Electronic components

Abstract

The present invention relates to an electronic component, comprising: a body including metal particles and a resin; and a resin electrode layer formed on a portion of the outer surface of the body, namely, an electrode opposing portion. The resin electrode layer includes a resin component and a conductive powder. In addition, the electrode opposing portion has an exposed portion where the resin on the outermost surface is removed and a portion of the outer periphery of the metal particles located on the outermost surface is exposed. Furthermore, the resin electrode layer and the exposed portion of the electrode opposing portion are bonded.

Description

Technical Field

[0001] The present invention relates to an electronic component having terminal electrodes. Background Art

[0002] As one type of electronic component, there is known an electronic component in which a terminal electrode (sometimes also referred to as an external electrode) is formed on the outer surface of the element body. In such an electronic component, the terminal electrode is usually formed by applying a conductive paste on the outer surface of the element body and performing a sintering process. In addition, it is sometimes formed by a plating method or a sputtering method. However, in the case where the element body of the coil device contains a resin component, sometimes the terminal electrode is not sufficiently adhered to the outer surface of the element body, and the bonding strength of the terminal electrode cannot be fully ensured.

[0003] On the other hand, Patent Document 1 discloses a technique for forming a portion in contact with a terminal electrode on the outer surface of a body by cutting a portion of the body with a dicer. When the body is processed with a dicer, the metal particles contained in the interior of the body are also removed, and the cross-section of the metal particles is exposed on the outer surface of the body. As a result, it is easy to form a terminal electrode composed of a plating film on the portion processed with the dicer. However, in the technique of Patent Document 1, not only the cross-section of the metal particles is exposed on the outer surface of the body, but also much of the resin component contained in the body is exposed (see FIG. 4 of Patent Document 1). Therefore, in the technique of Patent Document 1, it can be said that the bonding strength of the terminal electrode relative to the outer surface of the body is not sufficient.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: International Publication No. 2015 / 115180 Summary of the invention

[0007] Technical problem to be solved by the invention

[0008] The present invention has been made in view of such actual circumstances, and an object of the present invention is to provide an electronic component having improved bonding strength between a terminal electrode and an element body.

[0009] Technical solutions for solving technical problems

[0010] In order to achieve the above object, the electronic component of the present invention has:

[0011] a body comprising metal particles and a resin; and

[0012] a resin electrode layer formed on a portion of the outer surface of the element body, namely, an electrode facing portion;

[0013] The resin electrode layer comprises a resin component and a conductor powder,

[0014] The electrode facing portion includes an exposed portion where the resin is removed from the outermost surface of the element body and a portion of the outer periphery of the metal particles located on the outermost surface is exposed.

[0015] The resin electrode layer is bonded to the exposed portion of the electrode opposing portion.

[0016] In the electronic component of the present invention, by having the above-mentioned structure, a part of the resin electrode layer enters between the metal particles exposed at the electrode opposing portion, thereby improving the bonding strength of the terminal electrode (resin electrode layer) relative to the electrode opposing portion of the element body. In addition, in the electronic component of the present invention, an insulating coating may remain on the surface of the metal particles located at the exposed portion. In this case, the insulating coating of the metal particles is exposed at the outermost surface of the exposed portion. That is, in the coil device of the present invention, even if the insulating coating of the metal particles is not removed at the electrode opposing portion, the bonding strength of the terminal electrode can be fully ensured. In addition, in the electronic component of the present invention, the resin electrode layer constitutes at least a part of the terminal electrode.

[0017] Preferably, the conductor powder of the resin electrode layer includes first particles having a particle size of micrometer order and second particles having a particle size of nanometer order. With the above structure, the second particles are filled between the first particles in the resin electrode layer. As a result, the resistance value of the terminal electrode can be reduced.

[0018] In addition, it is preferred that the metal particles contained in the element body are composed of at least two or more particle groups with different average particle diameters. By having the above structure, the filling ratio of the metal particles contained in the element body can be increased, and the proportion of the resin exposed in the electrode relative portion can be reduced. As a result, the adhesion between the electrode relative portion and the resin electrode layer can be improved, and the bonding strength of the terminal electrode can be further improved.

[0019] In addition, it is preferred that the second particles contained in the resin electrode layer enter between the metal particles on the outermost surface of the exposed portion. In particular, by the nano-scale second particles entering between the metal particles located on the outermost surface of the exposed portion, the adhesion between the electrode opposing portion and the resin electrode layer can be improved, and the bonding strength of the terminal electrode can be further improved.

[0020] In addition to the exposed portion, the electrode relative portion may also have an extraction electrode portion where the conductor is exposed and a non-exposed portion where the resin is not removed. In this case, preferably, in the plane direction of the electrode relative portion, the exposed portion is located around the extraction electrode portion. In addition, in the plane direction of the electrode relative portion, the non-exposed portion may be located outside the exposed portion. By having the above structure, the closeness between the extraction electrode portion and the terminal electrode can be improved, and the bonding strength of the terminal electrode can be further improved. In addition, the resistance value of the terminal electrode can also be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a perspective view showing a coil device according to one embodiment of the present invention.

