JP2020019263A - Mold release film for resin sealing process by compression molding method - Google Patents

Abstract

To provide a mold release film for process capable of easily releasing a molded product after resin sealing without depending on a mold structure and a mold release agent and the like, and capable of obtaining a molded product without a poor appearance such as a wrinkle and chipping of resin, in a step for resin sealing a semiconductor chip and the like by a compression molding method.SOLUTION: A mold release film for process is used for a resin sealing process by a compression molding method. A contact angle of at least one surface to water is 90°-130°. A tensile strength is 1.0 MPa-10.0 MPa when the film is elongated by 37.5% at 175°C, 100 mm/min in the MD direction (flow direction of the film). A resilience (%) is 30-80% obtained from a return value, being a displacement obtained until a load becomes zero when returned toward an original point at 100 mm/min in the compression direction, after 2 min of standstill after 37.5% elongation in the MD direction in the same condition.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a process release film used in a resin sealing process by a compression molding method, and more preferably, when arranging a semiconductor chip or the like in a mold and injecting resin, the semiconductor chip or the like is used. The present invention relates to a process release film disposed between a mold inner surface and a process release film, wherein peeling failure after sealing is effectively suppressed.

In a method of manufacturing a semiconductor element or the like, as a method of sealing a semiconductor chip or the like with a resin, the semiconductor chip or the like is arranged so as to be located at a predetermined position in a mold, and the mold is filled with a curable resin. Transfer molding or compression molding is known.
In recent years, large-capacity NAND flash memories have been increasing. This type of element has a large overall thickness because memory chips are stacked in multiple stages. Therefore, the cavity of the mold for manufacturing the same is becoming deeper. When a release film is used by the compression molding method, the release film disposed on the surface of the mold is stretched once and then contracted, and thus there is a problem that the release film is wrinkled. The problem of wrinkles becomes more pronounced as the mold cavity becomes deeper, and in some cases, a phenomenon occurs in which the wrinkled release film does not bite into the curable resin and does not release. That is, in the manufacturing process of a device having a large thickness such as a large-capacity NAND flash memory, the problems of peeling failure and appearance failure due to wrinkles are more serious, and a solution to the problem has been strongly demanded.
As a countermeasure for preventing a peeling defect or a defective appearance when a semiconductor chip or the like is sealed with a resin, improvement of a mold design has been proposed (for example, see Patent Document 1). However, since this countermeasure complicates the structure of the mold and limits the degree of freedom in designing the mold, it is preferable to take measures against peeling failure with a release film for a process as much as possible.
In order to prevent wrinkles during expansion and contraction, it has been proposed to use an ethylene-tetrafluoroethylene copolymer film having specific physical properties as a release film for processing (for example, see Patent Document 2). However, there is room for further improvement in preventing peeling failure.

JP 2005-225133 A WO2018 / 008562 A1 pamphlet

  The present invention, in view of the above-described limitations of the conventional technology, depends on a mold structure, a release agent, and the like, in a step of resin-sealing an article such as a semiconductor chip by a compression molding method, in a step of resin-sealing the article. An object of the present invention is to provide a release film for a process, which can be easily released without a mold, and can obtain a molded article free from appearance defects such as wrinkles and chipped resin.

The present inventor has studied as a result, the tensile strength when the film is stretched under specific conditions, and the recovery rate of the film length when the load is removed thereafter, the wrinkles when the film is stretched. They found that the film had a close relationship with the occurrence, and succeeded in specifying a film capable of effectively suppressing the peeling failure and the appearance failure using the knowledge, and completed the present invention.
That is, the present invention
[1] A process release film used for a resin sealing process by a compression molding method, wherein a contact angle of at least one surface to water is 90 ° to 130 °,
A tensile strength of 1.0 MPa to 10.0 MPa when the film is stretched by 37.5% at 100 mm / min at a temperature of 175 ° C. in an MD direction (flow direction of the film);
And after 37.5% elongation in the MD direction under the same conditions, after resting for 2 minutes in the compression direction and returning to the origin direction at 100 mm / min in the compression direction, the following expression ( 1) The process release film, wherein a restoration rate (%) obtained according to the formula is 30 to 80 (%).
Return value / extended length × 100 = restoration rate% (1).

The following [2] to [10] are all preferable aspects or embodiments of the present invention.
[2]
The release film for processing according to [1], wherein a difference between an initial depth of the cavity and a final depth of the cavity is 1.0 mm or more in the resin sealing process by the compression molding method.
[3]
The release film for process according to [1] or [2], wherein the resin thickness after sealing is 0.5 mm or more in the resin sealing process by the compression molding method.
[4]
The process release film according to any one of [1] to [3], wherein a maximum temperature in the resin sealing process by the compression molding method is 110 to 190 ° C.
[5]
The sealing resin used in the resin sealing process by the compression molding method, wherein the sealing resin contains at least one resin selected from the group consisting of an epoxy resin, a polyimide resin, and a silicone resin, [1] to [4]. The release film for a process according to any one of the above.
[6]
The process release film according to any one of [1] to [5], wherein the semiconductor chip is sealed in the resin sealing process by the compression molding method.
[7]
The process according to any one of [1] to [6], including a release layer A and a heat-resistant resin layer B, wherein the at least one surface is constituted by a surface of the release layer A. Release film.
[8]
Any of [1] to [7], wherein the release layer A contains at least one resin selected from the group consisting of a fluororesin, a 4-methyl-1-pentene (co) polymer, and a polystyrene-based resin. The release film for a process according to claim 1.
[9]
It further has a release layer A ′, and the release layer A, the heat-resistant resin layer B, and the release layer A ′ are laminated in this order, and the release layer A and the release layer The release film for processing according to any one of [1] to [8], wherein the contact angle of the mold layer A ′ with water is 90 ° to 130 °.
[10]
[9] The release layer A 'includes a resin including at least one resin selected from the group consisting of a fluororesin, a 4-methyl-1-pentene (co) polymer, and a polystyrene-based resin. Release film for process.
The above object is also achieved by the second invention of the following [11].
[11] A process release film used for a resin sealing process by a compression molding method, wherein a contact angle of at least one surface of the film with water is 90 ° to 130 °, and the release layer A is heat-resistant. A heat-resistant resin layer B at a temperature of 175 ° C. at a rate of 100 mm / min in the MD direction (flow direction of the film). After the elongation of 0.5%, after resting for 2 minutes after returning to the origin at 100 mm / min in the compression direction, the restoration obtained from the return value, which is the displacement until the load becomes 0, is obtained according to the following equation (1). The release film for a process, wherein the rate (%) is 30 to 80 (%);
Return value / extended length × 100 = restoration rate% (1).
In addition, as preferable aspects and embodiments of the second invention of the present application, at least a part of the technical matters described in the above [1] to [10] is appropriately added to the second invention of the present invention described in [11], Can be mentioned.

  ADVANTAGE OF THE INVENTION According to the process release film of this invention, in the process of resin-sealing a semiconductor chip etc. by a compression molding method, the molded product after resin sealing can be easily separated without depending on the mold structure or the amount of the release agent. A remarkable technical effect having a high practical value that a molded article can be formed and a molded article free from appearance defects such as wrinkles and chipped resin can be obtained.

It is a schematic diagram which shows an example of the resin sealing process of a semiconductor chip using the process release film of this invention. It is a schematic diagram which shows the test method of the peeling state after shaping | molding in the Example / comparative example of this invention. It is a schematic diagram which shows the test method of the film tension test in the Example / comparative example of this invention, and the return value evaluation of a film elongation. It is a schematic diagram of the film tension test and the return value evaluation of a film elongation in the Example / comparative example of this invention.

Process release film The present invention is a process release film used for a resin sealing process by a compression molding method, wherein a contact angle of at least one surface to water is 90 ° to 130 °,
A tensile strength of 1.0 MPa to 10.0 MPa when the film is stretched by 37.5% at 100 mm / min at a temperature of 175 ° C. in an MD direction (flow direction of the film);
And after 37.5% elongation in the MD direction under the same conditions, after resting for 2 minutes in the compression direction and returning to the origin direction at 100 mm / min in the compression direction, the following expression ( 1) The process release film, wherein a restoration rate (%) obtained according to the formula is 30 to 80 (%).
Return value / extended length × 100 = restoration rate% (1).

