TWI910469B - Release film for semiconductor molding and method of producing semiconductor package - Google Patents

Abstract

A release film for semiconductor molding having a release layer, a conductive layer, and a substrate layer in this order, wherein the release layer contains a conductive particle, or there is a conduction path via the conductive particle from the conductive layer to a surface of the release layer.

Description

Manufacturing method of release film for semiconductor molding and semiconductor packaging

This disclosure relates to a release film for semiconductor molding and a method for manufacturing semiconductor packaging.

Semiconductor chips are typically sealed with resin to shield them from external air and provide protection, and are mounted on a substrate in the form of a molded package. Traditionally, the package was formed by connecting each chip via runners that act as flow paths for the sealant. The moldability of the package from the mold is ensured by the mold structure and the addition of release agents to the sealant.

In recent years, due to requirements for miniaturization and multi-pin packaging, the use of packaging methods such as Ball Grid Array (BGA), Quad Flat Non-leaded (QFN), and Wafer Level-Chip Size Package (WL-CSP) has increased. In the QFN method, to ensure standoff and prevent burrs on the sealing material at the terminals, and in the BGA and WL-CSP methods, to improve the release properties of the package from the mold, a release film is used (see, for example, Patent 1). This molding method using a release film is called "film-assisted molding." Generally, a resin-based film is used as the release film.

Recently, due to requirements for thinner packaging and improved heat dissipation, flip-chip bonding of semiconductor wafers is increasingly used, resulting in more packages with the back side of the wafer exposed. This molding method is called mold underfill (MUF). In MUF, a seal is achieved while the release liner is in contact with the semiconductor wafer for protection and shielding purposes.

In film-assisted molding, when the release film is rolled out from the roller for use, static electricity is generated during the peeling process. Therefore, foreign matter such as dust present in the packaging manufacturing environment can sometimes adhere to the release film. This release film with foreign matter adhering to it becomes a cause of foreign matter adhesion to the packaging and the generation of burrs.

Furthermore, in MUF (Metal-in-Flight) sealing, if the release film is easily charged during sealing while in contact with the semiconductor wafer, the semiconductor wafer may be damaged due to the charging and discharging that occurs when it is peeled off from the release film.

As an antistatic measure for release films, a release film is proposed consisting of a substrate, an antistatic layer, and a release layer, formed by coating an antistatic agent onto a substrate constituting the release film, and then coating a cross-linked acrylic adhesive onto it (see, for example, Patent 2).

[Existing technical literature]

[Patent Documents]

[Patent Document 1] Japanese Patent Application Publication No. 2002-158242

[Patent Document 2] Japanese Patent Application Publication No. 2005-166904

In a release film comprising a substrate, an antistatic layer, and a release layer, the release film is prone to becoming charged because the antistatic layer is covered by the release layer. Consequently, it is sometimes impossible to adequately suppress the charging of the release film.

The disclosed embodiment is based on the above-described situation.

The problem with this disclosed embodiment is to provide a release film for semiconductor molding with effectively low surface resistivity on the release layer side.

Specific methods for solving the aforementioned problem include the following forms.

<1> A release film for semiconductor molding, comprising sequentially a release layer, a conductive layer, and a substrate layer, wherein the release layer contains conductive particles.

<2> The release film for semiconductor molding as described in <1>, wherein the average particle size (μm) of the conductive particles is 50% to 300% of the thickness (μm) of the release layer.

<3> A release film for semiconductor molding as described in <1> or <2>, wherein a conductive path exists from the conductive layer to the surface of the release layer via the conductive particles.

<4> A release film for semiconductor molding as described in any one of <1> to <3>, wherein the conductive particles comprise metal particles.

<5> A release film for semiconductor molding as described in any one of <1> to <4>, wherein the conductive layer is a metal vapor-deposited layer or a layer containing a conductive polymer.

<6> A release film for semiconductor molding as described in any one of <1> to <5>, wherein the content of the conductive particles contained in the release layer is 0.5% to 80% by mass relative to the total amount of components other than the conductive particles contained in the release layer.

<7> A release film for semiconductor molding as described in any one of <1> to <6>, wherein the average particle size (μm) of the conductive particles is more than 100% and less than 300% of the thickness (μm) of the release layer, and the content of the conductive particles in the release layer is 0.5% to 50% by mass relative to the total amount of components other than the conductive particles in the release layer.

