JP6856489B2 - Inductor adhesives and inductors - Google Patents

Description

The present invention relates to an inductor adhesive used in an inductor. The present invention also relates to an inductor using the above-mentioned inductor adhesive.

Inductors are used in electronic devices such as mobile phones, televisions, and digital cameras. In particular, in inductors that can handle large currents, core materials such as ferrite cores are arranged with a gap. Conventionally, an adhesive containing no particles or an adhesive containing particles such as glass beads has been used in this gap (adhesive portion). However, it is difficult to control the thickness of the bonded portion with an adhesive containing no particles. Even with an adhesive containing particles such as glass beads, the thickness of the bonded portion is difficult to be uniform, and the yield, productivity, and reliability may be lowered.

As an example of the above-mentioned adhesive, Patent Document 1 below discloses an adhesive containing non-magnetic particles (grains). In the examples, glass beads are used as the particles.

Patent Document 2 below discloses an adhesive containing spacer particles having a CV value of 10% or less. In the examples, resin particles are used as the particles.

Japanese Unexamined Patent Publication No. 2004-235462 WO2010 / 104125A1

With conventional adhesives as described in Patent Documents 1 and 2, the adhesiveness may be lowered because the thickness of the bonded portion (interval between gap portions) cannot be controlled with high accuracy. Further, the adhesive portion (gap portion) formed by using the adhesive may have low moisture resistance.

Further, when a long-term reliability test that receives a thermal shock is performed, the performance of the inductor may deteriorate due to cracks in the ferrite core or a decrease in inductance as compared with the initial stage.

With conventional adhesives, it is difficult to achieve both high adhesiveness and high moisture resistance. In addition, conventional adhesives have poor long-term reliability.

An object of the present invention is to provide an adhesive for an inductor that can have high moisture resistance and can suppress a decrease in adhesiveness even when exposed to high humidity. Another object of the present invention is to provide an inductor using the above-mentioned inductor adhesive.

According to a broad aspect of the present invention, it is an adhesive for an inductor used for an inductor, and contains a thermosetting compound, a thermosetting agent, an inorganic filler, and spacer particles, and the spacer particles are resin particles or organic. Inorganic hybrid particles, the average particle size of the spacer particles is 20 μm or more and 200 μm or less, the CV value of the particle size of the spacer particles is 10% or less, and the inorganic filler in 100% by weight of the adhesive. An inductor adhesive (hereinafter, "adhesive for inductor" may be referred to as "adhesive") having a content of more than 30% by weight and 75% by weight or less is provided.

In a specific aspect of the adhesive according to the present invention, the glass transition point of the cured product obtained when the adhesive is heated at 120 ° C. for 20 minutes and then heated at 170 ° C. for 15 minutes to obtain a cured product. The temperature is 120 ° C. or higher and 210 ° C. or lower.

In a specific aspect of the adhesive according to the present invention, 30 mg of the adhesive is placed on a first slide glass, a second slide glass is placed on the adhesive, and then 50 g is placed on the second slide glass. When the weight is placed and left for 20 minutes, the number of the spacer particles is 2 pieces / mm ² or more and 1000 pieces / mm ² or less in a plan view.

In a specific aspect of the adhesive according to the present invention, the content of the thermosetting agent is 0.01 part by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the thermosetting compound.

In a specific aspect of the adhesive according to the present invention, the viscosity of the adhesive at 25 ° C. is 10 Pa · s or more and 150 Pa · s or less.

In a specific aspect of the adhesive according to the present invention, the content of the spacer particles is 1% by weight or more and 15% by weight or less in 100% by weight of the adhesive.

In certain aspects of the adhesive according to the present invention, the ratio of the content of the inorganic filler in 100% by weight of the adhesive to the content of the spacer particles in 100% by weight of the adhesive is 3 or more, 60. It is as follows.

In a specific aspect of the adhesive according to the present invention, the ratio of the average particle size of the inorganic filler to the average particle size of the spacer particles is 0.00005 or more and 0.1 or less.

In a specific aspect of the adhesive according to the present invention, 10% K value of the spacer particles is 980 N / mm ² or more and 4900 N / mm ² or less.

In certain aspects of the adhesive according to the present invention, the inductor adhesive is used to bond a ferrite core in an inductor.

According to a broad aspect of the present invention, there is provided an inductor that includes a ferrite core and an adhesive portion that adheres the ferrite core, and the material of the adhesive portion is the above-mentioned adhesive for an inductor.

The adhesive for an inductor according to the present invention contains a thermosetting compound, a thermosetting agent, an inorganic filler, and spacer particles, and the spacer particles are resin particles or organic-inorganic hybrid particles, and the spacer particles The average particle size is 20 μm or more and 200 μm or less, the CV value of the particle size of the spacer particles is 10% or less, and the content of the inorganic filler exceeds 30% by weight in 100% by weight of the adhesive. Since it is 75% by weight or less, the moisture resistance can be increased, and the decrease in adhesiveness can be suppressed even when exposed to high humidity.

FIG. 1 is a cross-sectional view schematically showing an inductor using an inductor adhesive according to an embodiment of the present invention.

