JP5940465B2 - Multilayer electronic component and manufacturing method thereof - Google Patents

Description

  The present invention relates to a multilayer electronic component typified by a multilayer inductor and a manufacturing method thereof.

  Conventionally, as one method of manufacturing a multilayer inductor, which is a representative example of multilayer electronic components, a method of printing an internal conductor pattern on a ceramic green sheet containing ferrite or the like, and laminating and firing these sheets is known. It has been.

  Inductors used in power supplies such as DC / DC converters are required to have higher frequencies as the current increases. So far, in response to a request for increasing the current, studies are underway to replace ferrite materials with Fe-based or alloy-based metallic materials. In the case of using these metal materials, methods have heretofore been employed in which magnetic particles are bonded with resin or glass or the magnetic particles are sintered together. However, when a resin is used, the amount of resin added must be increased in order to ensure strength. As a result, the filling rate of the magnetic particles is reduced, and sufficient magnetic permeability cannot be obtained. On the other hand, when sintered, high magnetic permeability can be obtained, but due to the influence of loss, there are frequency restrictions, and electronic parts used for portable devices and the like are limited. For this reason, methods that do not use resin or glass have been studied, and magnetic particles can be oxidized to form an oxide film on the surface of the particles, and the magnetic particles can be bonded together by this oxide film to produce a magnetic material with a high filling rate. all right. However, it has also been found that the capacity component between the particles increases as the distance between the magnetic particles becomes shorter.

  In the invention disclosed in Patent Document 1, the glass component is naturally integrated with the magnetic material as a binder, and the presence of a glass pattern having a specific shape is not recognized.

JP-A-9-148118 JP 7-272935 A

  In a multilayer inductor, magnetic layers and internal conductors are alternately formed, and in many cases, the internal conductors are formed in a plurality of layers. A magnetic substance having a high dielectric constant existing between the inner conductors can be evaluated as a capacitive component between the inner conductors. This is expected to have an effect when the distance between the internal conductors is narrowed in order to further increase the capacity in the future and when the operating frequency of the equipment is increased. Is required.

  In view of the above, the present invention provides a multilayer electronic component capable of supporting high frequencies by reducing stray capacitance between internal conductors in a situation where further downsizing and thinning are expected, and a method for manufacturing the same Is an issue.

As a result of intensive studies by the present inventors, the invention of a multilayer electronic component having the following characteristics has been completed. According to the present invention, a multilayer electronic component is composed of a plurality of magnetic layers formed of soft magnetic alloy particles, a plurality of coil segments made of a conductive material that forms part of a circular structure, and a conductive material. It has a relay segment and a glass segment made of Si-containing glass. The conductive material is preferably Ag. The magnetic layer and the coil segment constitute a laminated structure in which they are alternately laminated. The relay segment is formed so as to conduct between the coil segments formed on the plurality of magnetic layers, and constitutes an internal conductor in which the coil segment and the relay segment are electrically integrated. Here, the above-mentioned glass segment exists in at least a part between two adjacent coil segments with the magnetic layer interposed therebetween.
Preferably, the width of the coil segment is substantially constant and the circumferential structure is substantially the same, and the glass segment is wider than the coil segment and exists between the adjacent coil segments.
Preferably, the glass segment is formed in contact with the coil segment.
The Si-containing glass preferably has a softening temperature of 400 to 600 ° C., and is preferably Si glass or Si—B glass.
Preferably, the soft magnetic alloy particles are Fe-Si-M soft magnetic alloy, where M is a metal element that is more easily oxidized than Fe, and preferably M is Al or Cr.
Preferably, the magnetic layer and the glass segment are formed by heat treatment at 600 to 950 ° C.
The multilayer electronic component of the present invention preferably includes a step of forming a conductor pattern and / or a glass pattern on each of a plurality of green sheets containing soft magnetic alloy particles, and a conductor adjacent to the green sheet on which each pattern is formed. It is manufactured by a method having a step of obtaining a pre-heat treatment chip by stacking so that a glass pattern is arranged between the patterns, and a step of heating the obtained pre-heat treatment chip. At this time, the conductive pattern is formed by printing a conductive paste containing a conductive material so as to form a part of the surrounding structure, and the glass pattern is formed by printing a glass paste containing Si-containing glass. In the heating step, the conductive material and the Si-containing glass are respectively sintered, and the coil segment and the glass segment are obtained from the conductor pattern and the glass pattern, respectively.

