encapsulating semiconductor elements, but also in the process of molding and releasing various molded products using a molding die, such as the molding and release process of fiber-reinforced plastics, the molding and release process of plastic lenses, and so on. [Examples]

[0078] The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto.

[0079] In the following examples / comparative examples, the physical properties / characteristics were evaluated using the methods described below. (Developed interface area ratio (Sdr)) The film was vacuum-adsorbed onto a vacuum adsorption plate, and the plate was placed on the measurement stage of a laser microscope. Laser microscope images were acquired under the following conditions, and the Sdr of the uneven surface (on the release layer A side) was determined. Equipment: Laser microscope (Olympus Corporation, OLS5000) Objective lens: MPLAPON50XLET Measurement area: 720 x 720 μm (9 areas in total, 3x3 vertically and horizontally, stitched together in an image) Automatic tilt removal: Implemented Filtering: None

[0080] (Peak Count (RPc)) The peak count of the uneven surface (on the release layer A side) was measured in accordance with JIS B0601:2013 (ISO 4287:1997, Amd.1:2009). The reference length was set to 10 mm. For the measurement, a surface roughness measuring instrument SURFCOM 130A (manufactured by Tokyo Seimitsu Co., Ltd.) was used to determine the RPc at a total of six locations: three in the direction perpendicular to the flow direction during film manufacturing (TD direction) and three in the direction parallel to it (MD direction). The average value of these values ​​was taken as the RPc of the surface in question.

[0081] Contact angle with water (water contact angle) In accordance with JIS R3257, the water contact angle of the film surface (both sides) was measured using a contact angle measuring instrument (FACECA-W, manufactured by Kyowa Interface Science Co., Ltd.).

[0082] (Tensile modulus of elasticity) In accordance with JIS K7127, the tensile modulus at 120°C and 170°C was determined using the A&D Company, Limited (A&D) RTC-1225 constant temperature chamber tensile testing machine. Measurement conditions: Tensile mode Measurement direction: Longitudinal (MD) direction of the film (film transport direction)

[0083] (Degassing time) The process release film was placed between the upper and lower molds with a tension of 10N applied, as shown in Figure 1(a) (with the uneven surface (release layer A side) facing the upper mold), and then vacuum-adhered to the parting surface of the upper mold. The time it took for all the air to escape was measured. The semiconductor encapsulation molding equipment used was the WCM-300MS manufactured by Apic Yamada Co., Ltd. A mold with a 300mm diameter circular parting surface on the upper part was used. The mold temperature was set to 120°C.

[0084] (Mold releasability) Similar to the evaluation of the degassing time described above, the process release film was vacuum-adhered to the parting surface of the upper mold (with the uneven surface (release layer A side) facing the upper mold), then encapsulating resin was filled onto the substrate to cover the semiconductor chip, the semiconductor chip fixed to the substrate was placed in the lower mold, and the mold was clamped. At this time, the molding die temperature (molding temperature) was set to 120°C, the molding pressure to 10 MPa, and the molding time to 400 seconds. Then, as shown in Figure 1(c), after encapsulating the semiconductor chip with encapsulating resin, the resin-encapsulated semiconductor chip (semiconductor package) was released from the release film. The release properties of the release film were evaluated according to the following criteria. ◎: The release film peels off naturally as soon as the mold is opened. ○: The release film does not peel off naturally, but it can be easily removed by pulling it with your hands (applying tension). ×: The release film adheres tightly to the resin encapsulation surface of the semiconductor package and cannot be peeled off by hand.

[0085] (Appearance of the molded product) The wrinkle condition of the release film and the resin sealing surface of the semiconductor package after demolding in the above process was evaluated according to the following criteria. ◎: There are absolutely no wrinkles on either the release film or the semiconductor package. ○: The release film has slight wrinkles, but these wrinkles have not been transferred to the semiconductor package. ×: There are numerous wrinkles not only in the release film but also in the semiconductor packaging.

[0086] (Mold conformability) The mold conformability of the release film after demolding in the above process was evaluated according to the following criteria. ◎: The semiconductor package has absolutely no resin defects (areas where the resin is not filled). ○: There are slight resin chips at the edges of the semiconductor package (excluding chips due to wrinkles). ×: There are many resin chips at the edges of the semiconductor package (excluding chips due to wrinkles).

