JP7608837B2 - Release Film - Google Patents

Description

The present invention relates to a release film.

Conventionally, various technologies have been developed in the field of release films. For example, in the field of semiconductor device manufacturing processes, it is known to manufacture molded bodies by placing a release film between a mold and a molding object, and resin-sealing a molding object equipped with electronic components such as semiconductor elements using a molding method such as transfer molding or compression molding (e.g., Patent Documents 1 and 2). By placing a release film between the mold and the molding object, the molded body can be easily removed from the mold after resin sealing. In addition, release films used when resin molding using such molds are also generally called mold molding release films.

JP 2020-151949 A JP 2020-19264 A

However, wrinkles and distortions that occur in the release film may be transferred to the surface of molded articles obtained using conventional release films, leaving room for improvement in terms of obtaining molded articles with a higher level of appearance.

The present inventors have conducted extensive research into the causes of wrinkles and distortions occurring in release films and have found the following problems.
Usually, a suction port for vacuum exhaust is provided around the cavity recess of the lower mold in order to vacuum-adhere the release film to the inner surface of the cavity recess. After arranging the release film so as to cover both the cavity recess and the suction port around it, the air between the release film and the cavity recess is sucked through the suction port and vacuum exhausted, so that the release film can be vacuum-adhered to the inner surface of the cavity recess. During this vacuum exhaust, the release film is also drawn into the suction port to some extent, but if the deformation amount of the release film is not sufficient, a part of the release film may be drawn into the suction port, causing the end of the release film near the suction port to stand up. As a result, a small gap is generated between the end of the raised release film and the lower mold, and suction is not performed sufficiently, so that the adhesion of the release film to the cavity recess is reduced, and it has been revealed that the release film is more likely to develop wrinkles.
The upper die holds a molding object on which electronic components such as semiconductor elements are mounted. The molding object is clamped from above and below by the lower die, whose cavity recess is filled with a sealing resin material, and the upper die, to which the molding object is fixed, and compressed to form a resin mold. At this time, the base of the lower die rises, applying pressure to compress the sealing resin material. At this time, the depth of the cavity becomes shallow, so that a small gap is generated between the release film and the inner surface of the cavity recess. It has been revealed that this causes deformation of the release film, which causes distortion and wrinkles.

The inventors of the present invention therefore conducted further intensive research from the perspective of solving such problems, and came up with a new index for controlling the properties of the release film: the ratio of a predetermined tensile strength to a predetermined breaking strength. They then discovered that by simultaneously controlling these indexes, it is possible to obtain sufficient elongation (deformation) in response to the stress when the mold is fitted, while allowing the film to return to its original shape in response to the elongation (elastic recovery), thereby suppressing the occurrence of wrinkles in the release film, and thus completed the present invention. They also discovered that by controlling such new indexes, it is possible to effectively suppress the occurrence of wrinkles and distortions in the release film, not limited to applications in the manufacturing method described above.

According to the present invention,
There is provided a release film that satisfies the following (a) and (b):
(a) the release film has a 180°C 5% tensile strength (5% modulus) of 1.0 MPa or more and 5.0 MPa or less;
(b) When the breaking strength at 25° C. is X1 (MPa), the breaking strength at 180° C. is X2 (MPa), and (1-(X1-X2)/X1) is α1, α1 is 0.20 or more and 0.80 or less.

The present invention provides a release film that suppresses the occurrence of wrinkles and distortions in the release film and produces molded articles with good appearance.

1 is a cross-sectional view showing a schematic cross section of a release film according to an embodiment of the present invention;

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
In all drawings, similar components are given the same reference numerals, and explanations are omitted as appropriate. To avoid complexity, (i) when there are multiple identical components in the same drawing, only one of them is given a reference numeral, and not all of them are given a reference numeral, or (ii) especially in FIG. 2 and subsequent drawings, components similar to those in FIG. 1 are not given a reference numeral again. All drawings are for explanatory purposes only. The shapes and dimensional ratios of each member in the drawings do not necessarily correspond to the actual objects.

In this specification, the expression "a to b" in the description of a numerical range means from a to b, unless otherwise specified. For example, "1 to 5% by mass" means "1% by mass to 5% by mass."
In this specification, the MD direction stands for Machine Direction and refers to the direction in which the resin flows, and the TD direction stands for Transverse Direction and refers to the vertical direction.

<Release film>
The release film of the present embodiment may have a single layer structure, or may have a multilayer structure including a release layer on at least one side of the release film, i.e., the release surface, and a base layer made of a material different from the release layer. A multilayer structure is preferable from the viewpoint of achieving a high level of both sufficient elongation and elastic recovery against elongation. Hereinafter, the release film will be described in detail using a multilayer structure as an example.

FIG. 1 is a cross-sectional view that typically shows a cross section of the release film of the present embodiment.
As shown in FIG. 1, a release film 11 of the present embodiment includes a base layer 2 and a release layer 1 laminated on the base layer 2 .

The release film 11 of the present embodiment satisfies the following (a) and (b).
(a) the release film 11 has a 5% tensile strength (5% modulus) at 180° C. of 1.0 MPa or more and 5.0 MPa or less;
(b) When the breaking strength at 25° C. is X1 (MPa), the breaking strength at 180° C. is X2 (MPa), and (1-(X1-X2)/X1) is α1, α1 is 0.20 or more and 0.80 or less.
This makes it possible to obtain sufficient elongation while simultaneously obtaining shape recovery against elongation, and effectively suppress the occurrence of wrinkles and distortion in the release film 11. Although the details of the reason for this are not clear, it is presumed as follows.
First, it is presumed that the index (a) makes it easier to control the ability of the release film 11 to return to its original shape when stretched. It is presumed that the index (b) makes it possible to maintain strength against deformation while obtaining a suitable degree of ease of deformation when heated. It is presumed that by simultaneously controlling the indexes (a) and (b), it is possible to achieve a high level of balance between sufficient stretch and recovery from stretching, and as a result, it is possible to effectively suppress wrinkles and distortions that may occur during use of the release film.

In the above (a), the 5% tensile strength (5% modulus) at 180° C. is 1.0 MPa or more and 5.0 MPa or less, preferably 1.0 to 4.0, and more preferably 1.5 to 3.0.
In the above (b), α1 is equal to or greater than 0.20 and equal to or less than 0.80, preferably 0.20 to 0.70, and more preferably 0.20 to 0.50.

It is preferable that the release film 11 of the present embodiment further satisfies the following (c).
(c) The Young's modulus of the release film 11 at 180° C. is 25 MPa or more and 110 MPa or less, preferably 50 to 100 MPa, and more preferably 50 to 80 MPa.
By setting the Young's modulus at 180° C. within the above-mentioned range, it is possible to obtain an appropriate flexibility of the release film 11 and to improve the mold followability during vacuum contact. Since the mold is usually heated during vacuum contact, the followability of the release film 11 can be more appropriately controlled by controlling the Young's modulus at 180° C.

It is preferable that the release film 11 of the present embodiment further satisfies the following (d).
(d) When measured by thermomechanical analysis (TMA) with a tensile load of 500 mN and a temperature rise from 30° C. to 180° C. at a rate of 2° C./min, the dimensional change rate of the release film 11 is 4% or more and 40% or less, preferably 8 to 35%, and more preferably 9 to 30%.
By setting the dimensional change rate within the above numerical range, it becomes easier to obtain elongation and deformation in response to local stress, so that when the lower mold and the upper mold are mated, the release film 11 becomes more likely to elongate in parts, making it easier to suppress the occurrence of wrinkles and distortions in the entire release film 11.

The above indicators (a) to (d) can be achieved by appropriately selecting and combining known methods, such as the types and amounts of raw materials for the release layer 1, the method for preparing the raw materials, and the method for manufacturing the release film 11, and by using techniques different from conventional methods.
Among these, for example, when silicone resin is selected as the raw material of the release layer 1, factors for setting the above-mentioned indicators within the desired numerical range include appropriately controlling the type and compounding ratio of the silicone resin, the crosslinking density and crosslinking structure of the resin, and improving the compounding ratio of the inorganic filler and the dispersibility of the inorganic filler.
In addition, by adjusting the curing conditions, temperature, and time for obtaining the release layer 1, the crosslinking density and crosslinking structure of the resin can be appropriately controlled, and the above-mentioned indexes can be set to the desired numerical range. In addition, for example, in the manufacturing process of the release film, when the film is sandwiched between substrates, it is also possible to change the surface roughness depending on the surface condition. In addition, it is effective to control the combination of materials for the release layer 1 and the substrate layer 2.