<8> A release film for semiconductor molding as described in any one of <1> to <6>, wherein the average particle size (μm) of the conductive particles is 50% to 100% or less of the thickness (μm) of the release layer, and the content of the conductive particles in the release layer is 0.5% to 80% by mass relative to the total amount of components other than the conductive particles in the release layer.

<9> A release film for semiconductor molding as described in any one of <1> to <6>, wherein the average particle size (μm) of the conductive particles is less than 50% of the thickness (μm) of the release layer, and the content of the conductive particles in the release layer is 5% to 80% by mass relative to the total amount of components other than the conductive particles in the release layer.

<10> A release film for semiconductor molding as described in any one of <1> to <9>, wherein the release film is used for transfer molding or compression molding.

<11> A method for manufacturing a semiconductor package, using a semiconductor molding release film as described in any one of <1> to <10> for a transfer molding step or a compression molding step.

The embodiments disclosed herein provide a release film for semiconductor molding with effectively low surface resistivity on the release layer side.

In this disclosure, the term "step" is used not only to describe a step that is independent of other steps, but also to include a step in which the objective is achieved, even if it cannot be clearly distinguished from other steps.

In this disclosure, the range of values represented by "~" includes the minimum and maximum values recorded before and after the "~".

Within the numerical ranges described in stages in this disclosure, the upper or lower limit value described in one numerical range can be replaced by the upper or lower limit value of other numerical ranges described in stages. Furthermore, within the numerical ranges described in this disclosure, the upper or lower limit value of that range can be replaced by the values shown in the embodiments.

In this disclosure, each component may contain multiple substances corresponding to that component. Where multiple substances corresponding to each component are present in the composition, unless otherwise specified, the content or percentage of each component refers to the aggregate content or percentage of all such substances present in the composition.

This disclosure may include multiple types of particles corresponding to each component. Where multiple types of particles corresponding to each component are present in the composition, unless otherwise specified, the particle size of each component refers to a value for a mixture of those multiple particles present in the composition.

Release film for semiconductor molding.

This disclosure discloses a release film (also referred to simply as a "release film") for semiconductor molding with effectively low surface resistivity on the release layer side.

The release film disclosed herein sequentially comprises a release layer, a conductive layer, and a substrate layer, wherein the release layer contains conductive particles.

In the release film disclosed herein, the release layer contains conductive particles, thereby enabling the formation of conductive pathways through the conductive particles from the conductive layer to the surface of the release layer. As a result, the surface resistivity of the release layer side can be effectively reduced.

The release film disclosed herein preferably has conductive paths through conductive particles extending from the conductive layer to the surface of the release layer. Whether a conductive path through conductive particles exists in the release film from the conductive layer to the surface of the release layer can be determined by measuring the surface resistivity of the release layer side of the release film. When the surface resistivity of the release layer side is less than 1.0 × ^10⁷ (Ω/sq), it is determined that a conductive path through conductive particles exists from the conductive layer to the surface of the release layer.

The following describes the characteristics of each layer and the components contained in each layer of the release film disclosed herein.

[Conductive particles]

Examples of conductive particles included in the release layer include metal particles, carbon-based conductive particles, and particles with a metal layer on the surface of organic or inorganic core particles. One type of conductive particle can be used alone, or two or more types can be used together. From the viewpoint of ease of acquisition, metal particles and carbon-based conductive particles are preferred as conductive particles; from the viewpoint of reducing surface resistivity, metal particles are preferred.

The metal particles may be, for example, powders selected from the group consisting of elemental metals, alloys, and metal compounds. The alloy may comprise at least one selected from the group consisting of solid solutions, eutectics, and intermetallic compounds. The alloy may, for example, be stainless steel (Fe-Cr alloys, Fe-Ni-Cr alloys). The metal compound may, for example, be an oxide such as a ferrite.

Carbon-based conductive particles can be powdered conductive fillers such as carbon black and graphite, fibrous conductive fillers such as carbon nanotubes (CNTs) and carbon fibers.