  According to the present invention, stray capacitance generated between internal conductors can be suppressed by inserting glass segments between the internal conductors. For this reason, a resonance point becomes high and can respond to a higher frequency. In addition, the interval between the inner conductors can be narrowed, and the size can be reduced and the inductor can be made high. Until now, ferrite was the mainstream in power system multilayer inductors, so the influence of the capacitance component was small. However, in order to obtain current characteristics, a metal-based magnetic material is suitable. When alloy particles are bonded with an oxide film in order to obtain high magnetic permeability, the influence of dielectric constant cannot be ignored. According to the present invention, as described above, it is more effective to reduce the stray capacitance, increase the resonance point, and improve the characteristics up to a high frequency as the distance between the inner conductors is smaller. Means. Further, stray capacitance may be generated between the inner conductor and the outer electrode, and a similar effect can be obtained by providing a glass segment between these.

It is a schematic cross section of a multilayer inductor. It is a typical exploded view of a multilayer inductor.

  Hereinafter, the present invention will be described in detail with appropriate reference to the drawings. However, the present invention is not limited to the illustrated embodiment, and in the drawings, the characteristic portions of the invention may be emphasized and expressed, so that the accuracy of the scale is not necessarily guaranteed in each part of the drawings. Not.

  FIG. 1A is a schematic cross-sectional view of a multilayer inductor which is a typical example of a multilayer electronic component. FIG. 1B is a partially enlarged view of FIG. In the following description, a multilayer inductor is given as one of the specific embodiments of the multilayer electronic component that is the subject of the present invention. The multilayer electronic component includes, for example, a transformer, an LC filter, a common mode filter for power supply, and the like. It may be. The multilayer inductor 1 has a structure in which most of the inner conductor 20 is buried in a magnetic part (laminate of the magnetic layer 10). Typically, the inner conductor 20 is a coil formed in a spiral shape, and other examples include a spiral coil, a meander (meandering) conductor, a linear conductor, and the like.

  The inner conductor 20 has a coil segment and a relay segment. In FIG. 1, only the coil segment is shown, and the relay segment is not shown. The coil segments and the magnetic layer 10 constitute a laminated structure in which they are alternately laminated. The coil segment forms a part of the coil winding structure. The relay segment is formed so as to conduct the plurality of coil segments. FIG. 2 is a schematic exploded view of a typical multilayer inductor. However, in FIG. 2, the depiction of the glass segment described later is omitted. In the illustrated embodiment, the inner conductor 20 has a coil structure in which coil segments CS1 to CS5 and relay segments IS1 to IS4 connecting the coil segments CS1 to CS5 are spirally integrated. The coil segments CS1 to CS4 have a U shape, the coil segment CS5 has a strip shape, and each relay segment IS1 to IS4 has a column shape penetrating the magnetic layers ML1 to ML4.

  According to the present invention, the coil segment and the relay segment are preferably conductive materials. As the conductive material, various materials used as electrodes of conventional electronic components can be used without any particular limitation, typically Ag, and preferably Ag substantially free of other metals. A mixture or alloy of 100 parts by weight of Ag and 50 parts by weight or less of other metals may be used, and examples of the other metals include, but are not limited to, Au, Cu, Pt, and Pd.

According to the present invention, in the multilayer inductor 1, a large number of soft magnetic alloy particles are accumulated to constitute a magnetic part having a predetermined shape. The magnetic body portion can be evaluated as an assembly of the magnetic layers 10 divided by the coil segments, and at the same time, it can be evaluated that the magnetic layers 10 and the coil segments constitute a laminated structure. . Each of the soft magnetic alloy particles 11 has an oxide film 12 formed on at least a part of the periphery thereof, preferably substantially the whole, and the insulating property of the magnetic part 10 is ensured by the oxide film 12. Adjacent soft magnetic alloy particles 11 are generally bonded via an oxide film 12 of each soft magnetic alloy particle 11 to constitute a magnetic part 10 having a certain shape. The oxide film 12 is preferably a film formed by oxidizing the soft magnetic alloy particles themselves. In part, metal portions of adjacent soft magnetic alloy particles 11 may be bonded to each other. The soft magnetic alloy particles are preferably made of an Fe-M-Si alloy (where M is a metal that is more easily oxidized than iron), and in this case, the oxide film is preferably formed by oxidation of the soft magnetic alloy. It is confirmed that it contains at least Fe ₃ O _{4 that} is a magnetic material, Fe ₂ O ₃ that is a non-magnetic material, and MO _x (x is a value determined according to the oxidation number of the metal M). Yes.

