JP6414345B2 - Release film - Google Patents

Description

  The present invention relates to a release film.

  A semiconductor chip is usually sealed with a resin for shielding and protecting from the outside air, and mounted on a substrate in the form of a molded product called a package. This molded product is usually molded as a package molded product for each chip connected via a runner which is a flow path of the sealing resin. In this case, the mold release property of the molded product is obtained by the structure of the mold used for molding the molded product, the addition of a release agent to the sealing resin, and the like.

  On the other hand, demands for packages such as Ball Grid Array (BGA) method, Quad Flat Non-leaded (QFN) method, Wafer Level Chip Size Package (WL-CSP) method, etc. due to demands for smaller packages and higher pin counts. Has increased. In the QFN method, a resin is used to secure the standoff and prevent the occurrence of burrs on the terminal portion due to the sealing material. In the BGA method and the WL-CSP method, the resin is used to improve the release property of the package from the mold. A mold release film is used (see, for example, Patent Document 1). A molding method using such a release film is called “film assist molding”.

  In the fields of the BGA method and the WL-CSP method, the molding method is being changed from the conventional transfer mold method to the compression mold method for the purpose of increasing the size and efficiency of one shot.

  In addition, regardless of these molding methods, a process has been devised in which a functional sheet having another function is mounted in advance on the release film, and molding is performed so that the functional sheet is disposed on the semiconductor package in the molding process. (For example, refer to Patent Document 2 and Patent Document 3)

JP 2002-158242 A JP 2007-287937 A WO2013 / 183671 gazette

  In the methods described in Patent Document 2 and Patent Document 3, it is possible to collectively arrange functional sheets on a semiconductor package in the process of molding the semiconductor package. On the other hand, in the actual process, the release film is capable of holding the functional sheet without peeling from the release layer in the process up to the molding process, and the functional sheet is released in the molding process. It is desirable to satisfy the performance to be achieved.

  The performance of holding the functional sheet is not imparted to the release film that is currently widely used in the compression mold system. For this reason, in order to shape | mold a functional sheet | seat on a semiconductor package at a formation process using this release film, it is necessary to install a functional sheet | seat after a release film is arrange | positioned in a metal mold | die. However, it is difficult to automate the process of installing a functional sheet on a release film that is complex in shape and placed in a heated mold, and there is a problem that work efficiency and safety are poor in manual work.

  This invention is made | formed in view of the said situation, and provides the release film which is excellent in the performance which hold | maintains the functional sheet until a shaping | molding process, and the performance which releases the functional sheet in a shaping | molding process. Let it be an issue.

Means for solving the above problems include the following embodiments.
<1> A base material and a release layer provided on the base material and including a resin component and a filler, and a volume average particle diameter A (μm) of the filler and 1 m ^{2 of the} release layer. A release film in which the ratio (A / B) to the mass B (g / m ² ) is 1 or less.
<2> The release film according to <1>, wherein the filler has a volume average particle diameter A of 1 μm to 50 μm.
<3> release film according to the weight B per 1 m ² of the release layer is ^{0.1g / m 2 ~100g / m 2} , <1> or <2>.
<4> The release film according to any one of <1> to <3>, wherein the resin component includes a thermosetting resin.
<5> The release agent according to any one of <1> to <4>, further including a crosslinking agent, wherein the content of the crosslinking agent with respect to 100 parts by mass of the resin component is 1 part by mass to 10 parts by mass. Mold film.
<6> The mold release according to any one of <1> to <5>, wherein the base material contains at least one selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate. the film.

  ADVANTAGE OF THE INVENTION According to this invention, the release film excellent in the performance which hold | maintains the functional sheet until a shaping | molding process, and the performance which releases the functional sheet in a shaping | molding process is provided.

It is a figure which shows typically the cross section of the release film of the state holding the functional sheet. It is a figure which shows typically the cross section of the installation at the time of shape | molding by a transfer mold system using a release film. It is a figure which shows typically the cross section of the installation at the time of shape | molding by a transfer mold system using a release film. It is a figure which shows typically the cross section of the installation at the time of shape | molding by a transfer mold system using a release film.

  Hereinafter, embodiments for carrying out the present invention will be described in detail. However, the present invention is not limited to the following embodiments. In the following embodiments, the components (including element steps and the like) are not essential unless otherwise specified. The same applies to numerical values and ranges thereof, and the present invention is not limited thereto.

In this specification, the term “process” includes a process that is independent of other processes and includes the process if the purpose of the process is achieved even if it cannot be clearly distinguished from the other processes. It is.
In the present specification, the numerical ranges indicated by using “to” include numerical values described before and after “to” as the minimum value and the maximum value, respectively.
In the numerical ranges described stepwise in this specification, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of another numerical range. Good. Further, in the numerical ranges described in this specification, the upper limit value or the lower limit value of the numerical range may be replaced with the values shown in the examples.
In the present specification, the content rate or content of each component in the composition is such that when there are a plurality of substances corresponding to each component in the composition, the plurality of kinds present in the composition unless otherwise specified. It means the total content or content of substances.
In the present specification, the particle diameter of each component in the composition is a mixture of the plurality of types of particles present in the composition unless there is a specific indication when there are a plurality of types of particles corresponding to each component in the composition. Means the value of.
In this specification, the term “layer” or “film” refers to a part of the region in addition to the case where the layer or the film is formed when the region where the layer or film exists is observed. It is also included when it is formed only.
In this specification, the term “lamination” indicates that layers are stacked, and two or more layers may be combined, or two or more layers may be detachable.
In the present specification, “(meth) acryloyl group” means at least one of acryloyl group and methacryloyl group, “(meth) acryl” means at least one of acryl and methacryl, “(meth) acrylate” means acrylate and It means at least one of methacrylate.

