Release film for semiconductor molding and semiconductor package production method

Abstract

This release film for semiconductor molding has a release layer, a conductive layer, and a base material layer in this order, and the release layer contains an ionic compound.

Description

Release film for semiconductor molding and method for manufacturing semiconductor package

[0001] The present disclosure relates to a release film for semiconductor molding and a method for manufacturing a semiconductor package.

[0002] In recent years, as electronic devices, particularly mobile phones, have become thinner, further thinner electronic components such as semiconductor elements are also being required. Also, from the viewpoint of improving heat dissipation, exposed die molding, in which a portion of the surface of an electronic component is exposed, is increasingly being adopted instead of overmolding, in which the entire electronic component is covered with a sealing resin.

[0003] When sealing electronic components so that a portion of the electronic component is exposed, it is necessary to prevent leakage of the sealing material to the exposed portion of the electronic component (flash burrs). Therefore, sealing is performed with a film having releasability (release film) attached to the exposed portion of the electronic component, and then the release film is peeled off to expose the surface of the electronic component. For example, Patent Document 1 describes an example of such a release film for semiconductor molding, which includes a release layer and a base layer, and in which the release layer has a tensile strength of 7.0 MPa or more at 170°C.

[0004] JP 2023-41523 A

[0005] If the release film is made of a material that is easily charged, discharge may occur when the release film is brought into contact with an electronic component or when the release film is peeled off from the electronic component, which may result in electrostatic damage to the electronic component. In recent years, with the increasing integration of semiconductor elements, process nodes have become increasingly miniaturized, and the risk of electrostatic damage to electronic components is increasing.

[0006] In view of the above circumstances, an object of one aspect of the present disclosure is to provide a release film for semiconductor molding that has excellent antistatic performance while maintaining releasability.An object of another aspect of the present disclosure is to provide a method for manufacturing a semiconductor package using this release film.

[0007] Specific means for solving the above problems include the following aspects.

[0008] <1> A release film for semiconductor molding, comprising a release layer, a conductive layer, and a substrate layer in this order, wherein the release layer contains an ionic compound. <2> The release film for semiconductor molding according to <1>, wherein the ionic compound contains at least one selected from the group consisting of nitrogen-containing salt compounds and phosphorus-containing salt compounds. <3> The release film for semiconductor molding according to <1> or <2>, wherein the ionic compound contains an ionic liquid. <4> The release film for semiconductor molding according to any one of <1> to <3>, wherein the conductive layer contains a conductive polymer. <5> The release film for semiconductor molding according to <4>, wherein the conductive polymer contains polyethylenedioxythiophene. <6> The release film for semiconductor molding has a surface resistivity of 9 x 10 ７ <7> The release film for semiconductor molding according to any one of <1> to <5>, having a resistivity of Ω / sq or less. <7> The release film for semiconductor molding according to any one of <1> to <6>, wherein the content of the ionic compound in the release layer is 0.25 mass% or more with respect to the total amount of the release layer. <8> The release film for semiconductor molding according to any one of <1> to <7>, which is used in transfer molding or compression molding. <9> A method for manufacturing a semiconductor package, comprising carrying out a transfer molding step or a compression molding step using the release film for semiconductor molding according to any one of <1> to <8>. <10> The method for manufacturing a semiconductor package according to <9>, wherein exposure molding is carried out in the transfer molding step or the compression molding step.

[0009] According to the embodiments of the present disclosure, there are provided a release film for semiconductor molding that maintains releasability and has excellent antistatic properties, and a method for manufacturing a semiconductor package using the same.

[0010] 1 is a schematic cross-sectional view illustrating a configuration of a release film, and FIG. 2 is a schematic view illustrating a method for manufacturing a semiconductor package using a release film in exposure molding.

[0011] In the present disclosure, the term "process" includes not only processes that are independent of other processes, but also processes that cannot be clearly distinguished from other processes as long as the purpose of the process is achieved. In the present disclosure, numerical ranges indicated using "to" include the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In numerical ranges described in stages in the present disclosure, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another staged numerical range. Furthermore, in numerical ranges described in the present disclosure, the upper or lower limit value of that numerical range may be replaced with a value shown in the examples. In the present disclosure, each component may contain multiple corresponding substances. When multiple substances corresponding to each component are present in the composition, the content or amount of each component means the total content or amount of the multiple substances present in the composition, unless otherwise specified. In the present disclosure, each component may contain multiple types of particles. When multiple types of particles corresponding to each component are present in the composition, the particle size of each component means the value for a mixture of the multiple types of particles present in the composition, unless otherwise specified.