As described above, the process release film of the present invention has a water contact angle of at least one surface of 90 ° to 130 °. When the contact angle of at least one surface to water is within the above range, the process release film of the present invention is excellent in releasability from the sealing resin.
The process release film of the present invention has a water contact angle of at least one surface of preferably from 95 ° to 120 °, more preferably from 98 ° to 115 °, even more preferably from 100 ° to 110 °. is there.
In the process release film of the present invention, it is preferable that the contact angles with respect to water on both surfaces satisfy the above condition. When the contact angles of both surfaces with water satisfy the above conditions, it is possible to realize a process release film having excellent releasability from both the sealing resin and the mold.
The contact angle of the film surface with water may be measured by a usual method in the art, and for example, can be measured by the method described in Examples of the present application.

  The process release film of the present invention is formed of a resin whose contact angle with water satisfies the above condition such that the contact angle with water satisfies the above condition so that the contact angle of at least one surface with water satisfies the above condition. It is preferable to include a resin selected from the group consisting of (co) polymers and polystyrene-based resins, or to be formed of such a resin. Further, when the process release film of the present invention is a multilayer film, at least one layer constituting the surface is formed of a fluororesin, a 4-methyl-1-pentene (co) polymer, and a polystyrene resin. It is also preferable to use a resin selected from the group consisting of:

Similarly, as described above, the process release film of the present invention is such that the process release film of the present invention elongates at a temperature of 175 ° C. in the MD direction (film flow direction) at 100 mm / min by 37.5%. The tensile strength at the time of this is 1.0 MPa to 10.0 MPa.
When the tensile strength is within the above range, the process release film of the present invention can effectively suppress problems such as breakage and wrinkles in the resin sealing process.
The upper limit of the tensile strength of the release film for process of the present invention in the MD direction (the flow direction of the film) at a temperature of 175 ° C. and a stretch of 37.5% at 100 mm / min is 9.0 MPa. , And more preferably 8.0 MPa. Further, the lower limit of the tensile strength of the release film for process of the present invention in the MD direction (the flow direction of the film) at a temperature of 175 ° C. and a 37.5% elongation at 100 mm / min is 2.0 MPa. It is preferably, more preferably, 4.0 MPa, and even more preferably, 6.0 MPa.
Further, it is more preferable that the above conditions are satisfied in both the MD direction and the TD direction orthogonal to the MD direction.
The tensile strength of the film can be measured by a method conventionally known in the art, for example, by the method described in Examples of the present application.
The tensile strength of the release film for process of the present invention can be adjusted by appropriately setting the material, thickness, and production conditions of the film, particularly, stretching and heat treatment conditions. Further, when the process release film of the present invention is a multilayer film, it can be adjusted by appropriately combining the materials, thicknesses, production conditions and the like of the films constituting each layer.

Similarly, as described above, the release film for processing of the present invention at a temperature of 175 ° C., elongation of 37.5% in the MD direction at 100 mm / min, after standing still for 2 minutes, and then in the compression direction at the origin direction at 100 mm / min. When it is returned, the restoration rate (%) obtained from the return value, which is the displacement until the load becomes 0, according to the following equation (1) is 30 to 80 (%).
Return value / extended length × 100 = restoration rate% (1).
When the restoration rate satisfies the above condition, the release film for a process of the present invention can be separated by biting of the release film while effectively suppressing problems such as breakage and poor appearance of the molded product in the resin sealing process. Defects can be effectively prevented.
The restoration rate is preferably at least 43%, particularly preferably at least 45%.
Further, it is more preferable that the above conditions are satisfied in both the MD direction and the TD direction orthogonal to the MD direction.

FIG. 3 schematically shows a method of measuring the return value.
First, a film to be measured, is set at a chuck distance L ₀ to the tester can perform tensile tests such as Tensilon universal testing machine (Figure 3 (a)).
Next, a tensile stress is applied between the chucks at a temperature of 175 ° C., and elongation is performed at 100 mm / min by 37.5% (elongation ΔL ₁ = L ₀ × 0.375) (FIG. 3B).
After stationary as 2 minutes, when reconstituted with 100 mm / min (the direction opposite to the extension) compression direction, load is the return value [Delta] L ₂ mutations of points becomes 0 (Figure 3 (c)).
From the above measurement results, the restoration rate is calculated according to the following equation.
Restoration rate (%) = 100 × ΔL ₂ / ΔL ₁
FIG. 4 schematically shows the relationship between the load and the displacement obtained thereby.

When the restoration rate is within the above range, the mechanism for effectively preventing the peeling failure due to the bite of the release film is not necessarily clear, but, for example, a step in the resin sealing process as shown in FIG. It is presumed that there is some relationship.
More specifically, compared to immediately after the process release film is placed on the lower mold (FIG. 2A), after the vacuum suction step (FIG. 2B), the process release film is released. The mold film is stretched, for example, twice (2 × a ₁ ) the initial cavity depth.
Thereafter, when the mold is clamped and compressed, the process release film is returned to the compression direction (the direction opposite to the elongation), and the cavity depth is reduced to, for example, about 1/3 of the initial value. You. At this time, if the restoration rate is extremely small compared to the reduction rate of the cavity depth (a ₁ −a ₂ ) / a ₁ , wrinkles are likely to be generated in the release film on the side surface of the cavity, and as a result, the sealing resin and It is presumed that there is some relationship with the fact that it can act in a direction in which biting easily occurs.

  The restoration rate of the release film for process of the present invention can be adjusted by appropriately setting the material, thickness, and production conditions of the film, particularly, stretching and heat treatment conditions. Further, when the process release film of the present invention is a multilayer film, it can be adjusted by appropriately combining the materials, thicknesses, production conditions and the like of the films constituting each layer.

The process release film of the present invention may be a single-layer film or a multilayer film as long as the above-described required characteristics are provided. From the viewpoint of preparation, a multilayer film having a high degree of freedom in design is preferable.
Although there is no particular limitation on the film configuration in the case of a multilayer film, a laminated film including a release layer A having releasability from a molded product or a mold, and a heat-resistant resin layer B supporting the release layer A. It is preferred that In this embodiment, at least one surface of the process release film having a contact angle with water of 90 ° to 130 ° is constituted by the release layer A.
The process release film of this embodiment may further have a release layer A ′, if desired. At this time, the release layer A, the heat-resistant resin layer B, and the release layer A ′ It is preferable that the layers are stacked in this order. Further, at this time, the contact angle of the release layer A ′ with water is preferably from 90 ° to 130 °.

The process release film of the present embodiment is disposed on the inner surface of the molding die when the semiconductor element or the like is resin-sealed inside the molding die by a compression molding method. At this time, it is preferable that the release layer A of the release film (or the release layer A 'when the release layer A' is present) is disposed on the sealing resin side. By disposing the release film of this embodiment, the resin-sealed semiconductor element or the like can be easily released from the mold.
The contact angle of the release layer A with water is from 90 ° to 130 °, and by having such a contact angle, the release layer A has low wettability and adheres to the cured sealing resin or the mold surface. Thus, the molded product can be easily released from the mold.
The contact angle of the release layer A with water is preferably 95 ° to 120 °, more preferably 98 ° to 115 °, and even more preferably 100 ° to 110 °.

Release layer A
The release layer A constituting the process release film of the preferred embodiment has a contact angle with water of 90 ° to 130 °, preferably 95 ° to 120 °, more preferably 98 ° to 115 °. °, more preferably 100 ° to 110 °. It is preferable to include a resin selected from the group consisting of a fluororesin, a 4-methyl-1-pentene (co) polymer, and a polystyrene-based resin, from the viewpoint of excellent mold release properties of the molded article, easy availability, and the like.