The details of the present invention will be described below.

(Adhesive for inductor)
The inductor adhesive according to the present invention (hereinafter, may be abbreviated as an adhesive) is used for an inductor. The adhesive according to the present invention contains a thermosetting compound, a thermosetting agent, an inorganic filler, and spacer particles. In the adhesive according to the present invention, the spacer particles are resin particles or organic-inorganic hybrid particles. In the adhesive according to the present invention, the average particle size of the spacer particles is 20 μm or more and 200 μm or less. In the adhesive according to the present invention, the CV value of the particle size of the spacer particles is 10% or less. The content of the inorganic filler in 100% by weight of the adhesive according to the present invention exceeds 30% by weight and is 75% by weight or less.

In the present invention, since the above configuration is provided, the moisture resistance can be increased. For example, the adhesive portion formed by the adhesive is difficult to absorb water, and even if it is exposed to high humidity, a decrease in adhesiveness can be suppressed. Further, in the present invention, since the above configuration is provided, the uniformity of the thickness of the bonded portion can be enhanced, excellent adhesiveness can be exhibited, and variation in inductance can be suppressed. Further, in the present invention, the thermal shock resistance can be enhanced, and the thermal shock resistance (long-term reliability) of the inductor can be enhanced. Even if the inductor is exposed to a high temperature or a low temperature, or is exposed to a thermal cycle, the change in inductance can be reduced.

Further, in the present invention, since the above-mentioned configuration is provided, excessive wetting and spreading of the adhesive can be suppressed, and the applicability of the adhesive is also improved.

The average particle size of the spacer particles is 20 μm or more and 200 μm or less. From the viewpoint of further enhancing the adhesiveness, the average particle size of the spacer particles is preferably 25 μm or more, more preferably 30 μm or more, preferably 150 μm or less, and more preferably 130 μm or less.

From the viewpoint of further enhancing the adhesiveness, the ratio of the average particle size of the inorganic filler to the average particle size of the spacer particles (average particle size of the inorganic filler / average particle size of the spacer particles) is preferably 0.1 or less. , More preferably 0.01 or less. From the viewpoint of further enhancing the moisture resistance, the above ratio (average particle size of inorganic filler / average particle size of spacer particles) is preferably 0.00005 or more, more preferably 0.0005 or more.

The average particle size indicates a number average particle size. The average particle size of the inorganic filler and the spacer particles can be obtained, for example, by observing 50 arbitrary inorganic fillers or 50 arbitrary spacer particles with an electron microscope or an optical microscope and calculating an average value.

The CV value of the particle size of the spacer particles is 10% or less. From the viewpoint of further enhancing the adhesiveness, the CV value of the particle size of the spacer particles is preferably 1% or more, preferably 5% or less.

The CV value (coefficient of variation) is expressed by the following formula.

CV value (%) = (ρ / Dn) × 100
ρ: Standard deviation of particle size of spacer particles Dn: Mean value of particle size of spacer particles

From the viewpoint of effectively improving the coatability, further improving the uniformity of the thickness of the adhesive portion, further improving the adhesiveness, and further suppressing the generation of voids, the viscosity of the adhesive at 25 ° C. is It is preferably 10 Pa · s or more, more preferably 15 Pa · s or more, preferably 150 Pa · s or less, more preferably 100 Pa · s or less, still more preferably 70 Pa · s or less, particularly preferably 40 Pa · s or less, most preferably. Is 35 Pa · s or less.

The viscosity (η25) is determined by using, for example, an E-type viscometer (“TVE22L” manufactured by Toki Sangyo Co., Ltd.) under the conditions of 25 ° C. and 5 rpm, and a spiral viscometer (“PCU-02V” manufactured by Malcolm Co., Ltd.). In use, it can be measured under the conditions of 25 ° C. and 10 rpm. When the particle size of the spacer particles in the adhesive is 20 μm or less, an E-type viscometer (“TVE22L” manufactured by Toki Sangyo Co., Ltd.) is preferably used. When the particle size of the spacer particles in the adhesive exceeds 20 μm, a spiral viscometer (“PCU-02V” manufactured by Malcolm Co., Ltd.) is preferably used.

From the viewpoint of further enhancing the thermal shock resistance, when the adhesive is heated at 120 ° C. for 20 minutes and then heated at 170 ° C. for 15 minutes to obtain a cured product, the glass transition temperature of the obtained cured product is determined. It is preferably 120 ° C. or higher, preferably 210 ° C. or lower. When the adhesive according to the present invention is cured, it may be heated at 120 ° C. for 20 minutes and then at 170 ° C. for 15 minutes.

From the viewpoint of effectively enhancing the performances of moisture resistance, gap controllability, inductance variation and thermal shock resistance, 30 mg of the adhesive is placed on the first slide glass, and the second slide glass is placed on the adhesive. After mounting, when a weight of 50 g is placed on the second slide glass and left for 20 minutes, the number of the spacer particles is preferably 2 / mm ² or more, preferably 1000 in a plan view. / Mm ² or less. In this observation in a plan view, the adhesive between the first and second slide glasses is observed.