  The presence of the bond through the oxide film 12 is, for example, visually confirming that the oxide film 12 of the adjacent soft magnetic alloy particles 11 is in the same phase in an SEM observation image magnified about 3000 times. And can be clearly determined. The presence of the bond through the oxide film 12 improves the mechanical strength and insulation of the multilayer inductor 1. Moreover, since the oxide film 12 is usually relatively uneven, Ag migration is suppressed and moisture resistance is improved. The laminated inductor 1 is preferably bonded through the oxide film 12 of the adjacent soft magnetic alloy particles 11, but if it is partially bonded, the corresponding mechanical strength and insulation are improved. Such a form is also an embodiment of the present invention.

  Similarly, with respect to the bonding between the metal portions where the oxide film of the soft magnetic alloy particles 11 does not exist, adjacent soft magnetic alloy particles maintain the same phase in, for example, an SEM observation image magnified about 3000 times. However, the presence of a bond between the metal parts can be clearly determined by visually recognizing having a bond point. The magnetic permeability can be further improved by the presence of the coupling between the soft magnetic alloy particles 11. Here, the “joint part between metal parts where no oxide film is present” means a part in which adjacent alloy particles are in direct contact with each other, for example, in a strict sense. It is a concept including a metal bond, a mode in which metal parts are in direct contact with each other, and an exchange of atoms is not seen, and an intermediate mode between them. The metal bond in the strict sense means that the requirement such as “the atoms are regularly arranged” is satisfied.

  The adjacent soft magnetic alloy particles 11 are not physically bonded through the oxide film 12, nor are the soft magnetic alloy particles 11 connected to each other, and are merely in physical contact or approach. There may be.

  In the form of FIG. 1 (B), the oxide film is not formed in the part which touches the glass segment 30 among the soft magnetic alloy particles 11. FIG. By making the surface of the magnetic particles at the interface with the glass segment free of an oxide film, the glass material is less likely to spread from the glass segment 30 into the magnetic layer, and the glass segment 30 can be formed with high accuracy. The thickness can be reduced. In order to realize such a form, it is possible to use a soft magnetic alloy-based magnetic material and Si-containing glass having a softening temperature lower than the oxide film forming temperature of the soft magnetic alloy particles 11. As a result, during heat treatment, the Si-containing glass begins to soften from a temperature range lower than the oxide film formation temperature of the soft magnetic alloy particles 11, and the glass becomes film-like due to the surface tension at the portion in contact with the magnetic layer. The oxide film 12 of the soft magnetic alloy particles 11 is generated by raising the processing temperature. That is, an oxide film is generated on the soft magnetic alloy particles 11 that are not in contact with the glass segment 30, and an oxide film is not generated because the soft magnetic alloy particles in contact with the glass segment 30 are covered with the Si-containing glass. Since the glass segment and the magnetic layer are formed in this form, the wetting and spreading of the glass component from the glass segment to the magnetic layer can be prevented, and the soft magnetic particles at the interface of the magnetic layer in contact with the glass segment 30 Is covered with softened glass and heat-treated, so that no oxide film is formed on the soft magnetic alloy particles 11 in contact with the glass segment 30. Here, the fact that no oxide film is formed is confirmed by the fact that an oxide film having a thickness of 100 nm or more is not visually recognized by EDS (× 1000 times) observation of the polished cross section.

  In the multilayer inductor 1, both ends of the inner conductor 20 are typically drawn to opposite end surfaces of the outer surface of the multilayer inductor 1 through lead conductors (not shown), respectively, and external terminals (not shown). Connected to. Conventional technology can be used as appropriate for the structure and connection mode of the external terminals. More preferably, the glass segment 30 is also formed on the surface of the lead conductor and the inner conductor 20 on the side close to the outer electrode surface.

  In the present invention, the glass segment 30 is provided between two adjacent coil segments 20 with the magnetic layer 10 interposed therebetween. The glass segments 30 may be present at least at a part between the coil segments 20, and preferably are in contact with the coil segments 20.

