JP2000100628A - Inductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inductor having a high Q-value, high self-resonance frequency, low resistance and low cost by using a dielectric resin and a conductive wire formed like a coil in the dielectric resin made of a dielectric polymer material having a specified specific dielectric constant and decomposition temperature. SOLUTION: The inductor has a dielectric resin and a conductive wire formed like a coil in the dielectric resin which is a dielectric polymer material having a specific dielectric constant of 3.0 or less and a decomposition temperature of 290 deg.C or more. The dielectric resin is obtained by polymerizing a monomer composition, preferably containing a diester fumarate as a monomer. The diester fumarate is shown by the formula (R1 is alkyl group or cycloalkyl group, R2 is alkyl group, cycloalkyl group or aryl group, and R1 and R2 may be same or different).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface mount type chip inductor used for a mobile communication device such as a portable telephone, and more particularly, to a chip inductor using a novel low dielectric polymer material. .

[0002]

2. Description of the Related Art In recent years, with the rapid increase in the amount of communication information, there has been a strong demand for smaller, lighter, and faster communication devices, and electronic devices capable of responding to such demands. In particular, the frequency band of radio waves used for portable mobile communications such as automobile telephones and digital portable telephones, and satellite communications has a high frequency band of mega to giga band. With the rapid development of communication devices used as these communication means, small-sized, high-density mounting of housings, substrates, and electronic elements has been attempted. In order to reduce the size and weight of a communication device compatible with a high frequency range such as the megahertz to gigahertz band, it is necessary to develop an inductor having both a high Q and a high self-resonant frequency (SRF).

FIG. 7 shows a configuration example of a conventional chip inductor. The inductor 21 in the illustrated example has a conductor 23 formed in a coil shape in a dielectric ceramic 22, and has terminals 24 connected to the conductor 23 at both ends. This inductor can be obtained by alternately laminating and printing low-temperature sintered ceramic sheets and conductor paste. The relative dielectric constant of such a multilayer inductor is about 4 to 5. Multilayer inductors are very small,
It is widely used because it has a relatively large inductance value and is excellent in mass productivity.

However, since the Q value is low and the self-resonance frequency is low, it is not suitable as an inductor in a wireless device having a high operating frequency such as a portable telephone. This is because the conductor is formed by a sintering method, the conductivity is lower than that of bulk metal, the dielectric constant of the dielectric supporting the conductor is large, and the strip-shaped conductors face each other over a wide area. This causes the stray capacitance between the windings to increase.

In the Japanese Patent Application No. 8-345241, the present inventors were able to obtain good characteristics by forming a coil of an edgewise metal conductor in a resin dielectric. However, 1608 type (length: 1.6mm, width: 0.8m
m), 1005 type (vertical: 1.0 mm, horizontal: 0.5 mm), and even small type coils such as 0603 type (vertical: 0.6 mm, horizontal: 0.3 mm), have a sufficient coil diameter. Is difficult to do. Further, it is difficult to change the shape of the die for forming the edgewise type coil by changing the setting, which is not suitable for multi-product production.

Further, as described in Japanese Patent Publication No. 62-8924, for example, a conductor layer is provided on the outer periphery of a cylindrical insulator, and this conductor layer is spirally cut to form an inductance element. Methods are also being considered. However, since the conductor of the inductance element described in this publication is formed by plating, the conductor resistance is higher than that of the winding and the loss increases. Further, since a cutting process is required in the manufacturing process, mass productivity is poor, and the cost per product increases.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to make use of low dielectric properties, to have a high Q, a high self-resonant frequency, a low resistance, and a heat resistance that can withstand a high temperature reflow furnace. Moreover, it is to realize a low-cost inductor.

[0008]

Conventionally, many resins, including glass epoxy resins, have been developed as casting resins for high-frequency components. However, these resins have a dielectric loss tangent (tan δ) at a high frequency of 0.03 to 0.0
5, which was below 0.001 of ceramics.

However, in recent years, the present applicant has filed Japanese Patent Application No. 8-4.
No. 2073, a fumarate-based resin has been developed, and an attempt has been made by the present inventors to use the resin as a casting resin, and have reached the present invention.

That is, the fumarate resin has a relative dielectric constant (εr) of 2 to 3 and a dielectric loss tangent (tan δ) of 0.002 or less, and is excellent in castability and can be cast at room temperature. Normal metals can be used. Therefore, an inductor having a low conductor resistance and a high Q can be obtained as compared with the metal paste used for the ceramic sintered body inductor. Further, the dielectric constant of the fumarate resin impregnating the formed coil is low, and the interval between adjacent wires can be increased, so that the self-resonant frequency can be made higher than that of the conventional one.