From the viewpoint of effectively enhancing each performance of moisture resistance, gap controllability, inductance variation and thermal shock resistance, the adhesive is heated at 120 ° C. for 20 minutes and then heated at 170 ° C. for 15 minutes to obtain a cured product. At that time, the linear expansion coefficient of the obtained cured product is preferably 60 ppm or less, more preferably 50 ppm or less, still more preferably 40 ppm or less, and particularly preferably 30 ppm or less.

The above adhesive is suitably used for adhering a ferrite core in an inductor.

Hereinafter, other details of the above-mentioned inductor adhesive will be described.

Thermosetting compound:
The thermosetting compound contained in the adhesive is not particularly limited. The thermosetting compound is a compound that can be cured by heating. Only one type of the thermosetting compound may be used, or two or more types may be used in combination.

From the viewpoint of further enhancing moisture resistance and adhesiveness, the thermosetting compound preferably contains an epoxy compound.

From the viewpoint of further enhancing moisture resistance, adhesiveness and heat resistance, the thermosetting compound preferably has an aromatic skeleton.

Examples of the aromatic skeleton include a benzene skeleton, a naphthalene skeleton, a fluorene skeleton, a biphenyl skeleton, an anthracene skeleton, a pyrene skeleton, a xanthene skeleton, an adamantan skeleton, and a bisphenol A type skeleton. From the viewpoint of further enhancing moisture resistance, adhesiveness and heat resistance, the aromatic skeleton is preferably a benzene skeleton, a naphthalene skeleton or a fluorene skeleton, and more preferably a naphthalene skeleton. The aromatic skeleton may be a benzene skeleton or a naphthalene skeleton. From the viewpoint of further enhancing moisture resistance, adhesiveness and heat resistance, the thermosetting compound preferably contains a thermosetting compound having a naphthalene skeleton.

From the viewpoint of further enhancing moisture resistance and adhesiveness, the content of the thermosetting compound in 100% by weight of the adhesive is preferably 0.01% by weight or more, more preferably 0.1% by weight or more. It is more preferably 1% by weight or more, particularly preferably 15% by weight or more, preferably 90% by weight or less, more preferably 80% by weight or less, still more preferably 70% by weight or less.

From the viewpoint of further enhancing moisture resistance and adhesiveness, the content of the thermosetting compound having a naphthalene skeleton in 100% by weight of the adhesive is preferably 0.01% by weight or more, more preferably 0.1. By weight or more, more preferably 1% by weight or more, particularly preferably 15% by weight or more, preferably 90% by weight or less, more preferably 80% by weight or less, still more preferably 70% by weight or less, particularly preferably 50% by weight. % Or less, most preferably 30% by weight or less.

Thermosetting agent:
The thermosetting agent heat-cures the thermosetting compound. Examples of the heat curing agent include an imidazole curing agent, a phenol curing agent, a thiol curing agent, an amine curing agent, an acid anhydride curing agent, a thermal cation initiator, a thermal radical generator and the like. Only one type of the thermosetting agent may be used, or two or more types may be used in combination.

The imidazole curing agent is not particularly limited, and 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-phenylimidazolium trimerite, 2, 4-Diamino-6- [2'-methylimidazolyl- (1')]-ethyl-s-triazine and 2,4-diamino-6- [2'-methylimidazolyl- (1')]-ethyl-s- Examples thereof include triazine isocyanuric acid adduct.

The thiol curing agent is not particularly limited, and examples thereof include trimethylolpropane tris-3-mercaptopropionate, pentaerythritol tetrakis-3-mercaptopropionate, and dipentaerythritol hexa-3-mercaptopropionate. ..

Since the effect of the present invention is effectively exhibited, the solubility parameter of the thiol curing agent is preferably 9.5 or more, preferably 12 or less. The solubility parameter is calculated by the Fedors method. For example, the solubility parameter of trimethylolpropane tris-3-mercaptopropionate is 9.6 and the solubility parameter of dipentaerythritol hexa-3-mercaptopropionate is 11.4.

The amine curing agent is not particularly limited, and is hexamethylenediamine, octamethylenediamine, decamethylenediamine, 3,9-bis (3-aminopropyl) -2,4,8,10-tetraspiro [5.5]. Examples thereof include undecane, bis (4-aminocyclohexyl) methane, metaphenylenediamine and diaminodiphenylsulfone.

Examples of the thermal cation initiator include an iodonium-based cation curing agent, an oxonium-based cation curing agent, and a sulfonium-based cation curing agent. Examples of the iodonium-based cationic curing agent include bis (4-tert-butylphenyl) iodonium hexafluorophosphate and the like. Examples of the oxonium-based cationic curing agent include trimethyloxonium tetrafluoroborate. Examples of the sulfonium-based cationic curing agent include try-p-tolylsulfonium hexafluorophosphate.

The thermal radical generator is not particularly limited, and examples thereof include azo compounds and organic peroxides. Examples of the azo compound include azobisisobutyronitrile (AIBN) and the like. Examples of the organic peroxide include di-tert-butyl peroxide and methyl ethyl ketone peroxide.