The thickness of the release film 11 is preferably 5 μm or more and 150 μm or less, more preferably 10 μm or more and 100 μm or less, and even more preferably 15 μm or more and 80 μm or less.

The following describes each layer of the release film 11 of this embodiment.

[Release layer]
The release layer 1 forms one side of the release film 11 and has a release surface 3 .

The thickness of the release layer 1 is preferably 0.1 μm or more and 150 μm or less, more preferably 1 μm or more and 100 μm or less, even more preferably 5 μm or more and 50 μm or less, and even more preferably 30 μm or less.
By setting the thickness of the release layer 1 to the above lower limit or more, the rigidity of the release film 11 is increased, and excessive deformation and wrinkles are easily suppressed. As a result, mold followability and dimensional stability are obtained. On the other hand, by setting the thickness of the release layer 1 to the above upper limit or less, the rigidity of the release film 11 can be controlled, and a good balance between mold followability and releasability can be achieved.

The release surface 3 of the release layer 1 is the surface that comes into contact with a sealing resin, which will be described later, when the release film 11 is used. The surface roughness Rz of the release surface 3 is preferably 0.05 to 10 μm, and more preferably 0.08 to 7 μm.
By setting the surface roughness Rz of the release surface 3 to be equal to or greater than the above lower limit, a good balance between releasability and mold followability during molding can be achieved. On the other hand, by setting the surface roughness Rz of the release surface 3 to be equal to or less than the above upper limit, good releasability can be achieved while maintaining mold followability and dimensional stability.

The surface roughness of the release surface 3 can be controlled by known methods, such as by using an embossed roll to transfer an embossed pattern to the film during the production process of the release film, or by incorporating particles into the material of the release layer.
The surface roughness Rz of the release layer 1 is measured in accordance with JIS B0601:2013.

The release layer 1 is composed of a first resin composition containing a resin.
The resin contained in the first resin composition preferably contains one or more types selected from, for example, silicone resin, fluororesin, polyolefin resin, polyester resin, melamine resin, epoxy resin, and polyamide resin, and more preferably contains one or more types selected from silicone resin, fluororesin, melamine resin, epoxy resin, and polyolefin resin from the viewpoint of obtaining a release surface 3 with good releasability. Among them, silicone resin is more preferable from the viewpoint of achieving both deformation and recovery.

(Silicone resin)
The silicone resin is not particularly limited, and may be, for example, a compound containing two or more siloxane bonds (-Si-O-), such as various known or commercially available siloxane-based polymers.

The silicone resin preferably contains one or two selected from, for example, vinyl group-containing organopolysiloxane (A) and organohydrogenpolysiloxane (B). This provides rubber-like properties such as silicone elasticity and compressibility, making it easier to obtain sufficient stretchability of the release film and shape recovery against stretching.

<<Vinyl Group-Containing Organopolysiloxane (A)>>
The vinyl group-containing organopolysiloxane (A) can include a vinyl group-containing linear organopolysiloxane (A1) having a linear structure.

The vinyl group-containing linear organopolysiloxane (A1) has a linear structure and contains vinyl groups, which become crosslinking points during curing.

The vinyl group content of the vinyl group-containing linear organopolysiloxane (A1) is not particularly limited, but for example, it is preferable that the vinyl group content is 15 mol% or less and that the vinyl group content is 2 or more in the molecule. This optimizes the amount of vinyl groups in the vinyl group-containing linear organopolysiloxane (A1), and ensures the formation of a network with each component described below.

In this specification, the vinyl group content refers to the mole percent of vinyl group-containing siloxane units when all units constituting the vinyl group-containing linear organopolysiloxane (A1) are taken as 100 mole percent. However, it is considered that there is one vinyl group per vinyl group-containing siloxane unit.

The degree of polymerization of the vinyl group-containing linear organopolysiloxane (A1) is not particularly limited, but is preferably within the range of about 1,000 to 10,000, and more preferably about 2,000 to 5,000. The degree of polymerization can be determined, for example, as the number average degree of polymerization (or number average molecular weight) in terms of polystyrene in gel permeation chromatography (GPC) using chloroform as a developing solvent.

Furthermore, the specific gravity of the vinyl group-containing linear organopolysiloxane (A1) is not particularly limited, but is preferably in the range of about 0.9 to 1.1.

By using a vinyl group-containing linear organopolysiloxane (A1) having a degree of polymerization and specific gravity within the above ranges, the heat resistance, flame retardancy, chemical stability, etc. of the resulting silicone rubber can be improved.

The vinyl group-containing linear organopolysiloxane (A1) preferably has a structure represented by the following formula (1):

In formula (1), R ¹ is a substituted or unsubstituted alkyl group, alkenyl group, aryl group, or a hydrocarbon group consisting of a combination thereof, each having 1 to 10 carbon atoms. Examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, and a propyl group, with a methyl group being preferred. Examples of the alkenyl group having 1 to 10 carbon atoms include a vinyl group, an allyl group, and a butenyl group, with a vinyl group being preferred. Examples of the aryl group having 1 to 10 carbon atoms include a phenyl group.

Furthermore, ^R2 is a substituted or unsubstituted alkyl group, alkenyl group, aryl group, or a hydrocarbon group that is a combination of these groups, each having 1 to 10 carbon atoms. Examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, and a propyl group, and among these, a methyl group is preferable. Examples of the alkenyl group having 1 to 10 carbon atoms include a vinyl group, an allyl group, and a butenyl group. Examples of the aryl group having 1 to 10 carbon atoms include a phenyl group.

^R3 is a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms, an aryl group, or a hydrocarbon group consisting of a combination thereof. Examples of the alkyl group having 1 to 8 carbon atoms include a methyl group, an ethyl group, and a propyl group, and among these, a methyl group is preferable. Examples of the aryl group having 1 to 8 carbon atoms include a phenyl group.

In addition, examples of the substituents of R ¹ and R ² in the formula (1) include a methyl group and a vinyl group, and examples of the substituent of R ³ include a methyl group.

In formula (1), the R ^1s are independent of each other and may be different from each other or may be the same. The same applies to R ² and R ³ .

Furthermore, m and n are the numbers of repeating units constituting the vinyl group-containing linear organopolysiloxane (A1) represented by formula (1), where m is an integer from 0 to 2000 and n is an integer from 1000 to 10000. m is preferably 0 to 1000, and n is preferably 2000 to 5000.

Specific examples of the vinyl group-containing linear organopolysiloxane (A1) represented by formula (1) include those represented by the following formula (1-1):

In formula (1-1), R ¹ and R ² each independently represent a methyl group or a vinyl group, and at least one of them is a vinyl group.

The vinyl group-containing linear organopolysiloxane (A1) may contain a first vinyl group-containing linear organopolysiloxane (A1-1) having two or more vinyl groups in the molecule and having a vinyl group content of 0.4 mol% or less. The vinyl group content of the first vinyl group-containing linear organopolysiloxane (A1-1) may be 0.1 mol% or less.

The vinyl group-containing linear organopolysiloxane (A1) may also contain a first vinyl group-containing linear organopolysiloxane (A1-1) and a second vinyl group-containing linear organopolysiloxane (A1-2) having a vinyl group content of 0.5 to 15 mol %.

By combining a first vinyl group-containing linear organopolysiloxane (A1-1) and a second vinyl group-containing linear organopolysiloxane (A1-2) with a high vinyl group content as the raw rubber, which is the raw material of the silicone rubber, it is possible to unevenly distribute the vinyl groups and more effectively form a crosslinking density distribution in the crosslinked network of the silicone rubber. As a result, the tear strength of the release film is more effectively increased, and dimensional stability and transferability are easier to control.