[0022] Figure 2 Viewed from the mounting surface Figure 1 A three-dimensional view of the coil arrangement shown.

[0023] Figure 3A It is along Figure 1 A cross-sectional view taken along line IIIA-IIIA is shown.

[0024] Figure 3B Yes means Figure 1 and Figure 3A sectional view of a modified example of the coil device shown.

[0025] Figure 4A It is a cross-sectional view showing the interface between the element body (electrode facing portion) and the terminal electrode.

[0026] Figure 4B It is magnified Figure 4A A cross-sectional view of region IVB is shown.

[0027] Figure 4C It is magnified Figure 4A A cross-sectional view of region IVC is shown.

[0028] Explanation of symbols:

[0029] 2…Inductor

[0030] 4…Component body

[0031] 4a…upper surface

[0032] 4b… bottom surface

[0033] 4c~4f…side view

[0034] 41…First core

[0035] 41a…Flange

[0036] 41b…winding core

[0037] 41c…Incision

[0038] 42…Second core

[0039] 6α…Coil part

[0040] 6…Wire

[0041] 61…Conductor

[0042] 62…Insulation layer

[0043] 6a…lead wire

[0044] 8…Terminal electrode

[0045] 81…Resin electrode layer

[0046] 82…Resin composition

[0047] 83…Conductor powder

[0048] 83a…The First Particle

[0049] 83b…the second particle

[0050] 20…Electrode facing portion

[0051] 20a…lead-out electrode part

[0052] 20b…exposed part

[0053] 20c…non-exposed part DETAILED DESCRIPTION

[0054] Hereinafter, the present invention will be described in detail based on the embodiments shown in the drawings.

[0055] like Figure 1 As shown in FIG. 1 , an inductor 2 as an electronic component according to a first embodiment of the present invention includes an element body 4 having a substantially rectangular parallelepiped shape (substantially hexahedron).

[0056] The component body 4 has an upper surface 4a, a bottom surface 4b located on the opposite side of the upper surface 4a in the Z-axis direction, and four side surfaces 4c to 4f. The size of the component body 4 is not particularly limited. For example, the size of the component body 4 in the X-axis direction can be set to 1.2 to 6.5 mm, the size in the Y-axis direction can be set to 0.6 to 6.5 mm, and the size in the height (Z-axis) direction can be set to 0.5 to 5.0 mm.

[0057] like Figure 1 and Figure 2As shown, a pair of terminal electrodes 8 are formed on the bottom surface 4b of the element body 4. The pair of terminal electrodes 8 are formed separately in the X-axis direction and insulated from each other. In the inductor 2 of this embodiment, an external circuit can be connected to the terminal electrodes 8 via wiring, etc., which are not shown. In addition, the inductor 2 can be mounted on various substrates such as a circuit board using a bonding component such as solder or a conductive adhesive. When mounted on a substrate, the bottom surface 4b of the element body 4 is a mounting surface, and the terminal electrodes 8 and the substrate are bonded by a bonding component.

[0058] The element body 4 has a coil portion 6α therein. The coil portion 6α is formed by winding a conductive wire 6 as a conductor into a coil shape. Figure 1 In the embodiment, the coil portion 6α is an air-core coil wound with a normal width, but the winding method of the conductor 6 is not limited to this. For example, the conductor 6 may be an air-core coil wound with α winding or an air-core coil wound with flatness. Alternatively, the conductor 6 may be directly wound on the winding core portion 41b described later (see Figure 3A ).

[0059] The conductive wire 6 constituting the coil portion 6α is mainly composed of a conductor portion 61 containing copper and an insulating layer 62 covering the periphery of the conductor portion. More specifically, the conductor portion 61 is composed of pure copper such as oxygen-free copper or red copper, an alloy containing copper such as phosphor bronze or brass, red copper, beryllium copper, silver-copper alloy, or a copper-coated steel wire. On the other hand, the insulating layer 62 is not particularly limited as long as it has electrical insulation properties. For example, epoxy resin, acrylic resin, polyurethane, polyimide, polyamide-imide, polyester, nylon, polyester, etc., or a synthetic resin obtained by mixing at least two of the above resins are exemplified. In addition, in the present embodiment, as Figure 1 and Figure 3A As shown, the conductor 6 is a round wire, and the cross-sectional shape of the conductor portion is circular.

[0060] like Figure 1 and Figure 3A As shown in FIG. 1 , the element body 4 of the present embodiment includes a first core portion 41 and a second core portion 42 . The first core portion 41 and the second core portion 42 may be each formed of a powder compact containing metal particles 12 and a resin 14 .

[0061] The metal particles 12 contained in each core 41, 42 are not particularly limited as long as they are magnetic materials. For example, Fe-Ni alloy, Fe-Si alloy, Fe-Co alloy, Fe-Si-Cr alloy, Fe-Si-Al alloy, amorphous alloy containing Fe, nanocrystalline alloy containing Fe and other soft magnetic alloys are exemplified. In addition, accessory components may be appropriately added to the metal particles 12.