Further, since the fumarate resin has a good heat resistance and a decomposition temperature of 290 ° C. or higher, it can be used in a high temperature solder reflow furnace. In particular, since lead will be removed from the solder material in the future, there is a great merit that it can cope with lead-free solder reflow having a high melting temperature. Furthermore, since the temperature of the reflow furnace is equal to or higher than the annealing temperature of metallic copper, copper hardened by stress caused by machining during forming is softened by heating in the reflow furnace (softening temperature: 210).
° C), the effect of lowering the conductor resistance and further increasing the Q value can also be expected. This is a characteristic when a bulk metal is used for the conductor, and such an effect cannot be expected in a chip inductor made of sintered copper.

In addition, according to the resin molding, almost no phenomena such as distortion or peeling of the element body, which are often observed in ceramic sintered elements or the like, occur.

That is, the above-mentioned object is achieved by the following constitutions. (1) It has a dielectric resin and a conductor wire formed in a coil shape in the dielectric resin, wherein the dielectric resin comprises:
An inductor which is a dielectric polymer material having a relative dielectric constant of 3.0 or less and a decomposition temperature of 290 ° C. or more. (2) The inductor according to the above (1), wherein the dielectric polymer material is obtained by polymerizing a monomer composition containing at least a fumaric acid diester as a monomer. (3) The inductor according to the above (1) or (2), wherein the fumaric diester is represented by the following formula (I).

[0014]

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[In the formula (I), R ¹ represents an alkyl group or a cycloalkyl group, R ² represents an alkyl group, a cycloalkyl group or an aryl group, and R ¹ and R ²
May be the same or different. (4) The inductor according to any one of (1) to (3), wherein the monomer composition further contains a vinyl-based monomer represented by the following formula (II).

[0016]

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[In the formula (II), X represents a hydrogen atom or a methyl group, and Y represents a fluorine atom, a chlorine atom, an alkyl group, an alkenyl group, an aryl group, an ether group, an acyl group or an ester group. (5) The inductor according to any one of the above (1) to (4), wherein the conductor wire is mainly composed of copper and is formed of a metal conductive material having a diameter of 0.03 to 0.2 mm. (6) The inductor according to any one of (1) to (5), further including a terminal formed by partially processing the conductor wire.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An inductor according to the present invention has a dielectric resin and a conductor wire formed in a coil shape in the dielectric resin, and the dielectric resin has a relative permittivity of 3.0. Hereinafter, it is a dielectric polymer material having a decomposition temperature of 290 ° C. or higher.

By disposing the coil-shaped conductive material in the dielectric resin, the coil can be formed to the maximum size within a predetermined shape regulated as the whole inductor. Further, the number of parts constituting the inductor is reduced, and the weight is reduced.

The dielectric resin has a relative dielectric constant of 3.0 or less, preferably in the range of 2.0 to 3.0. As the relative dielectric constant increases, the self-resonant frequency (SRF) of the inductor decreases. The decomposition temperature is preferably 290 ° C or higher, and practically 280 ° C or higher. The upper limit is not particularly limited, but is usually about 310 ° C.

The dielectric resin of the present invention is preferably obtained by polymerizing a monomer composition containing a fumaric acid diester as a monomer, and comprises a fumarate having a repeating unit derived from the fumaric acid diester. It is a system polymer.

In the present invention, the fumaric acid diester monomer is not particularly limited as long as it imparts low dielectric property and heat resistance to the polymer material when the polymer material is used. ) A compound represented by the above formula 3 is preferred.

As for the formula (I), in the formula (I), R
¹ represents an alkyl group or a cycloalkyl group, R ² represents an alkyl group, a cycloalkyl group or an aryl group, and R ¹ and R ² may be the same or different.

The alkyl group represented by R ¹ and R ² is preferably one having a total of 2 to 12 carbon atoms, which may be linear or branched, and further having a substituent. You may have. When the compound has a substituent, examples of the substituent include a halogen atom (F, Cl), an alkoxy group (such as a methoxy group, an ethoxy group, a propoxy group, and a butoxy group);
And an aryl group (eg, a phenyl group).

Specific examples of the alkyl group represented by R ¹ and R ² include an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group and an n-pentyl group. (N-amyl group), sec-amyl group, isopentyl group, neopentyl group, tert-pentyl group, n-hexyl group, 4-methyl-2-pentyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl Group, dodecyl group, trifluoroethyl group, hexafluoroisopropyl group, perfluoroisopropyl group, perfluorobutylethyl group, perfluorooctylethyl group, 2-chloroethyl group, 1-butoxy-2-
Examples include a propyl group, a methoxyethyl group, and a benzyl group.