  In the preferred embodiment, as shown in FIG. 1 (A), a straight line connecting the shortest from one coil segment 20 to the other coil segment 20 between two adjacent coil segments 20 with the magnetic layer 10 interposed therebetween is always a glass segment. A glass segment 30 is provided so as to be blocked at 30. However, the glass segment 30 is not formed at a location where the relay segment exists. Preferably, the widths of the plurality of coil segments are substantially constant, the circumferential structures formed by the plurality of coil segments are substantially the same, and the glass segment is wider than the coil segment and between adjacent coil segments. Exists. Specifically, in the form of FIG. 1 (A), the coil segments 20 are formed as a pair immediately above a glass segment 30 having substantially the same shape, and between two adjacent coil segments 20. There is always a glass segment 30. Moreover, in the form of FIG. 1 (A), the glass segment 30 is formed wider than the coil segment 20 that exists as a pair. Thus, it is preferable that the glass segment 30 has substantially the same shape as or includes the coil segment 20.

  When the widths of the plurality of coil segments are substantially constant and the circumference structure formed by the plurality of coil segments is the same, the glass segment is between the adjacent coil segments, preferably 75% to It is preferable to be present to occupy 200%, more preferably 100 to 200%. For example, in the form of FIG. 1 (A), since the glass segment 30 is formed wider than the coil segment 20, the numerical value exceeds 100%. For example, if the numerical value is about 50%, the effect of the present invention is reduced, but the present invention does not exclude such a form.

  If the material which comprises the glass segment 30 is Si containing glass, there will be no limitation in particular, Typically, Si type glass or Si-B type glass will be mentioned, Preferably the glass material whose softening temperature is 400-600 degreeC is mentioned. It is done. As such a glass material, what is marketed as glass for glass pastes can be used suitably. When glass that is softened in the above temperature range is used, a magnetic layer having a high magnetic permeability and a high-precision glass segment can be formed at the same time, and a composite part composed of a magnetic material and a non-magnetic material can be obtained. At this time, the magnetic particles in the magnetic material are bonded by an oxide film on the particle surface, and there is no oxide film on the magnetic particle surface at the interface with the glass, so that the magnetic material layer and the glass segment are formed.

  Hereinafter, a typical and non-limiting manufacturing method of the multilayer inductor 1 according to the present invention will be described. In manufacturing the multilayer inductor 1, first, a magnetic paste (slurry) prepared in advance is applied to the surface of a base film made of resin or the like using a coating machine such as a doctor blade or a die coater. This is dried with a dryer such as a hot air dryer to obtain a green sheet. The magnetic paste includes soft magnetic alloy particles, typically a polymer resin as a binder, and a solvent.

  Soft magnetic alloy particles are particles exhibiting soft magnetism mainly composed of an alloy. Examples of the alloy include Fe-M-Si alloys (where M is a metal that is more easily oxidized than iron). Examples of M include Cr and Al, and Cr is preferable. Examples of the soft magnetic alloy particles include particles produced by an atomizing method.

  When M is Cr, that is, the chromium content in the Fe—Cr—Si alloy is preferably 2 to 15 wt%. The presence of chromium is preferable in that it forms a passive state during heat treatment to suppress excessive oxidation and develop strength and insulation resistance. On the other hand, from the viewpoint of improving magnetic properties, it is preferable that there is little chromium. The above preferred range is proposed in consideration.

  The Si content in the Fe—Cr—Si based soft magnetic alloy is preferably 0.5 to 7 wt%. A high Si content is preferable in terms of high resistance and high magnetic permeability, and a low Si content provides good moldability, and the above preferable range is proposed in consideration of these.

  In the Fe—Cr—Si alloy, the balance other than Si and Cr is preferably iron except for inevitable impurities. Examples of metals that may be contained in addition to Fe, Si, and Cr include aluminum, magnesium, calcium, titanium, manganese, cobalt, nickel, and copper, and examples of nonmetals include phosphorus, sulfur, and carbon. .

  For an alloy constituting each soft magnetic alloy particle in the multilayer inductor 1, for example, a cross section of the multilayer inductor 1 is photographed using a scanning electron microscope (SEM), and then energy dispersive X-ray analysis (EDS). The chemical composition can be calculated by the ZAF method.

  The particle diameter of the soft magnetic alloy particles used as a raw material for the magnetic body portion 10 can be appropriately selected. Typically, d50 is preferably 2 to 30 μm, more preferably 2 to 20 μm on a volume basis. It is. The d50 of the soft magnetic alloy particles is measured using a particle size / particle size distribution measuring device (for example, Microtrack manufactured by Nikkiso Co., Ltd.) using a laser diffraction scattering method. In the multilayer inductor 1 using soft magnetic alloy particles, it is known that the particle size of the soft magnetic alloy particles as the raw material particles is approximately equal to the particle size of the soft magnetic alloy particles constituting the magnetic part of the multilayer inductor 10. .