<Release film>
The release film of the present embodiment has a base material and a release layer provided on the base material and containing a resin component and a filler, and the volume average particle diameter A (μm) of the filler and the release film. The ratio (A / B) to the mass B (g / m ² ) per 1 m ^{2 of the} mold layer is 1 or less.

  The release film of this embodiment is excellent in the performance to hold the functional sheet until the molding step and the performance to release the functional sheet in the molding step. For this reason, for example, it can use suitably for the method of arrange | positioning a functional sheet | seat on the surface of a semiconductor package during the shaping | molding process of a semiconductor package.

  The reason why the release film of this embodiment is excellent in the performance of holding the functional sheet until the molding step and the performance of releasing the functional sheet in the molding step is not necessarily clear, but in the release layer It is presumed to be due to the moderate tackiness imparted by the resin component contained and the moderate surface irregularities imparted by the filler contained in the release layer.

From the viewpoint of the performance of retaining the functional sheet, the ratio between the volume average particle diameter A (μm) of the filler contained in the release layer and the mass B (g / m ² ) per 1 m ^{2 of the} release layer is It is preferably 1.0 or less, more preferably 0.7 or less, and even more preferably 0.5 or less.

  The lower limit value of A / B is not particularly limited. For example, depending on the type and application of the semiconductor package, if you want to increase the pressure during molding, or if you want to roughen the finish of the outermost surface of the semiconductor package, give the release film high release performance. From the viewpoint of roughening the surface roughness, it is preferable that the A / B value is large. For example, it is preferably 0.3 or more, and more preferably 0.5 or more.

[Release layer]
The release layer contains a resin component and a filler, and the ratio (A / B) of the volume average particle diameter A (μm) of the filler to the mass B (g / m ² ) per 1 m ^{2 of the} release layer is 1. It is as follows.

  In the present embodiment, the volume average particle diameter A (μm) of the filler is a value measured by a light diffraction / scattering method, and the particle diameter when the accumulation from the small diameter side is 50% in the volume-based particle size distribution ( D50).

The range of mass B (g / m ² ) per 1 m ^{2 of the} release layer is not particularly limited, and can be selected in consideration of the relationship with the average particle diameter of the filler. For ^example, it is preferably ^{0.1g / m 2 ~100g / m 2} , more preferably ^{1g / m 2 ~50g / m 2} .
When the mass B per 1 m ^{2 of the} release layer is 0.1 g / m ² or more, the release layer contains a sufficient amount of the resin component, and the flexibility and stretchability required in the molding process. Is sufficiently obtained, and peeling or missing of the release layer from the substrate tends to be suppressed. Further, sufficient flexibility is obtained, and the holding ability of the functional sheet tends to be maintained well.
When the mass B per 1 m ^{2 of the} release layer is 100 g / m ² or less, the phenomenon that the release layer becomes too thick and the flatness of the release film is impaired due to thermal contraction stress during thermosetting is suppressed. There is a tendency. In addition, the functional sheet mounted with the release layer becoming too flexible tends to be embedded in the release layer, and the phenomenon that it is not correctly placed on the package surface tends to be suppressed.

In the present embodiment, the method for obtaining the mass B (g / m ² ) per 1 m ² of the release layer is not particularly limited. For example, the release layer was removed from the release film by using an organic solvent or the like (g) of the release film cut out so as to have an area of 100 cm ² (for example, a size of 10 cm × 10 cm). Obtaining the mass (g) of the release layer from the mass (g) of the subsequent substrate, multiplying the obtained value by 100 and converting it to the mass (g) of the release layer per 1 m ^2. Can do.

  The thickness of the release layer is not particularly limited. For example, it is preferably 0.1 μm to 100 μm. When the thickness of the release layer is 0.1 μm or more, the resin component can sufficiently hold the filler, so that the problem that the filler is dropped and mixed into the package during molding is less likely to occur stably. There is a tendency to produce semiconductor packages. When the thickness of the release layer is 100 μm or less, the raw materials used for the release layer can be saved, which is preferable from the viewpoint of manufacturing cost.

  In the present embodiment, the thickness of the release layer is a number average value obtained by measuring five points at an arbitrary place. The thickness of the release layer can be measured using, for example, a general-purpose micrometer.

  The release layer may have irregularities on the outer surface (the surface opposite to the surface on the substrate side) depending on the application. When the release layer has irregularities on the outer surface, from the viewpoint of uniformity of the package surface appearance, the release layer has an arithmetic average roughness (Ra) of the outer surface (the surface opposite to the surface on the substrate side). Is preferably 0.5 μm to 5 μm. Moreover, it is preferable that the 10-point average roughness (Rz) of an outer surface is 5 micrometers-50 micrometers.

  In this embodiment, the arithmetic average roughness (Ra) and the ten-point average roughness (Rz) of the outer surface of the release layer are, for example, a surface roughness measuring device (for example, Kosaka Laboratory, Model No. SE-3500). ) Using stylus tip diameter: 2 μm, feed rate: 0.5 mm / s, and scanning distance: 8 mm, and the results specified in JIS B0601 (2013) or ISO 4287 (1997) It may be a value obtained by analysis in

  The release layer preferably has an outer surface tack force at 25 ° C. of 1.0 gf or more. When the tack force at 25 ° C. of the outer surface is 1.0 gf or more, the performance of holding the functional sheet until the molding process tends to be superior.

  The release layer preferably has a tack force on the outer surface at 170 ° C. of 20.0 gf or less. When the tack force at 170 ° C. of the outer surface is 20.0 gf or less, the performance of releasing the functional sheet in the molding process tends to be superior.