The cycloalkyl group represented by R ¹ and R ² preferably has 3 to 14 carbon atoms, and may be a single ring or a bridged ring. It may have a group. In this case, the substituent may be the same as those exemplified above for the alkyl group, and examples thereof include an alkyl group (a linear or branched one having 1 to 14 carbon atoms such as a methyl group). be able to.

Specific examples of the cycloalkyl group represented by R ¹ and R ² include a cyclopentyl group, a cyclohexyl group, an adamantyl group and a dimethyladamantyl group.

The aryl group represented by R ² is preferably one having a total of 6 to 18 carbon atoms, and is preferably a monocyclic ring, but may be a polycyclic ring (condensed ring or ring assembly) and has a substituent. May be. In this case, the substituents are the same as those exemplified for the alkyl group and the cycloalkyl group.

Specific examples of the aryl group represented by R ² include a phenyl group.

As R ¹ and R ² , an alkyl group and a cycloalkyl group are preferable. As the alkyl group, an alkyl group having a branch is preferable, and an isopropyl group, sec-
A butyl group and a tert-butyl group are preferred. Also,
As the cycloalkyl group, a cyclohexyl group or the like is preferable.

As preferred examples of the fumaric acid diester monomer represented by the formula (I), specifically, diethyl fumarate,
Di-n-propyl fumarate, di-n-hexyl fumarate, isopropyl-n-hexyl fumarate, diisopropyl fumarate, di-n-butyl fumarate, di-
sec-butyl fumarate, di-tert-butyl fumarate, di-sec-amyl fumarate, n-butyl-
Isopropyl fumarate, isopropyl-sec-butyl fumarate, tert-butyl-4-methyl-2-pentyl fumarate, isopropyl-tert-butyl fumarate, isopropyl-sec-amyl fumarate,
Dialkyl fumarate such as di-4-methyl-2-pentyl fumarate, di-isoamyl fumarate, di-4-methyl-2-hexyl fumarate, tert-butyl-isoamyl fumarate; dicyclopentyl fumarate;
Dicycloalkyl fumarate such as dicyclohexyl fumarate, dicycloheptyl fumarate, cyclopentyl-cyclohexyl fumarate, bis (dimethyladamantyl) fumarate, bis (adamantyl) fumarate; isopropyl-cyclohexyl fumarate, isopropyl-dimethyl adamantyl fumarate; Alkylcycloalkyl fumarate such as isopropyl-adamantyl fumarate and tert-butyl-cyclohexyl fumarate; alkylaryl fumarate such as isopropyl-phenyl fumarate; alkyl such as tert-butylbenzyl fumarate and isopropyl-benzyl fumarate Aralkyl fumarate; ditrifluoroethyl fumarate, dihexafluoroisopropyl fumarate, diperfluoroi Di-fluoroalkyl fumarate such as propyl fumarate and dibis (perfluorobutylethyl) fumarate; alkyl fluoroalkyl fumarate such as isopropyl-perfluorooctylethyl fumarate and isopropyl-hexafluoroisopropyl fumarate; 1-butoxy -2-propyl-
Other substituted alkylalkyl fumarate such as tert-butyl fumarate, methoxyethyl-isopropyl fumarate, 2-chloroethyl-isopropyl fumarate and the like can be mentioned.

Among them, diisopropyl fumarate, dicyclohexyl fumarate, di-sec-butyl fumarate, di-tert-butyl fumarate, isopropyl-tert-butyl fumarate, n-butyl-isopropyl fumarate, n-hexyl-fumarate Isopropyl fumarate and the like are particularly preferred.

These diesters can be synthesized by combining ordinary esterification techniques and isomerization techniques.

In obtaining the fumarate-based polymer which is the polymer material of the present invention, the above fumaric acid diester (fumarate-based compound) may be used alone or in combination of two or more. Therefore, the fumarate-based polymer of the present invention may be a homopolymer obtained by polymerizing only one type of the above fumaric acid diester, or a copolymer obtained by polymerizing two or more types. The copolymer may be any of a random copolymer, an alternating copolymer, a block copolymer and the like.

As described above, the fumarate-based polymer of the present invention may be one using only fumaric acid diester as a monomer component. However, other monomers besides fumaric acid diester may be used. And a copolymer with another monomer component. As such another monomer component, a vinyl monomer (monomer) may be used, and the vinyl monomer which is a comonomer imparts moldability, film forming property, and mechanical strength. The compound is not particularly limited as long as it can be copolymerized with the fumarate-based compound, but preferably includes a compound represented by the formula (II) [Formula 4].