[0087] [Example 1] (Heat-resistant resin layer B) As the heat-resistant resin layer B, a biaxially oriented PET (polyethylene terephthalate) film with a thickness of 12 μm (manufactured by Toray Industries, Inc., product name: Lumirror S10) was used. (Release layer A and A') As release layers A and A', an unstretched 4-methyl-1-pentene copolymer resin film was used. Specifically, a 15 μm thick unstretched film was formed by melt-extruding Mitsui Chemicals, Inc.'s 4-methyl-1-pentene copolymer resin (product name: TPX®, brand name: MX022) at 270°C and adjusting the slit width of the T-type die. The unoriented 4-methyl-1-pentene copolymer resin film was subjected to corona treatment on one of its surfaces to improve adhesion with adhesives, such that the water contact angle, according to JIS R3257, becomes 30° or less when it is 30° or more.

[0088] (glue) The following urethane-based adhesive A was used as the adhesive for the dry lamination process to bond the films together. [Urethane-based adhesive A] Main component: Takelac® A-616 (manufactured by Mitsui Chemicals, Inc.). Hardener: Takenate® A-65 (manufactured by Mitsui Chemicals, Inc.). The main component and hardener were mixed in a mass ratio (main component:hardener) of 16:1, and ethyl acetate was used as a diluent.

[0089] (Manufacturing of laminated films) On one side of a biaxially oriented PET (polyethylene terephthalate) film, apply a urethane-based adhesive A at a rate of 1.5 g / m² using gravure coating. 2 After coating and dry laminating the corona-treated surface of an unstretched 4-methyl-1-pentene copolymer resin film, 1.5 g / m² of urethane adhesive A is applied to the biaxially oriented PET (polyethylene terephthalate) film side of this laminate film. 2The film was coated with a 4-methyl-1-pentene copolymer resin film, and the corona-treated surface of the unstretched 4-methyl-1-pentene copolymer resin film was bonded to it by dry lamination to obtain a laminated film with a 5-layer structure (release layer A / adhesive layer / heat-resistant resin layer B / adhesive layer / release layer A'). The dry lamination conditions were as follows: substrate width 900 mm, conveying speed 30 m / min, drying temperature 50-60°C, laminating roll temperature 50°C, and roll pressure 3.0 MPa.

[0090] (Manufacturing of metal embossing rolls) A carbon steel roll with a face length of 570 mm and a diameter of 200 mm was uniformly blast-treated using 80-mesh alumina particles. Subsequently, a 15 μm thick hard chrome plating was applied to manufacture a metal embossing roll for creating textured surfaces.

[0091] (Formation of uneven surfaces) The laminated film with a five-layer structure (release layer A / adhesive layer / heat-resistant resin layer B / adhesive layer / release layer A') prepared as described above was conveyed between the pair of metal embossing rolls and rubber rolls prepared as described above, and irregularities were created on the surface of the film on the release layer A side, thereby producing the release film for the process of Example 1. The embossing conditions were as follows: conveying speed: 5 m / min, metal embossing roll temperature: 120°C, and inter-roll pressure: 75 kgf / cm.

[0092] Table 1 shows the evaluation results for the surface roughness (Sdr and RPc), water contact angle, tensile modulus, degassing time, release properties, wrinkles, and mold conformability of the process release film prepared as described above. When using the process release film of Example 1, whose surface Sdr (developed interface area ratio) satisfies the conditions of the present invention, it was possible to completely remove air between the upper mold and the film in a short degassing time. Furthermore, the release film exhibited excellent release properties, peeling off naturally at the same time as the mold was opened. There were no wrinkles whatsoever on either the release film or the semiconductor package, meaning that wrinkles were sufficiently suppressed, and the semiconductor package showed excellent mold conformability with no resin chipping whatsoever. In other words, the process release film of Example 1 was a process release film that had a short degassing time and good release properties, wrinkle suppression, and mold conformability.

[0093] [Example 2] In the manufacturing of the metal embossing roll, a release film for the process was prepared and evaluated in the same manner as in Example 1, except that alumina particles with a particle size of 40 mesh, followed by particles with a particle size of 100 mesh, were uniformly blasted. The results are shown in Table 1. This process release film had an even shorter degassing time than Example 1, and exhibited excellent release properties, wrinkle suppression, and mold conformability.