Specifically, as the vinyl group-containing linear organopolysiloxane (A1), it is preferable to use, for example, a first vinyl group-containing linear organopolysiloxane (A1-1) having in the molecule two or more units in which R ¹ is a vinyl group and/or units in which R ² is a vinyl group, and containing 0.4 mol % or less of these units in the above formula (1-1), and a second vinyl group-containing linear organopolysiloxane (A1-2) containing 0.5 to 15 mol % of units in which R ¹ is a vinyl group and/or units in which R ² is a vinyl group.

The first vinyl group-containing linear organopolysiloxane (A1-1) preferably has a vinyl group content of 0.01 to 0.2 mol %. The second vinyl group-containing linear organopolysiloxane (A1-2) preferably has a vinyl group content of 0.8 to 12 mol %.

Furthermore, when the first vinyl group-containing linear organopolysiloxane (A1-1) and the second vinyl group-containing linear organopolysiloxane (A1-2) are combined and blended, the ratio of (A1-1) to (A1-2) is not particularly limited, but for example, the weight ratio of (A1-1):(A1-2) is preferably 50:50 to 95:5, and more preferably 80:20 to 90:10.

The first and second vinyl group-containing linear organopolysiloxanes (A1-1) and (A1-2) may each be used alone or in combination of two or more.

The vinyl group-containing organopolysiloxane (A) may also contain a vinyl group-containing branched organopolysiloxane (A2) having a branched structure.

<<Organohydrogenpolysiloxane (B)>>
The organohydrogenpolysiloxane (B) is classified into a linear organohydrogenpolysiloxane (B1) having a linear structure and a branched organohydrogenpolysiloxane (B2) having a branched structure, and may contain either one or both of these.

The linear organohydrogenpolysiloxane (B1) has a linear structure and a structure in which hydrogen is directly bonded to silicon (≡Si-H), and undergoes a hydrosilylation reaction with the vinyl groups of the vinyl group-containing organopolysiloxane (A) and with the vinyl groups of the components contained in the raw materials of the release layer 1, forming a polymer that crosslinks these components.

The molecular weight of the linear organohydrogenpolysiloxane (B1) is not particularly limited, but for example, the weight average molecular weight is preferably 20,000 or less, and more preferably 1,000 or more and 10,000 or less.

The weight average molecular weight of the linear organohydrogenpolysiloxane (B1) can be measured, for example, by polystyrene conversion using GPC (gel permeation chromatography) with chloroform as the developing solvent.

In addition, it is generally preferred that the linear organohydrogenpolysiloxane (B1) does not have a vinyl group. This effectively prevents the crosslinking reaction from proceeding within the molecule of the linear organohydrogenpolysiloxane (B1).

As the linear organohydrogenpolysiloxane (B1) described above, for example, one having a structure represented by the following formula (2) is preferably used.

In formula (2), ^R4 is a substituted or unsubstituted alkyl group, alkenyl group, aryl group, a hydrocarbon group combining these groups, or a hydride group having 1 to 10 carbon atoms. Examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, and a propyl group, and among these, a methyl group is preferable. Examples of the alkenyl group having 1 to 10 carbon atoms include a vinyl group, an allyl group, and a butenyl group. Examples of the aryl group having 1 to 10 carbon atoms include a phenyl group.

Furthermore, ^R5 is a substituted or unsubstituted alkyl group, alkenyl group, aryl group, a hydrocarbon group combining these groups, or a hydride group having 1 to 10 carbon atoms. Examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, and a propyl group, and among these, a methyl group is preferable. Examples of the alkenyl group having 1 to 10 carbon atoms include a vinyl group, an allyl group, and a butenyl group. Examples of the aryl group having 1 to 10 carbon atoms include a phenyl group.

In addition, in formula (2), the multiple ^R4s are independent of each other and may be different from each other or may be the same. The same applies to ^R5 . However, among the multiple ^R4s and ^R5s , at least two or more are hydrido groups.

Furthermore, ^R6 is a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms, an aryl group, or a hydrocarbon group that is a combination of these. Examples of the alkyl group having 1 to 8 carbon atoms include a methyl group, an ethyl group, and a propyl group, and among these, a methyl group is preferable. Examples of the aryl group having 1 to 8 carbon atoms include a phenyl group. The multiple ^R6s are independent of each other and may be different from each other or the same.

In addition, examples of the substituents R ⁴ , R ⁵ and R ⁶ in the formula (2) include a methyl group and a vinyl group, and from the viewpoint of preventing an intramolecular crosslinking reaction, a methyl group is preferable.

Furthermore, m and n are the numbers of repeating units constituting the linear organohydrogenpolysiloxane (B1) represented by formula (2), where m is an integer from 2 to 150 and n is an integer from 2 to 150. Preferably, m is an integer from 2 to 100 and n is an integer from 2 to 100.

The linear organohydrogenpolysiloxane (B1) may be used alone or in combination of two or more.

The branched organohydrogenpolysiloxane (B2) has a branched structure, and therefore forms regions with high crosslink density, making it a component that contributes greatly to the formation of a sparsely-dense crosslink structure in the silicone rubber system. In addition, like the linear organohydrogenpolysiloxane (B1), it has a structure in which hydrogen is directly bonded to silicon (≡Si-H), and undergoes a hydrosilylation reaction with the vinyl groups of the vinyl group-containing organopolysiloxane (A) and with the vinyl groups of the components contained in the raw materials of the release layer 1, forming a polymer that crosslinks these components.

The specific gravity of the branched organohydrogenpolysiloxane (B2) is in the range of 0.9 to 0.95.

Furthermore, it is generally preferred that the branched organohydrogenpolysiloxane (B2) does not have a vinyl group. This effectively prevents the crosslinking reaction from proceeding within the molecule of the branched organohydrogenpolysiloxane (B2).

The branched organohydrogenpolysiloxane (B2) is preferably one represented by the following average composition formula (c):

Average composition formula (c)
(H _a (R ⁷ ) _3-a SiO _1/2 ) _m (SiO _4/2 ) _n
(In formula (c), ^R7 is a monovalent organic group, a is an integer ranging from 1 to 3, m is the number of H _a ( ^R7 ) _3-a SiO _1/2 units, and n is the number of SiO _4/2 units.)

In formula (c), ^R7 is a monovalent organic group, preferably a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, an aryl group, or a hydrocarbon group consisting of a combination thereof. Examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, and a propyl group, and among these, a methyl group is preferable. Examples of the aryl group having 1 to 10 carbon atoms include a phenyl group.

In formula (c), a is the number of hydride groups (hydrogen atoms directly bonded to Si) and is an integer ranging from 1 to 3, preferably 1.

In addition, in formula (c), m is the number of H _a (R ⁷ ) _3-a SiO _1/2 units, and n is the number of SiO _4/2 units.

Branched organohydrogenpolysiloxane (B2) has a branched structure. Linear organohydrogenpolysiloxane (B1) and branched organohydrogenpolysiloxane (B2) differ in that their structures are linear or branched, and the number of alkyl groups R bonded to Si (R/Si), where the number of Si is 1, is in the range of 1.8 to 2.1 for linear organohydrogenpolysiloxane (B1) and 0.8 to 1.7 for branched organohydrogenpolysiloxane (B2).

In addition, because the branched organohydrogenpolysiloxane (B2) has a branched structure, for example, when heated in a nitrogen atmosphere to 1000°C at a heating rate of 10°C/min, the amount of residue is 5% or more. In contrast, because the linear organohydrogenpolysiloxane (B1) is linear, the amount of residue after heating under the above conditions is almost zero.

Specific examples of branched organohydrogenpolysiloxane (B2) include those having a structure represented by the following formula (3):

In formula (3), ^R7 is a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms, an aryl group, or a hydrocarbon group consisting of a combination thereof, or a hydrogen atom. Examples of the alkyl group having 1 to 8 carbon atoms include a methyl group, an ethyl group, and a propyl group, and among these, a methyl group is preferable. Examples of the aryl group having 1 to 8 carbon atoms include a phenyl group. Examples of the substituent of ^R7 include a methyl group.