The conductive particle may contain one or more metallic elements. The metallic element contained in the conductive particle may be at least one selected from the group consisting of base metals, noble metals, transition metals, and rare earth elements. The metallic element contained in the conductive particle may be at least one selected from the group consisting of iron (Fe), copper (Cu), titanium (Ti), manganese (Mn), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), tin (Sn), chromium (Cr), barium (Ba), strontium (Sr), lead (Pb), silver (Ag), ferroalloy (Pr), neodymium (Nd), chromium (Sm), and pyroxene (Dy).

The conductive particles may also contain elements other than metallic elements. For example, the conductive particles may contain at least one element selected from the group consisting of oxygen, boron, and silicon. The conductive particles may also be particles selected from the group consisting of Fe-Si alloys, Fe-Si-Al alloys (aluminosilicate iron powder), Fe-Ni alloys (permalloy), Fe-Cu-Ni alloys (permalloy), Fe-Cr-Si alloys (electromagnetic stainless steel), Nd-Fe-B alloys (rare earth magnets), Al-Ni-Co alloys (aluminum-nickel-cobalt magnets), and ferrites. Ferrites may, for example, be spinel ferrite, hexagonal ferrite, or garnet ferrite. The conductive particles may contain one or more of the above elements and compositions.

When the conductive particles include metal particles, the content of metal particles relative to the total amount of conductive particles is preferably 50% by mass or more, more preferably 70% by mass or more, further preferably 80% by mass or more, and particularly preferably 90% by mass or more.

The shape of the conductive particles is not limited and can be spherical, plate-like, or irregular. However, from the perspective of minimizing damage to the semiconductor package surface, spherical particles are preferred.

From the viewpoint of efficiently forming conductive pathways, the average particle size of the conductive particles is preferably 50% or more, more preferably 60% or more, and even more preferably 70% or more of the thickness of the release layer. From the viewpoint of minimizing damage to the semiconductor package surface, the average particle size of the conductive particles is preferably 300% or less, more preferably 200% or less, and even more preferably 150% or less of the thickness of the release layer.

In this disclosure, the thickness of the release layer refers to the value determined by the following measurement method.

A portion of the release film was cut off, embedded in resin, and then cut along its thickness to create a thin section sample. The thin section sample was imaged using a scanning electron microscope (SEM). Ten locations (A) within the release layer in the SEM image where conductive particles did not protrude from the release layer were randomly selected. The thickness of these ten locations (distance from the interface between the conductive layer and the release layer to the surface of the release layer at location A) was measured, and the thicknesses of the ten locations were averaged.

The average particle size of the conductive particles is preferably 0.5 μm to 100 μm, more preferably 1 μm to 50 μm, and even more preferably 1 μm to 20 μm. If the average particle size is 0.5 μm or larger, a large number of conductive particles are not required to form conductive pathways, reducing concerns about the fragility of the release layer or the deterioration of release properties caused by an excess of conductive particles. If the average particle size is 100 μm or smaller, the deposition of conductive particles is less likely to occur in the composition used to form the release layer, resulting in good workability for forming the release layer.

The average particle size of the conductive particles is determined by the following method.

A portion of the release film was cut off, embedded in resin, and then cut along its thickness to create a thin-section sample. This thin-section sample was then imaged using a scanning electron microscope (SEM). From the SEM images, 100 randomly selected conductive particles (primary particles, but secondary particles if they agglomerate) within the release layer were measured, and their major and minor axes were measured. The arithmetic mean of these 100 major and minor axes was taken as the average particle size of the conductive particles.

The content of conductive particles in the release layer is preferably 0.5% to 80% by mass relative to the total amount of components other than conductive particles (solid components) in the release layer. If the content of conductive particles is 0.5% by mass or more relative to the total amount of components other than conductive particles, conductive pathways are easily formed. If the content of conductive particles is 80% by mass or less relative to the total amount of components other than conductive particles, there is less concern about the fragility of the release layer or the deterioration of its release properties. From the above perspective, the content of conductive particles in the release layer is more preferably 5% to 75% by mass, and more preferably 10% to 70% by mass relative to the total amount of components other than conductive particles in the release layer.

Regarding the content of conductive particles in the release layer, it is preferable that the larger the average particle size relative to the thickness of the release layer, the fewer the conductive particles, and the smaller the average particle size relative to the thickness of the release layer, the more conductive particles.