[0012] <Release Film for Semiconductor Molding> The release film for semiconductor molding of the present disclosure (hereinafter sometimes abbreviated as "release film") has a release layer, a conductive layer, and a base layer in this order, and the release layer contains an ionic compound. In the release film of the present disclosure, the release layer contains an ionic compound, which makes it possible to form a conductive path from the conductive layer to the surface of the release layer via conductive particles, and as a result, the surface resistivity on the release layer side can be effectively reduced, and the release property is maintained while exhibiting excellent antistatic performance.

[0013] An example of the configuration of a release film having a substrate layer, a release layer, and a conductive layer is shown schematically in Figure 1. The release film 10 shown in Figure 1 includes a substrate layer 12, a conductive layer 14, and a release layer 16, in this order.

[0014] [Release Layer] The release layer 16 is responsible for releasing the semiconductor package during molding. The release layer 16 contains an ionic compound. The release layer 16 generally contains a resin component (excluding ionic compounds in the case where the ionic compound is a polymer). The resin component of the release layer 16 is not particularly limited. From the viewpoints of releasability from the semiconductor package and heat resistance of the release layer 16, the resin component is preferably an acrylic resin or a silicone resin, and more preferably a cross-linked acrylic resin (hereinafter also referred to as a "cross-linked acrylic copolymer").

[0015] The acrylic resin is preferably an acrylic copolymer obtained by copolymerizing a low glass transition temperature (Tg) monomer such as butyl acrylate, ethyl acrylate, or 2-ethylhexyl acrylate as the main monomer with a functional group monomer such as acrylic acid, methacrylic acid, hydroxyethyl methacrylate, hydroxyethyl acrylate, acrylamide, or acrylonitrile. A crosslinked acrylic copolymer can be produced by crosslinking the above-mentioned monomer using a crosslinking agent.

[0016] Examples of crosslinking agents used in producing the crosslinked acrylic copolymer include known crosslinking agents such as isocyanate compounds, melamine compounds, epoxy compounds, etc. In order to form a network structure that spreads gently in the acrylic resin, the crosslinking agent is preferably a multifunctional crosslinking agent such as a trifunctional or tetrafunctional crosslinking agent.

[0017] The ionic compound contained in the release layer 16 is not particularly limited as long as it is a compound having ionic properties. The ionic compound contained in the release layer 16 may be used alone or in combination of two or more types.

[0018] From the viewpoint of effectively reducing the surface resistivity, the ionic compound preferably contains at least one selected from the group consisting of nitrogen-containing salt compounds and phosphorus-containing salt compounds.

[0019] The ionic compound may be a polymer, an oligomer, or a low molecular weight compound. From the viewpoint of more effectively reducing the surface resistivity, it is preferable that the ionic compound contains an ionic liquid. When the ionic compound contains an ionic liquid, peeling between the layers of the release film 10 tends to be suppressed. The ionic liquid refers to one that is liquid at room temperature. Being liquid at room temperature means that the viscosity at 25°C is 5,000 mPa·s or less. The ionic liquid preferably has a molecular weight of 500 or less.

[0020] When the ionic liquid is a nitrogen-containing salt compound, examples of the cation skeleton include imidazolium salts, pyrrolidinium salts, pyridinium salts, piperidinium salts, and quaternary ammonium salts. When the ionic liquid is a phosphorus-containing salt compound, examples of the cation skeleton include phosphonium salts.

[0021] Examples of imidazolium salts include the following compounds.

[0022]

[0023] In the above formula, R １ and R ２ R each independently represents a hydrocarbon group. １ and R ２ The hydrocarbon group represented by R may be a saturated hydrocarbon group or an unsaturated hydrocarbon group. １ and R ２ The hydrocarbon group represented by the formula (I) preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, even more preferably 1 to 4 carbon atoms, and particularly preferably 1 to 3 carbon atoms.

[0024] Examples of pyrrolidinium salts include the following compounds.

[0025]

[0026] In the above formula, R ３ and R ４ R each independently represents a hydrocarbon group or a hydrocarbon group containing an etheric oxygen atom. ３ and R ４ The hydrocarbon group represented by R is preferably a saturated hydrocarbon group. ３ and R４ The hydrocarbon group represented by R preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and even more preferably 1 to 6 carbon atoms. ３ and R ４ The hydrocarbon group containing an etheric oxygen atom represented by the formula (I) preferably has 2 to 12 carbon atoms, more preferably 2 to 10 carbon atoms, and even more preferably 2 to 8 carbon atoms.

