JP2023130117A - Release film for semiconductor molding and manufacturing method of semiconductor device - Google Patents

Abstract

To provide a release film for semiconductor molding which enables reduction of flow trace of sealing resin on a molded semiconductor package front surface while having release property with respect to the sealing resin, and a manufacturing method of a semiconductor device.SOLUTION: The release film for a semiconductor molding is provided, including a release layer including a (meth) acrylic resin particle, and a base material layer, wherein an average particle diameter of the (meth) acrylic resin particle is 1 μm to 7 μm.SELECTED DRAWING: None

Description

The present invention relates to a release film for semiconductor molding and a method for manufacturing a semiconductor device.

Semiconductor chips are usually sealed with resin to protect them from the outside air and are mounted on a substrate as a molded product called a package to produce a semiconductor device. Conventionally, molded products have been molded as package molded products in which each chip is connected via a runner, which is a flow path for sealing resin. In this case, the releasability of the molded product from the mold is achieved by the structure of the mold, the addition of a mold release agent to the sealing resin, and the like.
On the other hand, due to the demand for smaller packages and higher pin count, packages such as Ball Grid Array (BGA), Quad Flat Non-leaded (QFN), and Wafer Level Chip Size Package (WL-CSP) are increasing. ing. In the QFN method, a resin release mold is used to ensure standoff and to prevent the occurrence of burrs on the sealing material on the terminal part, and in the BGA method and WL-CSP method, to improve the releasability of the package from the mold. A film is used (for example, see Patent Document 1). A molding method that uses a release film in this way is called "film-assisted molding."

Japanese Patent Application Publication No. 2002-158242

When the above mold release film is used, it is possible to easily release the mold from the sealing resin of the semiconductor package when resin molding the semiconductor package. However, flow traces of the sealing resin may remain on the surface of the molded package. For example, in transfer molding, strong local pressure may be applied to the molten sealing resin, and it has been found that flow marks are likely to occur in these areas.

Particularly in recent years, semiconductor chip shapes have become more complex due to stacking of semiconductor chips and SiP (System in Package), which stores multiple semiconductor chips in one package, making it easier for high pressure to be applied locally to the sealing resin. . Semiconductor package structures using SiP include double-sided packages in which semiconductor chips are placed on both sides of a substrate, and in double-sided packages, bump connection surfaces are also molded with resin. In this case, since there are irregularities on the package surface due to the height of the bumps, flow traces of the sealing resin are more likely to occur.

The present invention was made in view of the above circumstances, and provides a release film for semiconductor molding that has releasability to the molding resin and can reduce flow traces of the molded semiconductor package on the surface of the molded semiconductor package. An object of the present invention is to provide a method for manufacturing a semiconductor device.

The present disclosure includes the following aspects.
<1> Includes a release layer containing (meth)acrylic resin particles and a base layer,
A release film for semiconductor molding, wherein the (meth)acrylic resin particles have an average particle diameter of 1 μm to 7 μm.
<2> The release film for semiconductor molding according to <1>, wherein the release layer has a surface roughness Sm of 0.02 mm to 0.20 mm.
<3> The release film for semiconductor molding according to <1> or <2>, wherein the content of the (meth)acrylic resin particles in the release layer is 5% by volume to 50% by volume.
<4> The release film for semiconductor molding according to any one of <1> to <3>, wherein the release layer has an average thickness of 3 μm to 25 μm.
<5> Any of <1> to <4>, wherein the ratio (T/D) of the average thickness T of the release layer to the average particle diameter D of the (meth)acrylic resin particles is 0.5 to 8.0. The release film for semiconductor molding according to item 1.
<6> The release film for semiconductor molding according to any one of <1> to <5>, wherein the base layer is a polyester film.
<7> The release film for semiconductor molding according to any one of <1> to <6>, which is used for transfer molding.
<8> A method for manufacturing a semiconductor device, comprising performing transfer molding using the release film for semiconductor molding according to any one of <1> to <7>.

According to the present invention, there is provided a mold release film for semiconductor molding that has mold releasability to the mold resin and can reduce flow traces of the molded semiconductor package on the surface of the molded semiconductor package, and a method for manufacturing a semiconductor device. be done.