[0062] Furthermore, the first core 41 and the second core 42 may be composed of, for example, the same type of metal particles 12, and the relative magnetic permeability μ1 of the first core 41 and the relative magnetic permeability μ2 of the second core 42 may be equal. Furthermore, the first core 41 and the second core 42 may be composed of metal particles 12 of different materials.

[0063] In addition, regarding the metal particles 12 contained in the first core 41 or the second core 42, the median particle size (D50) can be set to about 5μm to 50μm. In particular, in the present embodiment, the metal particles 12 contained in the second core 42 are preferably composed of a plurality of particle groups with different D50s mixed. For example, the metal particles 12 of the second core 42 are preferably composed of large particles 12a with a D50 of 8μm to 15μm, medium particles 12b with a D50 of 1μm to 5μm, and small particles 12c with a D50 of 0.3μm to 0.9μm. In addition to the combination of the three particle groups described above, it can also be a combination of large particles 12a and medium particles 12b, a combination of large particles 12a and small particles 12c, a combination of medium particles 12b and small particles 12c, etc. In addition, the large particles 12a, the medium particles 12b, and the small particles 12c can all be composed of the same material, or they can be composed of different materials.

[0064] As described above, when a plurality of particle groups are mixed, the content ratio of each particle group is not particularly limited. For example, when three particle groups (large particles 12a, medium particles 12b, and small particles 12c) are mixed, if the sum of the areas occupied by the large particles 12a, the medium particles 12b, and the small particles 12c in the cross section of the element body 4 is set to 100%, the area occupied by the large particles 12a is preferably set to 50% to 90%, the area occupied by the medium particles 12b is preferably set to 0% to 30%, and the area occupied by the small particles 12c is preferably set to 5% to 30%.

[0065] In addition, similarly to the above, the metal particles 12 of the first core portion 41 can also be composed of a mixture of multiple particle groups with different D50. As described above, by forming the metal particles 12 contained in the first core portion 41 or the second core portion 42 from multiple particle groups, the filling ratio of the metal particles 12 contained in the element body 4 can be increased. As a result, the various characteristics of the inductor 2 such as magnetic permeability, eddy current loss, and DC superposition characteristics are improved.

[0066] In addition, the particle size of the metal particles 12 and the area occupied by each particle group can be measured by observing the cross section of the element body 4 using a scanning electron microscope (SEM) or a scanning transmission electron microscope (STEM), and performing image analysis on the obtained cross-sectional photograph using software. At this time, the particle size of the metal particles 12 is preferably measured by converting the equivalent circle diameter.

[0067] In addition, with respect to the metal particles 12 contained in the element body 4, it is preferred that the particles are insulated from each other. As a method of insulation, for example, a method of forming an insulating film on the surface of the particles can be cited. As the insulating film, a film formed by a resin or an inorganic material and an oxide film formed by oxidizing the surface of the particles by heat treatment can be cited. In the case where the insulating film is formed by a resin or an inorganic material, as resins, silicone resins, epoxy resins, etc. can be cited. As inorganic materials, phosphates such as magnesium phosphate, calcium phosphate, zinc phosphate, and manganese phosphate, silicates such as sodium silicate (water glass), soda-lime glass, borosilicate glass, lead glass, aluminosilicate glass, borate glass, sulfate glass, etc. can be cited. In addition, the thickness of the insulating film of the metal particle 12 is preferably 5nm to 20nm. By forming an insulating film, the insulation between particles can be improved, and the withstand voltage of the inductor 2 can be improved.

[0068] In addition, the resin 14 contained in each core portion 41, 42 is not particularly limited, and for example, thermosetting resins such as epoxy resin, phenolic resin, melamine resin, urea resin, furan resin, alkyd resin, polyester resin, diallyl phthalate resin, or thermoplastic resins such as acrylic resin, polyphenylene sulfide (PPS), polypropylene (PP), liquid crystal polymer (LCP), etc. can be used.

[0069] like Figure 1 As shown, the first core portion 41 has a flange portion 41a, a winding core portion 41b and a cutout portion 41c. The flange portion 41a protrudes toward each side 4c~4f of the element body 4, and four flange portions 41a are formed corresponding to each side 4c~4f. The coil portion 6α is mounted on the upper surface of the flange portion 41a, and the flange portion 41a supports the coil portion 6α. Here, the two flange portions 41a protruding along the X-axis direction are respectively set as the first flange portion 41ax, and the two flange portions 41a protruding along the Y-axis direction are respectively set as the second flange portion 41ay. The thickness of the first flange portion 41ax is thinner than the thickness of the second flange portion 41ay, and there is a space below the first flange portion 41ax to accommodate a part of the lead portion 6a.