[0027] Examples of pyridinium salts include the following compounds:

[0028]

[0029] In the above formula, R ５ represents a hydrocarbon group. ５ The hydrocarbon group represented by R is preferably a saturated hydrocarbon group. ５ The hydrocarbon group represented by the formula (I) preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and even more preferably 1 to 6 carbon atoms.

[0030] Examples of piperidinium salts include the following compounds:

[0031]

[0032] In the above formula, R ６ and R ７ R each independently represents a hydrocarbon group. ６ and R ７ The hydrocarbon group represented by R is preferably a saturated hydrocarbon group. ６ and R ７ The hydrocarbon group represented by the formula (I) preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, and even more preferably 1 to 4 carbon atoms.

[0033] Examples of the quaternary ammonium salt include the following compounds.

[0034]

[0035] In the above formula, R ８ ~R １１ R each independently represents a hydrocarbon group or a hydrocarbon group containing an etheric oxygen atom. ８ ~R １１The hydrocarbon group represented by R is preferably a saturated hydrocarbon group. ８ ~R １１ The hydrocarbon group represented by R preferably has 1 to 12 carbon atoms, more preferably 1 to 10 carbon atoms, and even more preferably 1 to 8 carbon atoms. ８ ~R １１ The hydrocarbon group containing an etheric oxygen atom represented by the formula (I) preferably has 2 to 12 carbon atoms, more preferably 2 to 10 carbon atoms, and even more preferably 2 to 8 carbon atoms.

[0036] Examples of the phosphonium salt include the following compounds.

[0037]

[0038] In the above formula, R １２ ~R １５ R each independently represents a hydrocarbon group or a hydrocarbon group containing an etheric oxygen atom. １２ ~R １５ The hydrocarbon group represented by R is preferably a saturated hydrocarbon group. １２ ~R １５ The hydrocarbon group represented by R preferably has 1 to 12 carbon atoms, more preferably 1 to 10 carbon atoms, and even more preferably 1 to 8 carbon atoms. １２ ~R １５ The hydrocarbon group containing an etheric oxygen atom represented by the formula (I) preferably has 2 to 12 carbon atoms, more preferably 2 to 10 carbon atoms, and even more preferably 2 to 8 carbon atoms.

[0039] Examples of anion species of ionic liquids include halogen ions (chloride ions, bromide ions, iodide ions), boron tetrafluoride ions, phosphorus hexafluoride ions, bis(fluorosulfonyl)imide ions, bis(fluorosulfonyl)amide ions, bis(trifluoromethanesulfonyl)imide ions, bis(trifluoromethanesulfonyl)amide ions, and trifluoromethanesulfonate ions.

[0040] Examples of the polymeric ionic compound include those having the above-mentioned cationic skeleton in a side chain relative to the main chain of a polymer such as a (meth)acrylic resin.

[0041] Furthermore, from the viewpoint of affinity with the resin component contained in the release layer 16, an ionic liquid that is soluble in 1-methoxy-2-propanol is preferable. "An ionic liquid that is soluble in 1-methoxy-2-propanol" means that 0.01 g or more of the ionic liquid is soluble in 100 mL of 1-methoxy-2-propanol at 25°C. Note that 1-methoxy-2-propanol is used as an indicator of solubility, and solubility in other solvents is not limited. Furthermore, the solvent used to form the release layer 16 is not limited.

[0042] The content of the ionic liquid relative to the total amount of the ionic compounds is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and may be 100% by mass.

[0043] The content of the ionic liquid soluble in 1-methoxy-2-propanol relative to the total amount of the ionic compounds is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more, and may be 100% by mass.

[0044] The content of the ionic compound in the release layer 16 is preferably 0.25% by mass or more, more preferably 0.5% by mass or more, and even more preferably 0.7% by mass or more, relative to the total amount of the release layer 16. There is no particular upper limit to the content of the ionic compound in the release layer 16, and it may be 20% by mass or less, 10% by mass or less, or 7% by mass or less.

[0045] When the ionic compound is an ionic liquid, the content of the ionic compound in the release layer 16 is preferably 0.25% by mass or more, more preferably 0.3% by mass or more, and even more preferably 0.5% by mass or more, relative to the total amount of the release layer 16. When the ionic compound is a low-molecular-weight ionic compound, the content of the ionic compound in the release layer 16 is preferably 1% by mass or less, and more preferably 0.7% by mass or less.