Embodiments of the present invention will be described in detail below. However, the present invention is not limited to the following embodiments.
In the present disclosure, numerical ranges indicated using "~" include the numerical values written before and after "~" as minimum and maximum values, respectively.
In the numerical ranges described step by step in this disclosure, the upper limit or lower limit described in one numerical range may be replaced with the upper limit or lower limit of another numerical range described step by step. . Furthermore, in the numerical ranges described in this disclosure, the upper limit or lower limit of the numerical range may be replaced with the values shown in the Examples.
In the present disclosure, each component may contain multiple types of corresponding substances. If there are multiple types of substances corresponding to each component in the composition, the content rate or content of each component is the total content rate or content of the multiple types of substances present in the composition, unless otherwise specified. means quantity.
In the present disclosure, each component may include a plurality of types of particles. When a plurality of types of particles corresponding to each component are present in the composition, the particle diameter of each component means a value for a mixture of the plurality of types of particles present in the composition, unless otherwise specified.
In this disclosure, the term "layer" includes not only the case where the layer is formed in the entire area when observing the area where the layer exists, but also the case where the layer is formed only in a part of the area. included.
In this disclosure, the term "laminate" refers to stacking layers, and two or more layers may be bonded, or two or more layers may be removable.
In the present disclosure, "(meth)acrylic" means at least one of acrylic and methacrylic, "(meth)acryloyl group" means at least one of acryloyl group and methacryloyl group, and "(meth)acrylate" means acrylic and methacrylate.

In the present disclosure, the average thickness of a layer or film (also referred to as average thickness value) is a value given as the arithmetic mean value of the thicknesses measured at five points of the target layer or film.
The thickness of a layer or film can be measured using a micrometer or the like. In this disclosure, when the thickness of a layer or film can be measured directly, it is measured using a micrometer. On the other hand, when measuring the thickness of one layer or the total thickness of a plurality of layers, it may be measured by observing the cross section of the film using an electron microscope.

<Release film for semiconductor molding>
The release film for semiconductor molding of the present disclosure (hereinafter also referred to as "the release film of the present disclosure") includes a release layer containing (meth)acrylic resin particles and a base material layer, and includes (meth)acrylic resin particles. The average particle diameter of the resin particles is 1 μm to 7 μm.
More specifically, the release film of the present disclosure includes at least a release layer that comes into contact with a semiconductor package to be molded, on one side of a base layer that comes into contact with a mold used in resin molding of a semiconductor package.

By adopting the above structure, the release film of the present disclosure has mold releasability to the sealing resin and can reduce flow traces of the sealing resin on the surface of a molded semiconductor package. Although the reason for this is not clear, it is inferred as follows.
In the release film of the present disclosure, by including (meth)acrylic resin particles having an average particle size of 1 μm or more in the release layer, the outer surface of the release layer (the surface facing the semiconductor package) is roughened to some extent. , it is presumed that mold releasability is exhibited against the sealing resin. In addition, by setting the average particle diameter of the (meth)acrylic resin particles contained in the release layer to 7 μm or less, flow traces of the sealing resin can be reduced and the uniformity of the package surface appearance can be improved. It is inferred. Furthermore, since the acrylic resin particles have excellent adhesion with other components contained in the mold release layer, they are unlikely to fall off from the mold release layer, and it is presumed that contamination of the semiconductor package can be suppressed.

[Release layer]
The release film of the present disclosure has a release layer. The average particle diameter of the acrylic resin particles in the release layer is 1 μm to 7 μm.

(resin particles)
The resin particles in the present invention include (meth)acrylic resin. The (meth)acrylic resin refers to a resin having an acryloyl group, and preferably has a (meth)acryloyloxy group. One type of acrylic resin may be used alone, or two or more types may be used in combination.

Acrylic resin is a (co)polymer whose main component is a structural unit derived from a (meth)acrylic monomer. The acrylic resin contains more than 50% by mass of structural units derived from (meth)acrylic monomers, preferably 60% by mass or more, more preferably 70% by mass or more, and further preferably 80% by mass or more. Preferably, it is particularly preferably contained in an amount of 90% by mass or more, and may be a monopolymer of (meth)acrylic monomer.
Examples of the acrylic resin include (meth)acrylic acid resin, (meth)acrylic acid ester resin (for example, alkyl (meth)acrylate resin, and dimethylaminoethyl (meth)acrylate resin), and the like.