Referring to the formula (II), X represents a hydrogen atom or a methyl group, Y represents a fluorine atom, a chlorine atom,
Alkyl group, alkenyl group, aryl group, ether group,
Represents an acyl group or an ester group.

The alkyl group represented by Y is preferably one having a total carbon number of 1 to 14, and may be linear or branched.

The alkenyl group represented by Y is preferably one having a total of 2 to 14 carbon atoms, which may be linear or branched, and further having a substituent. Examples thereof include a vinyl group, an allyl group, a propenyl group, and a butenyl group.

The aryl group represented by Y is preferably an aryl group having a total of 6 to 18 carbon atoms, and may be a monocyclic ring or a polycyclic ring such as a condensed ring.
l) may have a substituent of an alkyl group (eg, a methyl group). Specifically, phenyl group, α-naphthyl group, β
-Naphthyl group, (o-, m-, p-) tolyl group, (o
-, M-, p-) chlorophenyl group and the like.

The ether group represented by Y is represented by —OR ³ , wherein R ³ is an alkyl group, an aryl group, or the like. The alkyl group represented by R ³ preferably has 1 to 8 carbon atoms in total, and may be linear or branched, and further has a substituent (eg, a halogen atom). You may have. The aryl group represented by R ³ preferably has 6 to 18 carbon atoms in total, and is preferably a single ring, but may be a polycyclic ring such as a condensed ring.

Examples of the ether group represented by Y include a methoxy group, an ethoxy group, a propoxy group, a butoxy group, an isobutoxy group and a phenoxy group.

The acyl group represented by Y is represented by —COR ⁴ , wherein R ⁴ is an alkyl group, an aryl group, or the like. The alkyl group represented by R ⁴ preferably has 1 to 8 carbon atoms in total, and may be linear or branched, and further has a substituent (eg, a halogen atom). It may be. The aryl group represented by R ⁴ preferably has 6 to 18 carbon atoms, and is preferably a single ring, but may be a polycyclic ring such as a condensed ring.

Examples of the acyl group represented by Y include an acetyl group, a propionyl group, a butyryl group, an isobutyryl group and a benzoyl group.

The ester group represented by Y is —OCOR ⁵
Or represented by -COOR ^5, the alkyl group as R ⁵ in this case, and an aryl group. The alkyl group represented by R ⁵ preferably has 1 to 20 carbon atoms in total, and may be linear or branched, and further has a substituent (eg, a halogen atom). You may have. The aryl group represented by R ⁵ preferably has 6 to 18 carbon atoms in total, and is preferably a single ring, but may be a polycyclic ring such as a condensed ring.

Examples of the ester group represented by Y include an acetoxy group, a propionyloxy group, a butyryloxy group, an isobutyryloxy group, a valeryloxy group, an isovaleryloxy group, -OCOC ₄ H ₉ (-sec), -OCOC
_{4 H 9 (-tert), -} OCOC (CH 3) 2 CH 2
CH ₃ , —OCOC (CH ₃ ) ₂ CH ₂ CH ₂ CH ₃ ,
Stearoyloxy group, benzoyloxy group, tert
-Butylbenzoyloxy group, methoxycarbonyl group,
Examples include an ethoxycarbonyl group, a butoxycarbonyl group, a 2-ethylhexyloxycarbonyl group, and a phenoxycarbonyl group.

The copolymer component used in the present invention is a vinyl comonomer mainly composed of an olefinic hydrocarbon. Examples of the vinyl monomer represented by the formula (II) include vinyl acetate, vinyl pivalate, Vinyl carboxylate such as vinyl 2-dimethylbutanoate, vinyl 2,2-dimethylpentanoate, vinyl 2-methyl-2-butanoate, vinyl propionate, vinyl stearate, vinyl 2-ethyl-2-methylbutanoate; p-tert-butyl vinyl benzoate, N, N-dimethylamino vinyl benzoate,
Aromatic vinyl monomers such as vinyl benzoate; α-substituted styrene derivatives such as styrene, o-, m-, p-chloromethylstyrene, α-methylstyrene and its core-substituted products; o-, m -, Alkyl nucleus-substituted styrenes such as p-methylstyrene; α such as vinyl chloride and vinyl fluoride
-Olefins; o-, m-, such as p-chlorostyrene;
halogen nucleus-substituted styrene such as p-halogenated styrene;
Vinyl ethers such as ethyl vinyl ether, vinyl butyl ether and isobutyl vinyl ether; α-, β-
Naphthalene derivatives such as vinyl naphthalene; alkyl vinyl ketones such as methyl vinyl ketone and isobutyl vinyl ketone; dienes such as butadiene and isoprene; methyl (meth) acrylate, ethyl (meth) acrylate;
Known radical polysynthetic monomers such as (meth) acrylates such as butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate and phenyl (meth) acrylate can be preferably exemplified.