[0046] When the ionic compound is a polymer, the content of the ionic compound in the release layer 16 is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 7% by mass or more, relative to the total amount of the release layer 16. When the ionic compound is a polymer, the content of the ionic compound in the release layer 16 is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 7% by mass or less.

[0047] The release layer 16 may contain conductive particles in addition to the ionic compound. The content of conductive particles in the release layer 16 is preferably 5% by mass or less, more preferably 1% by mass or less, and even more preferably contains no conductive particles (0% by mass).

[0048] The release layer 16 may contain a solvent, an anchoring enhancer, a crosslinking accelerator, an antistatic agent, a filler, a colorant, etc. as needed, as long as the effects of the release film 10 of the present disclosure are achieved.

[0049] The thickness of the release layer 16 is not particularly limited, and is preferably 0.1 μm to 100 μm. If the thickness of the release layer 16 is 0.1 μm or more, it can contain a resin component sufficient to exhibit the flexibility or extensibility required in the molding process, and peeling of the release layer 16 from the conductive layer 14 or chipping of the release layer 16 is unlikely to occur. If the thickness of the release layer 16 is 100 μm or less, when the release layer 16 is formed using a thermosetting resin, heat shrinkage during heat curing is suppressed, and the flatness of the release film 10 is maintained. From the above viewpoints, the thickness of the release layer 16 is more preferably 1 μm to 100 μm, and even more preferably 10 μm to 50 μm. In a release film 10 in which a conventional release layer is disposed on a conductive layer, if the thickness of the release layer 16 is 10 μm to 50 μm, the antistatic function of the conductive layer may be impaired. However, in the release film 10 of the present disclosure, a conductive path can be formed from the conductive layer 14 to the surface of the release layer 16 via the conductive particles, and therefore the antistatic function of the conductive layer 14 is exhibited.

[0050] [Conductive Layer] The conductive layer 14 has an antistatic function. Examples of the conductive layer 14 include metal thin film layers formed by various vapor deposition methods, lamination of metal foil, etc.; antistatic agent-containing layers; and conductive polymer-containing layers. The conductive layer 14 is preferably a metal vapor deposition layer or a conductive polymer-containing layer. From the viewpoint of reducing the surface resistivity of the release film 10, the conductive layer 14 is preferably a metal thin film layer. From the viewpoint of high uniformity of the formed layer, the conductive layer 14 is more preferably a metal vapor deposition layer. From the viewpoint of ease of peeling from the base layer 12, workability, suppression of oxidative degradation, and suppression of peeling between the layers in the release film 10, the conductive layer 14 is more preferably a conductive polymer-containing layer. In particular, when the conductive layer is a conductive polymer-containing layer and the ionic compound contained in the release layer is an ionic liquid, peeling between the layers in the release film 10 tends to be effectively suppressed.

[0051] There are no particular limitations on the metal that constitutes the metal thin film layer, but aluminum is preferred because it is relatively light as a metal and can be easily formed into a thin film by vapor deposition.

[0052] Examples of the antistatic agent contained in the antistatic agent-containing layer include various cationic antistatic agents having a cationic group such as a quaternary ammonium salt, a pyridinium salt, or a primary to tertiary amino group; anionic antistatic agents having an anionic group such as a sulfonate group, a sulfate ester group, a phosphate ester group, or a sulfonate group; amphoteric antistatic agents such as amino acid-based and amino sulfate-based; and nonionic antistatic agents such as amino alcohol-based, glycerin-based, and polyethylene glycol-based.

[0053] Examples of the conductive polymer contained in the conductive polymer-containing layer include polymeric antistatic agents obtained by increasing the molecular weight of the above-mentioned various antistatic agents, polyaniline, polyacetylene, polyparaphenylene, polypyrrole, polythiophene, polyvinylcarbazole, etc. From the viewpoint of effectively reducing the surface resistivity, it is preferable that the conductive polymer contains polyethylenedioxythiophene (hereinafter also referred to as PEDOT).

[0054] The content of PEDOT relative to the total amount of conductive polymers is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and may be 100% by mass.

[0055] The content of the conductive polymer contained in the conductive polymer-containing layer is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, particularly preferably 50% by mass or more, extremely preferably 70% by mass or more, and may be 100% by mass.

[0056] The conductive polymer contained in the conductive polymer-containing layer may be in the form of a dispersion in which the conductive polymer is dispersed in water in advance, or in the form of a solution in which the conductive polymer is dissolved in a solvent in advance. When the conductive polymer is in the form of a dispersion in which the conductive polymer is dispersed in water in advance, the binder resin may also be in the form of a dispersion in which the conductive polymer is dispersed in water in advance.