[0070] The winding core 41b is located above the flange 41a in the Z-axis direction and is formed integrally with the flange 41a. The winding core 41b is formed of a substantially elliptical cylinder protruding upward in the Z-axis direction and is inserted into the inner side of the coil 6α. The shape of the winding core 41b is not limited to Figure 1 and Figure 3A In the embodiment shown, any shape may be used as long as it matches the winding shape of the coil portion 6α, for example, a cylindrical shape or a prismatic shape.

[0071] The cutout portion 41c is located between the flange portions 41a, and four cutout portions 41c are formed at the four corners of the XY plane. That is, the cutout portion 41c is formed near the location where the side surfaces 4c to 4f of the element body 4 intersect with each other. The cutout portion 41c serves as a passage for the lead portion 6a led out from the coil portion 6α to pass through. In addition, the cutout portion 41c also serves as a passage for the molding material constituting the second core portion 42 to flow from the surface side to the back side of the first core portion 41 during the manufacturing process. Figure 1 In the embodiment, the cutout 41c is cut into a substantially square shape, but its shape is not particularly limited as long as it is a shape through which the lead 6a and the above-mentioned molding material pass. For example, the cutout 41c may also be a through hole that penetrates the front and back surfaces of the flange 41a.

[0072] like Figure 3A As shown, the second core portion 42 covers the first core portion 41. More specifically, the second core portion covers the coil portion 6α and the winding core portion 41b above the flange portion 41a, and fills the space existing below the cutout portion 41c and the first flange portion 41ax. Figure 2 As shown, the lower surface of the second flange portion 41ay constitutes a part of the bottom surface 4b of the element body 4, and the second core portion 42 is not filled below the second flange portion 41ay.

[0073] like Figure 1 As shown, a pair of lead portions 6a are led out from the coil portion 6α along the Y axis above the first flange portion 41ax. In addition, a pair of lead portions 6a are folded back near the side 4c of the element body 4 and extend from the side 4c side to the side 4d side below the first flange portion 41ax.

[0074] Here, if Figure 3A and Figure 4A As shown, the height h of the component body 4 from the bottom surface 4b to the first flange portion 41ax in the Z-axis direction is smaller than the outer diameter of the lead portion 6a. Therefore, below the first flange portion 41ax, most of the lead portion 6a is accommodated inside the component body 4 (especially the second core portion 42), but a portion of the outer peripheral edge of the lead portion 6a is exposed at the bottom surface 4b of the component body 4. The lead portion 6a is composed of the wire 6, but at the exposed portion of the bottom surface 4b, the insulating layer 62 existing on the outer peripheral side of the wire 6 is removed, and the conductor portion 61 of the wire 6 is exposed.

[0075] like Figure 2 and Figure 4AAs shown, the terminal electrode 8 is formed in a manner covering the conductor portion 61 of the lead portion 6a exposed on the bottom surface 4b. Moreover, the conductor portion 61 of the lead portion 6a is electrically connected to the terminal electrode 8. In the present embodiment, the outer surface of the element body 4 side in contact with the terminal electrode 8 is referred to as the electrode relative portion 20. In particular, in the present embodiment, the terminal electrode 8 is formed on the bottom surface of the second core portion 42, and the electrode relative portion 20 exists on a portion of the bottom surface of the second core portion 42.

[0076] In the present embodiment, the terminal electrode 8 has at least a resin electrode layer 81. In addition, the terminal electrode 8 may also be a laminated structure having the resin electrode layer 81 and other electrode layers. When the terminal electrode 8 is set as a laminated structure, the resin electrode layer 81 is located in the portion of the element body 4 that contacts the electrode relative portion 20, and the other electrode layers sandwich the outer side of the resin electrode layer 81, that is, the resin electrode layer 81 is laminated on the opposite side of the electrode relative portion 20. The other electrode layer may be a single layer or a multilayer, and its material is not particularly limited. For example, the other electrode layer may be composed of a metal such as Sn, Au, Cu, Ni, Pt, Ag, Pd, or an alloy containing at least one of these metal elements, and may be formed by plating or sputtering. In addition, the overall thickness of the terminal electrode 8 is preferably set to 3μm to 60μm on average, and the thickness of the resin electrode layer 81 is preferably set to 1μm to 50μm.

[0077] like Figure 4B and Figure 4C As shown, the resin electrode layer 81 includes a resin component 82 and a conductor powder 83. The resin component 82 in the resin electrode layer 81 is composed of a thermosetting resin such as an epoxy resin or a phenolic resin. On the other hand, the conductor powder 83 can be composed of a metal powder such as Ag, Au, Pd, Pt, Ni, Cu, Sn, or an alloy containing at least one of the above, and it is particularly preferred to contain Ag as a main component.

[0078] Furthermore, in the present embodiment, the conductor powder 83 of the resin electrode layer 81 is preferably composed of two particle groups with different particle size distributions, namely, first particles 83a and second particles 83b. The first particles 83a are a particle group with a particle size of micrometer order. In the present embodiment, "micrometer order particles" refer to particles with an average particle size of 0.05 μm or more and tens of μm or less. For the first particles 83a of the present embodiment, the average particle size on the cross section of the resin electrode layer 81 is preferably 1 μm to 10 μm, and more preferably 3 μm to 5 μm.