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

  The 4-methyl-1-pentene (co) polymer that can be used for the release layer A may be a homopolymer of 4-methyl-1-pentene, or 4-methyl-1-pentene; It may be a copolymer with another olefin having 2 to 20 carbon atoms (hereinafter referred to as "olefin having 2 to 20 carbon atoms").

In the case of a copolymer of 4-methyl-1-pentene and an olefin having 2 to 20 carbon atoms, the olefin having 2 to 20 carbon atoms to be copolymerized with 4-methyl-1-pentene is 4-methyl -1- It can impart flexibility to pentene. Examples of the olefin 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, -Octadecene, 1-eicosene and the like. These olefins may be used alone or in combination of two or more.

  In the case of a copolymer of 4-methyl-1-pentene and an olefin having 2 to 20 carbon atoms, the proportion of structural units derived from 4-methyl-1-pentene is 96 to 99% by mass, and Is preferably 1 to 4% by mass of a structural unit derived from an olefin having 2 to 20 carbon atoms. By reducing the content of the constituent unit derived from an olefin having 2 to 20 carbon atoms, the copolymer can be hardened, that is, the storage elastic modulus E ′ can be increased, and the generation of wrinkles in a sealing step or the like can be suppressed. Is advantageous. On the other hand, by increasing the content of the constituent unit derived from an olefin having 2 to 20 carbon atoms, the copolymer can be softened, that is, the storage elastic modulus E ′ can be reduced, and the mold followability can be improved. Is advantageous.

  The 4-methyl-1-pentene (co) polymer can be prepared by methods known to those skilled in the art. For example, it can be produced by a method using a known catalyst such as a Ziegler-Natta catalyst or a metallocene catalyst. The 4-methyl-1-pentene (co) polymer is preferably a (co) polymer having high crystallinity. As the crystalline copolymer, any of a copolymer having an isotactic structure and a copolymer having a syndiotactic structure may be used. In particular, the copolymer having an isotactic structure may be used. Is also preferable from the viewpoint of physical properties, and is easily available. Furthermore, if the 4-methyl-1-pentene (co) polymer can be formed into a film and has strength enough to withstand the temperature, pressure, and the like during molding, the stereoregularity and the molecular weight are also particularly limited. Not done. The 4-methyl-1-pentene copolymer may be, for example, a commercially available copolymer such as TPX (registered trademark) manufactured by Mitsui Chemicals, Inc.

The polystyrene-based resin that can be used for the release layer A includes a homopolymer and a copolymer of styrene, and the structural unit derived from styrene contained in the polymer is at least 60% by weight or more. Preferably, it is more preferably at least 80% by weight.
The polystyrene resin may be isotactic polystyrene or syndiotactic polystyrene, but is preferably isotactic polystyrene from the viewpoint of transparency, availability, etc., and has releasability, heat resistance, etc. From the viewpoint of, syndiotactic polystyrene is preferred. One type of polystyrene may be used alone, or two or more types may be used in combination.

The release layer A preferably has heat resistance that can be maintained at the maximum temperature of the mold during molding (typically 110 to 190 ° C.). From this viewpoint, the release layer A preferably contains a crystalline resin having a crystalline component, and the melting point of the crystalline resin is preferably 190 ° C. or higher, more preferably 200 ° C. or higher and 300 ° C. or lower.
In order to impart crystallinity to the release layer A, for example, it is preferable that a fluorine resin contains at least a structural unit derived from tetrafluoroethylene, and a 4-methyl-1-pentene (co) polymer is 4-methyl-1 -It is preferable to include at least a structural unit derived from pentene, and in a polystyrene-based resin, it is preferable to include at least syndiotactic polystyrene. Since the resin constituting the release layer A contains a crystal component, wrinkles hardly occur in the resin sealing step and the like, and it is suitable for suppressing the occurrence of appearance defects due to transfer of wrinkles to a molded product. .

  The resin containing the crystalline component constituting the release layer A has a heat of crystal fusion in the first heating step measured by differential scanning calorimetry (DSC) according to JIS K7221 of 15 J / g or more and 60 J / g or less. Is more preferable, and it is more preferable that it is 20 J / g or more and 50 J / g or less. When it is 15 J / g or more, in addition to being able to more effectively develop heat resistance and mold releasability that can withstand hot press molding in a resin sealing step and the like, it is also necessary to suppress a dimensional change rate. Therefore, the occurrence of wrinkles can be prevented. On the other hand, when the heat of crystal fusion is 60 J / g or less, since the release layer A has an appropriate hardness, sufficient followability of the film to the mold in the resin sealing step or the like can be obtained. There is no risk of damage to the film.

  The release layer A may further contain another resin in addition to the fluororesin, the 4-methyl-1-pentene copolymer, and / or the polystyrene resin. In this case, it is preferable that the hardness of the other resin is relatively high. Examples of other resins include polyamide-6, polyamide-66, polybutylene terephthalate, polyethylene terephthalate. As described above, even when the release layer A contains a large amount of a soft resin (for example, a case where the 4-methyl-1-pentene copolymer contains a large amount of an olefin having 2 to 20 carbon atoms), the release layer A has a relatively high hardness. By further containing a high resin, the release layer A can be hardened, which is advantageous for suppressing generation of wrinkles in a sealing step or the like.

  The content of these other resins is preferably, for example, 3 to 30% by mass based on the resin components constituting the release layer A. By setting the content of the other resin to 3 mass% or more, the effect of the addition can be made substantial, and by setting the content to 30 mass% or less, the mold releasability to a mold or a molded product is maintained. be able to.

  In addition, the release layer A may include, in addition to the fluororesin, the 4-methyl-1-pentene copolymer, and / or the polystyrene resin, a heat-resistant stabilizer, a weather-resistant stabilizer, and a heat-resistant stabilizer as long as the object of the present invention is not impaired. Known additives that are generally blended with film resins, such as rust inhibitors, copper damage stabilizers, and antistatic agents, may be included. The content of these additives can be, for example, 0.0001 to 10 parts by weight based on 100 parts by weight of the fluororesin, 4-methyl-1-pentene copolymer, and / or polystyrene resin.

  The thickness of the release layer A is not particularly limited as long as the release property from the molded product is sufficient, but is usually 1 to 50 μm, preferably 5 to 30 μm.

The surface of the release layer A may have a concavo-convex shape as needed, whereby the releasability can be improved. The method of providing the surface of the release layer A with irregularities is not particularly limited, but a general method such as embossing can be employed.

Release layer A '
The process release film of the above embodiment may further 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 the present embodiment may be a process release film that is a laminated film including the release layer A, the heat-resistant resin layer B, and the release layer A ′ in this order.
The contact angle with water of the release layer A ′ which may constitute the release film for a process of the present invention is from 90 ° to 130 °, preferably from 95 ° to 120 °, more preferably from 98 °. It is 115 °, more preferably 100 ° to 110 °. The preferable material, configuration, physical properties, and the like of the release layer A ′ are the same as those described above for the release layer A.

When the release film for a process is a laminated film including the release layer A, the heat-resistant resin layer B, and the release layer A ′ in this order, the release layer A and the release layer A ′ are the same. It may be a layer having a configuration or a layer having a different configuration.
From the viewpoint of prevention of warpage and ease of handling due to having the same releasability on both surfaces, the release layer A and the release layer A ′ may have the same or substantially the same configuration. Preferably, the viewpoint of optimally designing each in relation to the process using the release layer A and the release layer A ′, for example, the release layer A is made to have excellent releasability from the mold, It is preferable that the release layer A and the release layer A 'have different configurations from the viewpoint of making the layer A' excellent in the releasability from the molded product.
When the release layer A and the release layer A ′ have different configurations, the release layer A and the release layer A ′ may be made of the same material and have different configurations such as thickness. However, the material and other configurations may be different.

Heat resistant resin layer B
The heat-resistant resin layer B constituting the process release film of the above embodiment has a function of supporting the release layer A (and, in some cases, the release layer A ′) and suppressing the occurrence of wrinkles due to mold temperature and the like. Is preferred.