[0057] The antistatic agent-containing layer and the conductive polymer-containing layer may further contain a binder resin. When the antistatic agent-containing layer and the conductive polymer-containing layer further contain a binder resin in addition to the conductive polymer, the adhesion between the antistatic agent-containing layer and the conductive polymer-containing layer is improved, peeling of the antistatic agent-containing layer and the conductive polymer-containing layer is suppressed, and antistatic properties are easily maintained over time. Examples of binder resins contained in the antistatic agent-containing layer and the conductive polymer-containing layer include acrylic resins, styrene resins, and acrylic-urethane resins. In the antistatic agent-containing layer and the conductive polymer-containing layer, one type of binder resin may be used alone, or two or more types may be used in combination.

[0058] The weight-average molecular weight of the binder resin is not particularly limited, and may be, for example, 10,000 or more, 50,000 or more, or 100,000 or more. The upper limit may be, for example, 1,000,000. When the antistatic agent-containing layer and the conductive polymer-containing layer contain a binder resin, the content of the binder resin contained in the antistatic agent-containing layer and the conductive polymer-containing layer is preferably 5% by mass or more, more preferably 30% by mass or more, even more preferably 50% by mass or more, and particularly preferably 60% by mass or more. Furthermore, the content of the binder resin contained in the antistatic agent-containing layer and the conductive polymer-containing layer is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less.

[0059] The thickness of the conductive layer 14 is not particularly limited, and in the case of a metal vapor deposition layer, the thickness is preferably 10 nm to 100 nm, more preferably 30 nm to 70 nm, and even more preferably 40 nm to 60 nm, from the viewpoint of preventing peeling or chipping of the conductive layer 14 from the base layer 12. In the case of an antistatic agent-containing layer or a conductive polymer-containing layer, the thickness of the conductive layer 14 is preferably 50 nm to 500 nm, more preferably 70 nm to 400 nm, and even more preferably 100 nm to 300 nm, from the viewpoint of the surface resistivity of the release layer.

[0060] The thickness of the conductive layer 14 may be measured by a gravimetric method, which is a method for measuring the difference in weight between the presence and absence of the conductive layer.

[0061] [Substrate Layer] The substrate layer 12 supports the release layer 16 and the conductive layer 14. The release film 10 has the substrate layer 12, which provides the release film 10 with the necessary strength, and by appropriately selecting the material thereof, the physical properties such as the elongation percentage and elastic modulus can be adjusted.

[0062] The substrate layer 12 is not particularly limited and can be selected from resin-containing substrates used in this technical field. From the viewpoint of conformability to the shape of a mold, a resin-containing substrate with excellent stretchability is preferred.

[0063] Specific examples of the material of the base layer 12 include polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, as well as resins such as polyimide, polyamide, polyester ether, polyamideimide, fluorine-containing resins, and thermoplastic elastomers. The base layer 12 may contain one type of resin or two or more types of resins.

[0064] Considering that resin molding of semiconductor packages is performed at high temperatures (approximately 100° C. to 200° C.), it is desirable that the base material layer 12 has heat resistance at or above this temperature. In order to prevent the occurrence of wrinkles in the sealing resin and tears in the release film 10 when the release film 10 is attached to a mold and when the resin flows during molding, it is desirable to select the base material layer 12 taking into consideration the elastic modulus, elongation, etc. at high temperatures.

[0065] From the viewpoints of heat resistance and elastic modulus at high temperatures, the material of the base layer 12 is preferably a polyester resin. Examples of polyester resins include polyethylene terephthalate resin, polyethylene naphthalate resin, polybutylene terephthalate resin, and copolymers or modified resins thereof.

[0066] The base layer 12 is preferably a polyester film formed from a polyester resin, and from the viewpoint of conformability to a mold, a biaxially oriented polyester film is more preferred.

[0067] The thickness of the base material layer 12 is not particularly limited, and is preferably 10 μm to 300 μm, and more preferably 20 μm to 100 μm. When the thickness of the base material layer 12 is 10 μm or more, the base material layer 12 and the release film 10 are less likely to tear and are easier to handle. When the thickness of the base material layer 12 is 300 μm or less, the base material layer 12 and the release film 10 have excellent conformability to the mold, thereby suppressing the occurrence of wrinkles and the like in the molded semiconductor package.

[0068] The base layer 12 may be composed of only one layer or two or more layers. Methods for obtaining the base layer 12 composed of two or more layers include a method in which the materials for each layer are extruded by a co-extrusion method, a method in which two or more films are laminated, and the like.