(Meth)acrylic monomers include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-propyl acrylate, n-propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, and n-acrylate. Butyl, n-butyl methacrylate, isobutyl acrylate, isobutyl methacrylate, sec-butyl acrylate, sec-butyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, pentyl acrylate, pentyl methacrylate, acrylic acid Hexyl, hexyl methacrylate, heptyl acrylate, heptyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, octyl acrylate, octyl methacrylate, nonyl acrylate, nonyl methacrylate, decyl acrylate, decyl methacrylate, Dodecyl acrylate, dodecyl methacrylate, tetradecyl acrylate, tetradecyl methacrylate, hexadecyl acrylate, hexadecyl methacrylate, octadecyl acrylate, octadecyl methacrylate, eicosyl acrylate, eicosyl methacrylate, docosyl acrylate, docosyl methacrylate, acrylic acid Cyclopentyl, cyclopentyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, cycloheptyl acrylate, cycloheptyl methacrylate, benzyl acrylate, benzyl methacrylate, phenyl acrylate, phenyl methacrylate, methoxyethyl acrylate, methoxyethyl methacrylate, Dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, dimethylaminopropyl acrylate, dimethylaminopropyl methacrylate, 2-chloroethyl acrylate, 2-chloroethyl methacrylate, 2-acrylic acid Examples include fluoroethyl, 2-fluoroethyl methacrylate, dicyclopentanyl acrylate, dicyclopentanyl methacrylate, acrylic acid, and methacrylic acid. These may be used alone or in combination of two or more.

The (meth)acrylic resin may contain structural units derived from other monomers other than the (meth)acrylic monomer, and examples of other monomers include acrylonitrile, methacrylonitrile, styrene, and styrene. Examples include derivatives, vinyl compounds, and the like.
Examples of styrene derivatives include alkyl-substituted styrenes with alkyl chains such as α-methylstyrene, 4-methylstyrene, 2-methylstyrene, 3-methylstyrene, 2-ethylstyrene, 3-ethylstyrene, and 4-ethylstyrene; Examples include halogen-substituted styrenes such as -chlorostyrene, 3-chlorostyrene and 4-chlorostyrene, and fluorine-substituted styrenes such as 4-fluorostyrene and 2,5-difluorostyrene.
Examples of the vinyl compound include vinyltoluene, vinyl chloride, vinyl acetate, N-vinylpyrrolidone, and vinylnaphthalene.
From the viewpoint of suppressing the solubility of the (meth)acrylic resin particles in organic solvents, the acrylic resin contained in the (meth)acrylic resin particles is preferably a crosslinked resin.

The average particle diameter of the (meth)acrylic resin particles is 1 μm to 7 μm. The average particle diameter of the resin particles may be 2 μm or more, or 3 μm or more. Further, the average particle diameter of the (meth)acrylic resin particles is preferably 6 μm or less, and may be 5 μm or less.
When the average particle diameter of the (meth)acrylic resin particles is 1 μm or more, releasability from the sealing resin is exhibited. When the average particle diameter of the (meth)acrylic resin particles is 7 μm or less, flow traces of the sealing resin are reduced, and the uniformity of the package surface appearance is improved. In addition, when the average particle diameter of the (meth)acrylic resin particles is 7 μm or less, there is no need to increase the thickness of the release layer excessively in order to fix the (meth)acrylic resin particles in the release layer, which reduces costs. Preferred from this point of view.

The average particle diameter of the (meth)acrylic resin particles can be measured by a method using a laser diffraction scattering particle size distribution measurement method, a 3D CT method, or a scanning electron microscope (SEM).
The average particle diameter by laser diffraction scattering particle size distribution measurement method is determined as the particle diameter (50% D) at which the cumulative volume from the small particle diameter side is 50% in the volume cumulative particle size distribution curve. For example, it can be measured using a particle size distribution measuring device using a laser light scattering method (for example, "SALD-3000" manufactured by Shimadzu Corporation).
The (meth)acrylic resin particles can be taken out from the mold release layer by any method. For example, the (meth)acrylic resin particles can be taken out by dissolving other components contained in the mold release layer with an appropriate solvent. You can take it out. Examples of solvents used to dissolve other components include toluene, methyl ethyl ketone, and ethyl acetate.