In the release film for process of the present embodiment, the heat-resistant resin layer B elongates at a temperature of 175 ° C. at 37.5% at 100 mm / min, then stands still for 2 minutes, and then returns to the origin at 100 mm / min in the compression direction. In this case, it is preferable that the restoration rate (%) obtained from the return value that is the displacement until the load becomes 0 according to the following equation (1) is 30 (%) or more.
Return value / extended length × 100 = restoration rate% (1).
When the restoration rate of the heat-resistant resin layer B satisfies the above condition, the process release film of the present embodiment can easily have a predetermined restoration rate, and the process release film is formed by a resin sealing process. It is much easier to prevent peeling failure due to biting of the release film while effectively suppressing problems such as tearing and poor appearance of the molded article.
The restoration ratio of the heat-resistant resin layer B is preferably at least 40%, more preferably at least 45%, particularly preferably at least 50%.
In the process release film of the present embodiment, the restoration rate preferably satisfies the above condition in the MD direction of the heat-resistant resin layer B, and the restoration rate satisfies the above condition in the direction corresponding to the MD direction of the process release film. More preferably, it is satisfied. It is more preferable that the above conditions be satisfied in both the MD direction and the TD direction.

  As the heat-resistant resin layer B, any resin layer including a non-stretched film and a stretched film can be used.

  Among the non-stretched films, it is preferable that the resin has an elastomeric property from the viewpoint of the above-mentioned restoration rate. Examples of the resin having an elastomer property include a thermoplastic elastomer and silicone. These may be used alone or in combination of two or more. Among these, those having thermoplasticity are preferred, and thermoplastic elastomers are particularly preferred.

  The thermoplastic elastomer may be composed of a block copolymer having a hard segment and a soft segment, or may be composed of a polymer alloy of a hard polymer and a soft polymer, and has both of these properties. Is also good.

  The properties related to the restoration rate of the heat-resistant resin layer B can be controlled by adjusting these components. That is, it can be controlled by adjusting the type of resin, the ratio of the resins when plural types of resins are contained, and the molecular structure of the polymer constituting the resin (the ratio of the hard segment and the soft segment).

Examples of the thermoplastic elastomer include polyester-based thermoplastic elastomer (thermoplastic polyester elastomer), polyamide-based thermoplastic elastomer (thermoplastic polyamide elastomer), styrene-based thermoplastic elastomer (thermoplastic styrene elastomer), and olefin-based thermoplastic elastomer (thermoplastic elastomer). (Polyolefin elastomer), vinyl chloride thermoplastic elastomer (thermoplastic vinyl chloride elastomer), polyimide thermoplastic elastomer 系 thermoplastic polyimide elastomer, polyimide ester thermoplastic elastomer (thermoplastic polyimide ester elastomer), polyimide urethane thermoplastic elastomer ( Thermoplastic polyimide urethane elastomer), polyurethane thermoplastic elastomer (thermoplastic polyurethane elastomer), etc. And the like. These may be used alone or in combination of two or more.
Among these, polyester-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, polyimide-based thermoplastic elastomers, and polyurethane-based thermoplastic elastomers are preferable, and further, polyester-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, and polyurethane-based thermoplastic elastomers Elastomers are particularly preferred.

  The polyester-based thermoplastic elastomer may be any as long as it has a polyester component as a hard segment, and may have any other configuration. As the soft segment, polyester, polyether, polyetherester, and the like can be used. These may be used alone or in combination of two or more. The polyester component constituting the hard segment can include a structural unit derived from a monomer such as dimethyl terephthalate. On the other hand, components constituting the soft segment can include structural units derived from monomers such as 1,4-butanediol and poly (oxytetramethylene) glycol. More specifically, a PBT-PE-PBT type polyester thermoplastic elastomer is exemplified. In the description of the above “PBT-PE-PBT”, PBT means polybutylene terephthalate, and PE means polyether.

  The polyamide-based thermoplastic elastomer only needs to have a polyamide component as a hard segment, and may have any other configuration other than the above. As the soft segment, polyester, polyether, polyetherester, and the like can be used. These may be used alone or in combination of two or more. Examples of the polyamide component constituting the hard segment include polyamide 6, polyamide 11 and polyamide 12. These may be used alone or in combination of two or more. Various lactams and the like can be used as monomers for these polyamide components. On the other hand, the component constituting the soft segment may include a monomer such as dicarboxylic acid or a structural unit derived from polyether polyol. Among them, the polyether polyol is preferably a polyether diol, and examples thereof include poly (tetramethylene) glycol and poly (oxypropylene) glycol. These may be used alone or in combination of two or more. More specifically, examples thereof include a polyetheramide-type polyamide-based thermoplastic elastomer, a polyesteramide-type polyamide-based thermoplastic elastomer, and a polyetheresteramide-type polyamide-based thermoplastic elastomer.

The polyurethane-based thermoplastic elastomer only needs to have a polyurethane component as a hard segment, and may have any other configuration. As the soft segment, polyester, polyether, polyetherester, polycarbonate and the like can be used. These may be used alone or in combination of two or more.
The polyurethane component constituting the hard segment can include a structural unit derived from polyurethane obtained by reacting a short-chain glycol (low-molecular polyol) with an isocyanate. Here, polyurethane is a general term for compounds having a urethane bond (-NHCOO-) obtained by a polyaddition reaction (urethane-forming reaction) between isocyanate (-NCO) and alcohol (-OH). More specifically, examples thereof include a polyester-type polyurethane-based thermoplastic elastomer, a polyether-type polyurethane-based thermoplastic elastomer, and a polycarbonate-type polyurethane-based thermoplastic elastomer.

  Since the stretched film can be made into a film base material that exhibits elasticity by using a restoring force due to elasticity by making the film stretched in the in-plane direction, the restoring rate is 30% or more. Since it is relatively easy to realize the preferable characteristics described above, it can be suitably used as the heat-resistant resin layer B.

The stretched film may be a uniaxially stretched film or a biaxially stretched film. In the case of a uniaxially stretched film, any of longitudinal stretching and transverse stretching may be used.
The method and apparatus for obtaining the above-mentioned stretched film are not particularly limited, and stretching may be performed by a method known in the art. For example, stretching can be performed with a heating roll or a tenter-type stretching machine.

  As the stretched film, it is preferable to use a stretched film selected from the group consisting of a stretched polyester film, a stretched ethylene-vinyl alcohol copolymer film, a stretched polyamide film, a stretched polyethylene film, and a stretched polypropylene film. These stretched films are particularly suitable as stretched films in the heat-resistant resin layer B because their mechanical properties are suitable for the use of the present invention and they are relatively easy to obtain at low cost.

As the stretched polyester film, a stretched polybutylene terephthalate (PBT) film and a stretched polyethylene terephthalate (PET) film are preferable, and a biaxially stretched polybutylene terephthalate (PBT) film is particularly preferable.
The polyamide constituting the stretched polyamide film is not particularly limited, but polyamide-6, polyamide-66 and the like can be preferably used.
As the stretched polyethylene film, a uniaxially stretched polyethylene film, a biaxially stretched polyethylene film, or the like can be preferably used.
As the stretched polypropylene film, a uniaxially stretched polypropylene film, a biaxially stretched polypropylene film, or the like can be preferably used.
There is no particular limitation on the stretching ratio, and the thermal dimensional change rate is appropriately controlled, and an appropriate value may be appropriately set in order to realize suitable mechanical properties. It is preferably in the range of up to 10.0 times.

  The heat-resistant resin layer B has a heat resistance that can be maintained at the maximum temperature of the mold at the time of molding (typically 110 to 190 ° C.) from the viewpoint of controlling the strength of the film and the rate of change in the thermal dimension within an appropriate range. It is preferred to have. From this viewpoint, the heat-resistant resin layer B preferably contains a crystalline resin having a crystalline component, and the melting point of the crystalline resin is preferably 100 ° C or higher, more preferably 140 ° C or higher and 300 ° C or lower. The temperature is more preferably from 150 to 270 ° C, and particularly preferably from 170 to 240 ° C. The melting point does not necessarily need to be higher than the maximum temperature of the mold at the time of molding. The melting point can be measured by a thermal analysis method (DSC method). If a plurality of melting peaks are detected, the melting point is determined from the melting peak at the highest temperature.