[0069] The surface of the base material layer 12 on which the conductive layer 14 is provided may be subjected to a treatment to improve adhesion to the conductive layer 14. Examples of the treatment method include surface treatments such as corona treatment and plasma treatment, and application of a primer.

[0070] If necessary, a back treatment agent may be applied to the back surface of the base layer 12 (the surface opposite to the side to be attached to the adherend surface) to adjust the unwinding property of the release film 10 from the roll. Examples of back treatment agents include silicone resins, fluorine-containing resins, polyvinyl alcohol, and resins having an alkyl group. If necessary, these back treatment agents may be modified. One type of back treatment agent may be used alone, or two or more types may be used in combination.

[0071] [Physical Properties of Release Film] The overall thickness of the release film 10 is not particularly limited and can be set according to the desired physical properties (elongation, elastic modulus, etc.) For example, it may be 30 μm to 300 μm, 35 μm to 250 μm, or 40 μm to 200 μm.

[0072] The release film 10 of the present disclosure has a surface resistivity of 1.0×10 ９ (Ω / sq) or less, and preferably 1.0×10 ８ (Ω / sq) or less, and more preferably 9.0×10 ７ The surface resistivity of the release layer 16 side can be adjusted by changing the content of the ionic compound in the release layer 16 .

[0073] The surface resistivity of the release layer 16 side of the release film 10 is a value measured by the following measurement method. The release film 10 is placed on the measurement table of an insulation resistance meter with the release layer 16 facing up, and a circular electrode with an outer diameter of 50 mm and a ring-shaped electrode with an inner diameter of 70 mm and an outer diameter of 80 mm are placed on the release film 10. At this time, the center of the circular electrode and the center of the ring-shaped electrode are aligned. Terminals are connected to both electrodes, and the surface resistance (Ω) is measured at a voltage of 100 V for a measurement time of 1 minute. The surface resistivity (Ω / sq) is calculated using the following formula. The measurement environment is a temperature of 23±2°C and a relative humidity of 50±10%. Surface resistivity = π × (D + d) / (D - d) × R, where π is the circumference constant, D is the inner diameter of the ring-shaped electrode, d is the outer diameter of the circular electrode, and R is the surface resistance.

[0074] [Method for Producing Release Film] The release film 10 of the present disclosure is obtained by forming a conductive layer 14 on a substrate that will become the base layer 12, and then forming a release layer 16 on the conductive layer 14. The conductive layer 14 can be formed on the substrate by, for example, a vapor deposition method, a lamination method, or a coating method. The release layer 16 can be formed, for example, by applying a composition containing an ionic compound, a resin component, and a solvent onto the conductive layer 14 and then thermally curing the composition. The ionic compound may be used in the form of a solution in which it is previously dissolved in a solvent. The release layer 16 may be formed separately on a release sheet and then laminated on the conductive layer 14 by thermocompression bonding.

[0075] The release film 10 of the present disclosure may have a layer such as a colored layer between the conductive layer 14 and the substrate layer 12, if necessary.

[0076] [Uses of Release Film] The release film 10 of the present disclosure is used, for example, when sealing a semiconductor chip with an encapsulant. The release film 10 of the present disclosure is preferably used in transfer molding or compression molding. Use of the release film 10 of the present disclosure can sufficiently suppress charging and discharging when peeled from the semiconductor chip, and therefore it can also be suitably used in exposure molding.

[0077] <Method for Manufacturing Semiconductor Package> In the method for manufacturing a semiconductor package of the present disclosure, a transfer molding process or a compression molding process is performed using the release film 10 of the present disclosure. An outline of the method for manufacturing a semiconductor package using the release film 10 of the present invention in exposure molding is shown in Figure 2.

[0078] 2(A), the release film 10 of the present disclosure, which is stretched over a pair of rolls 20 and 21, is placed along the shape of the upper die 30 of the molding machine. When placing the release film 10, care must be taken not to wrinkle the film. The film may be made to conform to the upper die 30 by vacuum suction or the like.

[0079] The semiconductor chip 42 mounted on the substrate 40 is placed in the lower mold 32 of the mold so that the semiconductor chip 42 faces upward. Examples of the semiconductor chip include a semiconductor element, a capacitor, and a terminal.