  The above-mentioned magnetic paste preferably contains a polymer resin as a binder. The type of the polymer resin is not particularly limited, and examples thereof include polyvinyl acetal resins such as polyvinyl butyral (PVB). The type of solvent for the magnetic paste is not particularly limited, and for example, glycol ethers such as butyl carbitol can be used. The blending ratio of soft magnetic alloy particles, polymer resin, solvent and the like in the magnetic paste can be adjusted as appropriate, and the viscosity of the magnetic paste can be set accordingly.

  Conventional techniques can be used as appropriate for a specific method for obtaining a green sheet by applying and drying the magnetic paste.

  Next, using a punching machine such as a punching machine or a laser processing machine, the green sheet is punched to form through holes (through holes) in a predetermined arrangement. The arrangement of the through holes is set so that when the sheets are laminated, the internal conductor 20 is formed by the through holes (that is, the relay segments) filled with the conductors and the coil segments. As for the arrangement of the through holes for forming the inner conductor and the shape of the conductor pattern for forming the coil segment, conventional techniques can be used as appropriate, and specific examples are described with reference to the drawings in the following embodiments. Explained.

  A conductor paste is preferably used for filling the through holes and for printing the conductor pattern. The conductive paste contains a conductive material, typically a polymer resin as a binder, and a solvent.

  The particle diameter of the conductive material as the conductor particles can be appropriately selected, and d50 is preferably 1 to 10 μm on a volume basis. The d50 of the conductor particles is measured using a particle size / particle size distribution measuring apparatus (for example, Microtrack manufactured by Nikkiso Co., Ltd.) using a laser diffraction scattering method.

  The conductive paste preferably contains a polymer resin as a binder. The type of the polymer resin is not particularly limited, and examples thereof include polyvinyl acetal resins such as polyvinyl butyral (PVB). The kind of the solvent of the conductor paste is not particularly limited, and for example, glycol ether such as butyl carbitol can be used. The blending ratio of the conductive material, polymer resin, solvent and the like in the conductor paste can be adjusted as appropriate, and the viscosity of the conductor paste can be set accordingly.

  Next, using a printing machine such as a screen printing machine or a gravure printing machine, the conductor paste is printed on the surface of the green sheet, and this is dried with a dryer such as a hot air dryer to form a conductor pattern corresponding to the coil segment. Form. During printing, a part of the conductor paste is also filled in the above-described through hole. As a result, the conductor paste filled in the through hole and the printed conductor pattern constitute the shape of the internal conductor 20.

  The green sheet on which the conductor paste is printed as described above is also referred to as the first green sheet. In one form of the manufacturing method of the present invention, a second green sheet containing the same material as or a different magnetic material from the first green sheet is prepared as described above, and a glass paste containing Si-containing glass in the second green sheet A glass pattern can be formed, and a laminated body (chip before heat treatment) can be manufactured by appropriately laminating and pressing. In the formation of the glass pattern, a conventional technique such as printing a commercially available glass paste can be appropriately used. The glass pattern is preferably formed in a shape substantially identical to or including the shape of the above-described conductor pattern. However, it is not necessary to provide a glass pattern at a position corresponding to the through hole in the first green sheet. This is because a relay segment is formed at the position.

  Instead of the above-described manufacturing method in which the conductor pattern and the glass pattern are printed on separate green sheets and then laminated, it is also possible to adopt a manufacturing method in which a glass pattern is first formed on a green sheet and further a conductor pattern is printed thereon. . As described above, according to the manufacturing method of the present invention, one or both of the conductor pattern and the glass pattern may be formed on one green sheet. As a result, the conductor pattern and the glass pattern are laminated at the time of lamination. Should just face. The through hole may be formed before or after the glass pattern is formed. For the details of the production method in which a glass pattern is first formed on a green sheet and further a conductor pattern is printed thereon, refer to the description of the examples.

  Using a heating device such as a firing furnace, the chips before heat treatment are heat-treated in an oxidizing atmosphere such as air. The heat treatment atmosphere is not particularly limited as long as it is an oxidizing atmosphere, and air or dry air is desirable in consideration of production. In the temperature raising process, the temperature is preferably maintained at 300 to 600 ° C. for 1 to 600 minutes, and then the temperature is further raised. The maximum temperature is preferably 600 ° C. or higher, more preferably 600 to 950 ° C., and the maximum temperature is preferably maintained for 0.5 to 3 hours.