As described above, the heat-resistant resin layer B preferably contains a crystalline resin having a crystalline component. As the crystalline resin to be contained in the heat-resistant resin layer B, for example, a crystalline resin such as a polyester resin, an ethylene-vinyl alcohol copolymer resin, a polyamide resin, a polyethylene resin, and a polypropylene resin can be partially or entirely used. Specifically, polyester resin is polybutylene terephthalate or polyethylene terephthalate, polyamide resin is polyamide 6 or polyamide 66, and polyethylene resin is high density polyethylene, low density polyethylene, linear low density polyethylene, ultra high molecular weight polyethylene, polypropylene. It is preferable to use isotactic polypropylene as the resin. It is particularly preferable to include at least one resin selected from the group consisting of polybutylene terephthalate and ethylene-vinyl alcohol copolymer.
By including the crystalline component of the crystalline resin in the heat-resistant resin layer B, it is more advantageous to achieve the predetermined tensile strength and restoration rate of the present invention. In addition, wrinkles are less likely to occur in the resin sealing step and the like, and it is more advantageous to suppress transfer of the wrinkles to the molded product to cause poor appearance.

  The thickness of the heat-resistant resin layer B is not particularly limited as long as the film strength can be secured, but is usually 1 to 200 μm, preferably 5 to 100 μm, and particularly preferably 10 to 50 μm.

As another means for solving the problem of the present application, a process release film used for a resin sealing process by a compression molding method, wherein a contact angle of at least one surface to water is 90 ° to 130 °. Yes, it includes at least a release layer A and a heat-resistant resin layer B, the at least one surface is constituted by the surface of the release layer A, and the restoration rate of the heat-resistant resin layer B is 30 to 80 (%). A certain release film for a process may be used (hereinafter, also referred to as “the second invention of the present application”).
Here, the restoration rate of the heat-resistant resin layer B is such that the heat-resistant resin layer B alone (in a non-laminated state) elongates in the MD direction at a temperature of 175 ° C. at 100 mm / min in the MD direction, stands still for 2 minutes, and then compresses in the compression direction. Is returned according to the following equation (1) from the return value, which is the displacement until the load becomes 0, when returned to the origin at 100 mm / min.
Return value / extended length × 100 = restoration rate% (1)
The restoration ratio of the heat-resistant resin layer B is preferably 40% or more, more preferably 45% or more, and particularly preferably 50% or more.
The heat-resistant resin layer B constituting the second invention of the present application has a tensile strength in the MD direction of 1.0 MPa to 30.0 MPa when stretched at 175 ° C. and 37.5% at 100 mm / min at a temperature of 175 ° C. Is preferred. The tensile strength is more preferably from 5.0 MPa to 25.0 MPa, and particularly preferably from 10.0 MPa to 20.0 MPa.

The process release film of the second invention of the present application may or may not have the requirements described so far for the process release film of the present invention. For example, the restoration rate in the MD direction of the entire laminated film may be within a range of 30 to 80 (%), or may be outside the range. Further, the tensile strength in the MD direction of the entire laminated film may be in the range of 1.0 MPa to 10.0 MPa, or may be out of the range.
From the viewpoint of efficiently solving the problems of the present application, it is preferable that the process release film of the second invention of the present application has at least a part of the requirements for the present invention, and all of the requirements for the present invention are satisfied. It is particularly preferred to have it.

Further, the process release film of the second invention of the present application may or may not include some or all of the preferable technical features described in the specification of the present invention.
From the viewpoint of efficiently solving the problem of the present application, the process release film of the second invention of the present application has at least a part of preferable technical features described in the specification of the present invention. preferable.

Other Layers The process release film of the present embodiment may have a layer other than the release layer A, the heat-resistant resin layer B, and the release layer A ′, as long as the object of the present invention is not contravened. For example, an adhesive layer or a cushion layer may be provided between the release layer A (or the release layer A ′) and the heat-resistant resin layer B as necessary. 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 in the resin sealing step or the release step. The material used for the cushion layer is not particularly limited as long as it can follow steps without breaking the film so that it can smoothly follow irregularities on a mold or a molded product.

For example, when the release layer A (or the release layer A ′) contains a 4-methyl-1-pentene copolymer, the adhesive layer is made of modified 4-methyl-1 graft-modified with an unsaturated carboxylic acid or the like. -Pentene-based copolymer resin, olefin-based adhesive resin composed of 4-methyl-1-pentene-based copolymer and α-olefin-based copolymer, and the like are preferable. When the release layer A (or the release layer A ′) contains a fluororesin, the adhesive layer is preferably a polyester-based, acrylic-based, fluororubber-based adhesive, or the like. The thickness of the adhesive layer is not particularly limited as long as the adhesiveness between the release layer A (or the release layer A ′) and the heat-resistant resin layer B can be improved, but is, for example, 0.5 to 10 μm.
Further, for example, the cushion layer is preferably made of polyethylene resin, polypropylene resin, α-olefin-based copolymer, polyester-based, acrylic-based, fluororubber-based, or the like. The thickness of the cushion layer is not particularly limited as long as the cushioning property that can satisfy the desired step followability is obtained, but is preferably, for example, 10 to 250 μm.

  The total thickness of the process release film of the present invention is not particularly limited, but is preferably, for example, 10 to 300 μm, and more preferably 30 to 150 μm. When the total thickness of the release film is in the above range, the handleability when used as a roll is good, and the amount of the film to be discarded is small.

Process for producing process release film The process release film of the present invention can be produced by any method.
When the process release film of the present invention is a single-layer film, the process release film of the present invention can be manufactured by a conventionally known film manufacturing method such as an extrusion method or a stretching method.
Further, when the process release film of the present invention is a multilayer film, for example, a multilayer film including a release layer A and a heat-resistant resin layer B, for example, 1) co-extrusion molding of the release layer A and the heat-resistant resin layer B 2) A method of manufacturing a release film for process (coextrusion forming method) by laminating and laminating. 2) A molten resin of a release layer A and a resin to be an adhesive layer is applied on a film to be a heat resistant resin layer B. A method of producing a process release film by drying or applying and drying a resin solution obtained by dissolving a resin to be a release layer A or an adhesive layer in a solvent (application method); 3) A method of manufacturing a release film for a process (lamination method) by manufacturing a film to be a release layer A and a film to be a heat-resistant resin layer B, and laminating (laminating) these films. Can be adopted .

In the method 3), as a method for laminating the resin films, various known laminating methods can be adopted, and examples thereof include an extrusion laminating method, a dry laminating method, and a heat laminating method.
In the dry lamination method, each resin film is laminated using an adhesive. As the adhesive, those known as adhesives for dry lamination can be used. For example, a polyvinyl acetate adhesive; a homopolymer or a copolymer of an acrylate ester (ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, etc.), or an acrylate ester and another monomer (methacrylic acid) Polyacrylic ester adhesives comprising copolymers with methyl, acrylonitrile, styrene, etc.); cyanoacrylate adhesives; ethylene and other monomers (vinyl acetate, ethyl acrylate, acrylic acid, methacrylic acid) Ethylene copolymer-based adhesive comprising a copolymer or the like; a cellulose-based adhesive; a polyester-based adhesive; a polyamide-based adhesive; a polyimide-based adhesive; an amino resin-based material such as a urea resin or a melamine resin. Adhesives; phenolic resin adhesives; epoxy adhesives; polyols (polyether polyols) , Polyester polyol, etc.) and isocyanate and / or isocyanurate, a polyurethane adhesive; a reactive (meth) acrylic adhesive; a rubber adhesive composed of chloroprene rubber, nitrile rubber, styrene-butadiene rubber, etc .; Adhesives; inorganic adhesives made of alkali metal silicate, low melting point glass, etc .; and other adhesives can be used. As the resin film to be laminated by the method 3), a commercially available resin film may be used, or a resin film produced by a known production method may be used. The resin film may be subjected to a surface treatment such as a corona treatment, an atmospheric pressure plasma treatment, a vacuum plasma treatment, and a primer coating treatment. The method for producing the resin film is not particularly limited, and a known production method can be used.