[0079] In addition, the shape of the first particle 83a can be set to be approximately spherical, prolate, irregular block, needle-shaped, flat, and particularly preferably needle-shaped or flat. In the present embodiment, the flat particle refers to a particle having an aspect ratio (the ratio of the length in the long side direction to the length in the short side direction) of 2 to 30 on the cross section of the resin electrode layer 81. In addition, the average particle size of the first particle 83a can be measured by observing the cross section of the resin electrode layer 81 using SEM or STEM and performing image analysis on the obtained cross-sectional photograph. In this measurement, the average particle size of the first particle 83a is calculated by converting the maximum length.

[0080] On the other hand, the second particles 83b are a group of nanometer-level particles whose average particle size is smaller than that of the first particles 83a. The second particles 83b are condensed near the periphery of the first particles 83a or in the interparticle gaps of the first particles 83a. If the condensed portion of the second particles 83b is magnified and observed by STEM, the second particles 83b are identified as a collection of particles having a particle size of at least 100nm or less. In addition, the second particles 83b are preferably added as nanoparticles having a roughly spherical shape and an average particle size of 5nm to 30nm during the manufacturing process of the raw material of the resin electrode layer 81, i.e., the paste.

[0081] As described above, the resin electrode layer 81 includes the first particles 83a and the second particles 83b, thereby reducing the contact resistance of the resin electrode layer 81. In addition, in the resin electrode layer 81, the first particles 83a and the second particles 83b are preferably mixed in a predetermined ratio. Specifically, if the total area occupied by the resin component 82 and the conductive powder 83 in the cross section of the resin electrode layer 81 is set to 100%, the area occupied by the conductive powder 83 is preferably 60% or less.

[0082] In addition, the area occupied by each of the above elements can be measured by observing the cross section of the resin electrode layer 81 using SEM or STEM and performing image analysis on the obtained cross-sectional image. When using SEM, it is preferred to observe by reflected electron image; when using STEM, it is preferred to observe by BF image. In the above observed image, the dark contrast portion is the resin component 82, and the bright contrast portion is the conductor powder 83. In addition, in the above observation, the observation field of each field of view is preferably set to 0.04μm 2 ~0.36μm 2 The area occupied by each element is preferably calculated as an average value of at least 10 observation fields.

[0083] The resin electrode layer 81 having the above structure is directly bonded to the electrode facing portion 20 on the element body 4 side. Figure 4A As shown, the electrode facing portion 20 includes an extraction electrode portion 20a, an exposed portion 20b, and a non-exposed portion 20c.

[0084] The lead-out electrode portion 20a is formed by a portion of the outer periphery of the lead portion 6a exposed at the bottom surface 4b. That is, the surface portion of the conductor portion 61 exposed at the bottom surface 4b is the lead-out electrode portion 20a. At the interface between the lead-out electrode portion 20a and the resin electrode layer 81, a diffusion layer A (not shown) containing the metal component of the conductor portion 61 and the metal component of the resin electrode layer 81 is preferably formed. The diffusion layer A can be formed by the metal component of the conductor portion 61 diffusing to the conductor powder 83 side of the resin electrode layer 81 and alloying. The presence of the diffusion layer at the interface between the lead-out electrode portion 20a and the resin electrode layer 81 can reduce the contact resistance of the terminal electrode 8.

[0085] The exposed portion 20b exists in a manner surrounding the extraction electrode portion 20a on the XY plane. The exposed portion 20b is formed by laser processing a portion of the bottom surface 4b of the element body 4 before forming the terminal electrode 8. Therefore, the surface roughness of the surface of the exposed portion 20b becomes larger than that of the portion of the bottom surface 4b that is not in contact with the terminal electrode 8.

[0086] Figure 4B 2 is a cross-sectional view showing an enlarged interface between the exposed portion 20b on the element body 4 side and the resin electrode layer 81. Figure 4B As shown, in the exposed portion 20b on the side of the element body 4, the resin 14 contained in the element body 4 is removed by laser irradiation, and a part of the outer periphery of the metal particle 12 located on the outermost surface is exposed. That is, the metal particle 12 located on the outermost surface of the exposed portion 20b is not cut, and a part of the outer periphery of the metal particle 12 protrudes to the outside of the element body 4 and contacts the resin electrode layer 81.

[0087] In particular, the present embodiment Figure 4B A cross-sectional view of a metal particle 12 composed of a large particle 12a, a medium particle 12b, and a small particle 12c is shown. In this case, at the outermost surface of the exposed portion 20b, mainly a portion of the outer periphery of the large particle 12a and a portion of the outer periphery of the medium particle 12b are exposed. By irradiation with laser light, the small particle 12c is easily removed from the bottom surface 4b of the element body 4 together with the resin 14. Therefore, the proportion of the small particle 12c exposed at the exposed portion 20b is smaller than that of the large particle 12a or the medium particle 12b.