When the average particle size of the conductive particles exceeds 100% but is less than 300% of the thickness of the release layer, the content of conductive particles in the release layer relative to the total amount of components other than conductive particles is preferably 0.5% to 50% by mass, more preferably 1% to 30% by mass, and even more preferably 5% to 20% by mass.

When the average particle size of the conductive particles is 50% to 100% of the thickness of the release layer, the content of conductive particles in the release layer relative to the total amount of components other than conductive particles is preferably 0.5% to 80% by mass, more preferably 5% to 75% by mass, and even more preferably 10% to 70% by mass.

When the average particle size of the conductive particles is less than 50% of the thickness of the release layer, the content of conductive particles in the release layer relative to the total amount of components other than conductive particles is preferably 5% to 80% by mass, more preferably 8% to 75% by mass, and even more preferably 10% to 70% by mass.

[Mold Release Layer]

The release layer is responsible for demolding during semiconductor packaging. The release layer contains at least conductive particles and resin. There are no particular limitations on the resin used in the release layer. However, from the viewpoints of demolding properties in semiconductor packaging and the heat resistance of the release layer, the resin is preferably acrylic or silicone resin, and more preferably cross-linked acrylic resin (hereinafter also referred to as "cross-linked acrylic copolymer").

Acrylic resins are preferably acrylic copolymers, obtained by copolymerizing monomers with low glass transition temperature (Tg), such as butyl acrylate, ethyl acrylate, and 2-ethylhexyl acrylate, with functional monomers such as acrylic acid, methacrylic acid, hydroxyethyl methacrylate, hydroxyethyl acrylate, acrylamide, and acrylonitrile. Crosslinked acrylic copolymers can be manufactured by crosslinking the monomers using a crosslinking agent.

Crosslinking agents used in the manufacture of crosslinked acrylic copolymers include well-known crosslinking agents such as isocyanate compounds, melamine compounds, and epoxy compounds. To form a slowly expanding mesh-like structure in the acrylic resin, the crosslinking agent is preferably a multifunctional crosslinking agent, such as a trifunctional or tetrafunctional one.

The release layer, as long as it serves the function of a release film as disclosed herein, may include, as needed, solvents, anchoring agents, crosslinking accelerators, antistatic agents, fillers, colorants, etc.

The thickness of the release layer is not particularly limited and can be determined by considering the particle size of the conductive particles contained in the release layer. The thickness of the release layer is preferably 0.1 μm to 100 μm. If the thickness of the release layer is 0.1 μm or more, it can contain resins sufficient to provide the softness or extensibility required in the molding process, making it less likely for the release layer to peel off from the substrate layer or to detach. If the thickness of the release layer is less than 100 μm, when using thermosetting resins to form the release layer, thermal shrinkage during thermosetting is suppressed, and the flatness of the release film is maintained. From the aforementioned perspective, the thickness of the release layer is preferably 1 μm to 100 μm, and more preferably 10 μm to 50 μm.

From the viewpoint that the formation of the release layer (e.g., by coating and thermosetting a composition containing conductive particles and resin) is easy and that peeling from the substrate layer or detachment of the release layer is unlikely, the thickness of the release layer is preferably 10 μm to 50 μm. In a release film where a previous release layer is disposed on a conductive layer, if the thickness of the release layer is 10 μm to 50 μm, it may sometimes hinder the antistatic function of the conductive layer. However, in the release film disclosed herein, conductive pathways through conductive particles can be formed from the conductive layer to the surface of the release layer, thus enabling the antistatic function of the conductive layer to be performed.

In the second release film, the surface resistivity of the release layer side is less than 1.0 × ^10⁷ (Ω/sq). In the first release film, the surface resistivity of the release layer side is also preferably less than 1.0 × ^10⁷ (Ω/sq). More preferably, the surface resistivity of the release layer side is 1.0 × ^10⁶ (Ω/sq) or less, even more preferably 1.0 × ^10⁴ (Ω/sq) or less, and particularly preferably 1.0 × ^10³ (Ω/sq) or less.

The surface resistivity of the release layer side of the release film was determined using the following method.