  1) The co-extrusion molding method is preferable in that defects such as foreign matter being caught between the resin layer serving as the release layer A and the resin layer serving as the heat-resistant resin layer B and the warpage of the release film are hardly generated. . 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 necessary. In order to enhance the adhesion between the films, the interface between the films may be subjected to a surface treatment such as a corona discharge treatment, if necessary.

  The coating means in the above 2) coating method is not particularly limited, and for example, various coaters such as a roll coater, a die coater, and a spray coater are used. The melt extrusion means is not particularly limited. For example, an extruder having a T-type die or an inflation type die is used.

  The release film for processing may be uniaxially or biaxially stretched as necessary, thereby increasing the film strength of the film.

Resin sealing process The process release film of the present invention is used for a resin sealing process by a compression molding method. The release film for process of the present invention can be used by arranging it between the semiconductor chip or the like and the inner surface of the mold when arranging the semiconductor chip or the like in the mold and injecting resin. By using the release film for a process of the present invention, it is possible to effectively prevent defective peeling from a mold, generation of burrs, and the like.
The resin used in the production process by the compression molding method may be any of a thermoplastic resin and a thermosetting resin, but thermosetting resins are widely used in the technical field, and particularly, epoxy-based thermosetting resins. It is preferable to use a curable resin.

  The resin sealing process using the process release film of the present invention can appropriately employ a conventionally known one in the technical field, and is not particularly limited. For example, in the case of a resin sealing process of a semiconductor chip, Is the one shown in FIG. To 9. Are preferably performed in this order.

  More specifically, first, in the “1. film cut” step, the process release film 11 of the present invention is pulled out from a roll-shaped roll, developed on the XY stage 13, and reduced to a predetermined size. Disconnect. The predetermined size of the process release film 11 is not particularly limited, but covers the entire surface of the cavity 19c provided in the lower mold 19 used in the resin sealing process, and further configures the lower mold 19. It is preferable that the size has a fixing margin for fixing the film 11 between the clamper 19b and the upper mold 15.

  Next, in a “2. frame type installation” step, a frame 14 having a shape substantially overlapping with the fixing allowance is developed on the XY stage 13 and cut into a predetermined size. It is installed on the top so as to substantially overlap with the fixed allowance.

  Next, in a “3. resin measurement” step, a predetermined amount of the sealing resin 18 is placed on the process release film 11 and in the frame 14 while being measured. The amount of the sealing resin 18 is not particularly limited, but is preferably substantially the same as the volume of the cavity 19c after the “8.

  Next, in the “4. resin + film transport” step, the XY stage is held together with the sealing resin 18 disposed on the release film 11 while the process release film 11 is adsorbed on the frame 14. 13 and transported, and placed on a lower mold 19 for resin sealing. At this time, the process release film 11 covers the cavity 19c provided in the lower mold 19, and the sealing resin 18 disposed on the process release film 11 is located on the cavity 19c. It is preferable to arrange them.

Next, in the “5. Vacuum suction” step, the fixing allowance of the process release film 11 is fixed between the frame 14 and the clamper 19 b constituting the lower mold 19 while the lower mold 19 is being fixed. The process release film 11 is sucked and supported along the inner surface of the cavity 19c by degassing from the suction holes provided in the cavity 19c inside. At this time, the fixing allowance of the process release 11 film may be fixed by being sucked into a suction hole provided in a peripheral portion of the lower mold 19.
The process release film is stretched by a length substantially corresponding to the cavity depth by being suction-supported along the inner surface of the cavity 19c while the fixing margin at the film peripheral portion is fixed. The (initial) depth of the cavity 19c in this step can be appropriately set according to the thickness of the resin-sealed semiconductor element manufactured by the resin sealing process of the present embodiment. The (initial) depth of the cavity 19c in this step is usually 1.0 to 10.0 mm, but is not limited thereto.
In this step, the process release film 11 preferably has the flexibility to be easily sucked and supported along the inner surface of the cavity 19c, and preferably has the heat resistance to withstand the heating temperature of the molds 15 and 19. . Further, it is preferable that the resin can be easily released from the mold 19 after resin sealing and can be easily peeled off from the sealing resin 18.

  Next, in a “6. substrate installation” step, the substrate 16 on which the semiconductor chip 17 (and circuit components as necessary) are mounted is adsorbed to the upper mold 15 so that the semiconductor chip 17 faces downward. The upper die 15 is moved and aligned so that the semiconductor chip 17 is located substantially at the center of the cavity 19c in the lower die 19.

  Next, in the “7. mold clamping” step, the upper mold 15 and the lower mold 19 are separated while maintaining the space of the original cavity 19c (the cavity block 19a in the lower mold 19 is kept at the initial position). Contact and mold clamping.

Next, in the “8. Compression” step, the cavity block 19a is raised, and the sealing resin 18 in the cavity 19c is compression-molded. As a result, the semiconductor chip 17 (and, if necessary, circuit components) on the substrate 16 is sealed with the sealing resin 18.
The difference between the initial depth of the cavity 19c and the final depth of the cavity 19c after compression molding is preferably 1.0 mm or more, more preferably 1.3 mm or more, and more preferably 1.6 mm or more. Particularly preferred. When a semiconductor chip 17 having a large thickness such as a large-capacity NAND-type flash memory is sealed with a resin, the difference between the initial depth of the cavity 19c and the final depth of the cavity 19c after compression tends to increase. Even in such a case, the process release film of the present invention can appropriately seal the thick semiconductor chip 17 with resin while effectively suppressing problems such as peeling failure.
The final depth of the cavity 19c (resin thickness after compression molding) is preferably 0.5 mm or more, more preferably 0.7 mm or more, and particularly preferably 1.0 mm or more. When the final depth of the cavity 19c is 0.5 mm or more, the thick semiconductor chip 17 such as a large-capacity NAND flash memory can be appropriately resin-sealed.
In the compression molding, it is preferable that the sealing resin 18 is heated to a temperature at which the sealing resin 18 exhibits appropriate fluidity. If the sealing resin 18 is a thermosetting resin, the sealing resin after molding is sufficient. It is preferable to heat at a temperature and for a time to cure the resin. For example, the maximum temperature in the resin sealing process can be set at 110 to 190 ° C., and more preferably at 120 to 180 ° C.
The molding pressure and curing time at that time are not particularly limited, and preferable conditions may be appropriately set according to the type of the sealing resin 18 and the sealing temperature. For example, a molding pressure of 50 to 300 kN, more preferably It can be set appropriately within the range of 70 to 150 kN and the curing time of 1 to 60 minutes, more preferably 2 to 10 minutes.

  The sealing resin 18 may be a liquid resin or a resin that is solid at normal temperature. However, a sealing material such as a resin that becomes liquid by heating at the time of sealing the resin can be appropriately used. As the encapsulating resin material, specifically, an epoxy resin (a thermosetting resin that can be cured by forming a crosslinked network with epoxy groups remaining in the polymer, and is preferably a biphenyl type resin) Epoxy resin, bisphenol epoxy resin, o-cresol novolak type epoxy resin, etc.) are used, and as a sealing resin other than the epoxy resin, a polyimide resin (a polymer resin having an imide bond in a repeating unit of a main chain, Preferred are those commonly used as sealing resins, such as bismaleimide-based resins, and silicone-based resins (polymer resins having a siloxane bond in the repeating unit of the main skeleton, and preferably thermosetting addition-type resins). Can be used.