[0088] In addition, if Figure 4BAs shown, at the interface between the exposed portion 20b and the resin electrode layer 81, the resin electrode layer 81 enters between the metal particles 12 located on the outermost surface of the exposed portion 20b. In particular, in this embodiment, the resin electrode layer 81 includes nanometer-sized second particles 83b, and the second particles 83b mainly enter between the metal particles 12 located on the outermost surface of the exposed portion 20b. In addition, the second particles 83b show a higher reactivity than micrometer-sized particles, and therefore, a diffusion layer B (not shown) may also be formed at the interface between the exposed portion 20b and the resin electrode layer 81. In this case, the diffusion layer B may be formed at a position where the metal particles 12 on the element body 4 side and the second particles 83b of the resin electrode layer 81 are in contact.

[0089] In addition, when an insulating film is formed on the surface of the metal particle 12, the insulating film (not shown) may remain in the outer periphery of the metal particle 12 exposed outside the element body 4. In this case, the insulating film of the exposed metal particle 12 exists on the outermost surface of the exposed portion 20b, and the insulating film is in contact with the resin electrode layer 81.

[0090] On the other hand, Figure 4A As shown, the non-exposed portion 20c is located at the edge of the electrode opposing portion 20, and unlike the exposed portion 20b, no laser processing is performed. Therefore, the surface of the non-exposed portion 20c is in the state of the surface formed when the element body 4 is formed, and its surface roughness is the same as that of the portion of the bottom surface 4b that is not in contact with the terminal electrode 8. In addition, the formation location of the non-exposed portion 20c is not limited to Figure 4A In the illustrated embodiment, it is sufficient that the electrode facing portion 20 is located outside the exposed portion 20 c in the plane direction (XY plane) of the electrode facing portion 20 .

[0091] Figure 4C 2 is a cross-sectional view showing an enlarged interface between the non-exposed portion 20c on the element body 4 side and the resin electrode layer 81. Figure 4C As shown in FIG. 1 , the resin 14 is not removed from the surface of the non-exposed portion 20c. Therefore, the metal particles 12 located in the non-exposed portion 20c do not protrude to the outside of the element body 4, but are covered with the resin 14 and buried inside the element body 4. That is, at the interface between the non-exposed portion 20c and the resin electrode layer 81, there are many areas where the resin 14 of the element body 4 and the resin electrode layer 81 are in contact.

[0092] In such Figure 4A In the cross section shown, when the length of the boundary line between the electrode facing portion 20 and the resin electrode layer 81 is 100%, the length ratio of the exposed portion 20b is preferably 60% to 85%. On the other hand, the length ratio of the non-exposed portion 20c is preferably kept at 15% or less.

[0093] Next, a method for manufacturing the inductor 2 according to the present embodiment will be described.

[0094] First, the first core 41 is made by a stamping method or an injection molding method such as heat and pressure molding. In the production of the first core 41, the raw material powder of the metal particles 12 is kneaded with a binder, a solvent, etc. to form particles, and the particles are used as a raw material for molding. In the case of the metal particles 12 constituting the first core 41 by a plurality of particle groups, raw material powders with different particle size distributions are prepared and mixed in a prescribed ratio.

[0095] Next, the coil portion 6α is mounted on the obtained first core portion 41. The coil portion 6α is an air-core coil in which the conductive wire 6 is pre-wound into a predetermined shape, and the air-core coil is inserted into the winding core portion 41b of the first core portion 41. Alternatively, the conductive wire 6 may be directly wound around the winding core portion 41b of the first core portion 41 to form the coil portion 6α. After the first core portion 41 and the coil portion 6α are combined, as shown in FIG. Figure 1 As shown in FIG. 1 , a pair of lead wire portions 6a are led out from the coil portion 6α and are arranged below the first flange portion 41ax.

[0096] Next, the second core portion 42 is made by insert injection molding. In the making of the second core portion 42, first, the first core portion 41 equipped with the coil portion 6α is arranged inside the forming mold. It is preferred to cover the inner surface of the forming mold with a demoulding film in advance. As a demoulding film, a flexible sheet member such as a PET film can be used. By using a demoulding film, when the first core portion 41 is arranged in the forming mold, the lead portion 6 located below the first flange portion 41ax is closely fitted with the demoulding film. As a result, a portion of the outer periphery of the lead portion 6a is covered with a demoulding film, and after making the second core portion 42, a portion of the outer periphery of the lead portion 6a protrudes from the bottom surface 4b of the element body 4.

[0097] As the raw material constituting the second core portion 42, a composite material having fluidity during molding can be used. Specifically, a composite material is used by kneading the raw material powder of the metal particles 12 and a binder such as a thermoplastic resin or a thermosetting resin. A solvent, a dispersant, etc. can also be appropriately added to the composite material. In addition, as Figure 4B and Figure 4C As shown, in the case of the metal particle 12 of the second core portion 42 composed of large particles 12a, medium particles 12b and small particles 12c, the proportion of each particle in the raw material powder of the metal particle 12 is preferably a predetermined proportion. Specifically, the proportion of the large particles 12a is preferably 70wt% to 80wt%, the proportion of the medium particles 12b is preferably 10wt% to 15wt%, and the proportion of the small particles 12c is preferably 10wt% to 15wt%.