  In the present embodiment, the tack force (gf) of the outer surface of the release layer is measured using, for example, a tack tester (for example, manufactured by Reska) and a probe having a diameter of 5 mm, a pre-measurement load of 10 gf, a pre-measurement load time of 1 second, It may be a value measured at an hourly rising speed of 600 mm / min.

  The filler content in the release layer is not particularly limited. For example, it is preferable that it is 1.0 mass%-50.0 mass% of the total mass of a mold release layer. When the filler content is 1.0% by mass or more of the total mass of the release layer, the surface of the molded semiconductor package tends to have a uniform appearance without unevenness due to the surface roughness of the release layer. It is in. When the filler content is 50.0% by mass or less of the total mass of the release layer, the resin component can sufficiently hold the filler component, so that the filler component falls off and is mixed into the package at the time of molding. Defects are less likely to occur and semiconductor packages tend to be produced stably.

  The release layer may contain other components such as a solvent, an anchoring improver, a crosslinking accelerator, an antistatic agent, and a colorant in addition to the resin component and the filler, if necessary.

(Resin component)
The kind of the resin component contained in the release layer is not particularly limited. For example, it may be a resin (thermosetting resin) having a property of causing a cross-linking reaction by heating and curing. Resins that can be used as resin components include acrylic resins, olefin resins, styrene resins, acrylonitrile resins, silicone resins, epoxy resins, cyanate ester resins, maleimide resins, allyl nadiimide resins, phenol resins, urea resins, melamine resins, alkyds. Resin, unsaturated polyester resin, diallyl phthalate resin, resorcinol formaldehyde resin, xylene resin, furan resin, urethane resin, ketone resin, triallyl cyanurate resin, isocyanate resin, resin containing tris (2-hydroxyethyl) isocyanurate , A resin containing triallyl trimellitate, a thermosetting resin synthesized from cyclopentadiene, a thermosetting resin by trimerization of aromatic dicyanamide, and the like. The resin component contained in the release layer may be only one type or two or more types.

  From the viewpoint of releasability with respect to the semiconductor package, the release layer preferably contains at least one selected from an acrylic resin, an olefin resin, a styrene resin, and an acrylonitrile resin as a resin component.

  Examples of the acrylic resin include a homopolymer or a copolymer containing at least a (meth) acrylic monomer in the polymerization component. Specific examples include poly (meth) acrylic acid and poly (meth) acrylate.

  (Meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate as (meth) acrylic monomers constituting the acrylic resin N-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, ( Heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, tetradecyl (meth) acrylate, Hexadecyl (meth) acrylate, octadecyl (meth) acrylate, eikoshi (meth) acrylate , Docosyl (meth) acrylate, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, cycloheptyl (meth) acrylate, benzyl (meth) acrylate, phenyl (meth) acrylate, methoxy (meth) acrylate Ethyl, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 2-fluoroethyl (meth) acrylate, (meth) And dicyclopentanyl acrylate.

  As monomers other than the (meth) acrylic monomer constituting the acrylic resin, styrene, α-methylstyrene, cyclohexylmaleimide, vinyltoluene, vinyl chloride, vinyl acetate, N-vinylpyrrolidone, butadiene, isoprene, chloroprene, etc. Is mentioned.

  Examples of the olefin resin include homopolymers of olefin monomers or alkene monomers, and copolymers containing olefin monomers or alkene monomers as polymerization components. Specific examples include polyolefins such as polyethylene, polypropylene, and polymethylpentene.

  Examples of the styrene resin include a homopolymer of styrene or a styrene derivative, a copolymer containing styrene or a styrene derivative as a polymerization component, and the like. Examples of the styrene derivative include alkyl-substituted styrene having an alkyl chain such as α-methylstyrene, 4-methylstyrene, 2-methylstyrene, 3-methylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, and the like. -Halogen-substituted styrene such as chlorostyrene, 3-chlorostyrene and 4-chlorostyrene, fluorine-substituted styrene such as 4-fluorostyrene and 2,5-difluorostyrene, vinylnaphthalene and the like.

  Examples of the acrylonitrile resin include a homopolymer of a (meth) acrylonitrile monomer, a copolymer containing a (meth) acrylonitrile monomer as a polymerization component, and the like.

  When a thermosetting resin is used as the resin component, a crosslinking agent may be used. When using a crosslinking agent, content of the crosslinking agent with respect to 100 parts by mass of the thermosetting resin is not particularly limited. For example, the content of the crosslinking agent with respect to 100 parts by mass of the thermosetting resin may be 1 part by mass to 10 parts by mass.

  The kind in particular of a crosslinking agent is not restrict | limited, It can select according to the kind of thermosetting resin, desired hardening rate, etc. For example, when using an acrylic resin as a thermosetting resin, it can select from well-known crosslinking agents, such as an isocyanate compound, a melamine compound, and an epoxy compound.

[Filler]
The volume average particle size of the filler is such that the ratio (A / B) of the volume average particle size A (μm) to the mass B (g / m ² ) per 1 m ^{2 of the} release layer is 1 or less. There is no particular limitation as long as it meets the requirements. For example, it is preferably 1 μm to 50 μm.

  If the volume average particle diameter of the filler is 1 μm or more, sufficient unevenness tends to be formed on the outer surface of the release layer, the uniformity of the appearance of the molded semiconductor package surface is improved, and the flow of the sealing material The trace tends to be suppressed. When the volume average particle diameter of the filler is 50 μm or less, the thickness of the release layer necessary to suppress the filler from falling off from the release layer tends to be suppressed.