The content of the thermosetting agent is not particularly limited. With respect to 100 parts by weight of the thermosetting compound, the content of the thermosetting agent is preferably 0.01 parts by weight or more, more preferably 1 part by weight or more, preferably 200 parts by weight or less, more preferably. It is 100 parts by weight or less, more preferably 75 parts by weight or less, particularly preferably 50 parts by weight or less, and most preferably 10 parts by weight or less. When the content of the thermosetting agent is at least the above lower limit, it is easy to sufficiently cure the adhesive. When the content of the thermosetting agent is not more than the above upper limit, it becomes difficult for excess thermosetting agent that was not involved in curing to remain after curing, and the heat resistance of the bonded portion is further increased.

Spacer particles:
Examples of the spacer particles include resin particles, inorganic particles other than metal particles, organic-inorganic hybrid particles, and metal particles. In the present invention, the spacer particles are resin particles or organic-inorganic hybrid particles. The spacer particles may be core-shell particles having a core and a shell arranged on the surface of the core. The core may be an organic core. The shell may be an inorganic shell. Spacer particles excluding metal particles are preferable, and resin particles, inorganic particles excluding metal particles, or organic-inorganic hybrid particles are more preferable from the viewpoint of being able to relieve stress when stress is applied to the bonded portion and maintaining high adhesiveness. preferable. Resin particles or organic-inorganic hybrid particles are used in the present invention because they are more excellent than the effects of the present invention.

The spacer particles are preferably resin particles formed of resin. When the spacer particles are resin particles, when stress is applied to the adhesive portion, the stress can be relaxed and the adhesiveness can be maintained high.

Various organic substances are preferably used as the resin for forming the resin particles. Examples of the resin for forming the resin particles include polyolefin resins such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyisobutylene and polybutadiene; acrylic resins such as polymethylmethacrylate and polymethylacrylate; poly. Alkylene terephthalate, polycarbonate, polyamide, phenol formaldehyde resin, melamine formaldehyde resin, benzoguanamine formaldehyde resin, urea formaldehyde resin, phenol resin, melamine resin, benzoguanamine resin, urea resin, epoxy resin, unsaturated polyester resin, saturated polyester resin, polysulfone, polyphenylene Oxide, polyacetal, polyimide, polyamideimide, polyether ether ketone, polyether sulfone, and a polymer obtained by polymerizing one or more kinds of various polymerizable monomers having an ethylenically unsaturated group can be obtained. Can be mentioned. Since the hardness of the spacer particles can be easily controlled within a suitable range, the resin for forming the resin particles is a weight obtained by polymerizing one or more polymerizable monomers having a plurality of ethylenically unsaturated groups. It is preferably coalesced.

When the resin particles are obtained by polymerizing a polymerizable monomer having an ethylenically unsaturated group, the polymerizable monomer having an ethylenically unsaturated group is crosslinkable with a non-crosslinkable monomer. Examples of the monomer of.

Examples of the non-crosslinkable monomer include styrene-based monomers such as styrene and α-methylstyrene; carboxyl group-containing monomers such as (meth) acrylic acid, maleic acid, and maleic anhydride; and methyl ( Meta) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) Alkyl (meth) acrylate compounds such as meta) acrylate and isobornyl (meth) acrylate; oxygen atoms such as 2-hydroxyethyl (meth) acrylate, glycerol (meth) acrylate, polyoxyethylene (meth) acrylate and glycidyl (meth) acrylate. Contains (meth) acrylate compound; nitrile-containing monomer such as (meth) acrylonitrile; vinyl ether compound such as methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether; acid vinyl ester such as vinyl acetate, vinyl butyrate, vinyl laurate, vinyl stearate, etc. Compounds; unsaturated hydrocarbons such as ethylene, propylene, isoprene, and butadiene; halogen-containing monomers such as trifluoromethyl (meth) acrylate, pentafluoroethyl (meth) acrylate, vinyl chloride, vinyl fluoride, and chlorostyrene. Can be mentioned.

Examples of the crosslinkable monomer include tetramethylolmethanetetra (meth) acrylate, tetramethylolmethanetri (meth) acrylate, tetramethylolmethanedi (meth) acrylate, trimethylolpropane tri (meth) acrylate, and dipenta. Erislitol Hexa (meth) Acrylate, Dipenta Erythritol Penta (Meta) Acrylate, Gloxy Tri (Meta) Acrylate, Gglycerol Di (Meta) Acrylate, (Poly) Ethylene Glycol Di (Meta) Acrylate, (Poly) Propylene Glycol Di (Meta) Polyfunctional (meth) acrylate compounds such as acrylates, (poly) tetramethylene glycol di (meth) acrylates, 1,4-butanediol di (meth) acrylates; triallyl (iso) cyanurate, trimethyloltrimethylolate, divinylbenzene, Examples thereof include silane-containing monomers such as diallyl phthalate, diallyl acrylamide, diallyl ether, γ- (meth) acryloxypropyltrimethoxysilane, trimethoxysilylstyrene, and vinyltrimethoxysilane.

The resin particles can be obtained by polymerizing the polymerizable monomer having an ethylenically unsaturated group by a known method. Examples of this method include a method of suspension polymerization in the presence of a radical polymerization initiator, a method of swelling a monomer together with a radical polymerization initiator using non-crosslinked seed particles, and the like.

