TWI697406B - Release sheet for compression molding of a semiconductor, and semiconductor package molded using the same - Google Patents

Abstract

A release sheet for compression molding of a semiconductor includes a release layer containing a particle and a base material layer, wherein a content ratio of the particle in the release layer is from 5 to 65% by volume.

Description

Release sheet for semiconductor compression molding and semiconductor package molded using the mold release sheet

The present invention relates to a release sheet for semiconductor compression molding and a semiconductor package molded using the mold release sheet.

The semiconductor chip is usually sealed with a resin to block external air and protect it to form a molded product called a "package" and mounted on a substrate. Previously, the molded product was a package molded product molded into each wafer connected via a runner as a flow path of the sealing resin. In this case, by the structure of the mold, the mold release agent is added to the sealing resin, etc., the mold release property of the molded product from the mold is obtained. On the other hand, according to the requirements of miniaturization and multi-pin packaging, the Ball Grid Array (BGA) method, the Quad Flat Non-leaded (QFN) method, and the wafer level Packages such as the Wafer Level Chip Size Package (WL-CSP) method are increasing. In the QFN method, in order to ensure the standoff and prevent the generation of burrs of the sealing material in the terminal part, and in the BGA method and WL-CSP method, in order to improve the releasability of the package from the mold, resin release is used Film (for example, refer to Japanese Patent Laid-Open No. 2002-158242). The molding method using the release film as described above is referred to as "film assisted molding".

[Problem to be Solved by the Invention] If the mold release film is used, when the semiconductor package is resin molded, the sealing material and the mold of the semiconductor package can be easily released. However, the appearance of the molded package surface is uneven and traces of flow of the sealing material are found, which may cause contamination on the surface of the semiconductor package molded by the release film. Moreover, in the BGA method and the WL-CSP method, as the molding method is changed from the previous transfer mold method to the compression mold method, the size of one shot is continuously increasing, and the appearance of the molded package surface The requirements for uniformity, flow marks of sealing materials, etc. have become higher.

According to one embodiment of the present invention, there is provided a release sheet for semiconductor compression molding having the following properties: when a semiconductor package is resin molded by a compression mold method, the sealing material and the mold can be easily removed without causing damage to the semiconductor package With the mold, the surface appearance of the molded semiconductor package is excellent, and the contamination from the mold release sheet to the surface of the molded semiconductor package can be reduced. Moreover, according to another embodiment of the present invention, a semiconductor package molded using the release sheet for semiconductor compression molding is provided. [Means to solve the problem]

The present invention includes the following embodiments. <1> A release sheet for semiconductor compression molding, which includes a release layer containing particles and a substrate layer, and the content of the particles in the release layer is 5 to 65% by volume. <2> The release sheet for semiconductor compression molding according to <1>, wherein the average particle diameter of the particles is 1 μm to 55 μm. <3> The release sheet for semiconductor compression molding according to <1> or <2>, wherein the particles are resin particles. <4> The release sheet for semiconductor compression molding according to <3>, wherein the resin particles include those selected from acrylic resin, polyolefin resin, polystyrene resin, polyacrylonitrile resin, and silicone resin At least one of the group. <5> The release sheet for semiconductor compression molding according to any one of <1> to <4>, wherein the base layer is a polyester film. <6> A semiconductor package molded using the release sheet for semiconductor compression molding according to any one of <1> to <5>. [Effects of the invention]

According to an embodiment of the present invention, there is provided a release sheet for semiconductor compression molding having the following properties: when a semiconductor package is molded by compression molding, the sealing material and the mold can be easily released without causing damage to the semiconductor package, The surface appearance uniformity of the molded semiconductor package is excellent, and contamination from the mold release sheet to the surface of the molded semiconductor package can be reduced. Moreover, according to another embodiment of the present invention, a semiconductor package molded using the release sheet for semiconductor compression molding is provided.