[0098] In addition, in the insert injection molding, the composite material is introduced into the molding die in the state of being slurried. At this time, the introduced slurry is also filled to the bottom of the first flange portion 41ax through the cutout portion 41c of the first core portion 41. In addition, during injection molding, heating is appropriately performed according to the material of the adhesive used. In this way, the component body 4 after the first core portion 41, the second core portion 42 and the coil portion 6α are integrated is obtained.

[0099] Next, a portion of the bottom surface 4b of the element body 4 is irradiated with laser to form the lead electrode portion 20a and the exposed portion 20b. By the laser irradiation, the insulating layer 62 of the lead portion 6a protruding from the bottom surface 4b is removed to expose the conductor portion 61, thereby forming the lead electrode portion 20a. In addition, by the laser irradiation, the resin 14 contained in the element body 4 (the second core portion 42) is removed from the outermost surface of the bottom surface 4b, and the exposed portion 20b is formed at the portion of the bottom surface 4b irradiated with the laser.

[0100] In addition, the wavelength of the laser used above is preferably 400nm or less. That is, the irradiated laser is preferably a UV laser having a wavelength shorter than that of a green laser (wavelength: 532nm). As described above, by using a short-wavelength laser, the metal particles 12 such as large particles 12a or medium particles 12b are not removed, and the resin 14 and the insulating layer 62 of the lead portion 6a are selectively removed. In addition, when the above-mentioned short-wavelength laser is used, there is a tendency that the insulating coating formed on the surface of the metal particles 12 is hardly removed and remains.

[0101] Next, the resin electrode paste is applied to a portion of the bottom surface 4b of the element body 4 by a printing method or the like. At this time, the resin electrode paste is applied so as to cover the portion irradiated with the laser. That is, the lead electrode portion 20a and the exposed portion 20b are covered with the resin electrode paste. Figure 2 In the XY plane shown, the area of ​​the formed resin electrode layer 81 is larger than the area irradiated with the laser. In addition, the area of ​​the bottom surface 4b that is in contact with the resin electrode layer 81 and is not irradiated with the laser is a non-exposed portion 20c.

[0102] In addition, the resin electrode paste contains a binder that becomes the resin component 82 and a metal raw material powder that becomes the conductor powder 83. In the present embodiment, the metal raw material powder is composed of microparticles with a particle size of micrometer level and nanoparticles with a particle size of nanometer level. The microparticles are particles that become the first particles 83a after the paste is cured, and the average particle size is preferably 1μm to 10μm, and more preferably 3μm to 5μm. On the other hand, the nanoparticles are particles that become the second particles 83b after the paste is cured, and the average particle size is preferably 5nm to 30nm, and more preferably 5nm to 15nm.

[0103] After the resin electrode paste is applied to the element body 4, the element body 4 is heated under predetermined conditions to solidify the binder (resin component 82) in the paste. The conditions for the heating treatment may be appropriately set according to the type of binder used. In this way, a resin electrode layer 81 is formed on the bottom surface 4b of the element body 4.

[0104] Alternatively, a plating film or a sputtering film may be appropriately formed on the outer surface of the resin electrode layer 81. For example, by forming a plating film of Ni, Cu, Sn, or the like on the outer surface of the resin electrode layer 81 in advance, wettability with respect to solder is improved.

[0105] Through the above-described manufacturing method, the inductor 2 in which the pair of terminal electrodes 8 are formed on the element body 4 is obtained.

[0106] (Summary of Implementation Methods)

[0107] In the inductor 2 of the present embodiment, the exposed portion 20b exists in the electrode facing portion 20 of the element body 4 that is in contact with the terminal electrode 8, and the outermost surface resin 14 of the exposed portion is removed to expose a portion of the outer periphery of the metal particles located on the outermost surface. Furthermore, in the inductor 2 of the present embodiment, the resin electrode layer 81 of the terminal electrode 8 is bonded to the exposed portion 20b of the electrode facing portion 20.

[0108] With the above structure, the resin electrode layer 81 enters between the metal particles 12 located on the outermost surface of the exposed portion 20b at the interface between the exposed portion 20b and the resin electrode layer 81. As a result, the adhesion between the exposed portion 20b and the resin electrode layer 81 is improved, and the terminal electrode 8 and the element body 4 are firmly bonded.

[0109] In addition, the insulating film may remain on the surface of the metal particles 12 located on the outermost surface of the exposed portion 20b. That is, the insulating film of the metal particles 12 does not need to be removed from the outermost surface of the electrode opposing portion 20. In the inductor 2 of this embodiment, even if the insulating film is not removed, the bonding strength of the terminal electrode 8 can be sufficiently ensured.