In addition, in formula (3), multiple R ^7s are independent of each other and may be different from each other or may be the same.

In addition, in formula (3), "-O-Si≡" indicates that Si has a branched structure that extends three-dimensionally.

The branched organohydrogenpolysiloxane (B2) may be used alone or in combination of two or more.

In the linear organohydrogenpolysiloxane (B1) and the branched organohydrogenpolysiloxane (B2), the amount of hydrogen atoms (hydride groups) directly bonded to Si is not particularly limited.
However, in the release layer 1, the total amount of hydride groups in the linear organohydrogenpolysiloxane (B1) and the branched organohydrogenpolysiloxane (B2) is preferably 0.5 to 5 mol, more preferably 1 to 3.5 mol, per mol of vinyl groups in the vinyl group-containing linear organopolysiloxane (A1). This ensures that a crosslinked network is formed between the linear organohydrogenpolysiloxane (B1) and the branched organohydrogenpolysiloxane (B2) and the vinyl group-containing linear organopolysiloxane (A1).

(Fluorine resin)
Specific examples of the fluorine-based resin include polymers of monomers such as tetrafluoroethylene, hexafluoropropylene, chlorotrifluoroethylene, vinylidene fluoride, vinyl fluoride, and perfluoroalkyl vinyl ether, and copolymers of two or more kinds of monomers. These may be used alone or in combination of two or more kinds.

(Polyolefin resin)
The polyolefin resin is a resin having a structural unit derived from an α-olefin such as ethylene, propylene, or butene, and a known one can be used. Specific examples of the polyolefin resin include polyethylene (PE) such as low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), and linear low density polyethylene (mLLPE); polypropylene (PP); polyvinyl alcohol (PVA); ethylene-vinyl acetate copolymer (EVA); ethylene-methyl acrylate copolymer (EMA); ethylene-acrylic acid copolymer (EAA); ethylene-methyl methacrylate copolymer (EMMA); ethylene-ethyl acrylate copolymer (EEA); ethylene-methacrylic acid copolymer (EMAA); ionomer resin; ethylene-vinyl alcohol copolymer (EVOH), and cyclic olefin resin (COP). These may be used alone or in combination of two or more.

(Polyester resin)
Specific examples of the polyester resin include polyethylene terephthalate resin (PET), polybutylene terephthalate resin (PBT), polytrimethylene terephthalate resin (PTT), polyhexamethylene terephthalate resin (PHT), and polyethylene naphthalate resin (PEN). These may be used alone or in combination of two or more.

(Epoxy resin)
As the epoxy resin, any monomer, oligomer, or polymer having two or more epoxy groups in one molecule can be used regardless of its molecular weight or molecular structure. Specific examples of such epoxy resins include bisphenols such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol E type epoxy resin, bisphenol S type epoxy resin, hydrogenated bisphenol A type epoxy resin, bisphenol M type epoxy resin (4,4'-(1,3-phenylenediisopridiene)bisphenol type epoxy resin), bisphenol P type epoxy resin (4,4'-(1,4-phenylenediisopridiene)bisphenol type epoxy resin), and bisphenol Z type epoxy resin (4,4'-cyclohexydienebisphenol type epoxy resin). type epoxy resins; novolac type epoxy resins such as phenol novolac type epoxy resins, brominated phenol novolac type epoxy resins, cresol novolac type epoxy resins, tetraphenol group ethane type novolac type epoxy resins, and novolac type epoxy resins having a condensed ring aromatic hydrocarbon structure; biphenyl type epoxy resins; aralkyl type epoxy resins such as xylylene type epoxy resins and biphenyl aralkyl type epoxy resins; naphthylene ether type epoxy resins, naphthol type epoxy resins, naphthalene type epoxy resins, naphthalene diol type epoxy resins, bifunctional to tetrafunctional epoxy naphthol type epoxy resins, Epoxy resins having a naphthalene skeleton, such as naphthalene resins, binaphthyl type epoxy resins, and naphthalene aralkyl type epoxy resins; anthracene type epoxy resins; phenoxy type epoxy resins; dicyclopentadiene type epoxy resins; norbornene type epoxy resins; adamantane type epoxy resins; fluorene type epoxy resins, phosphorus-containing epoxy resins, alicyclic epoxy resins, aliphatic linear epoxy resins, bisphenol A novolac type epoxy resins, bixylenol type epoxy resins, triphenolmethane type epoxy resins, trihydroxyphenylmethane type epoxy resins, tetraphenylolethane type epoxy resins and heterocyclic epoxy resins such as triglycidyl isocyanurate; glycidyl amines such as N,N,N',N'-tetraglycidyl meta-xylylene diamine, N,N,N',N'-tetraglycidyl bisaminomethylcyclohexane, and N,N-diglycidyl aniline; copolymers of glycidyl (meth)acrylate and a compound having an ethylenically unsaturated double bond, epoxy resins having a butadiene structure, diglycidyl ethers of bisphenols, diglycidyl ethers of naphthalenediol, and glycidyl ethers of phenols.

(Polyamide resin)
Examples of the polyamide resin include aliphatic polyamides, aromatic polyamides, etc. Specific examples of the aliphatic polyamides include polyamide 6, polyamide 6,6, polyamide 6-6,6 copolymer, polyamide 11, and polyamide 12. Specific examples of the aromatic polyamides include polyamide 61, polyamide 66/6T, polyamide 6T/6, and polyamide 12/6T.

(Melamine resin)
The melamine resin can be obtained, for example, by polycondensing a melamine compound with formaldehyde under neutral or weakly alkaline conditions. Specific examples include alkylated melamine resins such as methylated melamine resins and butylated melamine resins, methylolated melamine resins, and alkyl etherified melamines.

[others]
In addition to the above-mentioned resins, the first resin composition may contain other components within a range that does not impair the properties of the release film 11. The other components are not limited, but may include a solvent, an inorganic filler, a coupling agent, an antistatic agent, a leveling agent, a dispersant, a pigment, a dye, an antioxidant, a flame retardant, a thermal conductivity improver, etc. Representative components will be described below.

(solvent)
The first resin composition may contain, for example, a solvent depending on the method for producing the release layer 1. When the first resin composition contains a solvent, the release layer 1 can be produced by dissolving the first resin composition in the solvent and applying the solution.
The solvent is not limited, and specific examples thereof include aliphatic hydrocarbons such as water, pentane, hexane, cyclohexane, heptane, methylcyclohexane, ethylcyclohexane, octane, decane, dodecane, and tetradecane; aromatic hydrocarbons such as benzene, toluene, ethylbenzene, xylene, trifluoromethylbenzene, and benzotrifluoride; ethers such as diethyl ether, diisopropyl ether, dibutyl ether, cyclopentyl methyl ether, cyclopentyl ethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, 1,4-dioxane, 1,3-dioxane, and tetrahydrofuran; haloalkanes such as dichloromethane, chloroform, 1,1-dichloroethane, 1,2-dichloroethane, 1,1,1-trichloroethane, and 1,1,2-trichloroethane; carboxylic acid amides such as N,N-dimethylformamide and N,N-dimethylacetamide; and sulfoxides such as dimethyl sulfoxide and diethyl sulfoxide. These may be used alone or in combination of two or more.

(Inorganic filler)
In the present embodiment, the first resin composition may contain an inorganic filler, which can form fine irregularities on the surface of the release layer 1 and improve the releasability.
The inorganic filler is not particularly limited, but may be one or more particles selected from the group consisting of diatomaceous earth, iron oxide, titanium oxide, barium oxide, magnesium oxide, cerium oxide, magnesium carbonate, zinc carbonate, glass wool, mica, calcium carbonate, zinc oxide, alumina, crystalline silica, amorphous silica, fused silica, and zeolite. Among these, one or more particles selected from the group consisting of calcium carbonate, zinc oxide, alumina, crystalline silica, amorphous silica, fused silica, and zeolite are preferred.
Furthermore, depending on the synthesis method of silica, fumed silica (flame-processed silica), fired silica, precipitated silica, etc. may be used.
The inorganic fillers may be used alone or in combination of two or more kinds.