Hereinafter, the embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments. In this specification, the numerical range indicated by "~" means a range that includes the numerical values described before and after "~" as the minimum and maximum values. As the amount of each component in the composition in this specification, when there are multiple substances corresponding to each component in the composition, unless otherwise specified, it means the total of the multiple substances present in the composition the amount. In this specification, the so-called "step" is not only an independent step, and even if it cannot be clearly distinguished from other steps, if the desired effect of the step can be achieved, it is included in this term. In this specification, the term "layer" and "membrane", when viewed in a plan view, includes not only the configuration formed on the entire surface but also the configuration formed on a part of the shape. In this specification, "(meth)acrylic acid" refers to at least one of "acrylic acid" and "methacrylic acid", and "(meth)acrylate" refers to "acrylate" and "methacrylate" At least one of. In addition, in the numerical ranges described stepwise in this specification, 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 stepwise. In addition, in the numerical range described in this specification, the upper limit or lower limit of the numerical range may be replaced with the value shown in the examples.

In this specification, the average thickness of a layer or film (also referred to as an "average thickness") is a value provided as an arithmetic average value of the thickness of the target layer or film at five points. The thickness of the layer or film can be measured using a micrometer or the like. When the thickness of the layer or the film can be directly measured, it is measured using a micrometer. On the other hand, in the case of measuring the thickness of one layer or the total thickness of a plurality of layers, it can also be measured by observing the cross section of the release sheet using an electron microscope.

In this specification, the "average particle size" is the particle size distribution curve of the volume accumulation by the laser diffraction scattering particle size distribution measurement method, as the cumulative 50% particle size from the side of the small particle size (50% D) and find out. For example, a particle size distribution measuring device (for example, Shimadzu Corporation, "SALD-3000") using a laser light scattering method can be used for measurement.

<Release sheet for semiconductor compression molding> The release sheet for semiconductor compression molding (hereinafter also referred to as "release sheet") contains a release layer containing particles and a substrate layer. The content of particles in the release layer is A release sheet for semiconductor compression molding of 5 vol% to 65 vol%. In more detail, the release sheet has a two-layer structure. The two-layer structure is provided on one side of the substrate layer that is in contact with the mold used in the resin molding of the semiconductor package, and is provided with a mold that contacts the molded semiconductor package. Release layer.

As the release sheet, by adopting the above-mentioned structure, when the semiconductor package is molded by compression molding, the sealing material and the mold can be easily released without causing damage to the semiconductor package, and the surface appearance of the molded semiconductor package can be improved The uniformity is improved, and the contamination from the mold release sheet to the surface of the molded semiconductor package can be reduced. The reason is not clear, but it can be estimated as follows. In the case of using the conventional release sheet when molding a semiconductor package, from the viewpoint of suppressing shape defects such as wrinkles in the molded semiconductor package, the release sheet is required to have a followability that can fully conform to the shape of the mold for molding . In addition, if excessive force is applied when taking out the semiconductor package from the mold for molding, the semiconductor package is easily damaged. Therefore, the mold release sheet is also required to have sufficient mold releasability for the semiconductor package. The release sheet in this specification includes two layers with different functions, that is, a release layer that has excellent release properties for sealing resins for semiconductor encapsulation (for example, epoxy resin), and a release layer that has excellent followability to molds for molding. Therefore, it is estimated that the substrate layer can maintain the followability to the molding die and improve the releasability from the molded semiconductor package. In addition, in the release sheet of this specification, since the release layer contains particles at a specific content rate, the outer surface of the release layer (the surface facing the semiconductor package) becomes rough, and the surface of the molded semiconductor package becomes rough. It is rough, so it is estimated that the flow marks of the sealing material can be reduced, and the uniformity of the package surface appearance can be improved. Furthermore, the particle diameter, shape, etc. of the particles can be easily selected, and it is easy to adjust the degree of unevenness in the roughness of the outer surface of the release layer. In addition, when the particles are resin particles, the resin particles have excellent adhesion to other components contained in the release layer, and therefore it is estimated that they are unlikely to fall off from the release layer, and contamination of the semiconductor package can be suppressed.

[Particle-containing mold release layer] The mold release sheet includes a particle-containing mold release layer (hereinafter also referred to as a "specific mold release layer"), and the content of particles in the specific mold release layer is 5 vol% to 65% by volume.