  In the chip before heat treatment, there are many fine gaps between individual soft magnetic alloy particles, and the fine gaps are usually filled with a mixture of a solvent and a binder. These mixtures disappear during the heating process, and the fine gaps turn into pores. In the high temperature range close to the maximum temperature, the soft magnetic alloy particles are densely formed to form a magnetic part, and typically, an oxide film is formed on the surface of each soft magnetic alloy particle. At this time, the conductive material is sintered to form the inner conductor 20. Thereby, the multilayer inductor 1 is obtained.

  Moreover, the glass material of a glass pattern softens at the time of this heating, and comprises a glass segment after cooling. At this time, if the softening point of the glass is about 400 to 600 ° C., the soft magnetic alloy at the interface with the glass is formed because the above-described oxide film of the soft magnetic alloy particles is formed after the softening of the glass starts during heating. An oxide film is not formed on the surface of the particle, and a glass segment is formed without the glass material being wet spread on the magnetic layer. In order to form the oxide film of the soft magnetic alloy particles after the softening of the glass material is started, it is preferable that the temperature increase rate during the heat treatment is made slow or kept at a temperature lower than the glass softening temperature.

  Usually, external terminals are formed after the heat treatment. Using a coating machine such as a dip coating machine or a roller coating machine, a conductor paste prepared in advance is applied to both ends in the length direction of the multilayer inductor 1, and this is applied using a heating device such as a firing furnace, for example, about 600. An external terminal is formed by performing a baking process at a temperature of about 1 hr. As the conductor paste for the external terminals, the above-described paste for printing a conductor pattern or a paste similar thereto can be used as appropriate.

  In the present invention, a multilayer electronic component may be manufactured by a so-called slurry build method. A typical example of the slurry build method is the method disclosed in Patent Document 2, for example. As a non-limiting example, a magnetic paste is printed by screen printing or the like to form a magnetic printed film, and a conductor paste is screen printed thereon to form a conductor pattern corresponding to the coil segment. At this time, a glass paste precursor can be further prepared, and a glass segment precursor can be formed all at once by forming a glass pattern having the same or similar shape as the conductor pattern before or after the formation of the conductor pattern. A magnetic paste is screen-printed on these so that a part of the conductor pattern is exposed and applied. Similarly, the conductor pattern and the glass pattern and the magnetic material printed film are alternately formed continuously with the partially exposed pattern, and finally the magnetic material printed film is applied to obtain a pre-heat treatment chip. About the obtained chip | tip before heat processing, the above-mentioned method can be used about subsequent heating and other processes.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the embodiments described in these examples.

[Concrete structure of multilayer inductor]
A specific structural example of the multilayer inductor 1 manufactured in this embodiment will be described. The multilayer inductor 1 as a part has a length of about 2.5 mm, a width of about 2.0 mm, a height of about 1.0 mm, and the whole has a rectangular parallelepiped shape.

  FIG. 2 is a schematic exploded view of the multilayer inductor. The magnetic part in the region where the inner conductor is formed has a structure in which a total of five magnetic layers ML1 to ML5 are integrated. An upper cover region and a lower cover region exist so as to sandwich the region where the inner conductor is formed, and the upper cover region has a structure in which eight magnetic layers ML6 are integrated. The lower cover region has a structure in which seven magnetic layers ML6 are integrated. The length of the multilayer inductor 1 is about 2.5 mm, the width is about 2.0 mm, and the height is about 1.0 mm. Each of the magnetic layers ML1 to ML6 has a length of about 2.5 mm, a width of about 2.0 mm, and a thickness of about 40 μm. Each of the magnetic layers ML1 to ML6 is mainly composed of soft magnetic alloy particles having the composition and average particle diameter (d50) shown in Table 1 which are soft magnetic alloy particles, and does not contain a glass component. In addition, an oxide film (not shown) exists on the surface of each soft magnetic alloy particle, and the soft magnetic alloy particles in the magnetic body part and the upper and lower cover regions pass through the oxide film of each adjacent alloy particle. The present inventors confirmed that they were mutually bonded by SEM observation (3000 times).

  The internal conductor 20 has a coil structure in which a total of five coil segments CS1 to CS5 and a total of four relay segments IS1 to IS4 connecting the coil segments CS1 to CS5 are spirally integrated. The inner conductor 20 is obtained by heat-treating silver particles, and the volume-based d50 of the silver particles used as a raw material is 5 μm.