The inorganic filler preferably has a specific surface area, as measured by the BET method, of, for example, 50 to 400 m ² /g, and more preferably 100 to 400 m ² /g.
The average primary particle size of the inorganic filler is preferably, for example, 1 to 100 nm, and more preferably about 5 to 20 nm.

By using an inorganic filler having a specific surface area and average particle size within this range, the hardness and mechanical strength of the release layer 1 formed can be improved, and the balance between releasability, mold conformability, and dimensional stability can be improved.

(Silane coupling agent)
The silane coupling agent can have a hydrolyzable group. The hydrolyzable group is hydrolyzed by water to become a hydroxyl group, and the hydroxyl group undergoes a dehydration condensation reaction with the hydroxyl group on the surface of the inorganic filler, thereby modifying the surface of the inorganic filler.

The silane coupling agent may contain a silane coupling agent having a hydrophobic group. This provides the surface of the inorganic filler with this hydrophobic group, which reduces the cohesive force of the inorganic filler in the first resin composition and thus in the release layer 1 (in the case of silica particles, the cohesion due to hydrogen bonding caused by silanol groups is reduced), and as a result, it is presumed that the dispersibility of the inorganic filler in the release layer 1 is improved. This increases the interface between the inorganic filler and the rubber matrix, and increases the reinforcing effect of the inorganic filler. Furthermore, it is presumed that the slipperiness of the inorganic filler in the matrix is improved when the rubber matrix is deformed. And, due to the improvement in the dispersibility and slipperiness of the inorganic filler, the mechanical strength (e.g., mold followability, dimensional stability, etc.) of the release layer 1 due to the inorganic filler is improved.

Furthermore, the silane coupling agent may contain a silane coupling agent having a vinyl group. This introduces a vinyl group to the surface of the inorganic filler. Therefore, when the release layer 1 is cured, that is, when the vinyl group of the vinyl group-containing organopolysiloxane (A) and the hydride group of the organohydrogenpolysiloxane (B) undergo a hydrosilylation reaction to form a network (crosslinked structure), the vinyl group of the inorganic filler (in the case of silica particles) also participates in the hydrosilylation reaction with the hydride group of the organohydrogenpolysiloxane (B), so that the inorganic filler is also incorporated into the network. This allows the release layer 1 to be formed with a low hardness and high modulus.

As the silane coupling agent, a silane coupling agent having a hydrophobic group and a silane coupling agent having a vinyl group can be used in combination.

An example of a silane coupling agent is represented by the following formula (4):

Y _n -Si-(X) _4-n (4)
In the above formula (4), n represents an integer of 1 to 3. Y represents a functional group having a hydrophobic group, a hydrophilic group, or a vinyl group. When n is 1, it is a hydrophobic group. When n is 2 or 3, at least one of them is a hydrophobic group. X represents a hydrolyzable group.

The hydrophobic group is an alkyl group having 1 to 6 carbon atoms, an aryl group, or a hydrocarbon group that is a combination of these. Examples include a methyl group, an ethyl group, a propyl group, and a phenyl group, and among these, a methyl group is preferable.

Examples of the hydrophilic group include a hydroxyl group, a sulfonic acid group, a carboxyl group, and a carbonyl group, and among these, a hydroxyl group is preferred. Note that a hydrophilic group may be included as a functional group, but it is preferable that it is not included from the viewpoint of imparting hydrophobicity to the silane coupling agent.

Further, examples of the hydrolyzable group include alkoxy groups such as methoxy and ethoxy groups, chloro groups, and silazane groups, among which silazane groups are preferred due to their high reactivity with inorganic fillers (in the case of silica particles).Note that those having silazane groups as hydrolyzable groups have two ( _Yn -Si-) structures in the above formula (4) due to their structural characteristics.

Specific examples of the silane coupling agent represented by the above formula (4) include, for example, alkoxysilanes such as methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, and decyltrimethoxysilane, chlorosilanes such as methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, and phenyltrichlorosilane, and hexamethyldisilazane, which have a hydrophobic group as a functional group. Examples of the silane having a vinyl group include alkoxysilanes such as methacryloxypropyltriethoxysilane, methacryloxypropyltrimethoxysilane, methacryloxypropylmethyldiethoxysilane, methacryloxypropylmethyldimethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, and vinylmethyldimethoxysilane; chlorosilanes such as vinyltrichlorosilane and vinylmethyldichlorosilane; and divinyltetramethyldisilazane. Among these, taking into consideration the above description, it is particularly preferable that the silane having a hydrophobic group is hexamethyldisilazane, and the silane having a vinyl group is divinyltetramethyldisilazane.

(catalyst)
When the first resin composition forms the release layer 1 by a curing reaction, it may contain a catalyst. Examples of the catalyst include platinum or a platinum compound. As the platinum or platinum compound, a known one can be used, for example, platinum black, platinum supported on silica or carbon black, chloroplatinic acid or an alcohol solution of chloroplatinic acid, a complex salt of chloroplatinic acid and an olefin, a complex salt of chloroplatinic acid and a vinylsiloxane, etc. Platinum or a platinum compound may be used alone or in combination of two or more kinds.

In this embodiment, the content ratio of each component of the first resin composition is not particularly limited, but is set, for example, as follows:

In this embodiment, the upper limit of the content of the inorganic filler may be, for example, 60 parts by weight or less, preferably 50 parts by weight or less, and more preferably 40 parts by weight or less, relative to 100 parts by weight of the total amount of the vinyl group-containing organopolysiloxane (A). This improves the mechanical strength, such as the hardness and tear strength, of the release film 11, and improves the balance of the releasability, mold followability, and dimensional stability. In addition, the lower limit of the content of the inorganic filler is not particularly limited, but may be, for example, 10 parts by weight or more, relative to 100 parts by weight of the total amount of the vinyl group-containing organopolysiloxane (A).

The silane coupling agent is preferably contained in an amount of 5 parts by weight or more and 100 parts by weight or less, and more preferably 5 parts by weight or more and 40 parts by weight or less, per 100 parts by weight of the vinyl group-containing organopolysiloxane (A). This ensures that the inorganic filler can be dispersed in the release layer 1 with improved dispersibility.

The content of organohydrogenpolysiloxane (B) is preferably, for example, 0.5 parts by weight or more and 20 parts by weight or less, and more preferably 0.8 parts by weight or more and 15 parts by weight or less, per 100 parts by weight of the total amount of vinyl group-containing organopolysiloxane (A), inorganic filler, and silane coupling agent. By keeping the content of (B) within the above range, a more effective curing reaction may be achieved.

[Method of manufacturing the release layer]
Next, a method for producing the release layer 1 of this embodiment will be described.
In the method for producing the release layer 1 of this embodiment, the release layer 1 can be obtained by preparing the above-mentioned first resin composition, forming the first resin composition into a film, and curing the film.
Details are provided below.

First, the components of the first resin composition are mixed uniformly using any kneading device to prepare the first resin composition.
Hereinafter, details will be described using an example in which a silicone resin is used as the resin.

[1] For example, a vinyl group-containing organopolysiloxane (A), an inorganic filler, and a silane coupling agent are weighed out in predetermined amounts, and then kneaded in any kneading device to obtain a kneaded product.

When obtaining this kneaded product, water may be added as necessary. This allows the reaction between the silane coupling agent and the inorganic filler to proceed more reliably.

Furthermore, the above kneading is preferably carried out through a first step of heating at a first temperature and a second step of heating at a second temperature. This allows the surface of the inorganic filler to be surface-treated with a coupling agent in the first step, and allows by-products generated by the reaction between the inorganic filler and the coupling agent to be reliably removed from the kneaded product in the second step. Thereafter, component (A) may be added to the kneaded product obtained as necessary, and further kneaded. This allows the compatibility of the components of the kneaded product to be improved.

The first temperature is preferably, for example, about 40 to 120°C, and more preferably, for example, about 60 to 90°C. The second temperature is preferably, for example, about 130 to 210°C, and more preferably, for example, about 160 to 180°C.

The atmosphere in the first step is preferably an inert atmosphere such as a nitrogen atmosphere, and the atmosphere in the second step is preferably a reduced pressure atmosphere.