From the viewpoint of reducing flow traces of the sealing resin, the maximum particle diameter of the (meth)acrylic resin particles is preferably 15 μm or less, more preferably 12 μm or less, and even more preferably 10 μm or less.
The maximum particle diameter of the (meth)acrylic resin particles can be confirmed by a method using the above-mentioned laser diffraction scattering particle size distribution measurement method, 3D CT method, or SEM.

The shape of the (meth)acrylic resin particles is not particularly limited, and may be spherical, elliptical, irregular, or the like.

Specific examples of (meth)acrylic resin particles include MX series manufactured by Soken Kagaku Co., Ltd.

The content of (meth)acrylic resin particles in the release layer is preferably 5% to 50% by volume, more preferably 5% to 40% by volume, and 5% to 30% by volume. The content may be 5% to 20% by volume, or 5% to 15% by volume.
When the content of (meth)acrylic resin particles in the mold release layer is 5% by volume or more, sufficient irregularities are formed on the surface of the mold release layer, and mold release properties tend to be easily expressed with respect to the sealing resin. It is in. When the content of (meth)acrylic resin particles in the release layer is 50% by volume or less, flow traces of the sealing resin tend to be reduced and the uniformity of the package surface appearance tends to be improved. In addition, if the content of (meth)acrylic resin particles in the release layer is 50% by volume or less, the (meth)acrylic resin particles are likely to be fixed by the resin component described below in the release layer, and (meth) The possibility of the acrylic resin particles falling off is reduced, the contamination of the surface of the molded semiconductor package can be suppressed, and this tends to be economically preferable.

The content of (meth)acrylic resin particles in the release layer can be determined as the ratio of resin particles per unit volume by, for example, observing the cross section of the release layer of the release film with a scanning electron microscope (SEM). It can be calculated. In detail, it can be calculated by the following method.
First, a cross section of the release layer is observed with a SEM, and the number and particle diameter of (meth)acrylic resin particles contained in an arbitrary area (hereinafter also referred to as "specific area") in this cross section are measured. Furthermore, an arbitrary volume (hereinafter also referred to as "specific volume") is set based on the specific area, and the number of (meth)acrylic resin particles contained in this specific volume is calculated. Furthermore, the volume per (meth)acrylic resin particle is calculated based on the particle diameter of the (meth)acrylic resin particle. Then, from the calculated number of (meth)acrylic resin particles and the volume per (meth)acrylic resin particle, the total volume of (meth)acrylic resin particles contained in the specific volume is calculated, and this (meth)acrylic resin particle is By dividing the total volume of the acrylic resin particles by the specific volume, the volume content of the resin particles contained in the release layer can be calculated.

Another method is to measure the mass (Wc) of the release layer at 25°C, dissolve the release layer in a solvent such as toluene, and then dissolve the mass (Wf) of the remaining (meth)acrylic resin particles at 25°C. ) to measure. Next, the specific gravity (df) of the resin particles at 25° C. is determined using an electronic hydrometer or a pycnometer. Next, the specific gravity (dc) of the release layer at 25° C. is measured in the same manner. Next, the volume (Vc) of the release layer and the volume (Vf) of the remaining (meth)acrylic resin particles are determined, and the volume of the remaining (meth)acrylic resin particles is calculated as shown in (Equation 1). By dividing by the volume, the volume ratio (Vr) of the (meth)acrylic resin particles is determined.
(Formula 1)
Vc=Wc/dc
Vf=Wf/df
Vr=Vf/Vc

Vc: Volume of release layer (cm ³ )
Wc: Mass of release layer (g)
dc: Specific gravity of mold release layer (g/cm ³ )
Vf: Volume of (meth)acrylic resin particles (cm ³ )
Wf: Mass (g) of (meth)acrylic resin particles
df: Specific gravity of (meth)acrylic resin particles (g/cm ³ )
Vr: Volume ratio of (meth)acrylic resin particles The release layer used in this measurement method may be one that has been peeled off from the release film, or may be one that has been separately prepared for this measurement method.

(resin component)
The release layer may further contain a resin component. The resin component of the release layer is not particularly limited. The resin component is preferably an acrylic resin or a silicone resin from the viewpoint of mold releasability from the semiconductor package, heat resistance, etc., and is a crosslinked acrylic resin (hereinafter also referred to as "crosslinked acrylic copolymer"). It is more preferable.