  The upper limit of the volume average particle diameter of the filler is preferably 50 μm and more preferably 20 μm from the viewpoint of the appearance of the semiconductor package surface. The lower limit of the volume average particle diameter of the filler is preferably 1 μm from the viewpoint of adjusting the surface roughness of the molded semiconductor package.

  The shape of the filler contained in the release layer is not particularly limited. For example, a spherical shape, an elliptical shape, an indefinite shape, and the like are given.

  As long as the filler can be retained in the form contained in the release layer (that is, it is difficult to dissolve in the organic solvent used for forming the release layer, the resin component contained in the release layer, etc.). The material is not particularly limited, and may be a filler made of an organic substance, a filler made of an inorganic substance, or a filler made of both an organic substance and an inorganic substance. The filler contained in the release layer may be only one type or two or more types.

  Examples of the inorganic substance serving as the filler material include metals such as silver, gold, and copper, silica, alumina, titania, and iron oxide. The inorganic substance may have conductivity or may not have conductivity.

When using a filler made of an inorganic substance, an inorganic ion exchanger may be used in combination. As the inorganic ion exchanger, when the release layer film is extracted in hot water, ions (Na ⁺ , K ⁺ , Cl ⁻ , F ⁻ , RCOO ⁻ , Br ^−, etc.) extracted in an aqueous solution, where R is an alkyl Those having a trapping action of the group, aryl group, etc.) are effective. Examples of such inorganic ion exchangers include naturally produced zeolites, natural minerals such as zeolites, acid clay, dolomite, hydrotalcites, and artificially synthesized synthetic zeolites.

  Examples of the organic substance serving as the filler material include acrylic resin, imide resin, amide resin, amideimide resin, olefin resin, styrene resin, carbonate resin, silicone resin, and ABS resin. These resins are preferably cured by a crosslinking reaction.

  Among the fillers described above, a filler containing an acrylic resin cured by a cross-linking reaction (hereinafter also referred to as a cross-linked acrylic resin) has excellent dispersibility in the resin component, and selects the type of monomer that becomes a polymerization component. It is preferable because the filler shape, particle diameter, heat resistance and other characteristics can be easily adjusted.

  As the cross-linked acrylic resin, (meth) acrylic monomer not containing a functional group such as butyl (meth) acrylate, ethyl (meth) acrylate, (meth) 2-ethylhexyl acrylate, (meth) acrylic acid, A (meth) acrylic copolymer obtained by copolymerizing a (meth) acrylic monomer having a functional group such as hydroxyethyl (meth) methacrylate, (meth) acrylamide, (meth) acrylonitrile, or other monomers preferable.

  The (meth) acrylic monomer that is a polymerization component of the cross-linked acrylic resin includes (1) a (meth) acrylic monomer having a chain alkyl group, and (2) a (meth) acrylic having an alicyclic skeleton. Monomers, (3) polyfunctional (meth) acrylic monomers, (4) (meth) acrylic monomers having functional groups, and the like. Hereinafter, each (meth) acryl monomer will be described.

(1) (Meth) acrylic monomer having a chain alkyl group (Meth) acrylic monomer having a chain hydrocarbon group in the ester moiety as a (meth) acryl monomer having a chain hydrocarbon group Acid ester (hereinafter, (meth) acrylic acid ester may be referred to as (meth) acrylate).

  Examples of the (meth) acrylic acid ester having a chain hydrocarbon group include (meth) acrylic acid esters having a chain hydrocarbon group having 1 to 20 carbon atoms. When the hydrocarbon group has 20 or less carbon atoms, the elastic modulus tends to be low. From the viewpoint of solubility of the acrylic polymer, the number of carbon atoms is preferably 2-18, and from the viewpoint of heat resistance in the molding step, the number of carbon atoms is more preferably 4-18. The chain hydrocarbon group is preferably an alkyl group having 1 to 20 carbon atoms.

  The chain hydrocarbon group may be linear or branched, but when branched, it preferably does not contain a tertiary carbon atom. By not containing a tertiary carbon atom, mass reduction due to thermal decomposition at low temperature hardly occurs, which is advantageous in terms of heat resistance.

  Specific examples of the (meth) acrylic acid ester having a chain and a hydrocarbon group having 1 to 20 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, Isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, pentyl (meth) acrylate, n-hexyl (meth) acrylate, (meta ) N-octyl acrylate, 2-ethylhexyl (meth) acrylate, decyl (meth) acrylate, 1-dodecanol (meth) acrylate, isostearyl (meth) acrylate, and the like.

(2) (Meth) acrylic monomer having alicyclic skeleton Examples of the (meth) acrylic monomer having an alicyclic skeleton include (meth) acrylic acid esters having an alicyclic skeleton. Examples of the alicyclic skeleton include a cycloalkane skeleton, a bicycloalkane skeleton, a norbornyl skeleton, and an isobornyl skeleton. Among these, from the viewpoint of improving transparency, a bicycloalkane skeleton and a norbornyl skeleton are preferable.

Specific examples of (meth) acrylic monomers having an alicyclic skeleton include cyclopentyl (meth) acrylate, cyclopentanyl (meth) acrylate, cyclohexyl (meth) acrylate, methyl cyclohexyl (meth) acrylate, Trimethylcyclohexyl (meth) acrylate, norbornyl (meth) acrylate, norbornyl methyl (meth) acrylate, phenyl norbornyl (meth) acrylate, cyanonorbornyl (meth) acrylate, (meth) acrylic acid Isobornyl, bornyl (meth) acrylate, menthyl (meth) acrylate, phentyl (meth) acrylate, adamantyl (meth) acrylate, dimethyladamantyl (meth) acrylate, tricyclo (meth) acrylate [5.2.1 .0 ^2,6] dec-8-yl, (meth) acrylate Acid tricyclo [5.2.1.0 ^2,6] dec-4-methyl, and (meth) cyclodecyl acrylic acid.