(Particles) The type of particles contained in the release layer is not particularly limited, and may be any of inorganic particles and organic particles. Examples of materials for inorganic particles include alumina, aluminum hydroxide, boron nitride, silicon oxide, graphite, and the like. Examples of the organic particles include resin particles. From the viewpoint of improving the adhesion with other components contained in the release layer, the particles are preferably resin particles. When the particles are resin particles, the adhesion between the particles and other components contained in the release layer is improved, and the particles become less likely to fall off from the release layer, thereby suppressing contamination of the semiconductor package. The resin particles preferably contain at least one selected from the group consisting of acrylic resin, polyolefin resin, polystyrene resin, polyacrylonitrile resin, and silicone resin. From the viewpoint of the releasability of the semiconductor package, the resin particles more preferably contain at least one selected from acrylic resin, polystyrene resin, and polyacrylonitrile resin. From the viewpoint of the uniformity of the appearance of the package surface, the resin particles are preferably in an organic solvent (for example, toluene, methyl ethyl ketone, or ethyl acetate) that can be used in the preparation of the release layer forming composition Insoluble or poorly soluble. Here, "insoluble or poorly soluble in organic solvents" means that in a gel fraction test based on JIS K6769 (2013) or ISO 15875-2 (2003), resin particles are dispersed in an organic solvent such as toluene , The gel fraction after keeping at 50℃ for 24 hours is over 97%.

Examples of acrylic resins include (meth)acrylic monomer (co)polymers, specifically, (meth)acrylic resins, (meth)acrylate resins (for example (meth)) Alkyl acrylate resin and (meth)acrylate dimethylamino ethyl resin) etc. (Meth) acrylic monomers include: methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-propyl acrylate, n-propyl methacrylate, isopropyl acrylate, methyl acrylate Isopropyl acrylate, n-butyl acrylate, n-butyl methacrylate, isobutyl acrylate, isobutyl methacrylate, second butyl acrylate, second butyl methacrylate, third butyl acrylate, T-butyl methacrylate, pentyl acrylate, pentyl methacrylate, hexyl acrylate, hexyl methacrylate, heptyl acrylate, heptyl methacrylate, 2-ethylhexyl acrylate, methacrylic acid -2-ethylhexyl, octyl acrylate, octyl methacrylate, nonyl acrylate, nonyl methacrylate, decyl acrylate, decyl methacrylate, dodecyl acrylate, dodecyl methacrylate Alkyl ester, tetradecyl acrylate, tetradecyl methacrylate, cetyl acrylate, cetyl methacrylate, stearyl acrylate, stearyl methacrylate Ester, eicosyl acrylate, eicosyl methacrylate, behenyl acrylate, behenyl methacrylate, cyclopentyl acrylate, cyclopentyl methacrylate, acrylic ring Hexyl ester, cyclohexyl methacrylate, cycloheptyl acrylate, cycloheptyl methacrylate, benzyl acrylate, benzyl methacrylate, phenyl acrylate, phenyl methacrylate, methoxyethyl acrylate, methyl methacrylate Methoxyethyl acrylate, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, diethylaminoethyl acrylate Methylaminopropyl, dimethylaminopropyl methacrylate, 2-chloroethyl acrylate, 2-chloroethyl methacrylate, 2-fluoroethyl acrylate, 2- methacrylic acid Fluoroethyl, styrene, α-methylstyrene, cyclohexyl maleimide, dicyclopentyl acrylate, dicyclopentyl methacrylate, vinyl toluene, vinyl chloride, vinyl acetate, N-ethylene Pyrrolidone, butadiene, isoprene, chloroprene, etc. These can be used alone or in combination of two or more. The polyolefin resin is not particularly limited as long as it is an olefin monomer or a (co)polymer of an olefin monomer. Specifically, polyethylene, polypropylene, polymethylpentene, etc. can be mentioned. Examples of polystyrene resins include (co)polymers of styrene or styrene derivatives. Examples of styrene derivatives include α-methylstyrene, 4-methylstyrene, 2-methylstyrene, 3-methylstyrene, 2-ethylstyrene, and 3-ethylstyrene , 4-ethylstyrene and other alkyl-substituted styrenes with alkyl chains, 2-chlorostyrene, 3-chlorostyrene, 4-chlorostyrene and other halogen-substituted styrenes, 4-fluorobenzene Fluorine-substituted styrene such as ethylene, 2,5-difluorostyrene, vinyl naphthalene, etc. As an example of the polyacrylonitrile resin, a (co)polymer of acrylonitrile monomer can be cited. From the viewpoint of suppressing the solubility of the resin particles in an organic solvent, the resin contained in the resin particles is preferably a crosslinked resin.