Acrylic resins have low glass transition temperature (Tg) monomers such as butyl acrylate, ethyl acrylate, and 2-ethylhexyl acrylate as main monomers, and also contain monomers such as acrylic acid, methacrylic acid, hydroxyethyl methacrylate, hydroxyethyl acrylate, acrylamide, acrylonitrile, etc. Preferably, it is an acrylic copolymer obtained by copolymerizing with a functional group monomer. Further, a crosslinked acrylic copolymer can be produced by crosslinking the above monomer with a crosslinking agent.
Examples of the crosslinking agent used in the production of the crosslinked acrylic copolymer include known crosslinking agents such as isocyanate compounds, melamine compounds, and epoxy compounds. Moreover, in order to form a network structure that spreads gently in the acrylic resin, it is more preferable that the crosslinking agent is a polyfunctional crosslinking agent such as a trifunctional or tetrafunctional crosslinking agent.

The cross-linked acrylic copolymer manufactured using the above-mentioned cross-linking agent has a gently expanding network structure, so when this cross-linked acrylic polymer is used as the resin component of the mold release layer, it is difficult to release the mold. Since the stretchability of the layer is improved and inhibition of the stretchability of the base layer is suppressed, the followability of the release film to the mold tends to be improved.
From this point of view, the amount of crosslinking agent used in the production of the crosslinked acrylic copolymer is preferably from 3 parts by mass to 100 parts by mass, and from 5 parts by mass to 100 parts by mass of the acrylic copolymer. More preferably, it is 70 parts by mass. When the amount of the crosslinking agent is 3 parts by mass or more, the strength of the resin component is ensured and contamination can be prevented, and when the amount is 100 parts by mass or less, the flexibility of the crosslinked acrylic copolymer is improved and mold release is facilitated. The extensibility of the layer is improved.

(Other ingredients)
The release layer may further contain a solvent, an anchoring improver, a crosslinking promoter, an antistatic agent, a coloring agent, etc., as necessary, as long as the effects of the present invention are not impaired.

(Average thickness of release layer)
The average thickness of the release layer is not particularly limited, and is appropriately set in consideration of the relationship with the average particle diameter of the resin particles used, and is preferably 3 μm to 25 μm. The average thickness of the release layer may be 20 μm or less, or 15 μm or less. Further, the average thickness of the release layer may be 3 μm or more, or 5 μm or more.
When the average thickness of the mold release layer is 3 μm or more, the retention of (meth)acrylic resin particles in the mold release layer tends to be excellent. When the average thickness of the mold release layer is 25 μm or less, there is a tendency for excellent mold release properties with respect to the sealing resin.

(Relationship between average thickness of release layer and average particle diameter of (meth)acrylic resin particles)
The ratio (T/D) of the average thickness T of the release layer to the average particle diameter D of the (meth)acrylic resin particles is preferably 0.5 to 8.0, and preferably 1.0 to 7.0. More preferably, it is 1.0 to 6.5.
When the ratio (T/D) is 6.5 or less, there is a tendency for excellent mold releasability from the sealing resin. When the ratio (T/D) is 6.5 or less, the retention of (meth)acrylic resin particles in the release layer tends to be excellent.

(Surface roughness Sm of release layer)
The surface roughness Sm of the release layer can be measured using a surface roughness measuring device (for example, Kosaka Institute Co., Ltd., model number SE-3500) with a stylus tip diameter of 2 μm and a feed rate of 0.5 mm/s. The results measured under the conditions of a scanning distance of 8 mm can be obtained by analyzing the results according to JIS B0601 (1994) or ISO 4287 (1997).

The surface roughness Sm represents the average interval between concavities and convexities, and is the average value of the interval between peaks and valleys determined from the intersection point where the roughness curve intersects with the average point. In the release film of the present disclosure, it has been confirmed that the Sm index has a greater influence on the reduction of flow marks than other surface roughness indexes such as Ra and Rz. Although the reason for this is not clear, it is inferred as follows. Ra, Rz, etc. are indicators that express the variation in the height of the unevenness, whereas Sm is an index that expresses the interval between the unevenness. Therefore, when (meth)acrylic resin particles with an average particle diameter of 1 μm to 7 μm are used in the release layer, it is inferred that the flow marks are more influenced by the spacing of the asperities than the height of the asperities. .