Furthermore, the time for the first step is, for example, preferably about 0.3 to 1.5 hours, and more preferably about 0.5 to 1.2 hours. The time for the second step is, for example, preferably about 0.7 to 3.0 hours, and more preferably about 1.0 to 2.0 hours.

By setting the above conditions for the first and second steps, the above effects can be obtained more significantly.

[2] Next, a predetermined amount of organohydrogenpolysiloxane (B) and a catalyst are weighed out, and then, using any kneading device, each component is kneaded into the kneaded product prepared in the above step [1] to obtain a first resin composition. The obtained first resin composition may be a paste containing a solvent.

When mixing the components (B) and the catalyst, it is preferable to mix the mixture prepared in the above step [1] with the organohydrogenpolysiloxane (B) and then mix the mixture prepared in the above step [1] with the catalyst, and then mix the mixtures together. This allows each component to be reliably dispersed in the first resin composition without allowing the reaction between the vinyl group-containing organopolysiloxane (A) and the organohydrogenpolysiloxane (B) to proceed.

The temperature at which each component (B) and catalyst are kneaded is, for example, preferably about 10 to 70°C, and more preferably about 25 to 30°C, as the roll setting temperature.

Furthermore, the kneading time is preferably, for example, about 5 minutes to 1 hour, and more preferably about 10 to 40 minutes.

In the above steps [1] and [2], by setting the temperature within the above range, the progress of the reaction between the vinyl group-containing organopolysiloxane (A) and the organohydrogenpolysiloxane (B) can be more accurately prevented or suppressed. In addition, in the above steps [1] and [2], by setting the kneading time within the above range, each component can be more reliably dispersed in the first resin composition.

The kneading device used in each step [1] and [2] is not particularly limited, but may be, for example, a kneader, a two-roll mill, a Banbury mixer (continuous kneader), a pressure kneader, etc.

In addition, in this step [2], a reaction inhibitor such as 1-ethynylcyclohexanol may be added to the kneaded mixture. This makes it possible to more accurately prevent or inhibit the progress of the reaction between the vinyl group-containing organopolysiloxane (A) and the organohydrogenpolysiloxane (B) even if the temperature of the kneaded mixture is set to a relatively high temperature.

[3] Next, the first resin composition obtained in step [2] may be made into a paste by dissolving it in a solvent.

[4] Next, the first resin composition is processed into a film and cured to form the release layer 1.
Specifically, the first resin composition is molded into a film by extrusion molding, calendar molding, press molding, coating, etc. During film formation, the surface shape of a roll or the like may be transferred or embossed.

In this embodiment, the curing process of the first resin composition is carried out, for example, by heating at 100 to 250°C for 1 to 30 minutes (first curing) and then post-baking at 100 to 250°C for 1 to 4 hours (secondary curing).

By going through the above steps, a release layer 1, i.e., a release film 11, is obtained using the first resin composition of this embodiment.

[Base layer 2]
In the release film 11 of the present embodiment, the base layer 2 is used from the viewpoint of imparting appropriate rigidity to the release film 11 in order to ensure shape stability, production stability, and release function of the release layer.

The thickness of the base layer 2 is preferably 5 μm or more and 50 μm or less, more preferably 9 μm or more and 35 μm or less, and even more preferably 12 μm or more and 25 μm or less.
By setting the thickness of the base layer 2 to the above-mentioned lower limit or more, the rigidity of the release film 11 is increased, and it becomes easier to suppress excessive deformation and wrinkles. As a result, mold followability and dimensional stability are obtained. On the other hand, by setting the thickness of the base layer 2 to the above-mentioned upper limit or less, the rigidity of the release film 11 can be controlled, and a good balance between mold followability and releasability can be achieved.

The material of the base layer 2 may be one or more selected from the group consisting of polyester resins, polyamide resins, and polyolefin resins.
The polyester resin, polyamide resin, and polyolefin resin may be the same as those described for the release layer 1.

A stretched film may also be used as the substrate layer 2, and the stretching can be performed using known methods such as sequential biaxial stretching, simultaneous biaxial stretching, and tubular stretching.

[Method of producing release film]
The release film 11 can be produced by using a known method such as a co-extrusion method, an extrusion lamination method, a dry lamination method, an inflation method, etc. The release layer 1 may be formed on the base layer 2 by applying a first resin composition prepared in a paste form to the surface of the base layer 2.
In the release film 11, for example, the release layer 1 and the base layer 2 may be produced separately and then bonded together by a laminator or the like. In addition, the release layer 1 and the base layer 2 may be bonded together as they are, or may be bonded together via an adhesive layer.
The method for producing the base layer 2 is not limited, and specific examples thereof include an inflation extrusion method and a T-die extrusion method.

[Uses and methods of use of release film]
The release film 11 of this embodiment is used for the purpose of being placed between a mold to which a sealing resin is supplied and a semiconductor device to be resin-sealed in a resin sealing process of a semiconductor device. That is, it may be a so-called mold-forming release film, or may be used for other purposes. As another use, for example, when a coverlay film (hereinafter also referred to as a "CL film") is bonded to a flexible film with an exposed circuit (hereinafter also referred to as a "circuit-exposed film") by a heat press to produce a flexible printed circuit board (hereinafter also referred to as an "FPC"), it may be placed between the cover film and a mold. In addition, it can also be used as a release film when hardening a prepreg of a thermosetting resin such as CFRP, a release film for molding a thermosetting resin, a transfer release film for decoration that applies printing or the like to a product having a three-dimensional shape, etc.

Below, an example of a method for manufacturing a resin-encapsulated semiconductor device using a release film 11 is described.

The method for manufacturing a resin-encapsulated semiconductor device includes the following steps.
(Step 1) Preparation of the semiconductor device (Step 2) Installation of a release film (Step 3) Supply of sealing resin (Step 4) Hardening (Step 5) Demolding of molded body Each step will be described in detail below.

(Step 1) Preparation of Semiconductor Device A semiconductor device is formed by electrically connecting electrode pads on circuit wiring provided on a support and electrodes provided on a semiconductor element.
Examples of the semiconductor element include optical elements such as a light emitting element and a light receiving element. An example of the light emitting element is an LED chip (light emitting diode), and an example of the light receiving element is an image sensor.
The support is a substrate formed in any shape such as a circle or a polygon. Examples of the support include a ceramic substrate, a silicone substrate, a metal substrate, a rigid substrate such as an epoxy resin or a BT resin, or a flexible substrate such as a polyimide resin or a polyethylene substrate.

(Step 2) Step of Setting the Release Film The release film 11 is placed on a lower mold having a cavity recess for supplying the sealing resin. At this time, the release surface 3 of the release film 11 is placed on the front side, that is, in contact with the sealing resin to be supplied later.
The release film 11 is disposed in the cavity recess of the lower mold and along the surface of the flat surface surrounding the cavity recess. At this time, the flat surface surrounding the cavity recess is provided with a suction port for making the release film 11 conform to the shape of the cavity recess of the lower mold. The air, moisture, gas, etc. in the space between the release film 11 and the mold is sucked and discharged from the suction port using a suction device or the like, and vacuum adsorption is performed. Furthermore, in order to firmly fix the release film 11 to the mold, the release film 11 may be clamped by a chuck mechanism arranged at a position corresponding to the outer periphery of the sealing resin injection area, the outer periphery of the entire release film 11, or the outer periphery of the entire mold.
Examples of the mold include a known metal mold and a resin mold.

(Step 3) Sealing resin supply step Next, the sealing resin is supplied to the recessed portion of the mold where the release film 11 is disposed. A known method can be used as the supply method. The sealing resin can be any known resin, such as silicone resin, epoxy resin, acrylic resin, fluorine resin, polyimide resin, silicone modified epoxy resin, or a mixture of these resins, or precursors thereof.
In this embodiment, when the release film 11 is applied to a compression molding method, the sealing resin is preferably processed into a tablet, granule, sealed particle, or sheet shape.
In the mold, the sealing resin is heated to a predetermined temperature and is in a fluid state.