  Next, in the "9. mold opening (release)" step, the upper mold 15 is separated from the lower mold 19, and the molded product (resin-sealed semiconductor chip) is taken out of the mold. At this time, it is preferable that the molded product is easily peeled off from the process release film 11, and it is particularly preferable that the process release film 11 on the side surface of the cavity 19c be peeled off without being bitten by the molded product. In addition, it is preferable that the surface of the molded article after peeling has a good appearance without resin chipping or the like. Use of the process release film of the present invention makes it easier to achieve such favorable results.

A resin sealing process using the process release film of the present invention including the above method, more preferably a method of resin sealing a semiconductor chip, or a method of manufacturing a resin sealed semiconductor element having such a step In this way, large-capacity NAND-type flash memory and other large-capacity molded products, including resin-encapsulated semiconductor elements in which semiconductor chips with large overall thickness are resin-sealed to stack memory chips in multiple stages, In addition, it is possible to manufacture with high productivity while suppressing poor appearance and poor appearance due to side surface biting.
Such resin-encapsulated molded products such as resin-encapsulated semiconductor elements are not limited to memory-based semiconductors, but may include logic-based semiconductors, heterogeneous semiconductor packages and semiconductor chips called SiP (system-in-package) in three dimensions. The present invention can be applied to a high-performance semiconductor chip to be laminated, and further can be applied to a resin molded product such as a lens used for a photoelectric element, a sensor element, or an optical element.
Molded products in which these high-performance semiconductor chips are sealed with resin are, for example, high value-added products such as excellent resin-sealed semiconductor elements in which high-performance semiconductor chips are appropriately sealed in sealing resin. Since the production efficiency can be improved, it can be mounted on electric and electronic equipment, transportation equipment, and the like, and contribute to higher functionality, higher performance, and lower cost.

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

  In the following Examples / Comparative Examples, evaluation of physical properties / characteristics was performed by the following methods.

(Contact angle to water (water contact angle))
The water contact angle on the surface of the release layer A or A 'was measured using a contact angle measuring device (Foica-W, manufactured by Kyowa Interface Science) in accordance with JIS R3257.

(Tensile strength)
Using the process release film produced in each Example / Comparative Example, the initial chuck distance was set to 20 mm, and the film was stretched by 7.5 mm (37.5%) at 100 mm / min in an environment of 175 ° C. The load was measured as tensile strength.

(Return value, restoration rate)
Using the process for releasing the film produced in the Examples / Comparative Examples, among the initial chuck and 20 mm, under a 175 ° C. environment, 7.5 mm elongation at 100 mm / min (elongation [Delta] L at this time, extension length [Delta] L ₁ After holding for 2 minutes, the amount of displacement (return) of the elongation ΔL when the load when the chuck was returned in the direction opposite to the elongation at 100 mm / min became 0 was measured, and the return value ΔL was obtained. ₂ (mm).
FIG. 3 shows specific expansion and contraction of the film. 3 in (a), the initial film length _{L 0} is a 20 mm, in FIG. 3 (b), the maximum film elongation [Delta] L ₁ was 7.5 mm. 3 in (c), the return value [Delta] L ₂ when the load becomes 0 is measured for each sample was calculated restoration rate in accordance with the following formula from [Delta] L ₁ and [Delta] L _2.

Restoration rate (%) = 100 × ΔL ₂ / ΔL ₁

(Melting point (Tm))
Using a Q100 manufactured by TA Instruments as a differential scanning calorimeter (DSC), about 5 mg of a polymer sample was precisely weighed, and in accordance with JIS K7121, a nitrogen gas inflow rate: 25 ml / min. The temperature was raised from ° C. to 280 ° C. at a heating rate of 10 ° C./min to measure the heat melting curve, and the melting point (Tm) of the sample was determined from the obtained heat melting curve.

(Releasability)
Using the process release film produced in each of the examples / comparative examples, resin sealing of the semiconductor chip was performed in a process as shown in FIG.
As a sealing resin, an epoxy-based lead frame package sealing material (brand name: CEL-9750ZHF10) manufactured by Hitachi Chemical Co., Ltd. was used.
The detailed conditions of “4. resin + film conveyance”, “5. vacuum suction”, “7 mold clamping” and “9. compression” in the process of FIG. 1 are shown in FIGS. 2 (a) and 2 (b). , And (c). In FIG. 2 (a), the depth _{a 1} of the mold clamping initial cavity 29c is 2.4 mm, in FIG. 2 (b), the width of the cavity 29c is 54 mm, in FIG. 2 (b), the the length of the direction perpendicular to the plane of the cavity 29c is 221Mm, in FIG. 2 (c), the mold clamping, the cavity final depth _{a 2} after compression was 0.8 mm. The temperature of the molding die (molding temperature) was 175 ° C., the molding pressure was 96 kN, and the molding time was 120 seconds.
Thereafter, as shown in "9. Mold opening (release)" in FIG. 1, the upper die was pulled up, and the resin-sealed semiconductor chip (semiconductor package) was released from the release film. The releasability of the release film was evaluated according to the following criteria.
：: The release film peels off naturally when the mold is opened.
：: The release film does not peel off spontaneously, but peels off easily when pulled (by applying tension) by hand.
×: The release film is in close contact with the resin sealing surface of the semiconductor package and cannot be removed by hand.

(Mold followability)
The mold following property of the release film when the release was performed in the above process was evaluated according to the following criteria.
：: There is no chipped resin (portion not filled with resin) in the semiconductor package.
：: The resin chip is slightly missing at the end of the semiconductor package.
X: There are many resin chips at the end of the semiconductor package. Or a film tear occurs at the time of molding.

(Peel defect due to side biting)
When the release was performed in the above process, the peeling failure due to the side surface of the release film was evaluated according to the following criteria.
：: No biting marks and no peeling failure on the side of the semiconductor package.
：: There is a biting mark on the side of the semiconductor package, but no peeling failure.
×: There is a biting mark on the side of the semiconductor package, and peeling failure also occurs.

[Example 1]
As the heat-resistant resin layer B, a 15 μm-thick biaxially stretched PBT (polybutylene terephthalate) film (produced by Kojin Film & Chemicals Co., Ltd., brand name: Boblet ST, melting point: 223 ° C.) was used, and release layers A and A ′ were used. A non-stretched 4-methyl-1-pentene copolymer resin film was used. Specifically, a 4-methyl-1-pentene copolymer resin (product name: TPX, brand name: MX022) manufactured by Mitsui Chemicals, Inc. is melt-extruded at 270 ° C. to adjust the slit width of the T-die. Was used to form a non-stretched film having a thickness of 15 μm.
The unstretched 4-methyl-1-pentene copolymer resin film is coated with an adhesive so that one of the film surfaces serving as an adhesive surface has a water contact angle of 30 ° or more according to JIS R3257, which is 30 or less. Corona treatment was performed from the viewpoint of improving adhesion.

(adhesive)
The following urethane-based adhesive A was used as the adhesive used in the dry lamination process for bonding the films.
[Urethane adhesive A]
Main agent: Takelac A-616 (manufactured by Mitsui Chemicals, Inc.). Curing agent: Takenate A-65 (manufactured by Mitsui Chemicals, Inc.). The main agent and the curing agent were mixed such that the mass ratio (main agent: hardening agent) became 16: 1, and ethyl acetate was used as a diluent.

(Manufacture of release film)
On one surface of the biaxially stretched PBT film, a urethane-based adhesive A is applied at 1.5 g / m ² by gravure coating, and the corona-treated surface of a non-stretched 4-methyl-1-pentene copolymer resin film is coated. After lamination by dry lamination, a urethane-based adhesive A was applied at 1.5 g / m ² on the biaxially stretched PBT film side of the laminated film, and another unstretched 4-strand The corona-treated surface of the methyl-1-pentene copolymer resin film is laminated by dry lamination to form a five-layer process (release layer A / adhesive layer / heat-resistant resin layer B / adhesive layer / release layer A '). A release film for use was obtained.
Dry lamination conditions were a substrate width of 900 mm, a transport speed of 30 m / min, a drying temperature of 50 to 60 ° C, a laminating roll temperature of 50 ° C, and a roll pressure of 3.0 MPa.