When the spacer particles are inorganic particles other than metal particles or organic-inorganic hybrid particles, examples of the inorganic substance for forming the spacer particles include silica and carbon black. It is preferable that the inorganic substance is not a metal. The particles formed of the silica are not particularly limited, but for example, after hydrolyzing a silicon compound having two or more hydrolyzable alkoxysilyl groups to form crosslinked polymer particles, firing is performed if necessary. Examples include particles obtained by doing so. Examples of the organic-inorganic hybrid particles include organic-inorganic hybrid particles formed of a crosslinked alkoxysilyl polymer and an acrylic resin.

From the viewpoint of further enhancing the adhesiveness and the adhesive reliability, the compressive elastic modulus (10% K value) when the spacer particles are compressed by 10% is preferably 980 N / mm ² or more, more preferably 1200 N / mm ^2. or more, preferably 4900 N / mm ² or less, and more preferably not more than 3000N / mm ^2.

The 10% K value of the spacer particles can be measured as follows.

Using a microcompression tester, the spacer particles are compressed on the smoothing indenter end face of a cylinder (diameter 50 μm, made of diamond) under the condition that a maximum test load of 90 mN is applied over 30 seconds at 25 ° C. At this time, the load value (N) and the compressive displacement (mm) are measured. From the obtained measured values, the compressive elastic modulus can be calculated by the following formula. As the microcompression tester, for example, "Fisherscope H-100" manufactured by Fisher Co., Ltd. is used.

K value (N / mm ² ) = (3/2 ^1/2 ) ・ F ・ S ^-3/2・ R- ^{1 / 2}
F: Load value (N) when the spacer particles are compressed and deformed by 10%
S: Compressive displacement (mm) when the spacer particles are compressed and deformed by 10%
R: Radius of spacer particles (mm)

From the viewpoint of further enhancing the moisture resistance and adhesiveness and further enhancing the uniformity of the thickness of the adhesive portion, the content of the spacer particles in 100% by weight of the adhesive is preferably 1% by weight or more. It is preferably 2% by weight or more, more preferably more than 5% by weight, preferably 15% by weight or less, and more preferably 12% by weight or less.

Inorganic filler:
Examples of the material of the inorganic filler include silica, talc, clay, mica, hydrotalcite, alumina, magnesium oxide, aluminum hydroxide, aluminum nitride, and boron nitride.

From the viewpoint of further enhancing the moisture resistance, the inorganic filler is preferably silica or alumina, more preferably silica, and even more preferably molten silica. By using silica, the coefficient of thermal expansion of the bonded portion is further lowered, and the bond reliability is further improved.

From the viewpoint of further enhancing the moisture resistance, the inorganic filler is preferably a surface-treated product with a coupling agent.

Examples of the coupling agent include a silane coupling agent, a titanium coupling agent, an aluminum coupling agent, and the like. From the viewpoint of further enhancing the adhesiveness, the inorganic filler is preferably a surface-treated product with a silane coupling agent.

Examples of the silane coupling agent include phenylsilane, vinylsilane, aminosilane, imidazolesilane, and epoxysilane. Phenylsilane is preferable from the viewpoint of further enhancing moisture resistance.

The content of the inorganic filler in 100% by weight of the adhesive is more than 30% by weight and 75% by weight or less. From the viewpoint of further enhancing the moisture resistance, the content of the inorganic filler in 100% by weight of the adhesive is preferably more than 35% by weight, more preferably 40% by weight or more. From the viewpoint of further enhancing the adhesiveness, the content of the inorganic filler is preferably 70% by weight or less, more preferably 65% by weight or less, still more preferably 60% by weight or less.

When the content of the inorganic filler exceeds 35% by weight in 100% by weight of the adhesive, the moisture resistance becomes considerably high.

From the viewpoint of improving both adhesiveness and moisture resistance in a well-balanced manner, the ratio of the content of the inorganic filler in 100% by weight of the adhesive to the content of the spacer particles in 100% by weight of the adhesive (inorganic filler). Content / content of spacer particles) is preferably 3 or more, more preferably 4 or more, preferably 60 or less, and more preferably 30 or less.

Other ingredients:
The adhesive may contain a photocurable component, or may contain a photocurable compound and a photopolymerization initiator.

From the viewpoint of further enhancing the adhesiveness, the adhesive preferably contains a coupling agent.

Examples of the coupling agent include a silane coupling agent, a titanium coupling agent, an aluminum coupling agent, and the like. From the viewpoint of further enhancing the adhesiveness, the adhesive preferably contains a silane coupling agent.

Examples of the silane coupling agent include phenylsilane, vinylsilane, aminosilane, imidazolesilane, and epoxysilane.

From the viewpoint of further enhancing the adhesiveness, the content of the coupling agent in 100% by weight of the adhesive is preferably 0.01% by weight or more, more preferably 0.1% by weight or more, and preferably 2 By weight or less, more preferably 1% by weight or less.