  The four coil segments CS1 to CS4 have a U shape, and the one coil segment CS5 has a strip shape. Each coil segment CS1 to CS5 has a thickness of about 20 μm and a width of about 0.2 mm. It is. The uppermost coil segment CS1 has a continuous L-shaped lead portion LS1 used for connection with an external terminal, and the lowermost coil segment CS5 is L-shaped used for connection with an external terminal. The lead-out portion LS2 is continuously formed. Each relay segment IS1 to IS4 has a columnar shape penetrating the magnetic layers ML1 to ML4, and each aperture is about 150 μm.

  Each external terminal (not shown) extends to each end face in the length direction of the multilayer inductor 1 and four side faces in the vicinity of the end face, and has a thickness of about 20 μm. One external terminal is connected to the edge of the lead portion LS1 of the uppermost coil segment CS1, and the other external terminal is connected to the edge of the lead portion LS2 of the lowermost coil segment CS5. These external terminals were obtained mainly by heat-treating silver particles having a volume-based d50 of 5 μm.

[Manufacture of multilayer inductors]
A commercially available alloy powder having a composition of Cr 4.5 wt%, Si 3.5 wt% and the balance Fe manufactured by the atomizing method and having an average particle diameter d50 of 6 μm, or Al 5.0 wt% manufactured by the atomizing method and Si 3 Commercially available alloy powder having a composition of 0.0 wt% and the balance Fe and having an average particle diameter d50 of 6 μm was used as soft magnetic alloy particles. A magnetic paste composed of 85 wt% of the soft magnetic alloy particles, 13 wt% of butyl carbitol (solvent), and 2 wt% of polyvinyl butyral (binder) was prepared. Using a doctor blade, this magnetic paste was applied to the surface of a plastic base film, and this was dried with a hot air dryer at about 80 ° C. for about 5 minutes. In this way, a green sheet was obtained on the base film. Thereafter, the green sheet was cut to obtain first to sixth sheets corresponding to the magnetic layers ML1 to ML6 (see FIG. 2) and having a size suitable for multi-cavity.

  As the glass material for the glass segment, Si glass having a softening temperature shown in Table 1 was used. A glass paste containing this glass material, butyl carbitol and polyvinyl butyral was prepared. A glass pattern was formed by printing a glass paste on the first to fifth sheets described above in a pattern corresponding to a glass segment. At this time, the pattern width (pattern area) was adjusted. The width of the printed layer of the conductor paste described later is normalized as 100%, and the printed width of the glass paste is shown in Table 1. Subsequently, using a punch, the first sheet (after the glass pattern was formed) corresponding to the magnetic layer ML1 was punched to form through holes corresponding to the relay segment IS1 in a predetermined arrangement. Similarly, through holes corresponding to the relay segments IS2 to IS4 were formed in a predetermined arrangement in the second to fourth sheets corresponding to the magnetic layers ML2 to ML4, respectively.

  Subsequently, using a printing machine, a conductive paste composed of 85 wt% of the Ag particles, 13 wt% of butyl carbitol (solvent), and 2 wt% of polyvinyl butyral (binder) was applied to the surface of the first sheet (glass pattern). The first printed layer corresponding to the coil segment CS1 was produced in a predetermined arrangement by drying with a hot air dryer under conditions of about 80 ° C. and about 5 minutes. Similarly, the 2nd-5th printing layer corresponding to coil segment CS2-CS5 was produced by the predetermined arrangement | sequence on each surface of the said 2nd-5th sheet | seat.

  Since the through-hole formed in each of the first to fourth sheets exists at a position overlapping the end of each of the first to fourth printed layers, a part of the conductor paste is formed when printing the first to fourth printed layers. Filling each through-hole, the first to fourth filling portions corresponding to the relay segments IS1 to IS4 are formed.

  Subsequently, using an adsorption transporter and a press, the first to fourth sheets facing the sheet provided with the print layer and the filling unit, the fifth sheet provided with only the print layer, the print layer, and The 6th sheet | seat with which the filling part was not provided was piled up in the order shown in FIG. 2, and was thermocompression-bonded, and the laminated body was produced. This laminated body was cut into a component body size with a cutting machine to obtain a chip before heat treatment.

  Subsequently, a large number of chips before heat treatment were heat-treated in a lump in an air atmosphere using a firing furnace. First, as a binder removal process, heating is performed under conditions of about 300 ° C. and about 1 hr, and then held at the heating temperature shown in Table 1 for 1 hour, so that soft magnetic alloy particles are densely formed and the magnetic body portion 10 is formed. In addition, the silver particles were sintered to form the internal conductor 20, and the glass segment was formed, thereby obtaining the component main body.