From the viewpoint of heat resistance, cyclopentanyl acrylate, cyclohexyl acrylate, isobornyl acrylate, norbornyl acrylate, norbornyl acrylate, tricyclo [5.2.1.0 ^2,6 ] deca-8 -Yl, tricyclo [5.2.1.0 ^2,6 ] deca-4-methyl acrylate, adamantyl acrylate, cyclopentyl methacrylate, cyclohexyl methacrylate, methyl cyclohexyl methacrylate, trimethyl cyclohexyl methacrylate, norbornyl methacrylate, Norbornyl methyl methacrylate, isobornyl methacrylate, bornyl methacrylate, menthyl methacrylate, fentyl methacrylate, adamantyl methacrylate, dimethyladamantyl methacrylate, tricyclomethacrylate [5. .1.0 ^2,6] dec-8-yl methacrylate tricyclo [5.2.1.0 ^2,6] dec-4-methyl, cyclodecyl methacrylate and methacrylic acid phenyl norbornyl are preferred.

Furthermore, from the point of high heat resistance, cyclopentanyl acrylate, cyclohexyl acrylate, isobornyl acrylate, norbornyl acrylate, norbornyl methyl acrylate, tricyclo [5.2.1.0 ^2,6 ] decaacrylate. -8-yl, tricyclo [5.2.1.0 ^2,6 ] dec-4-methyl acrylate, adamantyl acrylate, and the like are more preferable.

(3) Polyfunctional (meth) acrylic monomer The polyfunctional (meth) acrylic monomer is not particularly limited as long as it has two or more (meth) acryloyl groups. As the polyfunctional (meth) acrylic monomer, a (meth) acrylic monomer having two or more (meth) acryloyl groups and an alicyclic skeleton, two or more (meth) acryloyl groups and an aliphatic skeleton are used. (Meth) acrylic monomer having, (meth) acrylic monomer having two or more (meth) acryloyl groups and a dioxane glycol skeleton, two or more (meth) acryloyl groups, and (4) functional group described later And a (meth) acrylic monomer having a functional group that the (meth) acrylic monomer may have.

  Examples of the polyfunctional (meth) acrylic monomer include cyclohexane-1,4-dimethanol di (meth) acrylate, cyclohexane-1,3-dimethanol di (meth) acrylate, and tricyclodecane dimethylol di (meth) acrylate (for example, Manufactured by Nippon Kayaku Co., Ltd., KAYARAD R-684, tricyclodecane dimethylol diacrylate, etc.), tricyclodecane dimethanol di (meth) acrylate (for example, Shin-Nakamura Chemical Co., Ltd., A-DCP, tricyclode Candimethanol diacrylate), dioxane glycol di (meth) acrylate (for example, KAYARAD R-604, dioxane glycol diacrylate, etc., manufactured by Nippon Kayaku Co., Ltd.), neopentyl glycol di (meth) acrylate, dicyclopentanyl (Meth) acrylate, 1,6-hexanediol di (meth) acrylate, ethylene oxide-modified 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, (poly) ethylene oxide modified neopentyl glycol Di (meth) acrylate, hydroxypivalate neopentyl glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, ethylene oxide modified bisphenol A type di (meth) acrylate (preferably polyethylene oxide Modified bisphenol A type di (meth) acrylate, more preferably ethylene oxide 5-15 mol modified bisphenol A type di (meth) acrylate) and (poly) Examples thereof include ethylene oxide-modified phosphoric acid di (meth) acrylate.

(4) (Meth) acrylic monomer having functional group As the (meth) acrylic monomer having functional group, carboxy group, hydroxy group, acid anhydride group, amino group, amide group and epoxy are present in the molecule. And (meth) acrylic monomers having at least one functional group selected from the group consisting of groups.

  Examples of the (meth) acrylic monomer having a carboxy group as a functional group include (meth) acrylic acid, 2- (meth) acryloyloxyethyl succinic acid, 2- (meth) acryloyloxyethylphthalic acid, and 2- (meth). Examples include acryloyloxyethyl hexahydrophthalic acid and 2- (meth) acryloyloxypropyl hexahydrophthalic acid.

  Examples of the (meth) acrylic monomer having a hydroxy group as a functional group include hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, cyclohexanedimethanol mono (meth) acrylate, N-methylol (meth) acrylamide etc. are mentioned.

  Examples of the (meth) acrylic monomer having an acid anhydride group as a functional group include trimellitic anhydride (meth) acryloyloxyethyl ester, cyclohexanetricarboxylic anhydride (meth) acryloyloxyethyl ester, and the like.

  Examples of the (meth) acrylic monomer having an amino group as a functional group include diethylaminoethyl (meth) acrylate, (2,2,6,6-tetramethylpiperidinyl) (meth) acrylamide, etc. Is mentioned.

  Examples of the (meth) acrylic monomer having an amide group as a functional group include N- (meth) acryloylglycinamide.