[0080] Then, as shown in FIG. 2(B), the upper mold 30 and the lower mold 32 are closed. In this state, the release film 10 and the semiconductor chip 42 are in contact with each other. After the mold is closed, molten encapsulant 50 is injected into the space within the mold, and the semiconductor chip is encapsulated with the encapsulant. There are no particular limitations on the type of encapsulant, and examples include resin compositions containing epoxy resin, acrylic resin, etc. After the semiconductor chip is encapsulated, the mold is opened as shown in FIG. 2(C), and the semiconductor package in which the semiconductor chip is encapsulated with the encapsulant is removed. When the mold is opened, the release film 10 is peeled off from the semiconductor chip 42.

[0081] In the method for manufacturing a semiconductor package according to the present disclosure, the release film 10 according to the present disclosure is used, and therefore, charging and discharging can be sufficiently suppressed when peeling the film from the semiconductor chip. Therefore, in addition to being applicable to the encapsulation of semiconductor chips of conventional sizes, the method can also be suitably applied to the encapsulation of semiconductor chips of smaller sizes. For example, it can be applied to the encapsulation of semiconductor chips of 10 mm x 10 mm or less.

[0082] Furthermore, suppressing the occurrence of static electricity and discharge tends to suppress the occurrence of burrs on the surface of the semiconductor chip, thereby improving the yield of semiconductor package production in the method of manufacturing the semiconductor package of the present disclosure.

[0083] After the semiconductor chips are sealed, the release film 10 is wound up in a roll-to-roll manner, and a new surface is placed on the upper mold 30. In this way, in the case of the roll-to-roll method, the release film 10 is used continuously.

[0084] The above-described embodiment will be specifically described below using examples, but the scope of the above-described embodiment is not limited to these examples.

[0085] The ionic compounds used in the examples and comparative examples are as follows: Ionic compound 1: an ionic compound having a 1-butyl-3-methylpyridinium cationic skeleton and a lithium bis(trifluoromethanesulfonyl)imide ion as the anionic species; Ionic compound 2: a copolymer of a methacrylic acid ester monomer and a (meth)acrylic acid quaternary ammonium salt monomer, containing ethyl acetate as a solvent, having a non-volatile content of 51.0±2.0% by mass at 105°C for 2 hours and a viscosity of 50±30 mPa·s at 25°C; Ionic compound 3: a copolymer of a methacrylic acid ester monomer and a (meth)acrylic acid quaternary ammonium salt monomer, containing methanol and methoxypropanol as solvents, having a non-volatile content of 41.0±1.5% by mass at 105°C for 2 hours and a viscosity of 25±15 mPa·s at 25°C.

[0086] Example 1 Preparation of Substrate and Formation of Conductive Layer S-38 (a PET film, one side mirrored and one side matte, manufactured by Unitika Ltd.) was prepared. PEDOT (Sepulgida, manufactured by Shin-Etsu Polymer Co., Ltd., referred to as PEDOT1, soluble in 1-methoxy-2-propanol) was applied to the mirror surface of this PET film to form a conductive layer 1 having a thickness of 200 nm.

[0087] [Formation of Release Layer] A mixture was prepared by stirring 100 parts by weight of S-43 (acrylic ester copolymer, manufactured by Soken Chemical & Engineering Co., Ltd.), 25 parts by weight of Coronate L (multifunctional isocyanate crosslinking agent, manufactured by Tosoh Corporation), 80 parts by weight of toluene, and 20 parts by weight of methyl ethyl ketone. To this mixture, ionic compound 1 dissolved in 1-methoxy-2-propanol was added to prepare release layer composition 1. Table 1 shows the amount of ionic compound added. The amount of ionic compound added shown in Table 1 is the content of ionic compound relative to the total amount of solid components (acrylic ester copolymer as resin components, crosslinking agent, and ionic compound) excluding the solvent. Release layer composition 1 was applied to the conductive layer 1 prepared above using a bar coater. The film coated with the coating liquid was placed in an explosion-proof oven preheated to 120°C and removed after 2 minutes. In this way, a release layer was formed on the conductive layer, and a release film was obtained. The thickness of the release layer was 10 μm.

[0088] Examples 2 and 3 Release films were obtained in the same manner as in Example 1, except that the amount of ionic compound added was changed as shown in Table 1.

[0089] <Examples 4 to 6> Release films were obtained in the same manner as in Example 1, except that the type of PEDOT used in the conductive layer 1 was changed (referred to as PEDOT 2) to form the conductive layer 2, and an ionic compound was added in the amount shown in Table 1.

[0090] <Examples 7 to 10> Release films were obtained in the same manner as in Example 1, except that the type of PEDOT1 used in the conductive layer 1 was changed to a different type (referred to as PEDOT3) to form the conductive layer 3, and an ionic compound was added in the amount shown in Table 1.