In order to produce such a vinyl monomer, for example, the transesterification reaction between vinyl acetate and the corresponding organic acid is carried out in the presence of mercury acetate or sulfuric acid, or another catalyst such as platinum or rhodium. Can be easily synthesized by performing the reaction in the presence of a metal complex and a catalyst.

One of these vinyl monomers may be used alone or two or more of them may be used in combination.

The fumarate-based polymer of the present invention having a repeating unit derived from such a vinyl-based monomer is a copolymer, such as a random copolymer, an alternating copolymer, or a block copolymer. Any of them may be used.

The polymer material having a repeating unit derived from the fumaric acid diester of the present invention has low dielectric properties,
It is excellent in film formability, film adhesion, and mechanical properties. As described above, such a polymer material is, as described above, a homopolymer using only the same fumaric diester, a copolymer of fumaric diesters, and a fumaric diester and another vinyl monomer copolymerizable therewith. Any of a copolymer with a monomer may be used.

Although the molecular weight of the fumarate-based polymer is not particularly limited, for example, to form an electric insulating film and an electric insulating substrate obtained by laminating the same, a considerable stress generated during the production of electronic parts is required. Since mechanical strength enough to withstand the electrically insulating substrate is required, a high molecular weight material is desirable in view of its use and the like, and the number average molecular weight is preferably 10,000 to 1500,000. When the molecular weight is small, mechanical strength and chemical stability are likely to be inferior, and heat resistance is also poor. In particular, it is desirable that the molecular weight be as high as possible in order to eliminate film defects, film adhesion to a substrate, and film defects. However, if the molecular weight is too large, workability is poor, such as difficulty in forming a uniform and smooth film, and workability is also poor.

The polymer material of the present invention can be obtained by polymerizing a monomer composition substantially containing only the above-mentioned fumaric acid diester as a monomer component, or by further polymerizing a monomer composition as described above as a monomer component. It is obtained by polymerizing a monomer composition containing various vinyl monomers.

In this case, the content of the fumaric acid diester is preferably at least 50% by weight, more preferably at least 60% by weight, and particularly preferably at least 80% by weight, based on the total amount of the raw material monomer (raw material monomer). When the amount of fumaric acid diester is small, electric characteristics (dielectric constant and low dielectric loss tangent), heat resistance and the like become insufficient, which is not preferable.

On the other hand, the ratio of the above-mentioned vinyl monomer to the total amount of the raw material monomers is as follows: low dielectric properties (low dielectric constant, low dielectric loss tangent), moldability, solution viscosity, film adhesion, mechanical properties and the like. In view of the above, it is preferably 0 to 50% by weight, more preferably 0 to 40% by weight, and particularly preferably 0 to 20% by weight.

The component derived from the fumaric acid diester in such a fumarate-based polymer is preferably at least 50% by weight, more preferably at least 60% by weight, particularly preferably at least 80% by weight.

The softening temperature of the fumarate-based polymer used in the present invention is 200 ° C. or higher, and is usually from 230 to 2
It is in the range of 90 ° C. Since the softening temperature is high as described above, the heat resistance in the soldering step essential for the device forming step is sufficient. The reason for having such a high softening temperature is that the main chain structure does not have a methylene group and the substituent is bonded on the carbon of the main chain, thereby suppressing the thermal kinetic of the main chain. Conceivable.

As described above, the fumarate-based polymer used in the present invention has a rod-like structure and is a rigid polymer. Therefore, they are not easily attacked by the side chain bond,
A polymer having excellent heat resistance, acid resistance and alkali resistance (etching resistance) can be obtained.

The fumarate-based polymers preferably used in the present invention are described below. The polymer is represented by a raw material monomer.

I) Di-alkyl fumarate type I-1 di-isopropyl fumarate I-2 di-cyclohexyl fumarate I-3 di-sec-butyl fumarate I-4 di-tert-butyl fumarate I-5 tert-butyl-isopropyl fumarate I-6 di-isopropyl fumarate / di-sec-butyl fumarate I-7 tert-butyl-isopropyl fumarate /
Di-isopropyl fumarate I-8 Di-isopropyl fumarate / di-cyclohexyl fumarate I-9 Di-isopropyl fumarate / n-butyl-isopropyl fumarate I-10 Di-isopropyl fumarate / n-hexyl-
Isopropyl fumarate I-11 di-cyclohexyl fumarate / n-butyl-
Isopropyl fumarate I-12 di-cyclohexyl fumarate / di-sec-
Butyl fumarate