  Examples of the (meth) acrylic monomer having an epoxy group as a functional group include glycidyl (meth) acrylate, glycidyl α-ethyl (meth) acrylate, glycidyl α-n-propyl (meth) acrylate, 2- (2 , 3-epoxypropoxy) ethyl (meth) acrylate, 3- (2,3-epoxypropoxy) propyl (meth) acrylate, 4- (2,3-epoxypropoxy) butyl (meth) acrylate, 5- (2,3 -Epoxypropoxy) pentyl (meth) acrylate, 6- (2,3-epoxypropoxy) hexyl (meth) acrylate, (meth) acrylic acid-3,4-epoxybutyl, (meth) acrylic acid-4,5-epoxy Pentyl, (meth) acrylic acid-6,7-epoxyheptyl, α-ethyl (meth) acrylic acid-6,7- Poxyheptyl, (meth) acrylic acid-3-methyl-3,4-epoxybutyl, (meth) acrylic acid-4-methyl-4,5-epoxypentyl, (meth) acrylic acid-5-methyl-5,6- Epoxyhexyl, (meth) acrylic acid-β-methylglycidyl, α-ethyl (meth) acrylic acid-β-methylglycidyl, (meth) acrylic acid-3-methyl-3,4-epoxybutyl, (meth) acrylic acid Examples include -4-methyl-4,5-epoxypentyl and (meth) acrylic acid-5-methyl-5,6-epoxyhexyl.

  Among the (meth) acrylic monomers having a functional group, an acrylic resin obtained by polymerizing a (meth) acrylic monomer having an epoxy group as a functional group (preferably glycidyl methacrylate) is excellent in airtightness. From the viewpoint of improving the antifouling property of the release film.

(Other monomers)
The crosslinkable acrylic resin may contain a monomer (other monomer) other than the above (meth) acrylic monomer as a polymerization component. Examples of other monomers include (meth) acrylic monomers containing a benzene ring or a heterocyclic ring, aromatic vinyl compounds, vinyl cyanide compounds, unsaturated dicarboxylic acid anhydrides, and N-substituted maleimides.

  Examples of (meth) acrylic monomers containing a benzene ring or a heterocyclic ring include phenyl (meth) acrylate, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, naphthyl (meth) acrylate, and (meth) acrylic. Acid tetrahydrofurfuryl etc. are mentioned.

  As aromatic vinyl compounds, 4-vinylpyridine, 2-vinylpyridine, α-methylstyrene, α-ethylstyrene, α-fluorostyrene, α-chlorostyrene, α-bromostyrene, fluorostyrene, chlorostyrene, bromostyrene , Methylstyrene, methoxystyrene, (o-, m-, p-) hydroxystyrene, styrene and the like.

  Examples of the vinyl cyanide compound include acrylonitrile and methacrylonitrile.

  Examples of unsaturated dicarboxylic acid anhydrides include maleic anhydride.

  Examples of N-substituted maleimides include N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-isopropylmaleimide, N-butylmaleimide, N-isobutylmaleimide, Nt-butylmaleimide, N-laurylmaleimide, Examples thereof include N-cyclohexylmaleimide, N-benzylmaleimide, N-phenylmaleimide and the like.

(Crosslinking agent)
The kind of the crosslinking agent used for causing the crosslinking reaction of the crosslinked acrylic resin is not particularly limited. For example, well-known crosslinking agents, such as an isocyanate compound, a melamine compound, an epoxy compound, are mentioned. In order to form a network structure that gently spreads in the cross-linked acrylic resin, it is preferable to use a polyfunctional cross-linking agent. In this specification, “polyfunctional” means trifunctional or higher.

[Base material]
The type of substrate is not particularly limited. It is preferable that the base material has both heat resistance that can withstand the heating of the mold during molding for a predetermined time and flexibility that can sufficiently follow the structure of the mold. Examples of the substrate having such characteristics include a substrate including a heat-resistant resin. When the substrate contains a resin, the resin may be only one type or two or more types.

  Considering that the molding of the sealing material is performed at a high temperature (usually about 100 ° C. to 200 ° C.), the base material desirably has heat resistance that can withstand this temperature for a predetermined time. In addition, when mounting the release film on the mold and in order to suppress the occurrence of wrinkles of the sealing resin flowing during molding, tearing of the release film, etc., the elastic modulus, elongation, etc. at high temperatures It is important to select in consideration of

  From the viewpoint of heat resistance and elastic modulus at high temperature, the substrate preferably contains polyester as a resin. Examples of the polyester include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, resins containing two or more polymerization components of these polyesters as polymerization components, and resins obtained by modifying these polyesters. Among these, it is preferable to include at least one selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate.

  The substrate is preferably in the form of a sheet. Specifically, what molded resin into the sheet form is mentioned. From the viewpoint of followability to the mold, it is preferably a biaxially stretched resin sheet (film).

  The thickness of the substrate is not particularly limited. For example, it is preferably 1 μm to 100 μm, and more preferably 3 μm to 20 μm. When the thickness of the substrate is 1 μm or more, the handleability of the release film is excellent and wrinkles tend not to occur. When the thickness is 100 μm or less, the followability to the mold during molding is excellent, and the occurrence of wrinkles and the like in the molded semiconductor package tends to be suppressed.

  In the present embodiment, the thickness of the base material is a number average value of values obtained by measuring five points at an arbitrary place. The thickness of the substrate can be measured using, for example, a general-purpose micrometer.

  Since the base material contacts the surface of the mold, depending on the material, a larger peeling force may be required to peel the release film from the mold. When the base material is difficult to peel from the mold, it is preferable to adjust the base material so that it is easy to peel from the mold.

  As a method of adjusting the base material so that it can be easily peeled off from the mold, the surface such as matte finish with respect to the surface opposite to the surface of the release layer side of the base material (the surface in contact with the mold) And the like, and a method of providing another release layer (second release layer) on the substrate.

  When providing a 2nd mold release layer on a base material, the material in particular of a 2nd mold release layer is not restrict | limited. For example, you may form using the same material as the material used for the mold release layer mentioned above. The thickness of the second release layer is not particularly limited, but is preferably 0.1 μm to 100 μm. The thickness of the second release layer is defined similarly to the thickness of the release layer described above.