[0091] Example 11 A release film was obtained in the same manner as in Example 1, except that the type and amount of the ionic compound used in the release layer were changed as shown in Table 1.

[0092] <Example 12> A release film was obtained in the same manner as in Example 1, except that PEDOT1 used in conductive layer 1 was changed to PEDOT3 to form conductive layer 3, and the type and amount of ionic compound used in the release layer were changed as shown in Table 1.

[0093] Example 13 A release film was obtained in the same manner as in Example 1, except that the type and amount of the ionic compound used in the release layer were changed as shown in Table 1.

[0094] Example 14 Preparation of Substrate and Formation of Conductive Layer A cationic antistatic agent, which is an acrylic copolymer containing a quaternary ammonium salt (product name "Bondip PA-100 main agent", Konishi Corporation) was diluted to 2.5 mass % with a mixed solvent (water / isopropyl alcohol = 1 / 1 (mass ratio)) to prepare a conductive layer coating liquid. The conductive layer coating liquid was applied to the mirror surface of a PET film (S-38, manufactured by Unitika Ltd., one side mirror finish and one side matte finish), and heated at 100°C for 1 minute to form a conductive layer 4 with a thickness of 200 nm.

[0095] [Formation of Release Layer] A release layer was formed on the conductive layer 4 obtained above in the same manner as in Example 1, except that the amount of ionic compound added was changed as shown in Table 1, thereby obtaining a release film. The thickness of the release layer was 10 μm.

[0096] Comparative Examples 1 to 4 Release films were obtained in the same manner as in Example 1, except that a release layer not containing an ionic compound was provided on each of the conductive layers 1 to 4.

[0097] <Evaluation> (Measurement of Surface Resistivity) The surface resistivity was measured by the method described above for each of the release films of Examples 1 to 14 and Comparative Examples 1 to 4. The evaluation results are shown in Table 1.

[0098]

[0099] In Comparative Examples 1 to 4, the surface resistivity of the release layer side was 1×10 ９ (Ω / sq), and the surface resistivity of the release layer side is large. In contrast, in Examples 1 to 14, the surface resistivity is 1×10 ９ (Ω / sq), and the surface resistivity on the release layer side was effectively reduced. Therefore, it can be seen that the release films of Examples 1 to 14 have excellent antistatic performance. In particular, in Examples 1 to 13, in which the conductive layer contains PEDOT, the surface resistivity on the release layer side was 9×10 ７(Ω / sq) or less, which is significantly lower, and it is clear that the effect of adding an ionic compound to the release layer is synergistic. Furthermore, it is clear that Examples 1 to 10, in which the ionic compound is an ionic liquid, can reduce the surface resistivity of the release layer side with a smaller amount of addition than Examples 11 to 13, in which the ionic compound is a polymer.

[0100] The disclosure of Japanese Patent Application No. 2023-173837 is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards mentioned herein are incorporated by reference into this specification to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

[0101] REFERENCE SIGNS LIST 10 Release film 12 Base layer 14 Conductive layer 16 Release layer 20, 21 Roll 30 Upper die 32 Lower die 40 Substrate 42 Semiconductor chip

Claims

1. A release film for semiconductor molding, comprising a release layer, a conductive layer, and a substrate layer in this order, the release layer containing an ionic compound.

2. The release film for semiconductor molding according to claim 1, wherein the ionic compound comprises at least one selected from the group consisting of nitrogen-containing salt compounds and phosphorus-containing salt compounds.

3. The release film for semiconductor molding according to claim 1 or 2, wherein the ionic compound includes an ionic liquid.

4. The release film for semiconductor molding according to claim 1 or 2, wherein the conductive layer contains a conductive polymer.

5. The release film for semiconductor molding according to claim 4, wherein the conductive polymer comprises polyethylenedioxythiophene.

6. The surface resistivity of the release layer side is 9×10 ７ The release film for semiconductor molding according to claim 1 or 2, having a surface roughness of Ω / sq or less.

7. A release film for semiconductor molding as described in claim 1 or 2, wherein the content of the ionic compound contained in the release layer is 0.25 mass% or more with respect to the total amount of the release layer.

8. The release film for semiconductor molding according to claim 1 or 2, which is used for transfer molding or compression molding.

9. A method for manufacturing a semiconductor package, comprising carrying out a transfer molding process or a compression molding process using the release film for semiconductor molding according to claim 1 or 2.

10. The method for manufacturing a semiconductor package according to claim 9, wherein exposure molding is performed in the transfer molding step or the compression molding step.

Images