The average particle diameter of the particles is preferably 1 μm to 55 μm. If the average particle size of the particles is 1 μm or more, there is a tendency that the unevenness can be sufficiently formed on the surface of the specific release layer, the uniformity of the surface appearance of the molded semiconductor package is improved, and the flow mark of the sealing material is suppressed. In addition, if the average particle diameter of the particles is 55 μm or less, the particles are fixed in the specific release layer, so there is no need to excessively increase the thickness of the specific release layer, which is preferable from the viewpoint of cost. From the viewpoint of the surface appearance of the semiconductor package, the upper limit of the average particle diameter of the particles is preferably 55 μm, more preferably 50 μm. From the viewpoint of cost, the lower limit of the average particle diameter of the particles is more preferably 3 μm, and still more preferably 10 μm.

The shape of the particles contained in the specific release layer is not particularly limited, and may be any of spherical, elliptical, and amorphous shapes.

As a specific example of the particle, a TAFTIC series such as TAFTIC FH-S010 (Toyobo Co., Ltd.), which is an acrylic resin particle, can be cited.

The content rate of the particles contained in the specific release layer is 5 to 65% by volume. If the particle content is 5 vol% or more, there is a tendency that the surface of the specific release layer can be sufficiently uneven, the uniformity of the appearance of the molded semiconductor package surface is improved, and the flow mark of the sealing material is sufficiently suppressed. effect. From this viewpoint, the lower limit of the particle content is preferably 10% by volume, and more preferably 20% by volume. In addition, if the content of particles is 65% by volume or less, there is a tendency that the particles are easily fixed by the resin component described later in the specific release layer, the possibility of particles falling off is reduced, and the impact on the molded semiconductor can be suppressed. Pollution of the package surface, and the economy is also better. From this viewpoint, the upper limit of the content of particles is preferably 60% by volume, and more preferably 50% by volume.

The content of particles can be calculated as the ratio of particles per unit volume by observing the cross section of the specific release layer of the release sheet with a scanning electron microscope (Scanning Electron Microscope, SEM), for example. Specifically, it can be calculated by the following method.

First, the cross-section of a specific release layer is observed by SEM, and the number of particles and the particle size contained in an arbitrary area (hereinafter also referred to as "specific area") in the cross-section are measured. In addition, an arbitrary volume (hereinafter also referred to as "specific volume") is set based on the specific area, and the number of particles contained in the specific volume is calculated. In addition, the volume of each particle is calculated based on the particle diameter of the particle. Furthermore, based on the calculated number of particles and the volume of each particle, the total volume of the particles contained in the specific volume is calculated, and the total volume of the particles is divided by the specific volume to calculate the particles contained in the specific release layer The volume content rate.

As another method, the mass (Wc) of the specific release layer at 25°C is measured, and the specific release layer is dissolved in an organic solvent such as toluene to measure the mass (Wf) of the remaining particles at 25°C. Next, use an electronic hydrometer or a pycnometer to obtain the specific gravity (df) of the particles at 25°C. Next, the specific gravity (dc) of the specific release layer at 25°C was measured by the same method. Next, the volume (Vc) of the specific release layer and the volume (Vf) of the remaining particles are calculated. As shown in (Equation 1), the volume of the remaining particles is divided by the volume of the specific release layer, thereby It is calculated as the volume ratio (Vr) of particles.