(Step 4) Curing Step Next, the semiconductor device to be molded is attached to an upper mold provided with a protruding fixture for holding the outer edge of the molded object so that the molded object does not fall, and the surface of the semiconductor device on which the semiconductor element is provided is placed opposite the lower mold, and the mold is pressed against the mold in which the sealing resin has been supplied into the recess. At this time, the fixture of the upper mold fits into the groove of the lower mold, and the semiconductor element is covered with the sealing resin. The sealing resin is then heated and pressurized to harden it, and a molded body is obtained.
When the sealing resin is a precursor of a curable resin, it may be cured by heating and irradiation with active energy rays, examples of which include radiation, ultraviolet rays, visible light, and electron beams.

(Step 5) Demolding step of molded body After that, the molded body is demolded. In the demolding step of the molded body, air, moisture, gas, etc. are supplied between the release film 11 and the mold, so that the release film 11 is peeled off from the mold and the molded body is demolded. At the same time or after this, the release film 11 is demolded from the molded body.
When there is one semiconductor element provided on the support, this molded body becomes a resin-sealed semiconductor device.
This makes it possible to obtain a semiconductor device with a good appearance.

The above describes the embodiments of the present invention, but these are merely examples of the present invention, and various configurations other than those described above can be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and modifications and improvements that can achieve the object of the present invention are included in the present invention.

The present invention will be described in detail below with reference to examples, but the present invention is not limited to the description of these examples.

(1) Raw Materials The raw material components used in the Examples and Comparative Examples shown in Table 1 are as follows.
(Vinyl Group-Containing Organopolysiloxane (A))
Low vinyl group-containing linear organopolysiloxane (A1-1): a vinyl group-containing dimethylpolysiloxane synthesized according to Synthesis Scheme 1 (a structure represented by formula (1-1) in which only R ¹ (terminal) is a vinyl group)
High vinyl group-containing linear organopolysiloxane (A1-2): A vinyl group-containing dimethylpolysiloxane synthesized according to Synthesis Scheme 2 (a structure represented by formula (1-1) in which R ¹ and R ² are vinyl groups).

(Organohydrogenpolysiloxane (B))
・Momentive: "TC-25D"

(Inorganic filler)
Inorganic filler (C): silica fine particles (particle size 7 nm, specific surface area 300 m ² /g), manufactured by Nippon Aerosil Co., Ltd., "AEROSIL300"

(Silane coupling agent)
Silane coupling agent (D-1): hexamethyldisilazane (HMDZ), manufactured by Gelest, "HEXAMETHYLDISILAZANE (SIH6110.1)"
Silane coupling agent (D-2): Divinyltetramethyldisilazane, manufactured by Gelest, "1,3-DIVINYLTETRAMETHYLDISILAZANE (SID4612.0)"

(Platinum or platinum compound (E))
・Momentive: "TC-25A"

(Synthesis of vinyl group-containing organopolysiloxane (A))
[Synthesis Scheme 1: Synthesis of low-vinyl-group-containing linear organopolysiloxane (A1-1)]
A low-vinyl-group-containing linear organopolysiloxane (A1-1) was synthesized according to the following formula (5).
That is, 74.7 g (252 mmol) of octamethylcyclotetrasiloxane and 0.1 g of potassium siliconate were placed in a 300 mL separable flask equipped with a cooling tube and stirring blade and substituted with Ar gas, and the temperature was raised and the mixture was stirred for 30 minutes at 120° C. During this time, an increase in viscosity was confirmed.
The temperature was then raised to 155° C. and stirring was continued for 3 hours. After 3 hours, 0.1 g (0.6 mmol) of 1,3-divinyltetramethyldisiloxane was added and the mixture was further stirred at 155° C. for 4 hours.
After 4 hours, the mixture was diluted with 250 mL of toluene and washed three times with water. The washed organic layer was washed several times with 1.5 L of methanol for reprecipitation purification, and the oligomer and polymer were separated. The resulting polymer was dried overnight under reduced pressure at 60° C. to obtain a low-vinyl-group-containing linear organopolysiloxane (A1-1) (Mn=2.2×10 ⁵ , Mw=4.8×10 ⁵ ). The vinyl group content calculated by H-NMR spectrum measurement was 0.04 mol%.

[Synthesis Scheme 2: Synthesis of Highly Vinyl Group-Containing Linear Organopolysiloxane (A1-2)]
A vinyl-rich linear organopolysiloxane (A1-2) was synthesized as shown in the following formula (6) by the same synthesis process as for (A1-1), except that 0.86 g (2.5 mmol) of 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane was used in addition to 74.7 g (252 mmol) of octamethylcyclotetrasiloxane in the synthesis process for (A1-1). (Mn=2.3×10 ⁵ , Mw=5.0×10 ⁵ ). The vinyl group content calculated by H-NMR spectrum measurement was 0.92 mol%.

(2) Preparation of first resin composition (preparation of release layer)
Each of the first resin compositions was prepared as follows.
First, a mixture of 90% vinyl group-containing organopolysiloxane (A), a silane coupling agent, and water (F) was pre-kneaded in the proportions shown in Table 1 below, and then an inorganic filler was added to the mixture and further kneaded to obtain a kneaded product (silicone rubber compound).
Here, the kneading after the addition of the inorganic filler was carried out through a first step of kneading for 1 hour under conditions of 60 to 90°C in a nitrogen atmosphere for the coupling reaction, and a second step of kneading for 2 hours under conditions of 160 to 180°C in a reduced pressure atmosphere for the removal of the by-product (ammonia), after which the mixture was cooled, and the remaining 10% of the vinyl group-containing organopolysiloxane (A) was added in two portions, followed by kneading for 20 minutes.
Next, organohydrogenpolysiloxane (B) (TC-25D) and platinum or platinum compound (E) (TC-25A) were added to 100 parts by weight of the obtained kneaded product (silicone rubber compound) in the ratios shown in Table 1 below, and the mixture was kneaded with a roll to obtain each first resin composition.

(3) Preparation of a release film having a substrate layer <Example 1>
As shown in Table 2, biaxially oriented polybutylene terephthalate (OPBT1: Toyobo Co., Ltd., Toyobo Ester (registered trademark) film, DE048) 15 μm thick was used as a substrate layer, and a paste (solid content 25 mass%, solvent decane) made of the first resin composition prepared in (2) above was applied onto the substrate layer using a bar coater and cured at 180 ° C. for 120 minutes to obtain a release film having a release layer on the substrate layer. The thickness of the release layer of the obtained release film was 35 μm, and the surface roughness Rz of the release surface of the release layer was 0.1 μm.

Example 2
As shown in Table 2, a release film was produced in the same manner as in Example 1, except that a matte film was sandwiched in the film-forming process using a paste made of the first resin composition to provide an uneven surface on the surface of the release layer.

Example 3
As shown in Table 2, a release film was prepared in the same manner as in Example 1, except that the thickness of the release layer was changed to 10 μm.

Example 4
As shown in Table 2, a release film was prepared in the same manner as in Example 1, except that the thickness of the release layer was changed to 70 μm.

Example 5
A release film was prepared in the same manner as in Example 1, except that the first resin composition used to form the release layer was changed to the composition shown in Table 2.

Example 6
As shown in Table 2, a release film was produced in the same manner as in Example 1, except that the base layer was changed to biaxially oriented polybutylene terephthalate (OPET2: manufactured by Kohjin Film & Chemicals Co., Ltd., Boblet ST20) having a thickness of 20 μm and the release layer was changed to a thickness of 30 μm.

Example 7
As shown in Table 2, a release film was produced in the same manner as in Example 1, except that the base layer was changed to biaxially oriented polyethylene terephthalate (OPET1: Toyobo Co., Ltd., Toyobo Ester (registered trademark) film) with a thickness of 9 μm and the release layer was changed to a thickness of 41 μm.

Example 8
As shown in Table 2, a release film was prepared in the same manner as in Example 1, except that the base layer was changed to a thickness of 12 μm of biaxially oriented polyethylene terephthalate (manufactured by Toyobo Co., Ltd., Toyobo Ester (registered trademark) film), and the thickness of the release layer was changed to 38 μm.