  The process release film had a tensile strength of 7.5 MPa, a return value of 3.6 mm, and a restoration rate of 48%. Table 1 shows the evaluation results of the releasability, the mold followability, and the peeling failure. The release film exhibited good releasability in which the mold was peeled off spontaneously upon opening of the mold, and showed good mold followability without any resin chipping in the semiconductor package. In addition, no biting marks were observed on the side surfaces of the semiconductor package, there was no peeling failure, and the peeling failure due to the side biting was effectively suppressed. That is, the process release film of Example 1 was an excellent process release film having good releasability and good mold followability, and effectively suppressing peeling failure due to side biting.

[Examples 2-3]
A process release film was prepared in the same manner as in Example 1, except that the films shown in Table 1 were used as the release layers A and A 'and the heat-resistant resin layer B in the combinations shown in Table 1, and sealed. The mold was released and the characteristics were evaluated. Table 1 shows the results.
In some cases, the suppression of peeling failure due to side biting was not as good as in Example 1. However, in all Examples, good releasability, suppression of wrinkles, and good mold followability were balanced at a high level. Release film for process.

The details of each film described in the table are as follows.
(TPX-1) Non-stretched 4MP-1 (TPX) film 15-μm-thick using 4-methyl-1-pentene copolymer resin (product name: TPX, brand name: MX022, melting point: 229 ° C.) manufactured by Mitsui Chemicals, Inc. Of a non-stretched film.
(TPX-2) Unstretched 4MP-1 (TPX) film 50 μm thick using 4-methyl-1-pentene copolymer resin (product name: TPX, brand name: MX022, melting point: 229 ° C.) manufactured by Mitsui Chemicals, Inc. Of a non-stretched film.
(OPBT1) Biaxially-stretched PBT film A 15-μm-thick biaxially-stretched polybutylene terephthalate film (brand name: Boblet ST, melting point: 223 ° C, tensile strength: 20.0 MPa) manufactured by Kojin Film & Chemicals Co., Ltd. was used.
(OPBT2) Biaxially stretched PBT film A 25 μm thick biaxially stretched polybutylene terephthalate film (brand name: Boblet ST, melting point: 223 ° C, tensile strength: 19.2 MPa) manufactured by Kojin Film & Chemicals Co., Ltd. was used.
(CPBT1) Non-stretched PBT film A non-stretched single-layer film having a thickness of 50 µm was formed using a polybutylene terephthalate resin (brand name: 5020, melting point: 223 ° C) manufactured by Mitsubishi Engineering-Plastics Corporation.
(CPBT2) Non-stretched PBT film A non-stretched single-layer film with a thickness of 20 µm is formed using a polybutylene terephthalate resin (brand name: 5020, melting point: 223 ° C, tensile strength: 2.1 MPa) manufactured by Mitsubishi Engineering-Plastics Corporation. What you did.
(Unstretched Ny) Unstretched Nylon Film A non-stretched nylon film having a thickness of 20 μm (trade name: Diamilon C, melting point: 220 ° C., tensile strength: 1.9 MPa) manufactured by Mitsubishi Chemical Corporation was used.
(OPET1) Biaxially stretched PET film A 13 μm thick biaxially stretched PET (polyethylene terephthalate) film (product name: Teleflex FT, melting point: 227 ° C.) manufactured by Teijin Film Solutions Ltd. was used.
(OPET2) Biaxially stretched PET film A 13 μm-thick biaxially stretched PET (polyethylene terephthalate) film (product name: Teleflex FW2, melting point: 227 ° C.) manufactured by Teijin Film Solutions Ltd. was used.
(EVOH) Biaxially stretched EVOH film A 15 μm thick biaxially stretched EVOH (ethylene / vinyl alcohol copolymer) film (trade name: EVAL EF-XL, melting point: 182 ° C., tensile strength: 2.2 MPa) manufactured by Kuraray Co., Ltd. used.
Among these films, those used as the heat-resistant resin layer B were also measured for the return value and the restoration rate in accordance with the above-described measurement method also for the film alone (in a state of no lamination). Table 2 shows the results.

[Comparative Examples 1-2]
Alternatively, each of the films shown in Table 1 was used alone as a process release film, sealed and released in the same manner as in Example 1, and the characteristics of the process release film were evaluated. Table 1 shows the results. For Comparative Example 1, the results of the film tensile test and the evaluation of the return value of the film elongation are also shown in FIG.
In all of the comparative examples, the performance was inferior to the examples in general, and in particular, the peeling failure due to the biting in the side face could not be effectively suppressed.

[Comparative Examples 3 to 6]
A process release film was prepared and sealed in the same manner as in Example 1, except that the films shown in Table 1 were used as the release layers A and A 'and the heat-resistant resin layer B in the combinations shown in Table 1. The mold was released, and the characteristics were evaluated. Table 1 shows the results.
The mold releasability and the mold followability were good as in the examples, but the generation of wrinkles could not be suppressed.

  The release film for process of the present invention can easily form a molded product after resin sealing by a compression molding method without depending on a mold structure or a release agent in a step of sealing a semiconductor chip or the like with a resin. Since it is possible to release the mold and effectively suppress the appearance defect of the molded article, it is possible to manufacture a resin-encapsulated semiconductor element or the like with high productivity by using the molded article. It has an effect and has high applicability in various industrial fields such as the semiconductor process industry and the optical element manufacturing industry.

11, 21: release film for process 12: cutter 13: XY stage 14, 24: frame 15, 25: upper mold 16:26 substrate 17:27: semiconductor chip 18: sealing resin 19, 29: lower mold 19a, 29a: cavity block 19b, 29 b: clamper 19c, 29c: cavity _a 1: initial cavity depth _a 2: final depth _L 0 of the cavity: the initial film length [Delta] L _1: maximum film elongation [Delta] L _2: return value

Claims (10)

A process release film used in a resin molding process by a compression molding method, wherein a contact angle of at least one surface of the film with water is 90 ° to 130 °,
The tensile strength in the MD direction of the film at a temperature of 175 ° C and a tensile strength of 37.5% at a rate of 100 mm / min from 1.0 MPa to 10.0 MPa;
And after 37.5% elongation in the MD direction under the same conditions, after resting for 2 minutes in the compression direction and returning to the origin direction at 100 mm / min in the compression direction, the following expression ( 1) the process release film, wherein a restoration rate (%) obtained according to the formula is 30 to 80 (%);
Return value / extended length × 100 = restoration rate% (1).   The process release film according to claim 1, wherein a difference between an initial depth of the cavity and a final depth of the cavity is 1.0 mm or more in the resin sealing process by the compression molding method.   The release film for processing according to claim 1, wherein a resin thickness after sealing is 0.5 mm or more in the resin sealing process by the compression molding method.   4. The process release film according to claim 1, wherein a maximum temperature in a resin sealing process by the compression molding method is 110 to 190 ° C. 5.   The sealing resin used in the resin sealing process by the compression molding method, contains at least one resin selected from the group consisting of an epoxy resin, a polyimide resin, and a silicone resin. The release film for a process according to claim 1.   The release film for processing according to any one of claims 1 to 5, wherein a semiconductor chip is sealed in the resin sealing process by the compression molding method.   The process release according to any one of claims 1 to 6, comprising a release layer A and a heat-resistant resin layer B, wherein the at least one surface is constituted by the surface of the release layer A. the film.   The release layer A includes at least one resin selected from the group consisting of a fluororesin, a 4-methyl-1-pentene (co) polymer, and a polystyrene-based resin. The release film for a process according to 1.   It further has a release layer A ′, and the release layer A, the heat-resistant resin layer B, and the release layer A ′ are laminated in this order, and the release layer A and the release layer The release film for processing according to any one of claims 1 to 8, wherein the contact angle of the mold layer A 'with water is 90 ° to 130 °.   The release layer A ′ contains a resin containing at least one resin selected from the group consisting of a fluororesin, a 4-methyl-1-pentene (co) polymer, and a polystyrene-based resin. Release film for process.