On the measuring stage of the insulation resistance meter, place the release film with the release layer facing upwards. Place a circular electrode with an outer diameter of 50 mm and an annular electrode with an inner diameter of 70 mm and an outer diameter of 80 mm on the release film. Ensure the center of the circular electrode is aligned with the center of the annular electrode. Measure the surface resistance (Ω) at the electrode connection terminals under a voltage of 100V and a measurement time of one minute. Calculate the surface resistivity (Ω/sq) using the following formula. The measurement environment is a temperature of 23℃±2℃ and a relative humidity of 50%±10%.

Surface resistivity = π × (D + d) / (D - d) × R

Here, π represents the mathematical constant Pi, D represents the inner diameter of the annular electrode, d represents the outer diameter of the circular electrode, and R represents the surface resistance.

[Conductive layer]

The conductive layer is responsible for anti-static properties. Examples of conductive layers include thin metal films formed through various vapor deposition methods, lamination of metal foils, etc.; layers formed by coating with known anti-static agents; and layers containing conductive polymers. The conductive layer is preferably a metal vapor-deposited layer or a layer containing conductive polymers.

From the viewpoint of reducing the surface resistivity of the release film, the conductive layer is preferably a metal thin film layer, and more preferably a metal vapor-deposited layer from the viewpoint of high uniformity of the formed layer. On the other hand, from the viewpoints of resistance to peeling from the substrate layer, workability, and inhibition of oxidative degradation, the conductive layer is preferably a layer containing a conductive polymer.

There are no particular limitations on the metal used to form the thin film layer, but aluminum, which is relatively lightweight and easy to form thin films using vapor deposition, is preferred.

As antistatic agents, examples include various cationic antistatic agents with cationic groups such as quaternary ammonium salts, pyridinium salts, and primary to tertiary amino groups; anionic antistatic agents with anionic groups such as sulfonates, sulfates, phosphates, and sulfonates; amphoteric antistatic agents such as amino acid-based and amino sulfate-based agents; and nonionic antistatic agents such as amino alcohol-based, glycerol-based, and polyethylene glycol-based agents.

The conductive polymer constituting the layer containing the conductive polymer is not particularly limited, and examples include polymeric antistatic agents obtained by increasing the molecular weight of the aforementioned antistatic agents, such as polyaniline, polyacetylene, poly(p-phenylene), polypyrrole, polythiophene, and polyvinylcarbazole.

The thickness of the conductive layer is not particularly limited. However, in the case of metal vapor deposition, from the viewpoint of preventing the conductive layer from peeling off from the substrate or detaching, a thickness of 5nm to 1000nm is preferred, more preferably 20nm to 500nm, and even more preferably 30nm to 100nm. In the case of a layer containing conductive polymers, the thickness of the conductive layer is preferably 50nm to 1000nm, more preferably 100nm to 800nm, and even more preferably 200nm to 800nm. Thicknesses above 50nm tend to have excellent anti-static properties, while thicknesses below 1000nm tend to be more cost-effective.

[Substrate Layer]

The substrate layer supports the release layer and the conductive layer. There is no particular limitation on the substrate layer; it can be selected from resin-containing substrates used in this art. From the viewpoint of conformability to the mold shape, a resin-containing substrate with excellent extensibility is preferred.

Considering that semiconductor packaging resin molding is carried out at high temperatures (around 100℃~200℃), the substrate layer ideally needs to possess heat resistance above this temperature. When the release liner is placed in the mold and during resin flow, to suppress wrinkles in the sealing resin and rupture of the release liner, it is ideal to select properties such as elastic modulus and elongation at high temperatures to prevent these issues.

From the viewpoint of heat resistance and elastic modulus at high temperatures, the substrate layer material is preferably a polyester resin. Examples of polyester resins include polyethylene terephthalate (PET), polyethylene naphthalate (PET), polybutylene terephthalate (PET), copolymers of these, or modified resins.

As the substrate layer, a polyester film molded from polyester resin is preferred; from the viewpoint of mold conformability, a biaxially stretched polyester film is even more preferred.

The thickness of the substrate layer is not particularly limited, but is preferably 10μm to 300μm, more preferably 20μm to 100μm. If the substrate layer thickness is 10μm or more, the substrate layer and release film are less prone to damage, resulting in excellent processing performance. If the substrate layer thickness is less than 100μm, the substrate layer and release film exhibit excellent mold conformity, thus suppressing wrinkles and other defects in the molded semiconductor package.