<Example 9>
As shown in Table 2, a release film was produced in the same manner as in Example 1, except that the base layer was changed to biaxially oriented polyethylene terephthalate (OPET2: manufactured by Toyobo Film Solutions Co., Ltd., Teflex (registered trademark) film FW2) with a thickness of 13 μm and the thickness of the release layer was changed to 37 μm.

<Comparative Example 1>
A release film was prepared in the same manner as in Example 1, except that the first resin composition used to form the release layer was changed to the composition shown in Table 2.

<Comparative Example 2>
As shown in Table 2, a release film was produced in the same manner as in Example 1, except that the base layer was changed to biaxially oriented polyethylene terephthalate (OPET1: Toyobo Co., Ltd., Toyobo Ester (registered trademark) film) having a thickness of 19 μm and the release layer was changed to a thickness of 31 μm.

<Comparative Example 3>
As shown in Table 2, a release film was prepared in the same manner as in Example 1, except that the base layer was changed to a film (thickness: 35 μm) prepared using poly 4-methyl 1-pentene resin (manufactured by Mitsui Chemicals, Inc., TPX RT31).

<Comparative Example 4>
As shown in Table 2, a release film was produced in the same manner as in Example 1, except that the base layer was a film (25 μm thick) made from polybutylene terephthalate elastomer resin (Hytrel 6347, manufactured by Toray DuPont) and the thickness of the release layer was changed to 25 μm.

(4) Measurement and Evaluation The following measurements and evaluations were carried out using the obtained release film. The results are shown in Table 2.

(a) The 180°C, 5% tensile strength (5% modulus) of the release film was calculated from the S-S curve obtained by measuring in accordance with tensile test JIS-K7127.

(b) The breaking strength X1 (MPa) at 25° C. and the breaking strength X2 (MPa) at 180° C. were measured in accordance with JIS-K7127. The obtained X1 and X2 were substituted into the following formula to calculate α1.
α1=((1-(X1-X2)/X1))

(c) The Young's modulus of the release film 11 at 180°C was measured in accordance with JIS-K7127.

(d) Thermomechanical analysis (TMA) was used to measure the dimensional change (%) of the release film when the temperature was raised from 30°C to 250°C at a rate of 2°C/min under a tensile load of 500 mN using a TMA7100 (Hitachi High-Tech Science Corporation).

(i) Measurement of surface roughness Rz of release surface of release film Measured in accordance with JIS B0601:2013.

(ii) Evaluation of Appearance of Molded Article First, the following granular thermosetting resin composition was prepared as an encapsulating resin.
(Raw materials)
Epoxy resin 1: Biphenyl aralkyl type epoxy resin (manufactured by Nippon Kayaku Co., Ltd., NC-3000)
Epoxy resin 2: Biphenyl type epoxy resin (manufactured by Mitsubishi Chemical Corporation, YL6677)
Hardener 1: Biphenylene skeleton-containing phenol aralkyl resin (manufactured by Nippon Kayaku Co., Ltd., GPH-65)
Hardener 2: Triphenylmethane type phenolic resin modified with formaldehyde (HE910-20, manufactured by Air Water Corporation)
Curing accelerator: Triphenylphosphine (TPP, manufactured by Hokko Chemical Industry Co., Ltd.)
Inorganic filler: fused spherical silica (manufactured by Denki Kagaku Kogyo Co., Ltd., FB-950FC)
Colorant: Carbon black (Mitsubishi Chemical Corporation, MA-600)
Coupling agent: N-phenyl-γ-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-573)
Release agent: Carnauba wax (Nikko Fine Co., Ltd., Nikko Carnauba)
(procedure)
The above-mentioned epoxy resin 1 was prepared in an amount of 4.5 parts by mass, epoxy resin 2 in an amount of 4.5 parts by mass, curing agent 1 in an amount of 2.8 parts by mass, curing agent 2 in an amount of 2.8 parts by mass, curing accelerator in an amount of 0.4 parts by mass, inorganic filler in an amount of 84.2 parts by mass, colorant in an amount of 0.2 parts by mass, coupling agent in an amount of 0.4 parts by mass, and release agent in an amount of 0.2 parts by mass. Then, the raw material components were mixed at room temperature using a mixer, and then roll-kneaded while being heated with two rolls at 45°C and 90°C to obtain a kneaded product. Then, the kneaded product was cooled and then pulverized to obtain a granular thermosetting resin composition.

Next, using each release film, curing of the thermosetting resin composition (resin sealing) was carried out in the following procedure.
First, five semiconductor elements each having a thickness of 0.3 mm and a square of 7.5 mm were bonded with silver paste onto an organic substrate having a thickness of 0.4 mm, a width of 65 mm, and a length of 190 mm, and gold wires having a diameter of 18 μm and a length of 7 mm were bonded at a pitch interval of 60 μm. Next, the mold temperature of a compression molding machine (TOWA Corporation, PMC1040) was set to 175° C. in advance. Next, the organic substrate was fixed to the upper mold so that the surface on which the semiconductor elements were mounted faced the lower mold. Next, the release film prepared in each Example and Comparative Example was placed on the lower mold, and the mold internal space was evacuated to allow the release film to follow the mold. Then, the granular thermosetting resin composition (encapsulating resin composition) prepared was uniformly supplied onto the release film. Next, immediately after supplying the encapsulating resin composition, the mold was clamped until the gap between the organic substrate and the release film was 4 mm, and at the same time, the inside of the cavity formed by the lower mold and the upper mold was depressurized to a vacuum degree of 0.8 Torr in 4 seconds. Then, while continuing the depressurization, the mold was completely clamped in 12 seconds, and encapsulating molding was performed under conditions of a molding pressure of 3.9 MPa and a curing time of 90 seconds.

(iii) Evaluation of release film [mold followability]
In the above procedure, the degree of air entrapment between the mold and the release film when the release film was made to follow the mold by vacuum drawing was evaluated according to the following criteria.
◎: No air pockets were found. ◯: Small air pockets were found, but no practical problems were found. △: Small air pockets were found, and the degree of vacuum for film adsorption was reduced. ×: Large air pockets caused poor tracking (or evaluation was impossible).

[Dimensional stability]
In the above procedure, the appearance (wrinkles, etc.) of the cured product after it was released from the release film after molding was evaluated according to the following criteria.
◯: No wrinkles or deformations, no problem △: Some wrinkles, but no practical problem ×: Large wrinkles and molding defects

[Releasability]
In the above procedure, the release behavior when the cured product was released from the release film after molding and the state of the cured product (displacement, bending, etc.) were evaluated according to the following criteria.
◯: No problems with demolding or molded products △: The molded product shifted or warped when demolded, but no practical problems ×: Demolding was impossible, or the molded product shifted or warped significantly

[Interlaminar strength]
In the above procedure, the state of the release layer when the cured product was released from the release film after molding was evaluated according to the following criteria.
◯: No peeling of the release layer, no problem △: Some of the release layer is lifted from the base layer, but no problem in practical use ×: The release layer is largely peeled off from the base layer

1 Release layer 2 Base layer 3 Release surface 11 Release film

Claims (5)

A release film that satisfies the following (a) to (b):
(a) the release film has a 180°C 5% tensile strength (5% modulus) of 1.0 MPa or more and 5.0 MPa or less;
(b) When the breaking strength at 25° C. is X1 (MPa), the breaking strength at 180° C. is X2 (MPa), and (1-(X1-X2)/X1) is α1, α1 is 0.20 or more and 0.80 or less. The release film according to claim 1 , which satisfies the following (c):
(c) The release film has a Young's modulus at 180° C. of 25 MPa or more and 110 MPa or less. The release film according to claim 1 or 2, which satisfies the following (d):
(d) When the release film is subjected to a tensile load of 500 mN and heated from 30° C. to 180° C. at a rate of 2° C./min, the dimensional change rate is 4% or more and 40% or less. The release film according to any one of claims 1 to 3, wherein the release film has a multi-layer structure including a release layer that forms at least one surface of the release film and a base layer made of a material different from that of the release layer. The release film according to any one of claims 1 to 4, which is used for disposing the release film between a mold and a semiconductor device in a resin-sealed semiconductor device molding process in which the semiconductor device is resin-sealed.

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