II) Di-alkyl fumarate / vinyl type II-1 di-isopropyl fumarate / styrene II-2 di-sec-butyl fumarate / vinyl tert-butyl benzoate II-3 di-cyclohexyl fumarate / 2 -Ethyl-
Vinyl 2-methylbutanoate II-4 Di-isopropyl fumarate / vinyl tert-butyl benzoate II-5 Di-isopropyl fumarate / vinyl p-N, N-dimethylaminobenzoate II-6 Di-cyclohexyl fumarate / tert -Butyl vinyl benzoate II-7 cyclohexyl-isopropyl fumarate / vinyl acetate II-8 di-tert-butyl fumarate / di-cyclohexyl fumarate-tert-vinyl vinyl benzoate II-9 di-isopropyl fumarate / di- Cyclohexyl fumarate / vinyl 2-ethyl-2-methylbutanoate II-10 di-isopropyl fumarate / di-sec-butyl fumarate / vinyl N, N-dimethylaminobenzoate II-11 di-sec-butyl fumarate / Di-cyclohexyl fumarate / tert-butyl Vinyl benzoate II-12 di - cyclohexyl fumarate / di - isopropyl fumarate / styrene

In the present invention, in order to produce the fumarate-based polymer, a usual radical polymerization method can be preferably used. The polymerization initiator used for the polymerization has a 10-hour half-life temperature of 80 to increase the molecular weight.
One or more of an organic peroxide and an azo compound having a temperature of not higher than
More than one species can be preferably used. Examples of such a polymerization initiator include benzoyl peroxide, diisopropyl peroxydicarbonate, tert-butyl peroxydi-2-ethylhexanoate, tert-butyl peroxydiisobutyrate, cumene peroxide,
Organic peroxides such as tert-butyl hydroperoxide, tert-butyl peroxypivalate, lauroyldiacyl peroxide, 2,2′-azobisbutyronitrile, 2,2′-azobis (2-methylbutyro Nitrile), azobis (2,4-dimethylvaleronitrile), 1,1′-azobis (cyclohexane-1-carbonitrile), 2,2′-azobis (isobutyric acid) dimethyl, 2,2′-azobis (2 Azo compounds such as 4-dimethylvaleronitrile) and tert-butylperoxyisopropyl carbonate. The amount of the polymerization initiator to be used is 10 to 100 parts by weight of the raw material monomer.
It is preferably at most 5 parts by weight, more preferably at most 5 parts by weight.

The conditions for polymerizing or copolymerizing each monomer in such a preparation method are as follows: a polymerization system is appropriately set with an inert gas such as nitrogen, carbon dioxide, helium,
It is preferable to carry out the polymerization under a substitution or atmosphere with argon or the like, or under degassing conditions. The temperature at the time of polymerization or copolymerization varies depending on the type of polymerization initiator used, but is preferably in the range of 30 ° C to 120 ° C. The total time required for the polymerization is desirably about 10 to 72 hours. It is also possible to polymerize the starting monomer by adding a coloring agent such as a dye or an additive such as an ultraviolet absorber.

The radical polymerization can be carried out by any of a number of polymerization methods used for radical polymerization of general-purpose vinyl monomers such as solution polymerization, bulk polymerization, emulsion polymerization, suspension polymerization and radiation polymerization. In the present invention, in the application for a high frequency band, it is important to make the low dielectric loss tangent extremely low as an electrical characteristic of the low dielectric electric insulating substrate. The presence of low-molecular-weight polymers in the polymer material causes external plasticization, which increases the dielectric loss tangent, and deteriorates the dielectric properties in the high-frequency band, so that the molecular weight of the fumarate-based polymer and copolymer becomes extremely high. It is important to take such a polymerization method, it is possible to increase the concentration of the charged monomer, for example, fumaric acid diester which is a charged monomer at the time of copolymerization,
A bulk polymerization method or a suspension polymerization method that can sufficiently increase the concentration of both monomers with a vinyl monomer is most desirable. Further, as the polymerization temperature becomes higher, the molecular weight of the polymer or copolymer becomes smaller.
It is preferable to carry out radical polymerization or copolymerization at a low temperature of ° C.

The fumarate polymer of the present invention has a nuclear magnetic resonance spectrum (NMR) and an infrared absorption spectrum (IR).
And the like.

Various terminal groups can be introduced according to the purpose.

The shape of the coil disposed in the dielectric resin is not particularly limited. The coil may be formed in a required shape or size depending on the required performance and the overall shape of the inductor. Good.