[0110] In addition, in this embodiment, the conductive powder 83 of the resin electrode layer 81 includes first particles 83a with a particle size of micrometers and second particles 83b with a particle size of nanometers. With the above structure, the second particles 83b aggregate in the interparticle gaps of the first particles 83a inside the resin electrode layer 81, and play a role in electrically connecting the first particles 83a. As a result, the contact resistance of the terminal electrode 8 can be further reduced.

[0111] Furthermore, since the resin electrode layer 81 includes the second particles 83b, the second particles 83b enter between the exposed metal particles 12 on the outermost surface of the exposed portion 20b. As a result, the adhesion between the exposed portion 20b and the resin electrode layer 81 is further improved, and the bonding strength of the terminal electrode 8 to the element body 4 can be further improved.

[0112] In addition, in the present embodiment, the metal particles 12 contained in the element body 4 are composed of at least two or more particle groups having different average particle diameters and D50. By having the above structure, the filling ratio of the metal particles 12 contained in the element body 4 can be increased, and the proportion of the resin exposed in the electrode opposing portion 20b can be reduced. As a result, the adhesion between the exposed portion 20b and the resin electrode layer 81 can be improved, and the bonding strength of the terminal electrode 8 can be further improved.

[0113] In addition to the exposed portion 20b, the electrode opposing portion 20 of the present embodiment also includes the lead electrode portion 20a where the conductor portion 61 of the lead portion 6a is exposed and the non-exposed portion 20c where the resin 14 is not removed. Moreover, in the plane direction (XY plane) of the electrode opposing portion 20, the exposed portion 20b is located around the lead electrode portion 20a. In the inductor 2 of the present embodiment, as described above, the exposed portion 20b and the resin electrode layer 81 are firmly adhered to each other. Therefore, the presence of the exposed portion 20b around the lead electrode portion 20a also improves the adhesion between the lead electrode portion 20a and the resin electrode layer 81. As a result, the bonding strength of the terminal electrode 8 can be further improved, and the contact resistance of the terminal electrode 8 can be reduced.

[0114] (Variation Example)

[0115] As mentioned above, although the embodiment of the present invention has been described, the present invention is not limited to the above-mentioned embodiment, and various changes can be made within the scope of the present invention.

[0116] For example, in Figure 1 to Figure 3A In the embodiment, the coil portion 6α is composed of a round wire 6, but the type of the wire 6 is not limited thereto and may also be Figure 3B The cross-sectional shape of the conductor portion shown is a substantially rectangular flat wire. Alternatively, it may be a square wire or a Litz wire formed by twisting thin wires. Furthermore, the coil portion 6α may be formed by stacking conductive plates.

[0117] In the above embodiment, the terminal electrode 8 is formed on the bottom surface 4b of the element body 4, but the formation position of the terminal electrode 8 is not limited thereto, and the terminal electrode 8 may be formed on the top surface 4a or the side surfaces 4c to 4f, or may be formed across multiple surfaces.

[0118] In addition, the first core portion 41 constituting the element body 4 may also be a sintered body of ferrite powder or metal magnetic powder. Furthermore, the element body 4 itself may be a FT type, ET type, EI type, UU type, EE type, EER type, UI type, drum type, ring type, pot type, cup type pressed powder core, and the coil may be wound around the pressed powder core to form an inductor element. In this case, the lead portion does not need to be buried inside the element body, but may be led out along the outer periphery of the core and connected to the outer surface of the terminal electrode 8.

[0119] Furthermore, the electronic component of the present invention is not limited to an inductor, and may be an electronic component such as a transformer, a choke coil, a common mode filter, or a composite electronic component composed of an inductor element and other elements such as a capacitor element.

Claims

1. An electronic component, wherein: have: a body comprising metal particles and a resin; and a resin electrode layer formed on an electrode facing portion, the electrode facing portion being a portion of an outer surface of the element body, The resin electrode layer comprises a resin component and a conductor powder, The electrode facing portion includes an exposed portion where the resin is removed from the outermost surface of the element body and a portion of the outer periphery of the metal particles located on the outermost surface is exposed. The electrode opposing portion further comprises: A lead-out electrode portion in which a portion of the conductor located inside the element body is exposed; and The non-exposed portion of the resin is not removed, In the planar direction of the electrode opposing portion, the exposed portion is located around the lead-out electrode portion, The non-exposed portion is located outside the periphery of the exposed portion, The resin electrode layer is bonded to both the exposed portion and the non-exposed portion of the electrode opposing portion.

2. The electronic component according to claim 1, wherein The conductive powder of the resin electrode layer includes first particles having a particle size of micrometer order and second particles having a particle size of nanometer order.

3. The electronic component according to claim 2, wherein: On the outermost surface of the exposed portion, the second particles of the resin electrode layer are embedded between the metal particles.

4. The electronic component according to claim 1, wherein The conductive powder of the resin electrode layer includes second particles having a particle size of nanometer order. On the outermost surface of the exposed portion, the second particles are embedded between the metal particles.

5. The electronic component according to any one of claims 1 to 4, wherein The metal particles contained in the element body are composed of at least two or more types of particle groups having different average particle diameters.

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