Power device package, method for manufacturing power device package, and moisture-proof film for power device

Abstract

A power device package comprising a power device sealed with a sealing material layer, and a moisture-proof film layer covering at least part of the sealing material layer of the power device, wherein the moisture-proof film layer has a heat-fusible resin layer, a metal foil layer, and a protective layer, in order from the power device side.

Description

Power device package, method for manufacturing a power device package, and moisture-proof film for power devices

[0001] This disclosure relates to a power device package, a method for manufacturing a power device package, and a moisture-proof film for power devices.

[0002] Semiconductor devices are sealed with a encapsulating material to protect them from the external environment. While this encapsulation provides sufficient moisture protection for semiconductor devices, it has been proposed to provide an additional moisture-proof film on the surface of the encapsulating material that has a lower moisture absorption rate than the encapsulating material (see, for example, Patent Document 1). Patent Document 1 describes a film containing fluororesin as the moisture-proof film.

[0003] Japanese Patent Publication No. 2021-180269

[0004] However, it has become clear that the moisture-proof films used for general semiconductor devices, as described above, do not provide sufficient moisture protection for power devices, which can lead to a decrease in the insulation reliability of power devices. Furthermore, moisture-proof films for power devices are also required to have heat resistance to withstand the heat generated by power semiconductor devices.

[0005] This disclosure is made in view of the above circumstances and aims to provide a power device package that has excellent moisture resistance and can also ensure heat resistance, a method for manufacturing a power device package, and a moisture-proof film for power devices.

[0006] This disclosure includes the following embodiments: <1> A power device package comprising a power device sealed with a sealing layer and a moisture-proof film layer covering at least a portion of the sealing layer of the power device, wherein the moisture-proof film layer has, in order from the power device side, a heat-fusible resin layer, a metal foil layer, and a protective layer. <2> The power device package according to <1>, wherein the heat-fusible resin layer comprises at least one heat-fusible resin selected from the group consisting of polyethylene, polypropylene, olefin copolymer, polyamide, polyamide-imide, acid-modified products thereof, acrylic resin, and ionomer. <3> The power device package according to <1> or <2>, wherein the heat-fusible resin layer is made using an unstretched film. <4> The power device package according to any one of <1> to <3>, wherein the heat-fusible resin layer is made using an unstretched three-layer co-extruded polypropylene film. <5> The power device package according to any one of <1> to <4>, wherein the protective layer comprises at least one selected from the group consisting of cellulose resin, polyimide, polyamideimide, polyamide, and polyester. <6> The power device package according to any one of <1> to <5>, wherein the protective layer is made of a biaxially oriented film. <7> The power device package according to any one of <1> to <6>, wherein the metal foil layer is an aluminum foil layer. <8> The power device package according to any one of <1> to <7>, wherein the metal foil layer has a chemical conversion coating on at least one of the surfaces facing the heat-fusible resin layer and the protective layer. <9> The power device package according to any one of <1> to <8>, wherein there is an outer adhesive layer between the metal foil layer and the protective layer. <10> The power device package according to any one of <1> to <9>, wherein there is an inner adhesive layer between the metal foil layer and the heat-fusible resin layer. <11> The power device package according to any one of <1> to <10>, wherein the heat-fusible resin layer is fused to the sealing layer or to a resin case disposed around the sealing layer.<12> A power device package according to any one of <1> to <10>, wherein the moisture-proof film layer surrounds the power device and a portion of the opposing heat-fusible resin layer is heat-fused. <13> A method for manufacturing a power device package, wherein the heat-fusible resin layer is placed on at least a portion of the surface of a power device, which is sealed with a sealing material layer, with the moisture-proof film for power devices having a heat-fusible resin layer, a metal foil layer, and a protective layer in that order, facing the sealing material layer. <14> A method for manufacturing a power device package according to <13>, wherein the heat-fusible resin layer is heat-fused to the sealing material layer or to a resin case arranged around the sealing material layer. <15> A method for manufacturing a power device package according to <13>, wherein a housing material is prepared, which is made of the moisture-proof film for power devices and is capable of housing the power device in a state of surrounding it, the power device which is sealed with a sealing material layer is housed in the housing material, and a portion of the opposing heat-fusible resin layers in the housing material are heat-fused. <16> A moisture-proof film for power devices having a heat-fusible resin layer, a metal foil layer, and a protective layer in that order. <17> The moisture-proof film for power devices according to <16>, wherein the heat-fusible resin layer comprises at least one heat-fusible resin selected from the group consisting of polyethylene, polypropylene, olefin copolymer, polyamide, polyamide-imide, acid-modified products thereof, acrylic resin, and ionomer. <18> The moisture-proof film for power devices according to <16> or <17>, wherein the heat-fusible resin layer is made using an unstretched film. <19> The moisture-proof film for power devices according to any one of <16> to <18>, wherein the heat-fusible resin layer is made using an unstretched three-layer co-pressed polypropylene film. <20> The moisture-proof film for power devices according to any one of <16> to <19>, wherein the protective layer comprises at least one selected from the group consisting of cellulose resin, polyimide, polyamide-imide, polyamide, and polyester. <21> A moisture-proof film for power devices according to any one of <16> to <20>, wherein the protective layer is made of a biaxially oriented film.<22> A moisture-proof film for power devices according to any one of <16> to <21>, wherein the metal foil layer is an aluminum foil layer. <23> A moisture-proof film for power devices according to any one of <16> to <22>, wherein the metal foil layer has a chemical conversion coating on at least one of the surfaces facing the heat-fusible resin layer and the protective layer. <24> A moisture-proof film for power devices according to any one of <16> to <23>, wherein the metal foil layer has an outer adhesive layer between the metal foil layer and the protective layer. <25> A moisture-proof film for power devices according to any one of <16> to <24>, wherein the metal foil layer has an inner adhesive layer between the metal foil layer and the heat-fusible resin layer.

[0007] According to this disclosure, it is possible to provide a power device package that has excellent moisture resistance and heat resistance, a method for manufacturing a power device package, and a moisture-proof film for power devices.

[0008] This is a schematic perspective view showing an example of a power device package according to this disclosure. This is a schematic cross-sectional view showing an example of a moisture-proof film layer. This is a diagram illustrating the shape of a sample prepared in the example.

[0009] The embodiments for carrying out the present invention will be described in detail below. However, the present invention is not limited to the following embodiments. In this disclosure, the components (including elemental steps, etc.) are not essential unless otherwise specified. The same applies to numerical values ​​and their ranges, and they do not limit the present invention. In this disclosure, numerical ranges indicated using "~" include the numerical values ​​before and after "~" as the minimum and maximum values, respectively. In numerical ranges described in steps in this disclosure, the upper or lower limit of one numerical range may be replaced with the upper or lower limit of another numerical range described in steps. Also, in numerical ranges described in this disclosure, the upper or lower limit of that numerical range may be replaced with the values ​​shown in the examples. In this disclosure, each component may contain multiple types of the corresponding substance. If multiple types of the substance 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 types of substances present in the composition, unless otherwise specified. In this disclosure, the term "layer" includes cases where the layer is formed over the entire region when the region in which the layer exists is observed, as well as cases where it is formed only over a portion of the region. When embodiments are described in this disclosure with reference to the drawings, the configuration of the embodiments is not limited to the configuration shown in the drawings. Furthermore, the sizes of the members in each figure are conceptual, and the relative relationships of the sizes between members are not limited thereto. In this disclosure, the up and down direction is not limited to the vertical up and down direction, and may be reversed. Also, the up and down direction may be replaced with the left and right direction.

[0010] <Power Device Package> The power device package of this disclosure comprises a power device sealed with a sealing material layer, and a moisture-proof film layer covering at least a portion of the sealing material layer of the power device, wherein the moisture-proof film layer has, in order from the power device side, a heat-sealable resin layer, a metal foil layer, and a protective layer.

[0011] The power device package having the above configuration offers excellent moisture resistance and heat resistance. The reason for this is presumed to be as follows, but the present invention is not limited by the following presumption.

[0012] In the power device package of this disclosure, at least a portion of the encapsulant layer in the power device is covered with a moisture-proof film layer. The moisture-proof film layer has a metal foil layer with excellent moisture resistance, and therefore has excellent moisture resistance. Furthermore, since the moisture-proof film layer has a layer structure consisting of a heat-sealable resin layer, a metal foil layer, and a protective layer, heat resistance is also ensured. In addition, when the moisture-proof film layer is heat-sealed to the encapsulant layer on the surface of the power device via the heat-sealable resin layer, gaps are less likely to occur between the moisture-proof film layer and the power device, and the moisture-proof properties of the metal foil layer are easily fully exhibited. Moreover, when the moisture-proof film layer surrounds the entire perimeter of the power device and the opposing heat-sealable resin layers are heat-sealed to each other, the heat sealing between the heat-sealable resin layers effectively prevents the intrusion of moisture from the outside, and therefore the moisture-proof properties of the metal foil layer are easily fully exhibited.

[0013] Figure 1 shows a schematic perspective view of an example of a power device package of the present disclosure. The power device package 100 in Figure 1 comprises a power device 10 and a moisture-proof film layer 20 that covers at least a portion of the power device 10. The entire power device 10, which is a semiconductor element (not shown), is sealed with a sealing material layer 12.

[0014] The sealing layer 12 can be made of any general sealing material, for example, it may be sealed with an epoxy resin or the like. A general method can be applied to seal the power device with the sealing material, such as transfer molding or compression molding.

[0015] The moisture-proof film layer 20 only needs to cover at least a portion of the sealing material layer 12 of the power device 10, or it may cover the entire layer. When the moisture-proof film layer 20 covers a portion of the sealing material layer 12 of the power device 10, it is preferable to cover the surface with the largest possible area among the surfaces constituting the power device 10. In Figure 1, the power device 10 has a top or bottom surface with a larger area than the side surface, so the moisture-proof film layer 20 is provided on the top surface of the power device 10.

[0016] The moisture-proof film layer 20 may be placed on one surface or on two or more surfaces. The surface on which the moisture-proof film layer 20 is placed may have steps or may be flat.

[0017] The coverage rate of the moisture-proof film layer 20 over the total surface area of ​​the power device 10 may be 5 area % or more, 10 area % or more, 20 area % or more, 30 area % or more, 40 area % or more, 50 area % or more, 60 area % or more, 70 area % or more, 80 area % or more, 90 area % or more, or 100 area %. Furthermore, the moisture-proof film layer 20 may be specifically placed in areas where moisture protection is particularly desired, in which case the coverage rate of the moisture-proof film layer 20 over the total surface area of ​​the power device 10 may be 90 area % or less, 60 area % or less, 50 area % or less, 40 area % or less, or 30 area % or less.

[0018] As shown in Figure 2, the moisture-proof film layer 20 has, in order from the power device 10 side, a heat-fusible resin layer 22, a metal foil layer 24, and a protective layer 26. The moisture-proof film layer 20 may further have an inner adhesive layer 23 between the metal foil layer 24 and the heat-fusible resin layer 22, and an outer adhesive layer 25 between the metal foil layer 24 and the protective layer 26. The moisture-proof film layer shown in Figure 2 includes an inner adhesive layer 23 and an outer adhesive layer 25, but the arrangement of the inner adhesive layer 23 and the outer adhesive layer 25 is arbitrary. In the moisture-proof film layer 20, these layers are joined (adhered) together in a laminated state.

[0019] The heat-fusible resin layer 22 is located on the power device 10 side. The surface 1a of the heat-fusible resin layer 22 on the power device 10 side may be fused to the sealing material layer 12 of the power device 10 or to the resin case arranged around the sealing material layer 12. Also, if the moisture-proof film layer 20 (a moisture-proof film for power devices described later) surrounds the power device, a portion of the opposing heat-fusible resin layer 22 may be heat-fused. In such a configuration, for example, the power device 10, which is sealed with a sealing material layer, may be housed in a housing material made of a moisture-proof film for power devices that can house the power device in a state of surrounding it, and the opposing heat-fusible resin layers in the housing material may be heat-fused to each other.

[0020] When heat-sealing the heat-sealable resin layers 22 together, the seal strength is preferably 5 N / 15 mm width or more, more preferably 20 N / 15 mm width or more, and even more preferably 40 N / 15 mm width or more. The seal strength is the value measured at a tensile speed of 300 mm / s according to the method of JIS Z 1707:2019.

[0021] Details of each layer of the moisture-proof film layer 20 can be found in the section on moisture-proof films for power devices, described later. For other details regarding the moisture-proof film layer 20, please refer to the section on moisture-proof films for power devices, described later.

[0022] <Moisture-proof film for power devices> The moisture-proof film for power devices of this disclosure (hereinafter also referred to as the "moisture-proof film") has a heat-sealable resin layer, a metal foil layer, and a protective layer in that order. The moisture-proof film for power devices of this disclosure can improve the moisture resistance of power devices and also ensure heat resistance.

[0023] (Heat-fusible resin layer) The type of heat-fusible resin layer 22 is not particularly limited, but it is preferable that it is composed of at least one heat-fusible resin selected from the group consisting of polyethylene, polypropylene, olefin copolymers, polyamides, polyamide-imides, acid-modified products thereof, acrylic resins, and ionomers, in terms of excellent heat-fusibility, and it is more preferable that it is composed of at least one heat-fusible resin selected from the group consisting of polyethylene, polypropylene, olefin copolymers, acid-modified products thereof, and ionomers (hereinafter also referred to as "specific heat-fusible resin"). In particular, in terms of excellent moisture resistance and strength, it is preferable that a coating layer containing random copolymer polypropylene is laminated and integrated on both sides of an intermediate layer containing block copolymer polypropylene. The thickness ratio of the polypropylene layer composed of such three layers is not limited, but it is preferable that ethylene-propylene random copolymer (rPP): ethylene-propylene block copolymer (bPP): ethylene-propylene random copolymer (rPP) = 1 to 1.5: 7 to 8: 1 to 1.5.

[0024] The thickness of the heat-fusible resin layer 22 is not particularly limited. When the heat-fusible resin layer 22 is composed of a specific heat-fusible resin, it is preferably in the range of 10 μm to 80 μm, preferably in the range of 15 μm to 80 μm, and more preferably in the range of 30 μm to 50 μm. A thickness of 10 μm or more can suppress the occurrence of pinholes when the moisture-proof film is molded to the shape of the power device. A thickness of 80 μm or less can reduce the amount of resin used, thereby reducing the manufacturing cost of the moisture-proof film. When the heat-fusible resin layer 22 is composed of acrylic resin, cellulose resin, etc., the thickness of the heat-fusible resin layer 22 is preferably in the range of 1 μm to 100 μm, and more preferably in the range of 3 μm to 50 μm. A thickness of 1 μm or more can suppress the occurrence of pinholes when the moisture-proof film is molded to the shape of the power device. A thickness of 100 μm or less can reduce the amount of resin used, thereby reducing the manufacturing cost of the moisture-proof film.

[0025] The heat-fusible resin layer 22 is formed, for example, from a heat-fusible resin film. It is preferable to use an unstretched heat-fusible resin film. As the unstretched heat-fusible resin film, it is preferable to use an unstretched film made of the above-mentioned resin in terms of excellent heat-fusibility, more preferable to use an unstretched film made of a specific heat-fusible resin, and even more preferable to use a three-layer co-extruded polypropylene film in which a coating layer containing random copolymerized polypropylene is laminated and integrated on both sides of an intermediate layer containing block copolymerized polypropylene in terms of excellent moisture resistance and strength. The layer thickness ratio of the unstretched three-layer co-extruded polypropylene film is the same as the layer thickness ratio of the polypropylene layer composed of the above three layers.

[0026] (Protective Layer) The protective layer 26 is also called the base layer and is located on the outer surface 1b side of the moisture-proof film layer 20 than the metal foil layer 24. The type of protective layer 26 is not particularly limited and, for example, is made of a heat-resistant resin. As the resin of the protective layer 26, cellulose resin, polyimide, polyamide-imide, polyamide, polyester, etc. may be used. In particular, as the resin of the protective layer 26, it is preferable that it is made of cellulose resin, polyimide, polyamide-imide, polyamide, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), or polyethylene naphthalate (PEN) in terms of excellent shape conformability and strength, and it is preferable that it is made of polyamide, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), or polyethylene naphthalate (PEN) (hereinafter referred to as "protective layer specific resin"), and it is more preferable that it is made of a protective layer specific resin.

[0027] Furthermore, polyamide is particularly preferred as the protective layer 26 due to its excellent strength and shape conformability. The type of polyamide is not limited, and examples include nylon 6, nylon 6,6, and MXD nylon.

[0028] The protective layer 26 is formed from, for example, a heat-resistant resin film. Examples of heat-resistant resin films include films composed of the above-mentioned resins, preferably stretched films of these materials. In particular, for the protective layer 26, it is preferable to use a biaxially oriented film in terms of its excellent shape conformability and strength, and it is more preferable to use a biaxially oriented polyamide film, a biaxially oriented polybutylene terephthalate (PBT) film, a biaxially oriented polyethylene terephthalate (PET) film, or a biaxially oriented polyethylene naphthalate (PEN) film.

[0029] The protective layer 26 may be formed as a single layer, or it may be formed as a multilayer, for example, consisting of a PET layer and a polyamide layer.

[0030] The thickness of the protective layer 26 is not particularly limited. When a protective layer-specific resin is used as the protective layer 26, it is preferable that the thickness be in the range of 9 μm to 50 μm. When polyester is used as the protective layer 26, its thickness is preferably in the range of 9 μm to 50 μm, and when polyamide is used, its thickness is preferably in the range of 10 μm to 50 μm. Furthermore, when the protective layer 26 is composed of cellulose resin or the like, it is preferable that the thickness be in the range of 1 μm to 10 μm. When the thickness of the protective layer 26 is above the lower limit of the above preferred range, it is easier to ensure sufficient strength, and when the thickness is below the upper limit of the above preferred range, shape conformability tends to improve.

[0031] When the protective layer 26 is formed as a multilayer, its thickness is preferably in the range of 20 μm to 50 μm. For example, when the protective layer 26 is formed as a multilayer of PET film / polyamide film, it is preferable to bond the two films together using a dry lamination method with an adhesive similar to that used for the outer adhesive layer 25 to form a multilayer.

[0032] (Metal foil layer) The metal foil layer 24 is a layer that provides moisture-proofing functionality. The metal thin layer may also play a role in providing gas barrier properties that suppress the intrusion of oxygen in addition to moisture.

[0033] The metal foil layer 24 is made of, for example, metal foil. The type of metal foil layer 24 is not particularly limited, but it is preferable to use aluminum foil, copper foil, stainless steel foil, etc., and it is more preferable to use aluminum foil. In particular, Al-Fe alloy foil containing 0.7% to 1.7% by mass of Fe as aluminum foil has excellent strength and ductility and good shape conformability.

[0034] The thickness of the metal foil layer 24 is not particularly limited, but is preferably in the range of 20 μm to 100 μm. A thickness of 20 μm or more tends to suppress the occurrence of pinholes during rolling when manufacturing the metal foil. A thickness of 100 μm or less tends to improve shape conformability.

[0035] 1. (Chemical conversion coating of the metal foil layer) It is preferable that a chemical conversion coating 24a is formed on at least one of the inner and outer surfaces of the metal foil layer 24 to improve the corrosion resistance of the metal foil layer 24. The chemical conversion coating 24a is formed by applying a chemical conversion treatment to the surface of the metal foil. The inner surface of the metal foil layer 24 refers to the surface of the metal thin layer 24 facing the heat-fusible resin layer, and the outer surface of the metal foil layer 24 refers to the surface of the metal thin layer 24 facing the protective layer.

[0036] The chemical conversion coating 24a is a film (layer) for improving the corrosion resistance of the metal foil layer 24, and can be formed, for example, by applying a chromate treatment or a non-chromium type chemical conversion treatment using a zirconium compound to the surface of the metal foil constituting the metal foil layer 24. For example, in the case of chromate treatment, an aqueous solution of one of the mixtures 1) to 3) below is applied to the surface of the degreased metal foil and then dried.

[0037] 1) A mixture of phosphoric acid, chromic acid, and at least one of a metal salt of fluoride and a non-metal salt of fluoride.2) A mixture of phosphoric acid, any one of an acrylic resin, a chitosan derivative resin, and a phenolic resin, and at least one of chromic acid and a chromium (III) salt. 3) A mixture of phosphoric acid, any one of an acrylic resin, a chitosan derivative resin, and a phenolic resin, at least one of chromic acid and a chromium (III) salt, and at least one of a metal salt of fluoride and a non-metal salt of fluoride.

[0038] The chromium deposition amount of the chemical conversion film 24a is not limited, but is preferably in the range of 0.1 mg / m ２ to 50 mg / m ２ and particularly preferably in the range of 2 mg / m ２ to 20 mg / m ２ The thickness of the chemical conversion film 24a is not limited and is preferably in the range of 0.001 μm to 0.1 μm. Such a chemical conversion film with such a chromium deposition amount or thickness can surely enhance the corrosion resistance of the metal foil layer 24.

[0039] The chemical conversion film 24a may be formed on both the inner and outer surfaces of the metal foil layer 24, may be formed on only one of the inner and outer surfaces of the metal foil layer 24, or may not be formed on both the inner and outer surfaces. [[ID=1⑥]]

[0040] (Outer adhesive layer) The outer adhesive layer 25 is a layer that bears the bonding between the metal foil layer 24 (specifically, when the metal foil layer 24 has the chemical conversion film 24a, the chemical conversion film 24a) and the protective layer 26. In the moisture-proof film of the present disclosure, the outer adhesive layer 25 may or may not be provided.

[0041] A known adhesive layer can be applied to the outer adhesive layer 25. The type of the outer adhesive is not limited, and as the outer adhesive, a polyurethane-based adhesive, an acrylic-based adhesive, a polyacrylate-based adhesive, a modified polypropylene-based adhesive, a polyester-based adhesive, a polyamide-based adhesive, an epoxy-based adhesive, etc. are used. Among these, it is preferable to use a polyurethane-based adhesive.

[0042] Further, the outer adhesive may be used as an adhesive for dry lamination (e.g., urethane-based adhesive, olefin-based adhesive). As an adhesive for dry lamination, specifically, for example, an adhesive containing a two-component curable polyester urethane resin composed of a polyester resin as the main component of the outer adhesive and a polyfunctional isocyanate compound as the curing agent can be mentioned.

[0043] The method of joining the metal foil layer 24 and the protective layer 26 with the outer adhesive composition is not limited, and for example, a dry lamination method can be mentioned.

[0044] For reference, several examples of the volume resistivity of the cured film of the adhesive (resin) generally used as the outer adhesive are described below.

[0045] Urethane resin (assuming the outer adhesive layer): 1×10 １１ ~1×10 １３ Ωcm Acrylic resin (methacrylic resin): ≧1×10 １４ Ωcm Polyester resin: 1×10 １5 ~1×10 １６ Ωcm Polypropylene resin: ≧1×10 １６ Ωcm Polyamide resin (polyamide 6): 1×10 １１ Ωcm.

[0046] The thickness of the outer adhesive layer 25 is not particularly limited, and for example, it may be 0.5 μm to 10 μm, may be 1 μm to 8 μm, or may be 2 μm to 6 μm.

[0047] (Inner adhesive layer) The inner adhesive layer 23 has an adhesive component such as an adhesive or an adhesive resin interposed between the metal foil layer 24 and the heat-fusible resin layer 22, and is a layer that laminates (adheres) the metal foil layer 24 and the heat-fusible resin layer 22 in a laminated state through this adhesive component.

[0048] Here, in order to easily distinguish the above-mentioned adhesive, adhesive resin, and adhesive component from the outer adhesive described above, hereinafter, they are also referred to as "inner adhesive", "inner adhesive resin", and "inner adhesive component", respectively.

[0049] For the inner adhesive, for example, the same adhesive used for the outer adhesive layer 25 described above may be used, or a different adhesive may be used.

[0050] As the internal adhesive resin, one type of resin such as polyolefin resin, polyvinyl acetate resin, (meth)acrylic resin, or amino resin may be used alone, or two or more types may be used in combination. Examples of the polyolefin resin mentioned above include polyolefin resin, carboxylic acid-modified polyolefin resin, and metal-modified polyolefin resin.

[0051] The thickness of the inner adhesive layer 23 is not particularly limited and may be, for example, 1 μm to 50 μm, 5 μm to 40 μm, or 10 μm to 30 μm.

[0052] When joining (adhering) the metal foil layer 24 and the heat-fusible resin layer 22 using an internal adhesive, for example, a dry lamination method is used as the joining method, and the method is as follows.

[0053] Specifically, the inner adhesive composition is applied in layers onto the metal foil layer 24 or the heat-fusible resin layer 22 using a gravure coating method, a reverse roll coating method, or the like. After the solvent in the composition is dried and evaporated to form a dry film, the metal foil layer 24 and the heat-fusible resin layer 22 are bonded together. Subsequently, the composition is cured according to the curing conditions for the composition. As a result, the metal foil layer 24 and the heat-fusible resin layer 22 are joined (bonded) in a laminated manner via the inner adhesive layer 23.

[0054] When joining (adhering) a metal foil layer 24 and a heat-fusible resin layer 22 in a laminated manner using an internal adhesive resin, for example, the following three methods can be used as joining methods.

[0055] Specifically, the following methods are used to join the metal foil layer 24 and the heat-fusible resin layer 22 in a laminated manner: co-extrusion of an internal adhesive resin and a heat-fusible resin onto the metal foil layer 24 (more precisely, the inner surface of the metal foil layer 24) (co-extrusion lamination method); forming a laminate in advance by laminating the internal adhesive resin and the heat-fusible resin, and then laminating this laminate onto the metal foil layer 24 by a heat lamination method; and joining the metal foil layer 24 and the heat-fusible resin layer 22 in a laminated manner by pouring molten internal adhesive resin between the metal foil layer 24 and a film-like heat-fusible resin, thereby bonding the metal foil layer 24 and the film-like heat-fusible resin together (sand lamination method).

[0056] <Method for Manufacturing Moisture-Proof Film> An example of a preferred method for manufacturing a moisture-proof film is as follows: Prepare a metal foil layer 24 with a chemical conversion coating 24a formed on its inner and outer surfaces. Next, apply an outer adhesive composition in layers to the outer surface of the metal foil layer 24 using a predetermined application method, dry and evaporate the solvent in the composition, then bond the outer surface of the metal foil layer 24 to the inner surface of the protective layer 26, and cure the composition by holding it at a predetermined temperature (aging) according to the curing conditions of the composition.

[0057] Next, the heat-fusible resin layer 22 is bonded to the inner surface of the metal foil layer 24 via an internal adhesive component (internal adhesive, internal adhesive resin, etc.), and the internal adhesive component is cured by holding it at a predetermined temperature (aging) according to the curing conditions of the internal adhesive component.

[0058] As a result, a protective layer 26 is bonded to the outer surface of the metal foil layer 24 via an outer adhesive layer 25, and a heat-fusible resin layer 22 is bonded to the inner surface of the metal foil layer 24 via an inner adhesive layer 23, thereby obtaining a moisture-proof film.

[0059] However, the moisture-proof film of this disclosure is not limited to those manufactured by the moisture-proof film manufacturing method described above, but may be manufactured by other methods.

[0060] The moisture-proof film of this disclosure is not limited to having the plurality of layers shown in Figure 2, and for example, another layer may be added to the plurality of layers shown in Figure 2.

[0061] The moisture-proof film of this disclosure can be suitably used for moisture protection of power devices. The moisture-proof film of this disclosure may be used not only for power devices but also for general semiconductor packages.

[0062] <Method for Manufacturing a Power Device Package> The method for manufacturing a power device package according to this disclosure is not particularly limited as long as a power device package having the above-described configuration can be manufactured. For example, a power device package may be manufactured by arranging the heat-fusible resin layer opposite the sealing layer on at least a part of the surface of a power device, which is sealed with a sealing layer, a moisture-proof film for power devices having a heat-fusible resin layer, a metal foil layer, and a protective layer in that order.

[0063] The heat-sealable resin layer 22 may be heat-sealed to the sealing material layer 12 that seals the power device 10, or to a resin case arranged around the sealing material layer 12. When the heat-sealable resin layer 22 is heat-sealed to the sealing material layer 12, if there is a step on the surface on which the moisture-proof film is to be placed, it is preferable to reduce the pressure or vacuum adsorption of the moisture-proof film to conform the moisture-proof film to the shape of the area to be placed, thereby forming the moisture-proof film layer 20. When the heat-sealable resin layer 22 is heat-sealed to the sealing material layer 12, if the surface on which it is to be placed is flat, it is preferable to press the moisture-proof film to form the moisture-proof film layer 20. The pressing method is not particularly limited, and methods such as heat pressing can be used.

[0064] Alternatively, a housing material made of a moisture-proof film and capable of enclosing the power device may be prepared, the power device sealed with a sealing layer may be housed in this housing material, and a portion of the opposing heat-sealable resin layers in the housing material may be heat-sealed. The housing material may take the form of a bag, as in the embodiment. In the embodiment, the moisture-proof film is folded in half so that the heat-sealable resin layers 22 face each other to form a bag, but two moisture-proof films may be sandwiched from above and below, and the opposing heat-sealable resin layers may be heat-sealed together. Furthermore, the housing material may be a housing case formed by deep drawing or stretch molding of a moisture-proof film for power devices.

[0065] The positional relationship between the power device and the moisture-proof film layer is not limited to the above. The moisture-proof film layer only needs to cover at least a portion of the sealing material layer of the power device, and the shape of the moisture-proof film layer may be appropriately processed according to the shape of the power device.

[0066] When a power device is housed in a housing and the heat-sealable resin layers are heat-sealed together, the heat-sealable resin layer 22 does not necessarily have to be heat-sealed to the sealing material layer 12 that seals the power device 10, but the heat-sealable resin layer 22 and the sealing material layer 12 may be heat-sealed together.

[0067] The temperature for heat fusion is not particularly limited. For example, from the viewpoint of suppressing thermal degradation of power devices, it is preferably 300°C or lower, but it may also be 250°C or lower, or 220°C or lower. Furthermore, from the viewpoint of improving the heat resistance of the power device package, the heat fusion temperature is preferably 100°C or higher, but it may also be 130°C or higher, or 150°C or higher.

[0068] The time for heat fusion is not particularly limited. For example, from the viewpoint of shortening the manufacturing time, it is preferably 60 seconds or less, but it may also be 30 seconds or less, or 20 seconds or less. Furthermore, from the viewpoint of ensuring reliable heat fusion, the time for heat fusion is preferably 0.1 seconds or more, but it may also be 0.5 seconds or more, or 1 second or more.

[0069] Specific examples and comparative examples of the present invention are shown below. However, the present invention is not limited to the following examples.

[0070] <Example 1> (Preparation of molded body using sealing material) A sealing material with the following composition was prepared: • Triphenylmethane type epoxy resin: 100 parts by mass • Biphenyl type phenol novolac resin: 87 parts by mass • Curing accelerator: Adduct of triphenylphosphine and p-benzoquinone, 2.5 parts by mass • Filler: Silica particles, 1049 parts by mass

[0071] The above sealing material was molded to a size of 4 mm × 10 mm × 80 mm using a transfer molding machine under the conditions of a mold temperature of 175°C, a molding pressure of 6.9 MPa, and a curing time of 90 seconds. Next, the molded product was post-cured at 175°C for 5 hours to obtain a cured product. The obtained cured product was cut into pieces of 4 mm × 10 mm × 26 mm to obtain molded bodies of the sealing material.

[0072] (Preparation of moisture-proof film) As the metal foil layer, aluminum foil with a thickness of 35 μm, aluminum alloy symbol A8079 as specified in JIS H4160:2006, was prepared. A chemical conversion coating was formed on the inner and outer surfaces of the aluminum foil. This chemical conversion coating was formed by applying a chemical conversion treatment solution consisting of polyacrylic acid, trivalent chromium compound, water, and alcohol to the inner and outer surfaces of the aluminum foil, and then drying it at 150°C. The amount of chromium deposited on one side of the aluminum foil was 10 mg / m². ２ The thickness of each chemical conversion coating was 0.01 μm.

[0073] A single layer of biaxially oriented nylon (ONY) film was prepared as a protective layer. The film thickness was 15 μm. The inner surface of the ONY film (i.e., the surface of the ONY film that is bonded to the metal foil layer) was pre-treated with corona to improve wettability with the outer adhesive composition. This ONY film had a TD hot water shrinkage rate of 2.7%, an MD hot water shrinkage rate of 2.0%, a difference in hot water shrinkage rates between TD and MD (TD-MD) of 0.7%, a TD modulus of elasticity of 1.7 GPa, an MD modulus of elasticity of 2.7 GPa, a TD breaking strength of 361 MPa, an MD breaking strength of 280 MPa, and a polyamide number-average molecular weight of 25,000. Note that MD is the flow direction of the ONY film, which is the longitudinal direction. TD is perpendicular to MD and is the width direction of the ONY film.

[0074] An unstretched three-layer co-extruded polypropylene (CPP) film was prepared as the heat-fusible resin layer. The thickness of the CPP film was 30 μm, and its layer thickness ratio was rPP:bPP:rPP = 1:8:1. In addition, the outer surface of the CPP film (i.e., the surface that is bonded to the metal foil layer in the CPP film) was pre-treated with corona to improve wettability with the inner adhesive component.

[0075] The metal foil layer and the heat-sealable resin layer were joined by dry lamination using an acid-modified polypropylene (PP) adhesive as the inner adhesive composition, while the metal foil layer and the heat protection layer were joined by dry lamination using a two-component curing polyester urethane resin as the outer adhesive. This resulted in a moisture-proof film.

[0076] (Covering with moisture-proof film) The moisture-proof film was cut to a size of 10 cm x 11 cm. As shown in Figure 3, the moisture-proof film 30 was folded in half along the longer side of 11 cm so that the heat-sealable resin layers 22 faced each other. The molded body 40 of the sealing material was placed inside the folded moisture-proof film 30, and the three sides of the moisture-proof film 30 (shaded areas in Figure 3) were heat-sealed. For heat sealing, a degassing sealer "V-301" from Fuji Impulse Co., Ltd. was used, and the process was carried out at 200°C for 1 second, resulting in a seal width (width of the shaded area in Figure 3) of 9 mm.

[0077] <Example 2> The same procedure was followed as in Example 1, except that the moisture-proof film used was replaced with the following: In Example 2, a 25 μm thick aluminum foil was used as the metal foil layer, a 3.5 μm thick coating layer was formed by applying cellulose resin to one side of the aluminum foil as a protective layer, and a 6.5 μm thick acrylic resin layer was formed by applying acrylic resin to the other side of the aluminum foil as a heat-sealable resin layer.

[0078] <Comparative Example 1> In Comparative Example 1, a molded body of the sealing material was prepared without being covered with a moisture-proof film.

[0079] [Evaluation] (Moisture-proof test) Samples prepared in Examples 1 and 2 and Comparative Example 1 were placed in a high-temperature, high-humidity chamber at 85°C and 85% RH for 1 day and 7 days, and their masses (W0 and W1) were measured before and after the test. The percentage of the mass change (W1 - W0) divided by W0 was calculated as the moisture absorption rate.

[0080]

[0081]

[0082] The moisture absorption rates of Examples 1 and 2 were lower than those of Comparative Example 1 in both the 85°C 85% RH 1-day and 85°C 85% RH 7-day moisture absorption tests, confirming their moisture-proofing effect. In particular, Example 1 showed a moisture absorption rate of 0.00% in the 85°C 85% RH 1-day and 85°C 85% RH 7-day moisture absorption tests, demonstrating high moisture-proofing properties. Compared to Example 1, Example 2 showed more variation in moisture absorption rates.

[0083] (Heat Resistance Test) Samples prepared in Examples 1-2 and Comparative Example 1 were heated at 150°C for 180 hours. The appearance and moisture absorption rate of the heated samples were checked. The criteria for appearance are as follows. "-" in Table 3 indicates N.D. A: No peeling in the heat-sealed area. B: Peeling in the heat-sealed area.

[0084]

[0085]

[0086] In Examples 1 and 2, no peeling occurred in the heat-sealed portion after the heat resistance test, and the moisture absorption rate in the 85°C 85% RH 1-day moisture absorption test was lower than that of Comparative Example 1, confirming that the material has a moisture-proof effect.

[0087] (Seal Strength) The seal strength of the heat-sealed portion (seal portion) of the samples prepared in Examples 1 and 2 before the moisture-proof test was measured using the method described above.

[0088]

[0089] Example 1 showed higher seal strength compared to Example 2. This may explain why Example 1 exhibited higher moisture resistance than Example 2. Therefore, it is possible that even the moisture-proof film used in Example 2 could exhibit even better moisture resistance by adjusting the pressure conditions, etc.

[0090] (Heat Permeability Measurement) The moisture permeability was measured using the differential pressure method in accordance with JIS K 7129-4:2019. The measurement conditions were as follows: Measurement device: GTR-30XADJ4, G2700T differential pressure gas / vapor permeability measuring device manufactured by GTR Tech Co., Ltd. and Yanako Technical Science Co., Ltd. Permeation area: 15.2 cm² ２(Φ4.4cm) Number of tests: N3 each

[0091] *In this test, the amount of water vapor permeation could not be detected in any of the three tests, so the result is the lower limit of the device's detection limit (0.01 gm). －２ (1 day) The following:

[0092] 10: Power device 12: Encapsulation layer 20: Moisture-proof film layer 22: Heat-sealable resin layer 23: Inner adhesive layer 24: Metal foil layer 25: Outer adhesive layer 26: Protective layer 30: Moisture-proof film 40: Encapsulation molded body 100: Power device package

Claims

1. A power device package comprising a power device sealed with a sealing material layer, and a moisture-proof film layer covering at least a portion of the sealing material layer of the power device, wherein the moisture-proof film layer has, in order from the power device side, a heat-sealable resin layer, a metal foil layer, and a protective layer.

2. The power device package according to claim 1, wherein the heat-sealable resin layer comprises at least one heat-sealable resin selected from the group consisting of polyethylene, polypropylene, olefin copolymer, polyamide, polyamide-imide, acid-modified products thereof, acrylic resin, and ionomer.

3. The power device package according to claim 1 or claim 2, wherein the heat-sealable resin layer is made of an unstretched film.

4. The power device package according to claim 1 or 2, wherein the heat-sealable resin layer is made of an unstretched three-layer co-extruded polypropylene film.

5. The power device package according to claim 1 or 2, wherein the protective layer comprises at least one selected from the group consisting of cellulose resin, polyimide, polyamideimide, polyamide, and polyester.

6. The power device package according to claim 1 or claim 2, wherein the protective layer is made of a biaxially oriented film.

7. The power device package according to claim 1 or claim 2, wherein the metal foil layer is an aluminum foil layer.

8. The power device package according to claim 1 or 2, wherein the metal foil layer has a chemical conversion coating on at least one of the surfaces facing the heat-fusible resin layer and the protective layer.

9. The power device package according to claim 1 or 2, further comprising an outer adhesive layer between the metal foil layer and the protective layer.

10. The power device package according to claim 1 or claim 2, further comprising an inner adhesive layer between the metal foil layer and the heat-fusible resin layer.

11. The power device package according to claim 1 or 2, wherein the heat-fusible resin layer is fused to the sealing material layer or to a resin case disposed around the sealing material layer.

12. The power device package according to claim 1 or 2, wherein the moisture-proof film layer surrounds the power device and a portion of the opposing heat-sealable resin layer is heat-sealed.

13. A method for manufacturing a power device package, comprising: a moisture-proof film for power devices having a heat-fusible resin layer, a metal foil layer, and a protective layer in that order; the heat-fusible resin layer being placed on at least a portion of the surface of a power device sealed with a sealing material layer, with the heat-fusible resin layer facing the sealing material layer.

14. The method for manufacturing a power device package according to claim 13, wherein the heat-sealable resin layer is heat-sealed to the sealing material layer or to a resin case disposed around the sealing material layer.

15. A method for manufacturing a power device package according to claim 13, comprising: preparing a housing material made of the moisture-proof film for power devices and capable of housing the power device in a state of surrounding it; housing the power device, which is sealed with a sealing material layer, in the housing material; and heat-sealing a portion of the opposing heat-sealable resin layers in the housing material.

16. A moisture-proof film for power devices having, in this order, a heat-sealable resin layer, a metal foil layer, and a protective layer.

17. The moisture-proof film for power devices according to claim 16, wherein the heat-sealable resin layer comprises at least one heat-sealable resin selected from the group consisting of polyethylene, polypropylene, olefin copolymers, polyamides, polyamide-imides, acid-modified products thereof, acrylic resins, and ionomers.

18. The moisture-proof film for power devices according to claim 16 or claim 17, wherein the heat-sealable resin layer is made using an unstretched film.

19. The moisture-proof film for power devices according to claim 16 or claim 17, wherein the heat-sealable resin layer is made of an unstretched three-layer co-extruded polypropylene film.

20. The moisture-proof film for power devices according to claim 16 or 17, wherein the protective layer comprises at least one selected from the group consisting of cellulose resin, polyimide, polyamideimide, polyamide, and polyester.

21. The moisture-proof film for power devices according to claim 16 or claim 17, wherein the protective layer is made of a biaxially oriented film.

22. The moisture-proof film for power devices according to claim 16 or claim 17, wherein the metal foil layer is an aluminum foil layer.

23. The moisture-proof film for power devices according to claim 16 or 17, wherein the metal foil layer has a chemical conversion coating on at least one of the surfaces facing the heat-fusible resin layer and the protective layer.

24. A moisture-proof film for a power device according to claim 16 or 17, further comprising an outer adhesive layer between the metal foil layer and the protective layer.

25. A moisture-proof film for a power device according to claim 16 or 17, having an inner adhesive layer between the metal foil layer and the heat-fusible resin layer.

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