The conductor wire constituting the coil is preferably a simple metal or an alloy thereof which is low in resistance and easy to form.
As such a metal wire, for example, Cu, Ag, A
u, Al, Cr, Co, Ni, Fe and the like can be used, and among them, Cu and Cu alloy are preferable. The wire diameter of the conductor wire is preferably 0.03-0.2 mm.
It is.

The method for forming the conductor wire into a coil shape is not particularly limited, but forming is preferred. In forming, it is preferable that the conductor wire is formed at a predetermined interval with a distance, and is wound in a space. At this time, by adjusting the winding diameter of the winding, it is possible to finely adjust the inductance, which is effective in suppressing variations among products.

The terminals of the inductor according to the present invention can be formed of various terminal materials (terminal plates and the like) conventionally used, but are formed by partially processing the conductor wire. It is preferable to have a terminal. By having the terminals formed by partially processing the conductor wire, the number of parts is reduced, and in the forming process, the terminal portion and the inductance portion can be formed almost simultaneously, thereby reducing the number of processes. I do. The terminal portion may be formed as a part of a plate-like terminal by crushing a wire.

As a method of arranging the coil in the dielectric resin, the formed coil is arranged in a mold having a predetermined size, immersed in the dielectric resin before curing, and cured. Just do it.

After curing, the mold is taken out of the mold, and if necessary, a coating material for preventing adhesion of plating is applied to portions other than the terminal portions, and cut into predetermined sizes so that the terminal portions are exposed. After cutting, if necessary, Cu, Ni, Cr,
An inductor element is obtained by plating with Co or the like, particularly Cu and Ni.

The inductor element of the present invention has a microwave,
It can be suitably used for high frequency circuits such as millimeter waves. In particular, it is preferably used as a surface mount type chip inductor used for mobile communication devices such as mobile phones.

The inductor of the present invention can obtain a larger inductance than a conventional type inductor having the same shape.
A larger self-resonant frequency can be obtained.

[0074]

Next, the present invention will be described more specifically with reference to examples.

Example 1 First, as shown in FIG. 1, using a wire (copper wire) 1 having a wire diameter of 0.08 mm, a terminal 1b and a coil 1a were formed almost simultaneously by a forming process. The inductance portion has a predetermined shape (1.6 in this example).
An air-core coil of 5.5 turns was formed with the maximum size that can be inserted into the wire (× 0.8 mm), and the distance between the wires was equal (0.02 mm). For the terminal portion, the wire 1 was crushed to form a plate-like terminal portion 1b. At this time, one set of the coil portion 1a and the terminal portion 1b and the other coil portion 1a and the terminal portion 1b are connected by the connection portion 1c, and are continuously formed, and the next molding step is performed. You can do it all at once.

Then, as shown in FIG. 2, a continuous body of the formed coil portion 1a and terminal portion 1b was charged into a mold 2, and cast with a liquid fumarate resin 3. As the fumarate resin, a cyclohexyl fumarate resin (or a secondary butyl fumarate resin) was used, dissolved in a solvent (toluene), and then injected into the mold. The solvent was removed at 60 to 80 ° C. for 12 hours, cured, and dried. Further, as shown in FIG. 3, the cured resin 3a is taken out from the mold 2, a resin 4 for preventing adhesion of plating is applied, and then cut at a predetermined position 6 where a terminal portion is exposed. did.
Then, as shown in FIG. 4, plating 7 was applied to the terminal portions as necessary to obtain an inductor element.

The substantially rectangular parallelepiped (vertical:
FIG. 5 shows the impedance-frequency characteristics of an inductor element (sample 1) of 1.6 mm, width: 0.8 mm, and height: 0.6 mm. In addition, the impedance-frequency characteristics of the conventional element of the winding type having the same shape (Comparative Sample 1) and the conventional element of a larger size (Sample 2) are also shown.

As a result of the constant measurement, the inductance was 25.
The Q value at 53 nH and 100 MHz was 32. This Q value was 70% higher than that of Comparative Sample 1 of the same shape having the same inductance. The self-resonant frequency of the sample of the present invention is 3 GHz or more, which is sufficiently higher than the self-resonant frequency of the conventional product of the same shape which cannot be space-wound. Also, it can be seen that the impedance-frequency characteristics are substantially the same as those of a conventional product (comparative sample 2) which is slightly larger.

<Example 2> An inductor was manufactured in the same manner as in Example 1 except that the number of windings was changed to about half, that is, 2.5 turns.