  Subsequently, external terminals were formed. A conductive paste containing 85 wt% of the above silver particles, 13 wt% of butyl carbitol (solvent) and 2 wt% of polyvinyl butyral (binder) is applied to both ends in the longitudinal direction of the component body, and this is fired Baking treatment was performed in a furnace under conditions of about 600 ° C. and about 1 hr. As a result, the solvent and the binder disappeared, the silver particles were sintered, the external terminals were formed, and the multilayer inductor 1 was obtained.

[Evaluation of multilayer inductor]
The cross sections of the multilayer inductors of all Examples and Comparative Examples were polished, and the presence or absence of an oxide film was observed with an electron microscope. When observed by EDS (x1000 times), the presence of an oxide film having a thickness of 100 nm or more was confirmed on the surface of the soft magnetic alloy particles in all Examples and Comparative Examples. In the same observation, it was confirmed that there was no oxide film having a thickness of 100 nm or more at the interface between the glass segment and the magnetic layer in all Examples and Comparative Examples 2 to 4.

The following measurements were performed on the multilayer inductors of all Examples and Comparative Examples.
The coil design was 220 [nH], and an LCR meter was used for measurement, and 10 samples were measured for each of the examples and comparative examples to obtain an average value.
・ Inductance: Inductance value at a frequency of 1 MHz ・ Frequency characteristics: Frequency at which the inductance value becomes zero due to resonance ・ Q characteristics: Q value at a frequency of 5 MHz

The manufacturing conditions and measurement results are summarized in Table 1.

1 multilayer inductor, 10 magnetic layer, 11 soft magnetic alloy particles, 12 oxide film, 20 inner conductor, 30 glass segment, ML1-ML6 magnetic layer, CS1-CS5 coil segment, IS1-IS4 relay segment

Claims (8)

  A plurality of magnetic layers made of soft magnetic alloy particles, a plurality of coil segments made of a conductive material forming a part of a circular structure, a relay segment made of a conductive material, and a glass segment made of Si-containing glass The magnetic material layer and the coil segment constitute a laminated structure alternately laminated, and the plurality of coil segments are connected to constitute an internal conductor electrically integrated by the relay segment, The portion of the soft magnetic alloy particles that is between two adjacent coil segments across the magnetic layer so as to be in contact with one of the two adjacent coil segments and is not in contact with the glass segment. Is a multilayer electronic component in which an oxide film is formed and no oxide film is formed on the portion in contact with the glass segment.   The widths of the plurality of coil segments are substantially constant, the circular structures formed by the plurality of coil segments are substantially the same, and the glass segments are wider than the coil segments and are between the adjacent coil segments. The multilayer electronic component according to claim 1, which is present.   The multilayer electronic component according to claim 1 or 2, wherein the softening temperature of the Si-containing glass is 400 to 600 ° C.   The laminated electronic component according to any one of claims 1 to 3, wherein the Si-containing glass is Si-based glass or Si-B-based glass.   The multilayer electronic component according to any one of claims 1 to 4, wherein the soft magnetic alloy particles are Fe-Si-M soft magnetic alloy (where M is a metal element that is more easily oxidized than Fe). .   The multilayer electronic component according to claim 5, wherein M is Al or Cr. Forming a conductor pattern and / or a glass pattern on each of a plurality of green sheets containing soft magnetic alloy particles;
The green sheets on which the respective patterns are formed are stacked so that a glass pattern is arranged between two adjacent conductor patterns and in contact with one of the two adjacent conductor patterns, thereby obtaining a chip before heat treatment. Process,
A step of heating the obtained pre-heat-treatment chip;
Have
The conductor pattern is formed by printing a conductive paste containing a conductive material so as to form a part of the surrounding structure,
The glass pattern is formed by printing a glass paste containing Si-containing glass,
In the heating step, the conductive material and the Si-containing glass are respectively sintered to obtain a coil segment and a glass pattern from the conductor pattern and the glass pattern, respectively, and portions of the soft magnetic alloy particles that are not in contact with the glass segment Oxide film is formed on the part, and no oxide film is formed on the part in contact with the glass segment.
A method of manufacturing a multilayer electronic component. The manufacturing method according to claim 7, wherein the step of heating the pre-heat treatment chip is performed by heat treatment at 600 to 950 ° C.

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