(Formula 1) Vc=Wc/dc Vf=Wf/df Vr=Vf/Vc

Vc: Volume of the release layer (cm ³ ) Wc: Mass of the release layer (g) dc: Specific gravity of the release layer (g/cm ³ ) Vf: Volume of particles (cm ³ ) Wf: Mass of particles (g ) Df: Specific gravity of particles (g/cm ³ ) Vr: Volume ratio of particles In addition, the specific release layer in the measurement method may be peeled from the release sheet, or it may be used separately for the purpose of the measurement method maker.

(Resin component of specific release layer) The specific release layer may further contain a resin component. By containing the resin component, the particles are fixed in the specific release layer. The resin component of the specific release layer is not particularly limited. From the viewpoints of mold releasability and heat resistance with semiconductor packages, the resin component is preferably acrylic resin or silicone resin, and more preferably cross-linked acrylic resin (hereinafter also referred to as "cross-linked acrylic copolymer") .

The acrylic resin is preferably a monomer with a low glass transition temperature (Tg) such as butyl acrylate, ethyl acrylate, 2-ethylhexyl acrylate, etc., and is combined with acrylic acid, methacrylic acid, and hydroxyethyl methacrylate. An acrylic copolymer obtained by copolymerizing functional monomers such as ester, hydroxyethyl acrylate, acrylamide, and acrylonitrile. Furthermore, the crosslinked acrylic copolymer can be produced by crosslinking the monomer using 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. Furthermore, in order to form a gradually expanding network structure in the acrylic resin, the crosslinking agent is more preferably a trifunctional, tetrafunctional, or other multifunctional crosslinking agent.

The cross-linked acrylic copolymer produced by using the above-mentioned cross-linking agent has a slowly expanding network structure. Therefore, if the cross-linked acrylic copolymer is used as the resin component of the specific release layer, the specific The extensibility of the release layer is improved, and the phenomenon that hinders the extensibility of the base layer is suppressed, and therefore, the followability of the release sheet to the mold during compression molding can be improved.

From this viewpoint, the amount of the crosslinking agent used in the production of the crosslinked acrylic copolymer is preferably 3 parts by mass to 100 parts by mass relative to 100 parts by mass of the acrylic copolymer, and more preferably 5 parts by mass to 70 parts by mass. If the amount of the crosslinking agent is 3 parts by mass or more, the strength of the resin component is ensured, and therefore contamination can be prevented; if the amount of the crosslinking agent is 100 parts by mass or less, the flexibility of the crosslinked acrylic copolymer is improved. The extensibility of the release layer is improved.

(Other ingredients)

As long as the effect of the present invention is not hindered, the specific release layer may further contain a solvent, anchoring enhancer, crosslinking accelerator, antistatic agent, coloring agent, etc. as necessary.

(The thickness of the specific release layer) The thickness of the specific release layer is not particularly limited, and can be appropriately set in consideration of the relationship with the average particle diameter of the particles used. The thickness of the specific release layer is preferably 0.1 μm to 100 μm, more preferably 1 μm to 50 μm. When the thickness of the specific release layer is extremely thinner than the average particle size of the particles used, there is a possibility that it becomes difficult to fix the particles in the specific release layer, and the possibility of particles falling off becomes higher. Causes of contamination on the surface of the molded semiconductor package. In addition, when the thickness of the specific release layer is extremely thicker than the average particle diameter of the particles used, there is a possibility that it becomes difficult to sufficiently form irregularities on the surface of the specific release layer, and the molded The effect of improving the uniformity of the surface appearance of the semiconductor package, and the effect of suppressing the flow mark of the sealing material. Moreover, it is economically disadvantageous. In addition, the "thickness of a specific release layer" in this specification means a dry thickness, and the specific release layer of a release sheet can be measured by the measuring method of the thickness of the said layer.

(Surface roughness of the specific release layer) The outer surface of the specific release layer (the surface facing the base material layer is the surface on the opposite side) preferably has unevenness. The surface roughness of a specific release layer can be evaluated by arithmetic average roughness (Ra) or ten-point average roughness (Rz). The arithmetic average roughness (Ra) and ten-point average roughness (Rz) can be, for example, the use of a surface roughness measuring device (such as Kosaka Research Institute Co., Ltd., model SE-3500), by JIS B0601 (2013) or ISO 4287 (1997) The value obtained by analyzing the results measured under the conditions of a stylus tip diameter of 2 μm, a feed rate of 0.5 mm/s, and a scanning distance of 8 mm. From the viewpoint of the uniformity of the package surface appearance, the arithmetic average roughness (Ra) of the specific release layer is preferably 0.5 μm to 5 μm, and the ten-point average roughness (Rz) is preferably 5 μm to 50 μm. By adjusting the average particle diameter of the particles and the thickness of the specific release layer, the surface roughness of the specific release layer can be adjusted within the above range.