From the viewpoint of reducing flow traces of the sealing resin while maintaining mold releasability to the sealing resin, the surface roughness Sm of the release layer is preferably 0.02 mm to 0.20 mm, and 0.03 mm. The thickness is more preferably 0.18 mm, and even more preferably 0.03 mm to 0.15 mm. By setting the surface roughness Sm of the release layer within the above range, light may be more scattered and flow traces may be less likely to be visually recognized.
Methods for adjusting the surface roughness of the release layer Sm within the above range include, for example, adjusting the average particle diameter of the (meth)acrylic resin particles and the average thickness of the release layer, and adjusting the type and addition of other components. Examples include a method of appropriately selecting and adjusting the amount and the like.

[Base material layer]
The release film of the present disclosure has a base layer. The base layer is not particularly limited, and can be appropriately selected from resin-containing base layers used in the technical field. From the viewpoint of improving followability to the shape of the mold, it is preferable to use a resin-containing base material layer that has excellent stretchability.
Considering that the molding of the sealing material is carried out at high temperatures (approximately 100° C. to 200° C.), it is desirable that the base layer has heat resistance at or above this temperature. In addition, from the perspective of suppressing the occurrence of wrinkles in the sealing resin and tearing of the release film when attaching the release film to the mold and when the resin flows during molding, the elastic modulus and elongation at high temperatures are It is preferable to make a selection by considering the following.

The material of the base layer is preferably polyester resin from the viewpoint of heat resistance and elastic modulus at high temperatures. Examples of polyester resins include polyethylene terephthalate resins, polyethylene naphthalate resins, polybutylene terephthalate resins, and copolymers and modified resins thereof.
The base layer is preferably a polyester resin molded into a sheet, more preferably a polyester film, and from the viewpoint of mold conformability, it is a biaxially stretched polyester film. is preferred.

The average thickness of the base material layer is not particularly limited, and is preferably from 5 μm to 300 μm, more preferably from 10 μm to 200 μm. When the average thickness is 5 μm or more, handling properties are excellent and wrinkles tend to be less likely to occur. When the average thickness is 300 μm or less, the conformability to the mold during molding is excellent, and the occurrence of wrinkles and the like in the molded semiconductor package tends to be suppressed.

[others]
The base layer is a layer that comes into contact with the mold surface, and depending on the material used, a larger peeling force may be required to peel the release film from the mold. When using a material that is difficult to peel off from the mold as described above for the base layer, it is preferable to adjust the release film so that it can be easily peeled off from the mold. For example, the surface of the base material layer opposite to the mold release layer, that is, the surface of the base material layer on the mold side, may be subjected to a surface treatment such as a satin finish to improve its releasability from the mold, or a new Another mold release layer (second mold release layer) may be provided. The material for the second mold release layer is not particularly limited as long as it satisfies heat resistance, peelability from the mold, etc., and the same material as the mold release layer may be used. The average thickness of the second release layer is not particularly limited, and may be 0.1 μm to 100 μm.

In addition, if necessary, between the mold release layer and the base material layer, between the base material layer and the second mold release layer, etc., an anchoring improvement layer of the mold release layer or the second mold release layer, an antistatic layer, etc. A layer such as a layer, a colored layer, etc. may be provided. A preferred layer structure includes a three-layer structure in which a base layer, an antistatic layer, and a release layer are provided in this order. The antistatic layer may include an antistatic polymer such as a quaternary ammonium salt-containing polymer or a polythiophene-based polymer.

The total thickness of the release film is preferably 350 μm or less, more preferably 200 μm or less, from the viewpoint of followability to the mold. Further, from the viewpoint of ease of handling, the total thickness of the release film is preferably 10 μm or more, more preferably 20 μm or more.

<Manufacturing method of release film>
The release film of the present disclosure can be manufactured by a known method. For example, the release film of the present disclosure can be produced by applying a release layer forming composition containing (meth)acrylic resin particles with an average particle size of 1 μm to 7 μm to one side of the base layer and drying. I can do it. The release layer forming composition may contain a resin component and other components added as desired.