[0094] [Example 3] In the manufacturing of the metal embossing roll, a release film for the process was prepared and evaluated in the same manner as in Example 1, except that the alumina particles with a particle size of 80 mesh, followed by particles with a particle size of 100 mesh, were uniformly blasted. The results are shown in Table 1. This process release film had an even shorter degassing time than Example 1, and exhibited excellent release properties, wrinkle suppression, and mold conformability.

[0095] [Example 4] A release film for the process was prepared and evaluated in the same manner as in Example 1, except that the temperature of the metal embossing roll used to form irregularities on the film surface was set to 150°C. The results are shown in Table 1. This process release film had an even shorter degassing time than Example 1, and exhibited excellent release properties, wrinkle suppression, and mold conformability.

[0096] [Comparative Example 1] In the manufacturing of the metal embossing roll, a process release film was prepared and evaluated in the same manner as in Example 1, except that a uniform blast treatment was performed using alumina particles with a particle size of 100 mesh. The results are shown in Table 1. Although it was a process release film with good release properties, wrinkle suppression, and mold conformability, the degassing time was longer compared to the above examples.

[0097] [Table 1] [Industrial applicability]

[0098] The process release film of the present invention exhibits high degassing properties that could not be achieved with conventional technology, and combines high degassing properties with excellent release properties, wrinkle suppression performance, and mold conformability at a level that surpasses the limits of conventional technology. By using this film, it is possible to manufacture molded products such as semiconductor chips encapsulated in resin with productivity and quality that surpasses the limits of conventional technology, resulting in highly practical and valuable technological effects, and it has high applicability in various fields of industry, including the semiconductor process industry. Furthermore, the process release film of the present invention can be used not only for semiconductor packaging but also for various mold molding processes such as fiber-reinforced plastic molding processes and plastic lens molding processes. Therefore, it has high applicability in various fields of industries other than the semiconductor industry that perform mold molding. [Explanation of Symbols]

[0099] 1, 1-2, 1-3: Release film 2: Upper mold 3: Suction port 4: Sealing resin 4-2: Semiconductor Packages 5: Lower mold 6: Semiconductor chips 7: Circuit board 8: Molding molds

Claims

1. A release film for processes, wherein at least one of its two surfaces has irregularities formed on it, and the Sdr (unfolded surface area ratio) of the surface with the irregularities, measured with a laser microscope, is 4.0 to 50.0%.

2. The process release film according to claim 1, wherein the surface having the irregularities and an Sdr (developed surface area ratio) of 4.0 to 50.0% has an RPc (peak count) of 30 to 87.

3. A process release film according to claim 1 or 2, wherein the water contact angle of the surface opposite to the surface having the irregularities and having an Sdr (unfolded surface area ratio) of 4.0 to 50.0% is 90 to 130°.

4. A process release film according to any one of claims 1 to 3, having a thickness of 10 to 100 μm.

5. A process release film according to any one of claims 1 to 4, wherein the tensile modulus of elasticity at 120°C is 30 to 500 MPa.

6. A process release film according to any one of claims 1 to 5, wherein the tensile modulus of elasticity at 170°C is 20 to 400 MPa.

7. A process for manufacturing a metal embossed roll by blasting the surface of a metal roll with particles of 40 to 100 mesh size, and A process of passing a film between the metal embossing roll and another roll to form irregularities on the surface of the film, A method for manufacturing a process release film according to any one of claims 1 to 6, comprising:

8. A process release film according to any one of claims 1 to 6, used in a semiconductor encapsulation process.

9. A method for manufacturing a resin-encapsulated semiconductor, A step of placing a semiconductor device to be resin-sealed in a predetermined position within a molding die, A step of placing the process release film according to any one of claims 1 to 6 on the inner surface of the molding die such that the surface having the irregularities and having an Sdr (unfolded surface area ratio) of 4.0 to 50.0% faces the inner surface of the molding die, A step of degassing the space between the release film for the process and the inner surface of the mold, After clamping the molding die, the process involves curing the sealing resin placed between the semiconductor device and the release film for the semiconductor encapsulation process. A method for manufacturing the resin-encapsulated semiconductor having the above-mentioned characteristics.

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