[Substrate layer] The release sheet includes a substrate layer. The substrate layer is not particularly limited, and can be appropriately selected from resin-containing substrate layers used in the technical field. From the viewpoint of improving the followability of the release sheet to the mold shape, it is preferable to use a resin-containing substrate layer having excellent extensibility. Considering that the sealing material is molded at a high temperature (about 100°C to 200°C), the base layer desirably has heat resistance above this temperature. In addition, in order to prevent wrinkles of the sealing resin and breakage of the release sheet when the release sheet is installed in the mold and during molding, it is important to consider the modulus of elasticity, elongation, etc. at high temperatures. Instead, select the substrate layer.

From the viewpoint of heat resistance and elastic modulus at high temperature, the material of the base layer is preferably a polyester resin. Examples of the polyester resin include polyethylene terephthalate resin, polyethylene naphthalate resin, and polybutylene terephthalate resin, and copolymers and modified resins of these. The base material layer is preferably a polyester resin molded into a sheet shape, and the base material layer is more preferably a polyester film. From the viewpoint of conformability to a mold, a biaxially stretched polyester film is preferable. The thickness of the substrate layer is not particularly limited, but is preferably 5 μm to 100 μm, more preferably 10 μm to 70 μm. If the thickness is 5 μm or more, the release sheet has excellent handleability and tends to be less likely to cause wrinkles. If the thickness is 100 μm or less, there is a tendency that the followability to the mold during molding is excellent, and therefore the generation of wrinkles or the like of the molded semiconductor package is suppressed.

[Other Configurations] The base material layer is a layer in contact with the surface of the mold, and due to the material used, a larger peeling force is required to peel the release sheet from the mold. When such a material that is difficult to peel from the mold is used for the base material layer, it is preferable to adjust the release sheet so that it becomes easy to peel the release sheet from the mold. For example, in order to improve the releasability from the mold, it is also possible to perform a satin process (satin process) on the opposite surface of the substrate layer that is in contact with the specific release layer, that is, the surface of the substrate layer on the mold side (for example, Surface finishing such as satin finishing or matt finishing), or resetting other release layer (second release layer). The material of the second release layer is not particularly limited as long as it satisfies heat resistance, releasability from the mold, and the like, and the same material as the specific release layer can be used. The thickness of the second release layer is not particularly limited, but is preferably 0.1 μm to 100 μm.

In addition, it is also possible to provide a specific release layer or a fixing promotion layer of the second release layer, an antistatic layer, etc. between the specific release layer and the base material layer, between the base material layer and the second release layer, etc. Colored layers and other layers.

＜Method of manufacturing release sheet＞

The release sheet can be manufactured by a known method. For example, a release sheet can be produced by applying a release layer forming composition containing 5 to 65% by volume of particles with respect to the total solid content on one side of the base layer, and performing dry. The composition for forming a release layer may contain a resin component and other components added as necessary.

[Preparation of composition for forming release layer]

The method of preparing the composition for forming a release layer is not particularly limited, and for example, a method of dispersing particles in a solvent is mentioned, and a known method of preparing the composition can be used.

The solvent used in the preparation of the composition for forming a release layer is not particularly limited, but an organic solvent that can disperse particles and dissolve the resin component is preferred. Examples of organic solvents include toluene, methyl ethyl ketone, ethyl acetate and the like.

[Apply and Dry]

The method of applying the composition for forming a release layer to one side of the base material layer is not particularly limited, and a known coating method such as roll coating, bar coating, and kiss coating can be used. In addition, when applying the composition for forming a release layer, it is applied so that the thickness of the composition layer (release layer) after drying becomes 0.1 μm to 100 μm.