[Manufacturing method of release film]

The release film disclosed herein can be obtained by forming a conductive layer on a substrate, which serves as a substrate layer, and then forming a release layer on the conductive layer. The conductive layer can be formed on the substrate, for example, by vapor deposition, lamination, or coating. The release layer can be formed, for example, by coating a composition comprising conductive particles, resin, and solvent onto the conductive layer and then thermosetting it. The release layer can be separately formed on a peel sheet and deposited on the conductive layer by thermoforming.

Depending on the requirements, the release film disclosed herein may include a coloring layer or other layers between the conductive layer and the substrate layer.

[Uses of release film]

The release film disclosed herein is used, for example, when sealing semiconductor wafers with a sealing material. The release film disclosed herein is preferably used in transfer molding or compression molding.

By using the release film disclosed herein, charging and discharging during peeling from a semiconductor wafer can be effectively suppressed.

<Semiconductor Packaging Manufacturing Methods>

In the semiconductor packaging manufacturing method disclosed herein, the release film of this invention is used for either a transfer molding step or a compression molding step.

In a semiconductor packaging manufacturing method, firstly, the release film disclosed herein is placed in a mold of a molding apparatus, causing the release film to conform to the shape of the mold. Methods for conforming the release film to the shape of the mold include vacuum adsorption.

Then, the semiconductor wafer is sealed within a mold, with the release liner following its movement, using a sealing material. By sealing the semiconductor wafer with the release liner inside the mold, a semiconductor package can be manufactured. After manufacturing the semiconductor package, the mold is opened, and the molded semiconductor package is removed.

In the semiconductor packaging manufacturing method disclosed herein, the use of the release film disclosed herein effectively suppresses charging and discharging during peeling from the semiconductor wafer.

Examples of semiconductor wafers used in the method include semiconductor components, capacitors, and terminals. The type of packaging material used in the method is not particularly limited; for example, resin compositions comprising epoxy resins, acrylic resins, etc., are examples.

[Implementation Example]

The embodiments described below are given in detail through examples, but the scope of the embodiments is not limited to these examples.

<Implementation Example 1>

[Preparation of Adhesive 1]

Adhesive 1 was prepared by adding 11.3 parts by weight of S-43 (manufactured by Reiken Chemical Co., Ltd., acrylate copolymer), 0.36 parts by weight of CORONATE L (manufactured by Tosoh Co., Ltd., polyfunctional isocyanate crosslinker), 30.6 parts by weight of toluene, and 7.7 parts by weight of methyl ethyl ketone to a resin container and stirring.

[Substrate Preparation]

SMH-38 (manufactured by UNITIKA, a company specializing in polyethylene terephthalate (PET) film, available in single-sided mirror/single-sided matte finish) is also available.

[Formation of the conductive layer (Al layer)]

An Al (aluminum) vapor deposition process is performed on the mirror surface of the PET film to obtain an Al vapor-deposited PET film.

[Formation of the release layer]

0.30 parts by weight of SQ (manufactured by BASF, iron powder, average particle size 6 μm), acting as conductive particles, were added to 50 parts by weight of adhesive 1 and stirred to prepare a coating solution. The coating solution was applied to the Al vapor-deposited surface of an Al vapor-deposited PET film placed on a horizontal table using a rod coating machine. The film coated with the solution was then placed in an explosion-proof oven preheated to 100°C for two minutes and removed. This process forms a release layer on the Al vapor-deposited layer, thus obtaining a release film.

<Implementation Examples 2 to 6>

Adhesives 1 to 3 were prepared using the formulations recorded in Table 1. Release coatings (in parts by weight) of the formulations recorded in Tables 2 and 3 were also prepared. Otherwise, the release film was prepared in the same manner as in Example 1.

Furthermore, the "Conductive Particle Content" in Tables 2 and 3 refers to the mass ratio of conductive particles to the solid component of the adhesive.

<Implementation Examples 7~10>

[Formation of the conductive layer (including layers of conductive polymers)]

A PET film is prepared by diluting a cationic antistatic agent (conductive polymer, manufactured by Konishi Co., Ltd., with Bondeip PA-100 main agent/Bondeip PA-100 hardener = 100 parts by weight/25 parts by weight) to 2.5% by weight in a mixed solvent (water/isopropanol = 1/1 by weight). The mixture is then dried to obtain a PET film with a layer containing the conductive polymer.