FIG. 6 shows the impedance frequency characteristics of the obtained inductor element (sample 2). In addition, the impedance-frequency characteristics of a conventional element (Comparative Sample 3) having the same shape and a conventional element larger than this (Sample 4) are also shown. As a result of element constant measurement, the inductance was 11.3 nH, and the Q value at 100 MHz was 33. This Q value was 70% or more higher than that of Comparative Sample 3 having the same inductance and the same shape. The self-resonant frequency of this chip inductor element is 6.7 GHz.
That is, the self-resonant frequency of the comparative sample 3 of the same shape was 3.2 times or more, which is a much higher value than twice. In addition, it can be seen that the impedance-frequency characteristics are substantially the same as those of a slightly larger conventional product (Comparative Sample 4).

In conventional chip inductors, the distance between layers and lines is structurally determined. Even when the constant required for an inductor having the same structure is small, the distance between layers and lines is the same and only the number of turns is small. In many cases, the distance between the layers can be easily increased when the number of turns is small and the same shape is applied to the present embodiment, so that the line capacitance per unit number of turns can be reduced. This is because the resonance frequency could be dramatically increased.

In addition, substantially the same results were obtained by using the other exemplified resins in place of the fumarate resin used in Examples 1 and 2.

In the present embodiment, the structure is such that the center axis of the coil passes through the mounting board, but a structure in which the center axis of the coil is parallel to the mounting board is also possible.

If the wire diameter is as large as about 0.2 mm, the terminal portion can be formed only by deforming the wire material.

Further, as in the present embodiment, the coil is wound around a rod or bobbin of a fumarate resin without forming an air-core coil by forming, including an inductance portion and a terminal portion, and the resultant is put into a mold, and the fumarate resin is used. A manufacturing method of molding is also possible.

In the chip inductor according to the present invention, since the maximum winding diameter that can be inserted into a predetermined shape by forming can be obtained, the inductance per unit volume increases, and the wire including the bulk copper wire and the terminal portion is wound. Are continuous, the resistance value is low and the Q value is high. The self-resonance frequency is high because the relative permittivity of the material holding the coil is low and the winding can be wound in space. Since the decomposition temperature of the resin is high, it can be used for reflow furnace treatment.

[0087]

As described above, according to the present invention, a high Q and a high self-resonant frequency are obtained by utilizing the low dielectric property.
An inductor having low resistance, heat resistance enough to withstand a high-temperature reflow furnace, and low cost can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram showing a manufacturing process as an example of an inductor element of the present invention, and is an external perspective view showing a state in which a wire is formed.

FIG. 2 is a view showing a manufacturing process which is an embodiment of the inductor element of the present invention.
FIG. 2 is an external perspective view showing a state in which molding with resin is performed.

FIG. 3 is a view showing a manufacturing process as an embodiment of the inductor element of the present invention, and is an external perspective view showing a state in which the inductor element is removed from a mold after molding and painted so as not to be plated.

FIG. 4 is a view showing a manufacturing process which is an embodiment of the inductor element of the present invention, and is an external perspective view showing a state where the inductor element is cut at a predetermined position after plating and plated.

FIG. 5 is a graph showing impedance-frequency characteristics of each sample of the first example of the present invention.

FIG. 6 is a graph showing impedance-frequency characteristics of each sample according to the second example of the present invention.

FIG. 7 is a partially cut external perspective view showing the structure of a conventional multilayer chip inductor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wire rod 1a Coil part 1b Terminal part 1c Connection part 2 Type 3 Resin 4 Painting 7 Plating

Claims (6)

[Claims] 1. A dielectric resin, and a conductor wire formed in a coil shape in the dielectric resin, wherein the dielectric resin has a relative dielectric constant of 3.0 or less and a decomposition temperature of 29 or less.
An inductor made of a dielectric polymer material at 0 ° C. or higher. 2. The inductor according to claim 1, wherein the dielectric polymer material is obtained by polymerizing a monomer composition containing at least a fumaric acid diester as a monomer. 3. The inductor according to claim 1, wherein the fumaric diester is represented by the following formula (I). Embedded image [In the formula (I), R ¹ represents an alkyl group or a cycloalkyl group, R ² represents an alkyl group, a cycloalkyl group or an aryl group, and R ¹ and R ² may be the same or different. ] 4. The composition of claim 1, wherein the monomer composition further comprises
The inductor according to any one of claims 1 to 3, further comprising a vinyl monomer represented by I). Embedded image [In the formula (II), X represents a hydrogen atom or a methyl group, and Y represents a fluorine atom, a chlorine atom, an alkyl group, an alkenyl group, an aryl group, an ether group, an acyl group, or an ester group. ] 5. The inductor according to claim 1, wherein said conductor wire is made of a metal conductive material having copper as a main component and a diameter of 0.03 to 0.2 mm. 6. The inductor according to claim 1, further comprising a terminal formed by partially processing said conductor wire.