The method of drying the provided composition for mold release layer formation is not specifically limited, A well-known drying method can be used. For example, it may be a method of drying at 50°C to 150°C for 0.1 minute to 60 minutes.

<Semiconductor Package Molding>

The release sheet for compression molding can be used in the molding of semiconductor packages, and can be suitably used in compression molding in particular.

Generally, in the compression molding of a semiconductor package, a release sheet is placed on a mold of a compression molding device, and the release sheet is made to follow the shape of the mold by vacuum suction or the like. After that, the sealing material of the semiconductor package (such as epoxy resin) is put into the mold, the semiconductor chip is placed on it, and the mold is heated while being heated, thereby hardening the sealing material and forming the semiconductor package. After that, the mold is opened, and the molded semiconductor package is taken out.

As described above, in compression molding, the release sheet is adsorbed to the mold, and therefore, the release sheet is required to have excellent followability to the shape of the mold. In the release sheet, a resin having excellent extensibility is used as the base material layer, thereby making it possible to further improve the followability to the mold.

The release sheet for compression molding in this specification is mounted in such a way that a specific release layer is in contact with the semiconductor package (molded product) when a semiconductor is molded by compression molding, thereby releasing the mold during the peeling process after molding The sheet can be easily peeled from the semiconductor package, the sealing material and the mold can be easily demolded without causing damage to the semiconductor package, and the surface appearance of the molded package is excellent and the flow marks of the sealing material can also be suppressed. Contamination of the film to the molded package surface. [Example]

Hereinafter, the present invention will be specifically described with reference to Examples. Among them, the present invention is not limited by these embodiments.

<Example 1> With respect to 100 parts by mass of acrylic resin (Imperial Chemical Industry Co., Ltd.; WS-023), 10 parts by mass of CORONATE L (Nippon Polyurethane Industry Co., Ltd.) as a crosslinking agent Co., Ltd., trade name), and 10 parts by mass of Tafchicool FH-S010 (Toyobo Co., Ltd., trade name, acrylic particles, average particle size of 10 μm) as particles (C) added to toluene A toluene solution having a solid content of 15% by mass was prepared to prepare a composition for forming a release layer. A 25 μm-thick biaxially stretched polyethylene terephthalate film (Universal Co., Ltd.; S-25) as a base layer was subjected to corona treatment. Thereafter, on one side of the biaxially stretched polyethylene terephthalate film, a roll coater was used to coat the release layer forming composition so that the average thickness after drying became 10 μm. It was dried to form a release layer, and a release sheet was obtained. The content rate of the particles (C) in the release layer of the obtained release sheet was measured by cross-sectional observation with SEM, and it was 10% by volume.

[Evaluation of the characteristics of the release sheet] The release sheet was mounted on the upper mold of the compression molding mold in which the semiconductor bare chip was placed on the lower mold, fixed by vacuum, and then the mold was clamped to seal the material (Hitachi Chemical Co., Ltd.; trade name "CEL-9750ZHF10") molding (compression molding) to obtain a semiconductor package. The mold temperature is 180°C, the molding pressure is 6.86 MPa (70 kgf/cm ² ), and the molding time is 180 seconds. The following methods were used to evaluate the releasability of the mold release sheet and the molded sealing material, the uniformity of the appearance of the molded semiconductor package surface (the presence or absence of flow marks of the sealing material), and the particles (C) to the molded semiconductor Whether the package surface is peeled off (whether it is contaminated). The evaluation results are shown in Table 1 and Table 2.

(Evaluation of the releasability from the molded sealing material) As an index of the releasability of the molded release sheet and the sealing material, when the peeling angle is 180° and the peeling speed is 300 mm/min, the peeling test is measured The peeling force of, was evaluated based on the following criteria. A: Less than 0.5 N/50 mm B: 0.5 N/50 mm or more and less than 5.0 N/50 mm C: 5.0 N/50 mm or more

(Evaluation of the appearance of the surface of the semiconductor package) The presence or absence of flow marks of the sealing material on the surface of the semiconductor package was observed by visual observation and an optical microscope (100 times), and the evaluation was performed based on the following criteria. A: No trace of flow was observed in any of visual observation and microscope observation. B: No trace of flow was observed visually, and trace of flow was slightly observed in microscope observation. C: Flow traces are observed in any of visual observation and microscope observation.