The conductive layer was changed from an Al vapor-deposited film to a layer containing a conductive polymer; otherwise, the release film was manufactured in the same manner as in Examples 3 to 6.

<Comparative Example 1~Comparative Example 9>

A release layer coating solution with the formulation described in Table 3 was prepared. Then, the coating solution was applied to the smooth surface of the PET film without forming an Al vapor deposition layer. Otherwise, a release film was obtained in the same manner as in Example 1. The "-" in the conductive layer column of Table 3 indicates that no conductive layer was provided.

<Comparative Example 10~Comparative Example 12>

Using the release coating liquid formulated as described in Table 3, a release film was obtained in the same manner as in Example 1.

<Comparative Example 13>

Using the release coating liquid formulated as described in Table 3, a release film was obtained in the same manner as in Example 7.

<Performance Evaluation of Release Film>

The following evaluation was performed on each release film of Examples 1 to 10 and Comparative Examples 1 to 13. The evaluation results are shown in Tables 2 and 3.

[Determination of the thickness of the release layer]

The thickness of the release layer was measured using the method described above.

[Average particle size of conductive particles relative to the thickness of the release layer]

The particle size of the conductive particles was measured using the described method, and the average particle size was calculated. The average particle size was then divided by the thickness of the release layer and converted to a percentage (%).

[Surface resistivity]

The surface resistivity was measured using the method described above.

[Presence or absence of a conduction pathway]

If the surface resistivity of the release layer side of the release film is less than 1.0 × ^10⁷ (Ω/sq), it is determined that there is a conductive path through the conductive particles from the conductive layer to the surface of the release layer.

[Table 2]

The surface resistivity of the release layer side of Comparative Examples 1 to 9 all exceeded 1.0 × ^10¹³ (Ω/sq), indicating a large surface resistivity on the release layer side.

As can be seen from Comparative Examples 10 to 12, the thicker the release layer, the greater the surface resistivity (Ω/sq) on the release layer side. Even in Comparative Example 10, where the release layer is thinned, since the release layer of Comparative Example 10 does not contain conductive particles, the surface resistivity on the release layer side exceeds 1.0 × ^10⁸ (Ω/sq), indicating a large surface resistivity on the release layer side.

On the other hand, the surface resistivity of Examples 1 to 10 is all less than 1.0× ^10⁷ (Ω/sq), and the surface resistivity of the demolding layer side is low.

Claims (9)

A release film for semiconductor molding has a release layer, a conductive layer and a substrate layer in sequence. The release layer contains conductive particles, the average particle size (μm) of which is 50% to 300% of the thickness (μm) of the release layer, and the conductive particles contain metal particles. The semiconductor molding release film as claimed in claim 1, wherein a conductive path exists from the conductive layer to the surface of the release layer via the conductive particles. The release film for semiconductor molding as described in claim 1, wherein the conductive layer is a metal vapor-deposited layer or a layer containing a conductive polymer. The release film for semiconductor molding as claimed in claim 1, wherein the content of the conductive particles contained in the release layer is 0.5% to 80% by mass relative to the total amount of components other than the conductive particles contained in the release layer. The release film for semiconductor molding as claimed in claim 1, wherein the average particle size (μm) of the conductive particles is more than 100% and less than 300% of the thickness (μm) of the release layer, and the content of the conductive particles contained in the release layer is 0.5% to 50% by mass relative to the total amount of components other than the conductive particles contained in the release layer. The release film for semiconductor molding as claimed in claim 1, wherein the average particle size (μm) of the conductive particles is 50% to 100% or less of the thickness (μm) of the release layer, and the content of the conductive particles contained in the release layer is 0.5% to 80% by mass relative to the total amount of components other than the conductive particles contained in the release layer. The release film for semiconductor molding as claimed in claim 1, wherein the content of the conductive particles contained in the release layer is 5% to 80% by mass relative to the total amount of components other than the conductive particles contained in the release layer. The semiconductor molding release film as described in claim 1, wherein the semiconductor molding release film is used for transfer molding or compression molding. A method for manufacturing a semiconductor package, using a semiconductor molding release film as described in any one of claims 1 to 8 to perform a transfer molding step or a compression molding step.