[Preparation of composition for forming release layer]
The method for preparing the composition for forming a release layer is not particularly limited, and examples thereof include a method of dispersing (meth)acrylic resin particles in a solvent, and any known method for preparing the composition may be used.
The solvent used to prepare the release layer forming composition is not particularly limited, and is preferably an organic solvent that can disperse (meth)acrylic resin particles and dissolve the resin component. Examples of organic solvents include toluene, methyl ethyl ketone, and ethyl acetate.

[Applying and drying]
The method for applying the release layer forming composition to one side of the base layer is not particularly limited, and known coating methods such as roll coating, bar coating, kiss coating, etc. can be used. When applying the release layer forming composition, it is preferable to apply it so that the average thickness of the composition layer (release layer) after drying is 3 μm to 25 μm.
The method for drying the applied release layer forming composition is not particularly limited, and any known drying method can be used. For example, a method of drying at 50° C. to 150° C. for 0.1 minutes to 60 minutes may be used.

<Application>
The release film of the present disclosure can be used for molding semiconductor packages, and can also be suitably used for transfer molding. In the transfer molding method, the molten sealing resin moves over a longer distance than in the compression molding method, so flow marks of the sealing resin tend to remain on the surface of the molded semiconductor package. Furthermore, in recent transfer molding, high pressure is applied locally to the sealing resin, which tends to leave flow traces of the sealing resin more easily. However, by having the above structure, the release film of the present disclosure has mold releasability to the sealing resin and can reduce flow traces of the sealing resin, so it is also suitable for transfer molding. Applicable to The release film of the present disclosure can be suitably used in transfer molding where flow marks are likely to occur, and can also be used in other molding methods such as compression molding.

<Method for manufacturing semiconductor devices>
The method for manufacturing a semiconductor device of the present disclosure includes performing transfer molding using the release film for semiconductor molding of the present disclosure.
For example, in transfer molding of semiconductor packages, a semiconductor chip is placed in a mold of a transfer molding device, a release film is placed in the other mold, and the release film follows the shape of the mold by vacuum suction or the like. Thereafter, the mold is closed, and a molten sealing resin (for example, epoxy resin) is injected into the heated mold by a transfer method to mold a semiconductor package. At this time, if the sealing resin used is thermosetting, the sealing resin is cured to become a cured resin. Thereafter, the mold is opened and the molded semiconductor package is taken out to obtain a semiconductor device.

The release film for semiconductor molding of the present disclosure is attached so that the surface of the release layer is in contact with the sealing resin when molding a semiconductor package, so that the release film can be easily peeled off from the sealing resin or cured resin. , it is possible to separate the mold from the sealing resin or cured resin without damaging the semiconductor device. Further, in the method for manufacturing a semiconductor device using the release film for semiconductor molding of the present disclosure, flow traces of the sealing resin are suppressed on the surface of the molded semiconductor package, and the resulting semiconductor device has excellent uniformity in appearance.

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

<Example 1>
Coronate L (Tosoh Corporation, trade name) as a crosslinking agent was added to 100 parts by mass of acrylic resin (80 parts by mass of hydroxyl group-containing acrylic ester polymer, 20 parts by mass of hydroxyl group-containing acrylic acid/methacrylic ester copolymer). 10 parts by mass of (meth)acrylic resin particles and 15 parts by mass of MX-150 (manufactured by Soken Kagaku Co., Ltd., trade name, average particle diameter 1.5 μm) were added to toluene to form a release layer forming composition. I prepared something.
A biaxially stretched polyethylene terephthalate film having a thickness of 38 μm and serving as a base layer was subjected to corona treatment. Thereafter, a release layer forming composition is applied to one side of the biaxially stretched polyethylene terephthalate film using a roll coater so that the average thickness after drying is 10 μm, and dried to form a release layer. A release film was obtained.
The content of (meth)acrylic resin particles in the release layer of the obtained release film was measured by cross-sectional observation using SEM, and was found to be 7% by volume.

[Characteristic evaluation of release film]
A molding test was conducted using a transfer molding device. A copper substrate with bumped chips attached was placed in the lower mold of a transfer molding device so that the bumps faced the upper mold. The height of the attached bump was 80 μm, and the bump width was 110 μm. The release film was attached to the upper mold of the mold and fixed in a vacuum, then the mold was clamped and transfer molded using an epoxy resin sealant to obtain a semiconductor package. The mold temperature was 170° C., the transfer pressure was 8 MPa, the clamp pressure was 500 kN, and the molding time was 200 seconds.