(The presence or absence of particles (C) falling off the surface of the semiconductor package) The presence or absence of particles (C) falling off the surface of the semiconductor package was observed by visual inspection and an optical microscope (100 times), and the evaluation was made based on the following criteria. A: No falling off of particles (C) was observed in any of visual observation and microscope observation. B: No falling off of particles (C) was observed visually, and falling off of particles (C) was slightly observed in microscopic observation. C: Falling off of particles (C) was observed in both of visual inspection and microscope observation.

<Example 2 to Example 9 and Comparative Example 1 to Comparative Example 3> The thickness of the layer A after drying, the presence or absence of a release layer, and the type or content of the particles (C) were changed as shown in Table 1 and Table 2 below Except for the rate, it carried out similarly to Example 1, and produced the release sheet of Example 2-Example 9 and Comparative Example 1-Comparative Example 3, and evaluated. The evaluation results are shown in Table 1 and Table 2.

The particles (C) shown in Table 1 and Table 2 are as follows. ·Tafkiku FH-S015 (Toyobo Co., Ltd., trade name) ·Tafkiku FH-S020 (Toyobo Co., Ltd., trade name) ·Tafkiku FH-S050 (Toyobo Co., Ltd., trade name) ) ·SX-500H (Zhongken Chemical Co., Ltd., trade name) ·Tafkiku ASF-7 (Toyobo Co., Ltd., trade name) ·E606 (Toray Dow Corning Co., Ltd., trade name) ·BM30X-12 ( Sekisui Chemical Industry Co., Ltd., trade name) ·HPS-3500 (Toa Gosei Co., Ltd., trade name) In addition, "PMMA" in Table 1 and Table 2 refers to polymethyl methacrylate, and "PMBA" refers to Refers to polybutyl methacrylate. The "-" in Table 2 means that no material is used or the characteristics cannot be detected.

[Table 1]

[Table 2]

As shown in Table 1 and Table 2, the release sheet of Examples 1 to 9 has good releasability from the molded sealing material, and the molded package has excellent surface appearance uniformity, and the particles (C) are molded The peeling of the package surface is also suppressed. In addition, although not shown in Table 1 and Table 2, a release sheet was produced and evaluated in the same manner as in Example 1 except that the content of particles (C) was set to 1% by volume. Flow marks were observed in any of the observations, and the uniformity of the surface appearance was not sufficiently obtained.

On the other hand, in Comparative Example 1 without a release layer, the sealing material and the release sheet could not be peeled off after molding. In Comparative Example 2 in which a particle-free release layer was used, the molded package surface had uneven appearance, and flow marks of the sealing material were observed. In Comparative Example 3 in which the content of particles exceeded 65% by volume, dropout of particles was observed.

As described above, if the release sheet according to the embodiment of the present invention is used, a release film having the following properties can be provided: when a semiconductor package is resin molded, the sealing material and the mold can be easily made without damaging the semiconductor package. The mold release has excellent uniformity in the appearance of the molded package surface, and contamination from the film to the molded package surface is also suppressed.

no

no

Claims (5)

A release sheet for semiconductor compression molding, comprising a release layer containing particles and a substrate layer. The release layer has a thickness of 0.1 μm to 100 μm, and the average particle size of the particles is 1 μm to 55 μm. The content rate of the particles in the release layer is 5 vol% to 65% by volume. The release sheet for semiconductor compression molding according to the first item of the patent application, wherein the particles are resin particles. The release sheet for semiconductor compression molding according to the second patent application, wherein the resin particles are selected from acrylic resins, polyolefin resins, polystyrene resins, polyacrylonitrile resins, and silicone resins. At least one of the group. According to the release sheet for semiconductor compression molding according to item 1 or item 2 of the scope of patent application, the substrate layer is a polyester film. A semiconductor package which is molded using the release sheet for semiconductor compression molding as described in any one of items 1 to 4 of the scope of patent application.