[Other parts]
If necessary, the release film may have a member other than the release layer and the substrate. For example, between the release layer and the base material, between the base material and the second release layer, etc., members such as a release layer or an anchoring improving layer of the second release layer, an antistatic layer, a colored layer, etc. May be provided. Moreover, you may provide a protective layer in order to protect the surface of a release film.

<Method for producing release film>
The method for producing the release film is not particularly limited. For example, a composition for forming a release layer is prepared, applied to one side of the substrate, and if necessary, volatile components in the composition are removed by drying to form a release layer on the substrate. A mold release film can be produced by forming. In this case, the volume average particle diameter A (μm) of the filler contained in the formed release layer and the release layer are adjusted by adjusting the amount of the composition applied on the substrate and the amount of filler used. ratio of 1 m ² per mass B (g / ^{m 2)} to (a / B) can be set to 1 or less.

  The method for preparing the composition for forming the release layer is not particularly limited. For example, a resin component, a filler, and a solvent may be mixed and prepared. From the viewpoint of forming a release layer with suppressed thickness unevenness on the substrate, an organic solvent capable of dissolving the resin component is preferably used as the solvent. Examples of the organic solvent include toluene, methyl ethyl ketone, and ethyl acetate.

  The method for applying the composition to the substrate is not particularly limited. For example, it may be applied by a known coating method such as a roll coating method, a bar coating method, or a kiss coating method. When the composition for forming the release layer is applied to the substrate, it is preferably applied so that the thickness of the formed release layer is 0.1 μm to 100 μm.

  As needed, you may dry the composition provided to the base material and remove volatile components, such as a solvent in a composition. The drying method is not particularly limited, and can be performed by a known method. Drying may be performed at 50 to 150 ° C. for 0.1 to 60 minutes, for example.

[How to use the release film]
Hereinafter, an example of a method for using the release film of the present embodiment will be described with reference to the drawings. Moreover, the magnitude | size of the member in each figure is notional, The relative relationship of the magnitude | size between members is not limited to this.

  FIG. 1 schematically shows a cross section of a release film in a state where a functional sheet is held. In FIG. 1, a release film 10 has a substrate 1 and a release layer 2, and a functional sheet 3 is disposed on the release layer 2.

  FIG. 2 schematically shows a cross section of the facility when the release film 10 unwound from the roll state is supplied and molded using a transfer mold type molding facility. In FIG. 2, reference numeral 4 indicates a mold, and reference numeral 5 indicates a plunger for injecting the sealing resin into the gap in the mold. Reference numeral 6 denotes a support member for a semiconductor package. In the case of a BGA type package or the like, an electric circuit is often provided inside the support member. Reference numeral 7 denotes a semiconductor chip, and a circuit on the semiconductor chip is generally connected to a circuit in the support member by a metal wire (not shown) such as gold or copper.

  As shown in FIG. 2, the release film 10 is unwound from the roll 8 </ b> A and disposed in the concave portion of the mold 4. At this time, the functional sheet 3 mounted on the release film 10 is also disposed in the recess of the mold 4. Further, the mold 4 is heated (for example, about 170 ° C.) so that the sealing resin to be injected in a later process is melted.

  FIG. 3 schematically shows a state in which the upper and lower molds 4 are brought into contact and the sealing resin 9 is injected into the gaps in the mold 4 using the plunger 5.

  FIG. 4 schematically shows a state in which the upper and lower molds 4 are separated after completion of molding. As shown in FIG. 4, the functional sheet 3 mounted on the release film 10 is disposed on the semiconductor package away from the release film 10. The release film 10 after use is wound around the roll 8B and collected.

  Since the release film of this embodiment is excellent in the retainability of the functional sheet until the molding step, the functional sheet is arranged in the mold without dropping from the release film. Moreover, since the performance of releasing the functional sheet in the molding process is excellent, the functional sheet is separated from the release sheet and placed on the semiconductor package when the upper and lower molds are released after the molding is completed.

  Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these examples.

<Examples 1 to 10, Comparative Examples 1 to 7>
(Preparation of release layer forming composition)
As a resin component, an acrylic resin, a crosslinking agent, and a filler are mixed with toluene so that the nonvolatile content of each material is the amount (part by mass) described in Table 1 or Table 2, and the solid content is 15% by mass. A release layer forming composition was prepared as a toluene solution.

As the acrylic resin, a copolymer of acrylic ester, ethyl acetate, and a 24 mass% toluene solution of n-butyl acrylate (Soken Chemical Co., Ltd., trade name “S-43”) were used.
As a crosslinking agent, a 75 mass% toluene solution of an isocyanate compound (Tosoh Corporation, trade name “Coronate L”) and an adduct-modified polyisocyanate of hexamethylene diisocyanate (Asahi Kasei Chemicals Corporation, trade name “Duranate AE710-100”) It was used.
As the filler, particles of a cross-linked acrylic resin that is a copolymer of methacrylate ester (Soken Chemical Co., Ltd., trade name “MX-150 (volume average particle diameter: 1.5 μm)”), “MX-300 (volume average) Particle size: 3.0 μm) ”and“ MX-1000 (volume average particle size: 10.0 μm) ”) or silica particles (volume average particle size: 5.0 μm, Fuji Silysia Chemical Co., Ltd., trade name“ Cyrosphere ” C-0809) was used.