(Evaluation of mold releasability)
An epoxy resin encapsulant was placed on the release film at 180° C. and 16 MPa, and the epoxy resin encapsulant was molded. After 5 minutes had passed, the release film was peeled off from the sealing material, and whether or not it could be peeled off was evaluated based on the following criteria. The evaluation results are shown in Table 1.
A: The release film or the release layer of the release film does not remain in the sealing material.
B: The release film or the release layer of the release film partially remained in the sealing material.

(Evaluation of presence or absence of flow traces)
The presence or absence of flow traces of the sealing material on the surface of the semiconductor package was observed visually and with an optical microscope (100x magnification), and evaluated based on the following criteria. The evaluation results are shown in Table 1.
A: No flow traces are observed either visually or by microscopic observation.
B: No flow traces are observed visually, but slightly observed under a microscope.
C: Flow traces are observed both visually and by microscopic observation.

(Evaluation of the presence or absence of falling off of (meth)acrylic resin particles)
The presence or absence of (meth)acrylic resin particles falling off the surface of the obtained semiconductor package was observed visually and with an optical microscope (100x magnification), and evaluated based on the following criteria. The evaluation results are shown in Table 1.
A: No drop-off of particles (C) is observed by both visual and microscopic observation.
B: The particles (C) are not observed to fall off visually, but are slightly observed under a microscope.
C: Falling off of particles (C) is observed both visually and under a microscope.

<Examples 2 to 5 and Comparative Examples 1 to 2>
Examples 2- Release films of No. 5 and Comparative Examples 1 and 2 were prepared and evaluated. The evaluation results are shown in Table 1.

The (meth)acrylic resin particles used in Examples 2 to 5 and Comparative Examples 1 and 2 are as follows.
Examples 2 and 3: MX-300 (Soken Kagaku Co., Ltd., trade name, average particle diameter 3 μm)
Examples 4 and 5: MX-500 (Soken Kagaku Co., Ltd., trade name, average particle size 5 μm)
Comparative Examples 1 and 2: MZ-10HN (Soken Kagaku Co., Ltd., trade name, average particle size 10 μm)

As shown in Table 1, the release films of Examples 1 to 5 had good releasability from the encapsulant after molding, and the flow marks of the encapsulant resin on the surface of the molded semiconductor package were reduced. It had been. Furthermore, the release films of Examples 1 to 5 also suppressed the (meth)acrylic resin particles from falling off onto the surface of the molded package.

On the other hand, in Comparative Examples 1 and 2 using (meth)acrylic resin particles having an average particle diameter exceeding 7 μm, flow traces of the sealing resin were observed on the surface of the molded semiconductor package. Further, in Comparative Examples 1 and 2, falling off of (meth)acrylic resin particles was observed.

As shown above, when the release film of the present disclosure is used, it is possible to reduce flow traces of the sealing resin on the surface of a molded semiconductor package while maintaining mold releasability to the sealing resin.

Claims (8)

A release layer containing (meth)acrylic resin particles and a base layer,
A release film for semiconductor molding, wherein the (meth)acrylic resin particles have an average particle diameter of 1 μm to 7 μm. The release film for semiconductor molding according to claim 1, wherein the release layer has a surface roughness Sm of 0.02 mm to 0.20 mm. The release film for semiconductor molding according to claim 1 or 2, wherein the content of the (meth)acrylic resin particles in the release layer is 5% by volume to 50% by volume. The release film for semiconductor molding according to any one of claims 1 to 3, wherein the release layer has an average thickness of 3 μm to 25 μm. Any one of claims 1 to 4, wherein the ratio (T/D) of the average thickness T of the release layer to the average particle diameter D of the (meth)acrylic resin particles is 0.5 to 8.0. The release film for semiconductor molding described in . The release film for semiconductor molding according to any one of claims 1 to 5, wherein the base material layer is a polyester film. The release film for semiconductor molding according to any one of claims 1 to 6, which is used for transfer molding. A method for manufacturing a semiconductor device, comprising performing transfer molding using the release film for semiconductor molding according to any one of claims 1 to 7.