From the viewpoint of effectively enhancing the coatability, further enhancing the uniformity of the thickness of the adhesive portion, further enhancing the adhesiveness, and further suppressing the generation of voids, the adhesive contains a thixotropy-imparting agent. Is preferable.

Examples of the thixotropy-imparting agent include metal particles, calcium carbonate, fumed silica, aluminum oxide, boron nitride, aluminum nitride, and inorganic particles such as aluminum borate.

From the viewpoint of effectively improving the coatability, further improving the uniformity of the thickness of the adhesive portion, further improving the adhesiveness, and further suppressing the generation of voids, the above-mentioned thixotropy is imparted in 100% by weight of the above-mentioned adhesive. The content of the agent is preferably 0.1% by weight or more, more preferably 0.5% by weight or more, preferably 10% by weight or less, and more preferably 5% by weight or less.

The adhesive may be, for example, a filler, a bulking agent, a softener, a plasticizer, a polymerization catalyst, a curing catalyst, a colorant, an antioxidant, a heat stabilizer, a light stabilizer, an ultraviolet absorber, or a lubricant, if necessary. , Antistatic agent, flame retardant and other various additives may be contained.

(Inductor)
The inductor according to the present invention includes a ferrite core and an adhesive portion for adhering the ferrite core. In the inductor according to the present invention, the material of the upper adhesive portion is the above-mentioned inductor adhesive. The adhesive portion is a cured product of the inductor adhesive. The adhesive portion is formed by curing the inductor adhesive.

It is preferable that the ferrite core is arranged on the surfaces of the adhesive portions on both sides facing each other. It is preferable that the ferrite core has a gap due to the adhesive portion.

FIG. 1 is a cross-sectional view schematically showing an inductor using an inductor adhesive according to an embodiment of the present invention.

The inductor 1 shown in FIG. 1 includes a ferrite core 11, a ferrite core 12, and an adhesive portion 13. The inductor 1 includes a plurality of ferrite cores (ferrite core 11 and ferrite core 12). The inductor 1 includes a coil iron core for transformer parts. The ferrite core 11 is an E-type ferrite core. The ferrite core 12 is an I-type farite core. Of the three convex portions of the E-type ferrite core 11, the tips of the two outer convex portions and the side surfaces of the I-type ferrite core 12 face each other and separate a gap. The adhesive portion 13 is arranged in this gap. The material of the adhesive portion 13 is the above-mentioned adhesive for an inductor. In the present embodiment, the thickness of the adhesive portion 13 is equivalent to the particle size of the spacer particles contained in the adhesive 13. The spacer particles are in contact with both the ferrite core 11 and the ferrite core 12.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. The present invention is not limited to the following examples.

The following materials were prepared.

Thermosetting compound 1: Resorcinol type epoxy compound, "Epolite TDG-LC" manufactured by Kyoeisha Chemical Co., Ltd.
Thermosetting compound 2: Bisphenol F type epoxy compound, "EXA-830CRP" manufactured by DIC
Thermosetting compound 3: Naphthalene type epoxy compound, "HP-4032D" manufactured by DIC Corporation
Thermosetting compound 4: Bisphenol A type epoxy compound, "EXA-850CRP" manufactured by DIC
Thermosetting compound 5: Naphthalene type epoxy compound, "HP-4710" manufactured by DIC Corporation
Thermosetting compound 6: Fluorene type epoxy compound, "OGSOL PG-100" manufactured by Osaka Gas Chemical Co., Ltd.

Thermosetting agent 1: Imidazole curing accelerator, "TEP-2E4MZ" manufactured by Nippon Soda Corporation
Thermosetting agent 2: Imidazole curing accelerator, "2MZA-PW" manufactured by Shikoku Chemicals Corporation

Coupling agent: Silane coupling agent, "KBM-573" manufactured by Shin-Etsu Chemical Co., Ltd.

Thixotropy imparting agent: "PM-20L" manufactured by Tokuyama Corporation

Inorganic filler 1: Silica, average particle size 1 μm, "SE4050-SPE" manufactured by Admatex
Inorganic filler 2: silica, average particle size 3.8 μm, "EXR-4" manufactured by Ryumori Co., Ltd.

Spacer 1: Average particle size 20 μm, CV value 5%, 10% K value 3600 N / mm ² , “SP-220” manufactured by Sekisui Chemical Co., Ltd., Resin particle spacer 2: Average particle size 150 μm, CV value 7%, 10% K value 2000N / mm ² , "SP-L150" manufactured by Sekisui Chemical Industry Co., Ltd., resin particle spacer 3: average particle diameter 50 μm, CV value 5%, 10% K value 3800N / mm ² , manufactured by Sekisui Chemical Industry Co., Ltd. "SP-L150" 250 ”, resin particle spacer 4: average particle diameter 200 μm, CV value 7%, 10% K value 3900 N / mm ² ,“ GS-L200 ”manufactured by Sekisui Chemical Industry Co., Ltd., resin particles

(Example 1)
(1) Preparation of Adhesive for Inductor According to the composition shown in Table 1, each material other than the spacer was stirred and mixed with a rotation / revolution mixer to obtain an adhesive composition. Spacer particles were added to the obtained adhesive composition according to the composition shown in Table 1, and the mixture was stirred and mixed using a rotation / revolution mixer to prepare an inductor adhesive.