(Production of release film)
The prepared release layer-forming composition was applied to one side of the substrate at a speed of 0.5 m / min to 3 m / min using a roll coater, and left at 100 ° C. in a drying furnace with a length of 3 m. And dried to form a release layer on the substrate to obtain a release film. Under the present circumstances, the gap at the time of application | coating was adjusted so that the application quantity (mass of a release layer) per 1 m < ² > of the composition after drying might become the value (g) shown in Table 1 or Table 2.

  As the base material, a 25 μm thick biaxially stretched polyethylene terephthalate (PET) film (Teijin DuPont Films Co., Ltd., trade name “FT3-25”) and a biaxially stretched polybutylene terephthalate (PBT) Each of the films (Okura Industries Co., Ltd.) subjected to corona treatment was used.

(Measurement of release layer mass)
The produced release film was cut into a size of 10 cm × 10 cm, and the mass was measured. Thereafter, the release layer was removed using methyl ethyl ketone, the mass was measured again after air drying, and the mass of the release layer was calculated from the difference in mass before and after. Multiplied by 100 to the obtained value was calculated on the weight of the release layer per ^{1m 2 (g / m 2)} . The results are shown in Table 1 or Table 2.

(Measurement of tack force)
The produced release film was placed on a tack tester (trade name “TAC-II”, manufactured by Reska Co., Ltd.) so that the measurement probe was in contact with the release layer at the time of measurement. Thereafter, using a probe having a diameter of 5 mm, the tack force (gf) was measured under the conditions of the probe descending speed: 120 mm / min, the pre-measurement load: 10 gf, and the ascent speed during measurement: 600 mm / min. The tack force was measured at a temperature assuming a room temperature (25 ° C.) and a temperature assuming a molding process (170 ° C.). The results are shown in Table 1 or Table 2.

(Evaluation of retention)
In order to evaluate the ability of the release film to hold the functional sheet, the following test was performed.
The produced release film was cut out to a size of 15 cm × 30 cm, and 50 cm × 100 cm of dust-free paper was bonded to the release layer of the cut out release film using a silicone rubber roll. After that, place it on a table so that the dust-free paper is at the bottom in an environment of 25 ° C, grab the edge of the release film and lift it in the direction of 90 ° by 50 cm to 100 cm. Observed. The results are shown in Table 1 or Table 2 with “OK” when the dust-free paper is not peeled and “NG” when the dust-free paper is peeled.

(Evaluation of surface roughness)
Arithmetic average roughness (Ra) and ten-point average roughness (Rz) of the outer surface of the release layer were measured using a surface roughness measuring device (Kosaka Laboratory, model number SE-3500), and the tip diameter of the stylus : 2 μm, feed rate: 0.5 mm / s, and scanning distance: 8 mm The results of measurement were obtained by analysis according to JIS B0601 (2013) or ISO 4287 (1997). The results are shown in Table 1 or Table 2.

<Comparative Example 8>
Evaluation similar to the example was performed on an ETFT (Ethylene Tetra Fluoro Ethylene) film (Asahi Glass Co., Ltd., trade name: “Aflex 50HK”) which is widely used mainly as a compression mold type release film. The results are shown in Table 2. Since Aflex 50HK does not have a resin layer (release layer), the measurement of the mass of the release layer was not performed.

Example 1 in which the ratio (A / B) of the volume average particle diameter A (μm) of the filler to the mass B (g / m ² ) per 1 m ^{2 of the} release layer is 1 or less as shown in Table 1 No. 10 to 10 release film had high tack at 25 ° C., and it was found that the dust-free paper was not peeled even in the holding property evaluation test and was excellent in holding property. On the other hand, the tack force at 170 ° C. was low, and it was found that the mold had a good release performance in the molding process. Furthermore, good results were obtained even if the surface roughness was changed by adjusting the type and content of filler contained in the release layer, so that the release film material and package while maintaining the desired characteristics It was found that it was possible to cope with diversification of combinations.

Release film of Comparative Examples 1 to 7 in which the ratio (A / B) of the volume average particle diameter A (μm) of the filler to the mass B (g / m ² ) per 1 m ^{2 of the} release layer exceeds 1. The tackiness at 25 ° C. was remarkably low, and the dust-free paper was peeled off in the retention evaluation test, and the retention was inferior to the examples.

  Aflex 50HK used as the release film of Comparative Example 8 had a low tack force at 25 ° C. and a low tack force at 170 ° C., and was excellent in releasability. However, peeling of dust-free paper was observed in the evaluation test for retention, and the retention was inferior to that of the examples.

  From the above results, it was found that the release film of this embodiment is excellent in the performance of holding the functional sheet until the molding step and the performance of releasing the functional sheet in the molding step.

  The disclosure of Japanese Patent Application No. 2016-101820 is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards mentioned in this specification are to the same extent as if each individual document, patent application, and technical standard were specifically and individually stated to be incorporated by reference, Incorporated herein by reference.

Claims (5)

A base material, and a release layer that is provided on the base material and includes an acrylic resin as a resin component and a cross-linked acrylic resin or silica as a filler, the volume average particle diameter A (μm) of the filler and the A release film having a ratio (A / B) of 1 or less with respect to mass B (g / m ² ) per 1 m ^{2 of the} release layer.   The release film of Claim 1 whose volume average particle diameter A of the said filler is 1 micrometer-50 micrometers. Release film of the mass B per 1 m ² of the release layer is ^{0.1g / m 2 ~100g / m 2} , according to claim 1 or claim 2.   The release film according to any one of claims 1 to 3, further comprising a crosslinking agent, wherein the content of the crosslinking agent with respect to 100 parts by mass of the resin component is 1 part by mass to 10 parts by mass.   The release film according to any one of claims 1 to 4, wherein the substrate contains at least one selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate.