Method for manufacturing molded articles and method for manufacturing semiconductor devices

Abstract

To provide a molded body manufacturing method capable of improving voltage resistance of the molded body and suppressing occurrence of a leakage current.SOLUTION: A molded body manufacturing method includes a step of molding a compound containing a resin and magnetic powder by compression molding or transfer molding using a release film to obtain a molded body.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing a molded article and a method for producing a semiconductor device. [Background Art]

[0002] A compound containing a metal powder and a resin composition is used as a raw material for various industrial products according to various physical properties of the metal powder. For example, the compound is used as a raw material for inductors, sealing materials, electromagnetic wave shields (EMI shields), bonded magnets, and the like (see Patent Document 1 below). [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Laid-Open No. 2014-13803 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] When an industrial product is produced from a compound, the molded article is produced by bringing the compound into close contact with a metal member and curing the compound. When the produced industrial product is an industrial product such as an inductor, the molded article may be required to have voltage resistance. Further, in industrial products such as inductors, if the molded article becomes a resistor before dielectric breakdown and leakage current occurs, the circuit efficiency of the inductor product decreases, which may cause deterioration of product characteristics. In addition, Joule heat is generated by the leakage current, and there is a risk of causing ignition of the coil. Therefore, the molded article may be required to be capable of suppressing the generation of leakage current.

[0005] In view of the above circumstances, an object of the present invention is to provide a method for producing a molded article and a method for producing a semiconductor device that can improve the voltage resistance of the molded article and suppress the generation of leakage current. [Means for Solving the Problem]

[0006] A method for manufacturing a molded article according to one aspect of the present invention comprises the step of obtaining a molded article by compression molding a compound containing resin and magnetic powder using a release film.

[0007] Another aspect of the present invention relates to a method for manufacturing a molded article, which includes the step of molding a compound containing resin and magnetic powder by transfer molding using a release film to obtain a molded article.

[0008] A method for manufacturing a semiconductor device according to one aspect of the present invention is a method for manufacturing a semiconductor device comprising an inductor element and a molded body that seals the inductor element, the method comprising the step of forming the molded body by the method for manufacturing the molded body. [Effects of the Invention]

[0009] The present invention provides a method for manufacturing a molded article and a semiconductor device that can improve the voltage resistance of the molded article and suppress the generation of leakage current. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic cross-sectional view showing the method for manufacturing a molded article according to this embodiment. [Figure 2] This is a schematic cross-sectional view showing the method for manufacturing a molded article according to this embodiment. [Modes for carrying out the invention]

[0011] Preferred embodiments of the present invention will be described below. However, the present invention is not limited in any way to the following embodiments.

[0012] In this specification, numerical ranges indicated using "~" represent a range that includes the numbers before and after "~" as the minimum and maximum values, respectively. In numerical ranges described in stages in this specification, the upper or lower limit of one stage of the numerical range may be replaced with the upper or lower limit of another stage of the numerical range. Also, in numerical ranges described in this specification, the upper or lower limit of that numerical range may be replaced with the values ​​shown in the examples. When referring to the amount of each component in a composition in this specification, if there are multiple substances corresponding to each component in the composition, unless otherwise specified, it refers to the total amount of those multiple substances present in the composition.

[0013] [Method for manufacturing molded products] The method for manufacturing a molded article according to this embodiment includes the step of molding a compound containing resin and magnetic powder using a release film by compression molding or transfer molding to obtain a molded article.

[0014] The compound used in the above manufacturing method includes a resin and magnetic powder. The compound may include a resin composition containing a resin and magnetic powder. The resin composition may contain at least one resin selected from the group consisting of epoxy resins and phenolic resins. The resin composition may contain epoxy resin and a curing agent. In the compound, the magnetic powder and the resin composition are mixed. The resin composition may further contain other components such as a coupling agent, a curing accelerator, a mold release agent, and additives. The resin composition may be a component that can include the resin, curing agent, coupling agent, curing accelerator, mold release agent, and additives, and may be the remaining components (non-volatile components) excluding the organic solvent and magnetic powder. Additives are the components of the resin composition excluding the resin, mold release agent, curing agent, curing accelerator, and coupling agent. Additives are, for example, flame retardants and lubricants. The compound may be a powder (compound powder).

[0015] The compound may comprise magnetic powder and a resin composition attached to the surface of individual magnetic particles constituting the magnetic powder. The resin composition may cover the entire surface of the magnetic particles or only a portion of the surface of the magnetic particles. The compound may comprise an uncured resin composition and magnetic powder. The compound may comprise a semi-cured resin composition (e.g., a B-stage resin composition) and magnetic powder. The compound may comprise both an uncured resin composition and a semi-cured resin composition. The compound may consist of magnetic powder and a resin composition.

[0016] (magnetic powder) The magnetic powder content in the compound may be 60% by mass or more and less than 100% by mass, based on the total mass of the compound. If the magnetic powder content is high, it becomes difficult to ensure the release properties of the molded article, and the workability tends to be poor. From the viewpoint of the magnetic properties of the molded article, the magnetic powder content in the compound may be 70% by mass or more, 80% by mass or more, 90% by mass or more, 92% by mass or more, 94% by mass or more, or 95% by mass or more. From the viewpoint of the fluidity of the compound, the upper limit of the magnetic powder content may be 99% by mass or less, 98% by mass or less, or 97.5% by mass or less. In this specification, the total mass of the compound means the total mass of components excluding volatile components such as organic solvents (non-volatile components).

[0017] Magnetic powder is magnetic particles that possess magnetism. Magnetic powder may contain at least one selected from the group consisting of, for example, elemental metals, alloys, and metal compounds. Magnetic powder may consist of at least one selected from the group consisting of elemental metals, alloys, and metal compounds. Alloys may contain at least one selected from the group consisting of solid solutions, eutectics, and intermetallic compounds. Alloys may be, for example, stainless steel (Fe-Cr alloys, Fe-Ni-Cr alloys, etc.). Metal compounds may be oxides such as ferrite. Magnetic powder may contain one or more metal elements. Metal elements contained in magnetic powder may be, for example, base metals, noble metals, transition metals, or rare earth elements. Compounds may contain one type of magnetic powder, or multiple types of magnetic powders with different compositions.

[0018] The metallic elements contained in the magnetic powder may be at least one selected from the group consisting of, for example, iron (Fe), copper (Cu), titanium (Ti), manganese (Mn), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), tin (Sn), chromium (Cr), niobium (Nb), barium (Ba), strontium (Sr), lead (Pb), silver (Ag), praseodymium (Pr), neodymium (Nd), samarium (Sm), and dysprosium (Dy). The magnetic powder may further contain elements other than metallic elements. For example, the magnetic powder may contain carbon (C), oxygen (O), beryllium (Be), phosphorus (P), sulfur (S), boron (B), or silicon (Si).

[0019] The magnetic powder may be a soft magnetic alloy or a ferromagnetic alloy. The magnetic powder may be, for example, a magnetic powder composed of at least one selected from the group consisting of Fe-Si alloys, Fe-Si-Al alloys (sendust), Fe-Ni alloys (permalloy), Fe-Cu-Ni alloys (permalloy), Fe-Co alloys (permendur), Fe-Cr-Si alloys (electromagnetic stainless steel), Nd-Fe-B alloys (rare earth magnets), Sm-Fe-N alloys (rare earth magnets), Al-Ni-Co alloys (alnico magnets), and ferrite. The ferrite may be, for example, spinel ferrite, hexagonal ferrite, or garnet ferrite. The magnetic powder may also be a copper alloy such as a Cu-Sn alloy, a Cu-Sn-P alloy, a Cu-Ni alloy, or a Cu-Be alloy.

[0020] The magnetic powder may be simple substance Fe. The magnetic powder may also be an iron-containing alloy (Fe-based alloy). The magnetic powder may include at least one Fe-based alloy selected from the group consisting of Fe-based amorphous alloys and Fe-based crystalline alloys. The Fe-based alloy may be, for example, an Fe-Si-Cr-based alloy or an Nd-Fe-B-based alloy. The magnetic powder may be at least one of amorphous iron powder and carbonyl iron powder. When the magnetic powder contains at least one of simple substance Fe and Fe-based alloys, it is easy to produce a molded body having a high space factor and excellent magnetic properties from the compound. The magnetic powder may be a Fe-based amorphous alloy.

[0021] As commercially available Fe-based amorphous alloy powder, for example, at least one selected from the group consisting of AW2-08, KUAMET 6B2, KUAMET 9A4-II (these are product names manufactured by Epson Atmix Corporation), DAP MS3, DAP MS7, DAP MSA10, DAP PB, DAP PC, DAP MKV49, DAP 410L, DAP 430L, DAP HYB series (these are product names manufactured by Daido Steel Co., Ltd.), MH45D, MH28D, MH25D, and MH20D (these are product names manufactured by Kobe Steel, Ltd.) may be used.

[0022] When iron-containing magnetic powder (magnetic powder containing iron) is used as the magnetic powder, the content of iron in the iron-containing magnetic powder may be 80% by mass or more, and may be 83 to 99% by mass, 84 to 97% by mass, 85 to 95% by mass, or 87 to 93% by mass. By using an iron-containing magnetic powder having an iron content within the above range, the compound can be more suitably used as a raw material for inductors, sealing materials, electromagnetic wave shields (EMI shields), bonded magnets, and the like.

[0023] The shape of individual metal particles constituting the magnetic powder is not limited, and may be, for example, spherical, flat, prismatic, or acicular. The average particle diameter of the magnetic powder is not particularly limited, and may be, for example, 0.1 µm or more, 0.5 µm or more, or 1.0 µm or more, and may be 100 µm or less, 80 µm or less, or 50 µm or less. The average particle diameter can be measured, for example, with a particle size distribution analyzer. The compound may include a plurality of types of magnetic powders having different average particle diameters. From the viewpoint of improving fluidity and magnetic properties, the magnetic powder preferably includes a first magnetic powder having an average particle diameter of 10 to 50 µm and a second magnetic powder having an average particle diameter of 0.1 to 10 µm. The average particle diameter of the first magnetic powder may be 11 to 45 µm, 15 to 40 µm, 18 to 35 µm, or 20 to 30 µm. The average particle diameter of the second magnetic powder may be 0.1 to 9 µm, 0.5 to 6 µm, 0.8 to 5 µm, or 1.0 to 4 µm.

[0024] (Resin Composition) The resin composition functions as a binder for the magnetic particles constituting the magnetic powder, and imparts mechanical strength to a molded article formed from the compound. For example, when the compound is molded under high pressure using a mold, the resin composition contained in the compound fills gaps between the magnetic particles and binds the particles to each other. By curing the resin composition in the molded article, the cured product of the resin composition binds the magnetic particles more firmly to each other, thereby improving the mechanical strength of the molded article.

[0025] The resin composition according to this embodiment may contain an epoxy resin as a thermosetting resin. The inclusion of an epoxy resin in the resin composition can improve the fluidity of the compound. The epoxy resin may, for example, be a resin having two or more epoxy groups in one molecule. The type of epoxy resin is not particularly limited and can be selected according to the desired properties of the resin composition.

[0026] Examples of epoxy resins include biphenyl-type epoxy resins, stilbene-type epoxy resins, diphenylmethane-type epoxy resins, sulfur atom-containing epoxy resins, novolac-type epoxy resins, dicyclopentadiene-type epoxy resins, salicylaldehyde-type epoxy resins, copolymer epoxy resins of naphthols and phenols, epoxidized aralkyl-type phenol resins, bisphenol-type epoxy resins, epoxy resins containing a bisphenol skeleton, glycidyl ether-type epoxy resins of alcohols, glycidyl ether-type epoxy resins of paraxylylene and / or metaxylylene-modified phenol resins, and terpene-modified phenol resins. Examples include glycidyl ether type epoxy resins of ol resins, cyclopentadiene type epoxy resins, glycidyl ether type epoxy resins of polycyclic aromatic ring-modified phenol resins, glycidyl ether type epoxy resins of naphthalene ring-containing phenol resins, glycidyl ester type epoxy resins, glycidyl type or methylglycidyl type epoxy resins, alicyclic epoxy resins, halogenated phenol novolac type epoxy resins, orthocresol novolac type epoxy resins, hydroquinone type epoxy resins, trimethylolpropane type epoxy resins, and linear aliphatic epoxy resins obtained by oxidizing olefin bonds with peracids such as peracetic acid.

[0027] In terms of fluidity, the epoxy resin may contain at least one selected from the group consisting of biphenyl-type epoxy resins, orthocresol novolac-type epoxy resins, phenol novolac-type epoxy resins, bisphenol-type epoxy resins, epoxy resins having a bisphenol skeleton, salicylaldehyde novolac-type epoxy resins, and naphthol novolac-type epoxy resins.

[0028] From the standpoint of mechanical strength, the epoxy resin may contain at least one selected from the group consisting of biphenylene aralkyl type epoxy resins and orthocresol novolac type epoxy resins.

[0029] The epoxy resin may be a crystalline epoxy resin. Despite having a relatively low molecular weight, crystalline epoxy resins have a relatively high melting point and excellent fluidity. The crystalline epoxy resin (highly crystalline epoxy resin) may include, for example, at least one selected from the group consisting of hydroquinone-type epoxy resins, bisphenol-type epoxy resins, thioether-type epoxy resins, and biphenyl-type epoxy resins.

[0030] Examples of commercially available crystalline epoxy resins include Epiclon 860, Epiclon 1050, Epiclon 1055, Epiclon 2050, Epiclon 3050, Epiclon 4050, Epiclon 7050, Epiclon HM-091, Epiclon HM-101, Epiclon N-730A, Epiclon N-740, Epiclon N-770, Epiclon N-775, Epiclon N-865, Epiclon HP-4032D, Epiclon HP-7200L, Epiclon HP-7200, Epiclon HP-7200H, Epiclon HP-7200HH, Epiclon HP-7200HHH, Epiclon HP-4700, Epiclon HP-4710, Epiclon HP-4770, Epiclon HP-5000, and Epiclon HP-6000, N500P-2, and N500P-10 (all product names manufactured by DIC Corporation); NC-3000, NC-3000-L, NC-3000-H, NC-310 0, CER-3000-L, NC-2000-L, XD-1000, NC-7000-L, NC-7300-L, EPPN-501H, EPPN-501HY, EPPN-50 Examples include 2H, EOCN-1020, EOCN-102S, EOCN-103S, EOCN-104S, CER-1020, EPPN-201, BREN-S, and BREN-10S (all product names manufactured by Nippon Kayaku Co., Ltd.); and YX-4000, YX-4000H, YL4121H, and YX-8800 (all product names manufactured by Mitsubishi Chemical Corporation).

[0031] The resin composition may contain one of the epoxy resins listed above. The resin composition may contain multiple types of epoxy resins listed above. Among the epoxy resins listed above, the resin composition may contain an epoxy resin containing a biphenyl skeleton, an orthocresol novolac type epoxy resin, or a polyfunctional epoxy resin containing two or more epoxy groups.

[0032] Curing agents are classified into two types: those that cure epoxy resins in a low temperature to room temperature range, and heat-curing curing agents that cure epoxy resins upon heating. Examples of curing agents that cure epoxy resins in a low temperature to room temperature range include aliphatic polyamines, polyaminoamides, and polymercaptans. Examples of heat-curing curing agents include aromatic polyamines, acid anhydrides, phenol novolac resins, and dicyandiamide (DICY). The type of curing agent is not particularly limited and can be selected according to the desired properties of the composition.

[0033] When a curing agent is used that cures epoxy resin in the range of low temperatures to room temperature, the glass transition point of the cured epoxy resin is low, and the cured epoxy resin tends to be soft. As a result, the molded article formed from the compound also tends to be soft. On the other hand, from the viewpoint of improving the heat resistance of the molded article, the curing agent may preferably be a heat-curing type curing agent, more preferably a phenolic resin, and even more preferably a phenol novolac resin. In particular, by using a phenol novolac resin as the curing agent, it is easier to obtain a cured epoxy resin with a high glass transition point. As a result, the heat resistance and mechanical strength of the molded article are easily improved.

[0034] The phenolic resin may include, for example, at least one selected from the group consisting of aralkyl phenolic resin, dicyclopentadiene phenolic resin, salicylaldehyde phenolic resin, novolac phenolic resin, copolymer phenolic resin of benzaldehyde phenol and aralkyl phenolic resin, paraxylylene and / or metaxylylene modified phenolic resin, melamine modified phenolic resin, terpene modified phenolic resin, dicyclopentadiene naphthol resin, cyclopentadiene modified phenolic resin, polycyclic aromatic ring modified phenolic resin, biphenyl phenolic resin, and triphenylmethane phenolic resin. The phenolic resin may also be a copolymer composed of two or more of the above. As commercially available phenolic resins, for example, Tamanol 758 manufactured by Arakawa Chemical Industries, Ltd. and HP-850N manufactured by Showa Denko Materials K.K. may be used.

[0035] The phenol novolac resin may be a resin obtained by condensing or co-condensing phenols and / or naphthols with aldehydes under an acidic catalyst. The phenols constituting the phenol novolac resin may include, for example, at least one selected from the group consisting of phenol, cresol, xylenol, resorcinol, catechol, bisphenol A, bisphenol F, phenylphenol, and aminophenol. The naphthols constituting the phenol novolac resin may include, for example, at least one selected from the group consisting of α-naphthol, β-naphthol, and dihydroxynaphthalene. The aldehydes constituting the phenol novolac resin may include, for example, at least one selected from the group consisting of formaldehyde, acetaldehyde, propionaldehyde, benzaldehyde, and salicylaldehyde.

[0036] The curing agent may be, for example, a compound having two phenolic hydroxyl groups in one molecule. The compound having two phenolic hydroxyl groups in one molecule may include, for example, at least one selected from the group consisting of resorcinol, catechol, bisphenol A, bisphenol F, and substituted or unsubstituted biphenols.

[0037] The resin composition may contain one of the above-mentioned phenolic resins. The resin composition may comprise multiple of the above-mentioned phenolic resins. The resin composition may contain one of the above-mentioned curing agents. The resin composition may comprise multiple of the above-mentioned curing agents.

[0038] The ratio of active groups (phenolic OH groups) in the curing agent that react with epoxy groups in the epoxy resin is preferably 0.5 to 1.5 equivalents, more preferably 0.6 to 1.4 equivalents, and even more preferably 0.7 to 1.2 equivalents per equivalent of epoxy groups in the epoxy resin. If the ratio of active groups in the curing agent is less than 0.5 equivalents, it is difficult to obtain a sufficient elastic modulus of the resulting cured product. On the other hand, if the ratio of active groups in the curing agent exceeds 1.5 equivalents, the mechanical strength of the molded article formed from the compound tends to decrease after curing. However, even if the ratio of active groups in the curing agent is outside the above range, the effects of the present invention can still be obtained.

[0039] The resin composition may further contain a curing accelerator (catalyst) to improve the moldability and release properties of the compound. The inclusion of a curing accelerator in the resin composition improves the mechanical strength of molded articles (e.g., electronic components) produced using the compound, and improves the storage stability of the compound in high-temperature and high-humidity environments. The curing accelerator is not limited to any composition that reacts with the epoxy resin to accelerate its curing. The curing accelerator may be, for example, a phosphorus-based curing accelerator, an imidazole-based curing accelerator, or a urea-based curing accelerator.

[0040] Examples of phosphorus-based curing accelerators include phosphine compounds and phosphonium salt compounds.

[0041] Examples of commercially available imidazole-based curing accelerators include 2MZ-H, C11Z, C17Z, 1,2DMZ, 2E4MZ, 2PZ-PW, 2P4MZ, 1B2MZ, 1B2PZ, 2MZ-CN, C11Z-CN, 2E4MZ-CN, 2PZ-CN, C11Z-CNS, 2P4MHZ, TPZ, and SFZ (all are product names manufactured by Shikoku Chemicals, Inc.).

[0042] While the urea-based curing accelerator is not particularly limited as long as it has a urea group, it is preferable to use an alkylurea-based curing accelerator having an alkylurea group from the viewpoint of improving storage stability. Examples of alkylurea-based curing accelerators having an alkylurea group include aromatic alkylureas and aliphatic alkylureas. Examples of commercially available alkylurea-based curing accelerators include U-CAT3512T (trade name, manufactured by Sunapro Co., Ltd., aromatic dimethylurea) and U-CAT3513N (trade name, manufactured by Sunapro Co., Ltd., aliphatic dimethylurea). Among these, aromatic alkylureas are preferred because they have a moderately low cleavage temperature and can efficiently cure compounds.

[0043] The amount of curing accelerator added is not particularly limited, as long as it is an amount that provides a curing acceleration effect. From the viewpoint of improving the curability and fluidity of the resin composition when it absorbs moisture, the amount of curing accelerator added may be 0.1 parts by mass or more and 20 parts by mass or less, 1 part by mass or more and 15 parts by mass or less, or 2 parts by mass or more and 10 parts by mass or less, per 100 parts by mass of epoxy resin. When the amount of curing accelerator added is 0.1 parts by mass or more, a sufficient curing acceleration effect is easily obtained. When the amount of curing accelerator added is 20 parts by mass or less, the storage stability of the compound is less likely to decrease.

[0044] The resin composition may further contain a coupling agent. The coupling agent can improve the adhesion between the resin composition and the metal element-containing particles constituting the magnetic powder, thereby improving the flexibility and mechanical strength of the molded body (such as an inductor) formed from the compound. The coupling agent may be at least one selected from the group consisting of, for example, silane compounds (silane coupling agents), titanium compounds, aluminum compounds (aluminum chelates), and aluminum / zirconium compounds. The silane coupling agent may be at least one selected from the group consisting of, for example, epoxysilane compounds, mercaptosilane compounds, aminosilane compounds, alkylsilane compounds, acrylicsilane compounds, methacrylicsilane compounds, ureidosilane compounds, acid anhydride silane compounds, and vinylsilane compounds. The compound may contain one of the above coupling agents, or it may contain multiple of the above coupling agents.

[0045] The content of the coupling agent in the compound according to this embodiment may be preferably 0.05 to 0.70% by mass, more preferably 0.10 to 0.60% by mass, and even more preferably 0.12 to 0.50% by mass, based on the total mass of the compound. When the content of the coupling agent is above the lower limit, the flexibility and mechanical strength of the molded article are more easily improved. When the content of the coupling agent is below the upper limit, the compound is less likely to block. However, even when the content of the coupling agent is outside the above range, the effects of the present invention can still be obtained.

[0046] The resin composition may contain a compound having a siloxane bond (siloxane compound) as an additive, as this easily reduces the molding shrinkage rate of the compound and improves the heat resistance and voltage resistance of the molded article. A siloxane bond is a bond containing two silicon atoms (Si) and one oxygen atom (O), and may be represented as -Si-O-Si-. The compound having a siloxane bond may be a polysiloxane compound.

[0047] When forming a molded product from a compound using a mold, the resin composition may contain wax. The wax enhances the fluidity of the compound during molding (compression molding or transfer molding) and also functions as a release agent. The wax may be at least one of fatty acids such as higher fatty acids and fatty acid esters.

[0048] Waxes include, for example, fatty acids such as montanic acid, stearic acid, 12-oxystearic acid, lauric acid, or esters thereof; fatty acid salts such as zinc stearate, calcium stearate, barium stearate, aluminum stearate, magnesium stearate, calcium laurate, zinc linoleate, calcium ricinoleate, and zinc 2-ethylhexoate; stearamide, oleamide, erucamide, behenamide, palmitamide, lauamide, hydroxystearamide, methylenebisstearateamide, ethylenebisstearateamide, ethylenebislaurateamide, distearyl adipic acid amide, ethylenebisoleamide, dioleyl adipic acid amide, N-stearyl stearate It may be at least one selected from the group consisting of: fatty acid amides such as mid, N-oleyl stearate amide, N-stearyl erucate amide, methylol stearate amide, and methylol behenate amide; fatty acid esters such as butyl stearate; alcohols such as ethylene glycol and stearyl alcohol; polyethers consisting of polyethylene glycol, polypropylene glycol, polytetramethylene glycol and modified products thereof; polysiloxanes such as silicone oil and silicone grease; fluorine compounds such as fluorine-based oils, fluorine-based greases, and fluorine-containing resin powders; and waxes such as paraffin wax, polyethylene wax, amide wax, polypropylene wax, ester wax, carnauba wax, and microwax.

[0049] For environmental safety, recyclability, moldability, and low cost, the compound may contain a flame retardant. The flame retardant may be at least one selected from the group consisting of, for example, brominated flame retardants, phosphorus-based flame retardants, hydrated metal compound-based flame retardants, silicone-based flame retardants, nitrogen-containing compounds, hindered amine compounds, organometallic compounds, and aromatic engineering plastics. The resin composition may contain one of the above flame retardants, or may contain multiple of the above flame retardants.

[0050] When preparing the compound, the magnetic powder and the resin composition (each component constituting the resin composition) are mixed while being heated. For example, the magnetic powder and the resin composition may be kneaded using a kneader, roll, or agitator while being heated. By heating and mixing the magnetic powder and the resin composition, the resin composition adheres to part or all of the surface of the metal element-containing particles constituting the magnetic powder, coating the metal element-containing particles, and part or all of the resin in the resin composition becomes a semi-cured material. As a result, a compound is obtained. Alternatively, a compound may be obtained by further adding wax to the powder obtained by heating and mixing the magnetic powder and the resin composition. The resin composition and wax may be mixed beforehand.

[0051] In the mixing process, magnetic powder, resin, curing agent, curing accelerator, and coupling agent may be mixed in the tank. Alternatively, the magnetic powder and coupling agent may be added to the tank and mixed, then the resin, curing agent, and curing accelerator may be added to the tank and the raw materials in the tank may be mixed. Alternatively, the resin, curing agent, and coupling agent may be mixed in the tank, then the curing accelerator may be added to the tank and the raw materials in the tank may be mixed further. Alternatively, a mixed powder of resin, curing agent, and curing accelerator (resin mixed powder) may be prepared in advance, then the magnetic powder and coupling agent may be mixed to prepare a metal mixed powder, and then the metal mixed powder and resin mixed powder may be mixed.

[0052] The mixing time depends on the type of mixing machine, the volume of the mixing machine, and the amount of compound to be produced, but for example, it is preferably 1 minute or more, more preferably 2 minutes or more, and even more preferably 3 minutes or more. The mixing time is preferably 20 minutes or less, more preferably 15 minutes or less, and even more preferably 10 minutes or less. If the mixing time is less than 1 minute, mixing is insufficient, the moldability of the compound is impaired, and variations in the degree of hardening of the compound occur. If the mixing time exceeds 20 minutes, for example, the hardening of the resin composition (e.g., epoxy resin and phenolic resin) progresses in the tank, and the fluidity and moldability of the compound are easily impaired.

[0053] When kneading the raw materials in the tank with a kneader while heating them, the heating temperature should be, for example, a temperature at which a semi-cured resin (stage B resin) is formed and the formation of a fully cured resin (stage C resin) is suppressed. The heating temperature may be lower than the activation temperature of the curing accelerator. The heating temperature is preferably 50°C or higher, more preferably 60°C or higher, and even more preferably 70°C or higher. The heating temperature is preferably 150°C or lower, more preferably 120°C or lower, and even more preferably 110°C or lower. When the heating temperature is within the above range, the resin composition in the tank softens easily and coats the surface of the metal element-containing particles constituting the magnetic powder, a semi-cured resin is easily formed, and the complete curing of the resin during kneading is easily suppressed.

[0054] The method for manufacturing a molded article according to this embodiment includes a step of obtaining a molded article by molding the compound described above using a release film by compression molding or transfer molding. By molding the compound described above using a release film, the dielectric strength of the obtained molded article can be improved, and the generation of leakage current can be suppressed. It was previously unknown and unexpected that using a release film not only improves the release properties of the molded article but also improves the dielectric strength and leakage current suppression of the molded article. The reason for these effects is not clear, but it is thought that the surface state of the molded article changes when a release film is used. For example, when a release film is used, magnetic powder is less likely to be exposed on the surface of the molded article, and it is presumed that this improves the dielectric strength and leakage current suppression.

[0055] The release film used in the method for manufacturing a molded article according to this embodiment may have a support substrate and a release layer formed on the support substrate.

[0056] In the method for manufacturing a molded article according to this embodiment, the release film is adsorbed onto the mold, so the release film is required to have excellent conformability to the shape of the mold. By using a resin with excellent stretchability as the support base material of the release film, the conformability to the mold can be further improved.

[0057] From the viewpoint of heat resistance, it is preferable that the supporting substrate has a melting point equal to or higher than the molding temperature (e.g., 100-200°C). Furthermore, in order to suppress the occurrence of tears in the release film when attaching it to the mold and during molding, and to suppress the occurrence of wrinkles in the molded product after molding, it is preferable to select the supporting substrate considering the elastic modulus and elongation at high temperatures.

[0058] As the support substrate, a commercially available resin film that has not undergone mold release treatment can be used. The resin component constituting the resin film may be at least one selected from the group consisting of polyester resin, polyimide resin, polyolefin resin, and fluorine-containing resin. From the viewpoint of heat resistance and elastic modulus at high temperatures, polyester resin is preferred as the resin component constituting the resin film. Examples of polyester resins include polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, copolymers thereof, and resins modified therefrom. The support substrate is preferably a polyester film formed from polyester resin into a sheet, and from the viewpoint of conformability to the mold, a biaxially oriented polyester film is more preferable.

[0059] The thickness of the support substrate is not particularly limited, but is preferably 5 μm to 100 μm, more preferably 10 μm to 70 μm, and even more preferably 15 μm to 50 μm. When the thickness of the support substrate is 5 μm or more, it is easy to handle and tends to be less prone to wrinkles, and when the thickness is 100 μm or less, it is easy to follow the mold during molding, so the occurrence of wrinkles and the like in the formed molded article tends to be suppressed.

[0060] The release layer can be prepared, for example, by applying a release agent to a support substrate and drying it. The release agent is not particularly limited and can be appropriately selected from release agents used in the art.

[0061] Examples of release agents include silicone-based release agents, fluorine-based release agents, polyolefin-based release agents, and alkyd resin-based release agents. From the viewpoint of being able to form a cross-linked structure in the release layer, it is preferable that the release agent be of the thermosetting type. Among thermosetting release agents, those containing amino alkyd resins are preferable. Examples of commercially available release agents include the product names "Tesfine 303" and "Tesfine 314" manufactured by Showa Denko Materials Co., Ltd. It is also possible to add lubricants, antistatic agents, etc. to the release agent as needed.

[0062] The thickness of the release layer is not particularly limited, but from the viewpoint of better release properties and suppression of wrinkles during molding, it is preferably 0.01 μm to 1 μm, more preferably 0.05 μm to 0.8 μm, and even more preferably 0.1 μm to 0.5 μm.

[0063] Furthermore, the surface of the support substrate that contacts the mold may be adjusted to facilitate release from the mold after molding. For example, the surface of the support substrate that contacts the mold may be given a textured finish or a separate release layer may be provided in addition to the existing release layer. The material constituting the release layer is not particularly limited as long as it satisfies the requirements of heat resistance, release from the mold, etc. The thickness of the release layer in this case is not particularly limited, but is preferably 0.01 μm to 1 μm. In addition, if necessary, layers such as an anchoring improvement layer for the release layer, an antistatic layer, or a colored layer may be provided between the release layer and the support substrate.

[0064] The release film preferably has an arithmetic mean roughness Ra of 0.1 to 20 μm and a maximum height Rz of 1 to 300 μm on the surface that comes into contact with the compound (e.g., the surface of the release layer). By having the arithmetic mean roughness Ra and maximum height Rz within the above ranges, the dielectric strength of the resulting molded article can be further improved, and the generation of leakage current can be further suppressed. From the viewpoint of obtaining the above effects to the fullest extent, an arithmetic mean roughness Ra of 0.2 to 10 μm is more preferable. From a similar viewpoint, a maximum height Rz of 5 to 250 μm is more preferable. In this specification, the arithmetic mean roughness Ra and maximum height Rz refer to values ​​measured in accordance with JIS B0601-2001.

[0065] Figure 1 is a schematic cross-sectional view showing a method for manufacturing a molded article according to this embodiment. Figure 1 shows a method for manufacturing a molded article by compression molding. The mold used in the compression molding method consists of a first mold 10 and a second mold 20, as shown in Figure 1(a). The second mold 20 is the part in which the inductor element 3 is placed and has a flat surface. The first mold 10 is the part in which the release film 1 is placed and has a recess.

[0066] First, as shown in Figure 1(b), the release film is attached to the first mold 10 along the recess so that the support substrate for the release film is in contact with the first mold 10. The first mold 10 is provided with a suction mechanism (such as vacuum suction), and the release film is held by suction to the first mold 10. Next, as shown in Figure 1(c), the inductor element 3 is attached to the second mold 20. The second mold 20 may also be provided with a suction mechanism (such as vacuum suction), and the inductor element 3 may be held by suction to the second mold 20.

[0067] Next, as shown in Figure 1(d), the compound 5 is placed on the inductor element 3. The compound 5 is positioned to face the recess of the first mold 10. Then, as shown in Figure 1(e), the first mold 10 and the second mold 20 are joined together, and the compound 5 is pressurized, compressed, and heated. As a result, the compound 5 hardens into a shape that conforms to the recess of the first mold 10, forming a molded body 7 and sealing the inductor element 3. From the viewpoint of ease of operation, the mold temperature during compression molding is preferably 100 to 200°C, the molding pressure is preferably 0.5 to 20 MPa, and the molding time is preferably 60 to 600 seconds.

[0068] After the molded body 7 is formed, the first mold 10 is separated from the second mold 20, as shown in Figure 1(f). Subsequently, the molded body 7 may be heat-treated (post-cured) to sufficiently harden it. The heat treatment temperature should be such that the resin composition in the molded body hardens sufficiently. The heat treatment temperature is preferably 100°C to 300°C, more preferably 110°C to 250°C. To suppress the oxidation of the magnetic powder in the molded body 7, it is preferable to perform the heat treatment in an inert atmosphere. If the heat treatment temperature exceeds 300°C, the magnetic powder may be oxidized or the resin cured product may deteriorate due to the trace amounts of oxygen inevitably contained in the heat treatment atmosphere. In order to sufficiently harden the resin composition while suppressing the oxidation of the magnetic powder and the deterioration of the resin cured product, the holding time of the heat treatment temperature may preferably be several minutes to 10 hours, more preferably 3 minutes to 8 hours.

[0069] Through the above process, a molded body 7 is formed, and a semiconductor device is obtained that comprises an inductor element 3 and a molded body 7 that seals the inductor element.

[0070] The resulting molded article 7 may contain the above-mentioned compound. The molded article 7 may also contain a cured product of the above-mentioned compound. The molded article 7 may contain at least one selected from the group consisting of an uncured resin composition, a semi-cured product of the resin composition (B-stage resin composition), and a cured product of the resin composition (C-stage resin composition).

[0071] Although preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments.

[0072] Figure 1 shows the case where the inductor element 3 and compound 5 are placed on the flat surface of the second mold 20. However, the arrangement of the first mold 10 and the second mold 20 in Figure 1(c) may be swapped so that the first mold 10 is placed below, and the compound 5 is placed in the recess on the release film 1 attached to the first mold 10 to perform molding.

[0073] The molded body 7 may be provided so as to completely cover the entire inductor element 3. The inductor element 3 may also be a silicon wafer, a substrate, a lead frame, a semiconductor package, etc.

[0074] Furthermore, although Figure 1 shows a method for manufacturing a molded body by compression molding, the molded body may also be manufactured by transfer molding.

[0075] Figure 2 is a schematic cross-sectional view showing the method for manufacturing a molded body according to this embodiment. Figure 2 shows a method for manufacturing a molded body by transfer molding. When manufacturing a molded body by transfer molding, as shown in Figures 2(a) to (c), a compound 5 is injected under pressure using a plunger 30 into the cavity between a first mold 10 on which a release film 1 is placed and a second mold 20. Then, as shown in Figure 2(c), a molded body 7 is formed by curing the compound 5, and a semiconductor device comprising an inductor element 3 and a molded body 7 that seals the inductor element is obtained. From the viewpoint of ease of work, the mold temperature during transfer molding is preferably 100 to 200°C, the molding pressure is preferably 0.5 to 20 MPa, and the molding time is preferably 60 to 600 seconds. In addition, in order to sufficiently cure the molded body 7, the molded body 7 may be heat-treated (post-cured) in the same manner as in compression molding. When manufacturing a molded body by transfer molding, the embodiment is not limited to the embodiment shown in Figure 2, and the same modifications as in compression molding may be made. [Examples]

[0076] The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way by these examples.

[0077] The details of each component used in the preparation of the compounds in the examples and comparative examples are shown below.

[0078] <Resin composition> Epoxy resin 1 (Biphenylene aralkyl type epoxy resin, manufactured by Nippon Kayaku Co., Ltd., product name: NC-3000, epoxy equivalent: 275 g / eq) Epoxy resin 2 (Multifunctional epoxy resin, product name: TECHMORE VG-3101L, manufactured by Printec Co., Ltd., epoxy equivalent: 215g / eq) Epoxy resin 3 (cresol novolac type epoxy resin, product name: N500P-2, manufactured by DIC Corporation, epoxy equivalent: 200g / eq)

[0079] Hardener 1 (Phenol novolac resin, product name: HF-3M, manufactured by Meiwa Chemicals Co., Ltd., hydroxyl group equivalent: 107 g / eq) Hardening agent 2 (Biphenylene aralkyl type phenolic resin, product name: MEHC7841-4S, manufactured by Meiwa Kasei Co., Ltd., hydroxyl group equivalent: 166 g / eq) Hardener 3 (Triphenylmethane-type phenolic resin, product name: HE910-09, manufactured by Air Water Inc., hydroxyl group equivalent: 101 g / eq)

[0080] Curing accelerator (triphenylphosphine) Coupling agent (methacryloxyoctyltrimethoxysilane, product name: KBM-5803, manufactured by Shin-Etsu Chemical Co., Ltd.) Release agent (partially saponified montanate wax, product name: Licowax-OP, manufactured by Clariant Chemicals Co., Ltd.)

[0081] <Magnetic powder> Magnetic powder 1 (amorphous iron powder, product name: 9A4-II, manufactured by Epson Atomics Corporation, average particle size: 24 μm) Magnetic powder 2 (FeSiCr alloy powder, manufactured by Shinto Kogyo Co., Ltd., average particle size: 2.1 μm)

[0082] [Examples 1-6 and Comparative Examples 1-6] (Compound preparation) The epoxy resin, curing agent, curing accelerator, and release agent in the amounts (in grams) shown in Tables 1 and 2 were placed in a plastic container. A resin mixture was prepared by mixing these materials in the plastic container for 10 minutes. The resin mixture represents all components of the resin composition except for the coupling agent.

[0083] Magnetic powder in the amounts (in g) shown in Tables 1 and 2 was mixed for 5 minutes in a pressurized twin-screw kneader (manufactured by Nippon Spindle Manufacturing Co., Ltd., 5L capacity), and then the coupling agents shown in Tables 1 and 2 were added to the twin-screw kneader. Subsequently, the contents of the twin-screw kneader were heated to 90°C, and while maintaining that temperature, the contents of the twin-screw kneader were mixed for 10 minutes. Next, the above resin mixture was added to the contents of the twin-screw kneader, and while maintaining the temperature of the contents at 120°C, the contents were melted and kneaded for 15 minutes. After the kneaded material obtained from the above melting and kneading was cooled to room temperature, the kneaded material was crushed with a hammer until it had the desired particle size. Note that "melting" above means the melting of at least a portion of the resin composition in the contents of the twin-screw kneader. The magnetic powder in the compound does not melt during the compound preparation process. Compounds for the examples and comparative examples were prepared by the above method. Tables 1 and 2 show the magnetic powder content based on the total amount of compound.

[0084] (Preparing the release film) The following release films 1-3 were prepared. The arithmetic mean roughness Ra and maximum height Rz are values ​​for the surface that comes into contact with the compound. Release film 1 (Product name: AFlex, manufactured by AGC Inc.; Arithmetic mean roughness Ra: 14.2 μm; Maximum height Rz: 128 μm; Thickness: 50 μm; Film composition: Fluorine resin) Release film 2 (Product name: RM-4100, manufactured by Showa Denko Materials Co., Ltd.; Arithmetic mean roughness Ra: 1.6 μm; Maximum height Rz: 28.8 μm; Thickness: 40 μm; Film composition: PET resin) Release film 3 (Product name: RM4200, manufactured by Showa Denko Materials Co., Ltd.; Arithmetic mean roughness Ra: 8.2 μm; Maximum height Rz: 113 μm; Thickness: 50 μm; Film composition: PET resin)

[0085] (Fabrication of molded parts) As shown in Figure 1(a), a first mold 10 having a recess and a second mold 20 having a flat surface were prepared for compression molding. In the example, as shown in Figure 1(b), release films 1 to 3 were placed on the first mold 10 and fixed in place under vacuum along the recess. In the comparative example, no release film was placed on the first mold 10. Next, compound 5 was placed on the second mold 20. Subsequently, the first mold 10 and the second mold 20 were clamped together, and the compound 5 was molded and cured to form a molded body 7 under the conditions of a mold temperature of 175°C, a molding pressure of 12 MPa, and a molding time of 180 seconds. After that, the first mold 10 was separated from the second mold 20, and post-curing was performed at 175°C for 5.5 hours to obtain a disc-shaped test piece with a diameter of 50 mm and a thickness of 2.0 mm.

[0086] [Evaluation of molded products] (Withstand voltage) For the withstand voltage test, a stainless steel plate with a ground wire connected, a conductive rubber plate, a test specimen, and a 10mm diameter stainless steel electrode with a high-voltage wire connected were arranged in that order on an insulating board. The high-voltage wire and ground wire were connected to the high-voltage output terminal and ground terminal of the high-voltage amplifier, respectively. The waveform output of the function generator was input to the high-voltage amplifier to generate a test voltage that was boosted from 0V to a maximum of 2000V at a rate of 10V per second, and applied to the test specimen. The voltage was read when the current passing through the test specimen exceeded 10mA. Next, stainless steel electrodes were placed at different positions on the test specimen, and the voltage was applied in the same manner. The test was repeated 7 times, and the average value of the voltages read was taken as the withstand voltage (dielectric breakdown voltage: V / mm) of the test specimen. The above test was performed on two test specimens, and the average withstand voltage of the two test specimens was calculated.

[0087] (Number of insulators (leakage current suppression)) To confirm the effect of suppressing leakage current, the following evaluation was performed. Specifically, in the above withstand voltage test, it was checked whether the leakage current value could be maintained at 0.25 mA or less until dielectric breakdown occurred. This check was performed on 14 test pieces, and the number and percentage of pieces that maintained a leakage current value of 0.25 mA or less were determined.

[0088] [Table 1]

[0089] [Table 2] [Explanation of Symbols]

[0090] 1…Release film, 3…Inductor element, 5…Compound, 7…Molded body, 10…First mold, 20…Second mold.

Claims

1. The process includes a step of obtaining a molded body by compression molding a compound containing resin and magnetic powder using a mold on which a release film is placed, under conditions of a mold temperature of 100 to 200°C and a molding pressure of 0.5 to 20 MPa. The aforementioned resin includes an epoxy resin, A method for producing a molded article, wherein the epoxy resin comprises a cresol novolac type epoxy resin.

2. A step of obtaining a molded body by compression molding a compound containing resin and magnetic powder using a mold on which a release film is placed, under the conditions that the mold temperature is 100 to 200°C and the molding pressure is 0.5 to 20 MPa, The material of the aforementioned release film contains polyester resin, A method for manufacturing a molded article, wherein the arithmetic mean roughness Ra of the surface of the release film that comes into contact with the compound is 8.2 to 10 μm, and the maximum height Rz is 113 to 300 μm.

3. The process includes a step of obtaining a molded body by transfer molding a compound containing resin and magnetic powder using a mold on which a release film is placed, under conditions of a mold temperature of 100 to 200°C and a molding pressure of 0.5 to 20 MPa. The aforementioned resin includes an epoxy resin, A method for producing a molded article, wherein the epoxy resin comprises a cresol novolac type epoxy resin.

4. A step of obtaining a molded body by transfer molding a compound containing resin and magnetic powder using a mold on which a release film is placed, under the conditions that the mold temperature is 100 to 200°C and the molding pressure is 0.5 to 20 MPa, The material of the aforementioned release film contains polyester resin, A method for manufacturing a molded article, wherein the arithmetic mean roughness Ra of the surface of the release film that comes into contact with the compound is 8.2 to 10 μm, and the maximum height Rz is 113 to 300 μm.

5. The method for producing a molded article according to claim 1 or 3, wherein the resin comprises a biphenylene aralkyl type phenolic resin.

6. The method for producing a molded article according to claim 2 or 4, wherein the resin comprises at least one selected from the group consisting of epoxy resins and phenolic resins.

7. The method for producing a molded article according to claim 2 or 4, wherein the resin comprises at least one selected from the group consisting of biphenylene aralkyl type epoxy resins and biphenylene aralkyl type phenolic resins.

8. The method for manufacturing a molded article according to any one of claims 1 to 7, wherein the magnetic powder includes at least one selected from the group consisting of Fe-based amorphous alloys and Fe-based crystalline alloys.

9. A method for manufacturing a molded article according to any one of claims 1 to 8, wherein the content of the magnetic powder in the compound is 60 to 98% by mass based on the total amount of the compound.

10. A method for manufacturing a molded article according to any one of claims 1 to 9, wherein the average particle size of the magnetic powder is 0.1 to 50 μm.

11. The method for manufacturing a molded article according to any one of claims 1 to 10, wherein the magnetic powder comprises two types: magnetic powder with an average particle size of 10 to 50 μm and magnetic powder with an average particle size of 0.1 to 10 μm.

12. The method for producing a molded article according to claim 1 or 3, wherein the material of the release film includes at least one selected from the group consisting of polyester resin, polyimide resin, polyolefin resin, and fluorine-containing resin.

13. The method for manufacturing a molded article according to claim 1 or 3, wherein the arithmetic mean roughness Ra of the surface of the release film that is in contact with the compound is 0.1 to 20 μm, and the maximum height Rz is 1 to 300 μm.

14. The method for manufacturing a molded article according to any one of claims 1 to 13, wherein the molded article seals an inductor element.

15. A method for manufacturing a semiconductor device comprising an inductor element and a molded body that seals the inductor element, A method for manufacturing a semiconductor device, comprising the step of forming the molded body by the method for manufacturing a molded body described in any one of claims 1 to 14.

Images