(2) Manufacture of Inductor The obtained inductor adhesive is filled in a 10 mL syringe (manufactured by Musashi Engineering Co., Ltd.), and a precision nozzle (manufactured by Musashi Engineering Co., Ltd., nozzle tip inner diameter: spacer particle diameter is less than 100 μm) at the tip of the syringe. , 0.3 mm, 0.6 mm when the particle size of the spacer is 100 μm or more), apply to the I-type core using a dispenser device (“SHOT MASTER300” manufactured by Musashi Engineering Co., Ltd.), and bond it to the E-type core. After that, it was cured in a reflow furnace to obtain an inductor.

(3) Preparation of sample for moisture resistance evaluation The obtained inductor adhesive is filled in a 10 mL syringe (manufactured by Musashi Engineering Co., Ltd.), and a precision nozzle (manufactured by Musashi Engineering Co., Ltd., nozzle tip inner diameter 0.3 mm) is attached to the tip of the syringe. Using a mounting and dispenser device (“SHOT MASTER300” manufactured by Musashi Engineering Co., Ltd.), 5 ferrite pieces of the same quality as the inductor with a length of 3 mm and a width of 3 mm and a thickness of 0.3 mm and a ferrite with the same quality as an inductor with a length of 20 mm and a width of 20 mm and a thickness of 0.3 mm. After bonding one piece together, it was cured in a reflow furnace to obtain a sample for moisture resistance evaluation.

(Examples 2 to 16, Comparative Examples 1 and 2)
Adhesives for inductors, inductors, and samples for evaluating moisture resistance were obtained in the same manner as in Example 1 except that the types and amounts of the compounding components were changed as shown in Tables 1 and 2.

(Evaluation)
(1) Viscosity When the particle size of the spacer particles in the adhesive is 20 μm or less, use an E-type viscometer (“TVE22L” manufactured by Toki Sangyo Co., Ltd.) to measure the viscosity (η25) of the adhesive at 25 ° C. It was measured at 25 ° C. and 5 rpm.

When the particle size of the spacer particles in the adhesive exceeds 20 μm, the viscosity (η25) of the adhesive at 25 ° C. is measured at 25 ° C. using a spiral viscometer (“PCU-02V” manufactured by Malcolm Co., Ltd.). It was measured under the condition of 10 rpm.

(2) Applicability The applicability was evaluated using a dispenser device (“SHOT MASTER 300” manufactured by Musashi Engineering Co., Ltd.). The coating conditions are fixed with a precision nozzle (manufactured by Musashi Engineering Co., Ltd., nozzle tip inner diameter 0.3 mm) and discharge conditions (temperature 25 ° C., discharge pressure 0.3 Mpa), and the coating property is improved by applying on a glass substrate. evaluated. The coatability was judged according to the following criteria.

[Criteria for applicability]
○ ○: Can be applied without blurring or sagging ○: Slightly faint or sagging occurred △: There was no coating breakage but large blurring or sagging occurred ×: Application was cut off or could not be applied at all

(3) Particle dispersibility (pieces / mm ² )
30 mg of the adhesive was placed on the first slide glass, the second slide glass was placed on the adhesive, and then a 50 g weight was placed on the second slide glass and left for 20 minutes. After standing, the number of spacer particles per ^{1 mm 2} was measured in a plan view using an optical microscope.

(4) Measurement of Glass Transition Point Temperature (Tg) The adhesive was heated at 120 ° C. for 20 minutes and then heated at 170 ° C. for 15 minutes to be cured to obtain a cured product. The tan δ of the obtained cured product was measured using a viscoelasticity measuring machine (manufactured by IT Measurement Control Co., Ltd.) under the conditions of a heating rate of 10 ° C./min and a grip width of 20 mm and 5 Hz. The peak temperature of Tan δ was defined as the glass transition temperature.

(5) Coefficient of linear expansion The adhesive was heated at 120 ° C. for 20 minutes and then heated at 170 ° C. for 15 minutes to be cured to obtain a cured product. The coefficient of linear expansion of the obtained cured product was measured using TMA / SS6000 (manufactured by Seiko Instruments Inc.) under the condition of heating from room temperature (25 ° C.) to 250 ° C. at a heating rate of 5 ° C./min.

(6) Moisture resistance Measure the adhesive strength between the obtained moisture resistance evaluation sample left in an oven at 85 ° C. and 85% humidity for 24 hours and the obtained moisture resistance evaluation sample left at room temperature. did. Moisture resistance was evaluated by measuring the die-share adhesive strength with a die-share tester "Dage series 4000" manufactured by Dage. Moisture resistance was judged according to the following criteria.

[Criteria for moisture resistance]
○○: The adhesive strength of the sample left under high temperature and high humidity is 90% or more of the adhesive strength of the sample left at room temperature. ○: The adhesive strength of the sample left under high temperature and high humidity is the adhesion of the sample left at room temperature. 80% or more and less than 90% of the force Δ: Adhesive strength of the sample left under high temperature and high humidity is 70% or more and less than 80% of the adhesive strength of the sample left at room temperature ×: Adhesion of the sample left under high temperature and high humidity The force is less than 70% of the adhesive force of the sample left at room temperature

(7) Gap controllability In the obtained inductor, the variation 3σ (σ; standard deviation) of the gap-to-gap distance and the gap-to-gap distance after curing is measured using a laser displacement meter (“KS-1100” manufactured by KEYENCE). did. The gap controllability was evaluated from the variation of the inter-gap distance of 3σ / the value X of the inter-gap distance after curing. The gap controllability was judged according to the following criteria.

[Gap controllability criteria]
○ ○: Value X is less than 0.1 ○: Value X is 0.1 or more and less than 0.2 Δ: Value X is 0.2 or more and less than 0.4 ×: Value X is 0.4 or more

(8) Inductance variation The inductance of the 20 obtained inductors was measured and the variation was evaluated. The variation in inductance was judged according to the following criteria.

[Criteria for determining inductance variation]
○ ○: Inductance CV value is less than 5% ○: Inductance CV value is 5% or more and less than 10% Δ: Inductance CV value is 10% or more and less than 15% ×: Inductance CV value is 15% or more

(9) Heat and shock resistance 1 (long-term reliability)
The obtained inductor was left in an environment where the temperature was changed at a high temperature of 125 ° C. for 30 minutes and at a low temperature of −40 ° C. for 30 minutes for 500 cycles. After that, the rate of change of inductance was measured. The characteristic change rate means the rate of variation in inductance due to peeling of the adhesive surface due to thermal shock or change in the distance between gaps.

[Criteria for thermal shock resistance 1]
○ ○: The rate of change from the initial value of inductance is less than 10% ○: The rate of change from the initial value of inductance is 10% or more and less than 20% △: The rate of change from the initial value of inductance is 20% or more and less than 30% × : The rate of change from the initial value of inductance is 30% or more

(10) Heat resistance and impact resistance 2 (long-term reliability)
The obtained inductor was left in an environment where the temperature was changed at a high temperature of 150 ° C. for 30 minutes and at a low temperature of −50 ° C. for 30 minutes for 500 cycles. After that, the rate of change of inductance was measured.

[Criteria for thermal shock resistance 2]
○ ○: The rate of change from the initial value of inductance is less than 10% ○: The rate of change from the initial value of inductance is 10% or more and less than 20% △: The rate of change from the initial value of inductance is 20% or more and less than 30% × : The rate of change from the initial value of inductance is 30% or more

Details and results are shown in Tables 1 and 2 below.

1 ... Inductor 11 ... Ferrite core (E type)
12 ... Ferrite core (I type)
13 ... Adhesive part

Claims (11)

Adhesive for inductors used for inductors
Contains a thermosetting compound, a thermosetting agent, an inorganic filler, and spacer particles.
The spacer particles are resin particles or organic-inorganic hybrid particles.
The average particle size of the spacer particles is 20 μm or more and 200 μm or less.
The CV value of the particle size of the spacer particles is 10% or less, and the particle size is 10% or less.
An inductor adhesive in which the content of the inorganic filler exceeds 30% by weight and is 75% by weight or less in 100% by weight of the adhesive. When the adhesive is heated at 120 ° C. for 20 minutes and then heated at 170 ° C. for 15 minutes to obtain a cured product, the glass transition temperature of the obtained cured product is 120 ° C. or higher and 210 ° C. or lower. Item 2. The adhesive for an inductor according to Item 1. When 30 mg of the adhesive was placed on the first slide glass, the second slide glass was placed on the adhesive, and then a 50 g weight was placed on the second slide glass and left for 20 minutes. The adhesive for an inductor according to claim 1 or 2, wherein the number of the spacer particles is 2 pieces / mm ² or more and 1000 pieces / mm ^{2 or less in a plan view.} The adhesive for an inductor according to any one of claims 1 to 3, wherein the content of the thermosetting agent is 0.01 part by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the thermosetting compound. Agent. The inductor adhesive according to any one of claims 1 to 4, wherein the adhesive has a viscosity at 25 ° C. of 10 Pa · s or more and 150 Pa · s or less. The inductor adhesive according to any one of claims 1 to 5, wherein the content of the spacer particles is 1% by weight or more and 15% by weight or less in 100% by weight of the adhesive. Any one of claims 1 to 6, wherein the ratio of the content of the inorganic filler in 100% by weight of the adhesive to the content of the spacer particles in 100% by weight of the adhesive is 3 or more and 60 or less. Adhesives for inductors as described in the section. The adhesive for an inductor according to any one of claims 1 to 7, wherein the ratio of the average particle size of the inorganic filler to the average particle size of the spacer particles is 0.00005 or more and 0.1 or less. The 10% K value of the spacer particles is 980 N / mm ² or more and 4900 N / mm ² or less, inductor adhesive according to any one of claims 1-8. The inductor adhesive according to any one of claims 1 to 9, which is used for adhering a ferrite core in an inductor. Ferrite core and
It is provided with an adhesive portion for adhering the ferrite core.
An inductor in which the material of the adhesive portion is the inductor adhesive according to any one of claims 1 to 10.

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