Electronic component and production method for electronic component

Abstract

An electronic component 1 comprising an element body 10 and external electrodes 21, 22 provided on the element body 10, wherein on the surface of the element body 10, grain boundaries 30 have a lower resistance than grain surfaces 40.

Description

Electronic component and method for manufacturing electronic component

[0001] The present invention relates to an electronic component and a method for manufacturing an electronic component.

[0002] Patent Document 1 describes a composite electronic component in which at least two parts made of different ceramic materials are integrally molded and then fired, and the fired chip components are processed by a barrel polishing process that includes at least a fine barrel polishing process using fine media.

[0003] Japanese Patent Publication No. 6-325978

[0004] The composite electronic component described in Patent Document 1 is believed to have high insulating properties on the surfaces of the chip components after fine barrel polishing. In such cases, static electricity may be generated due to friction between chip components, which may result in foreign matter such as processing debris, dust, and paper fibers adhering to the chip surface near the external electrodes or causing the chip components to adhere to each other. If chip components are soldered with foreign matter attached, gas may be generated during reflow soldering, or adhesion may be reduced. If chip components adhere to each other, the chip taping device may be unable to insert the chip components into the carrier tape.

[0005] The present invention has been made to solve the above problems, and has as its object to provide an electronic component having an excellent antistatic property on the surface of the element body, and a method for manufacturing the electronic component.

[0006] The electronic component of the present invention comprises an element body and external electrodes provided on the element body, and the element body has grain boundaries on its surface that have a lower resistance than the grain surfaces.

[0007] The method for manufacturing an electronic component of the present invention includes a barrel processing step of polishing an element body with a first polishing powder to round off corners and ridges of the element body, a firing step of firing the barrel-processed element body, and a fine polishing step of polishing the fired element body with a second polishing powder that is finer than the first polishing powder and has an average particle size of less than 0.1 mm.

[0008] According to the present invention, it is possible to provide an electronic component having an excellent antistatic property on the surface of the element body, and a method for manufacturing the electronic component.

[0009] FIG. 1 is a perspective view schematically illustrating an example of an electronic component according to an embodiment of the present invention. FIG. 2 is a cross-sectional view schematically illustrating an example of a cross section taken along line A-A of the electronic component shown in FIG. 1. FIG. 3 is a cross-sectional view schematically illustrating another example of a cross section taken along line A-A of the electronic component shown in FIG. 1, in which the electronic component is a multilayer ceramic capacitor. FIG. 4 is a plan view schematically illustrating an example of an element body surface of the electronic component shown in FIG. 1. FIG. 5 is a cross-sectional view schematically illustrating an example of a cross section taken along line B-B of the electronic component shown in FIG. 4. FIG. 6 is a plan view schematically illustrating another example of an element body surface of the electronic component shown in FIG. 1. FIG. 7 is a cross-sectional view schematically illustrating an example of a cross section taken along line C-C of the electronic component shown in FIG. 6. FIG. 8 shows an example of a manufacturing flow of a method for manufacturing an electronic component according to an embodiment of the present invention. FIG. 9 shows an SPM image of the element body surface near the external electrodes of the sample of Example 1. Fig. 10 is an image showing the results of TEM-EDX observation and analysis of the element surface near the external electrodes of the sample of Example 1, and shows an image in which the ceramic component, which is a component of the dielectric layer, the silver component, which is a component of the electrode paste, and the silicon component, which is a component of the glass component, are mapped onto the TEM image. Fig. 11 is an image in which only the silicon component is mapped onto the image of Fig. 10. Fig. 12 is an image in which the results of TEM-EDX observation and analysis of the element cross section near the external electrodes of the sample of Example 1 are shown as a TEM image. Fig. 13 is an image in which only the silicon component, which is a component of the glass component, is mapped onto the image of Fig. 12.

[0010] The electronic component and the method for manufacturing the electronic component of the present invention will be described below. However, the present invention is not limited to the following configurations, and can be appropriately modified and applied within the scope of the present invention. Note that a combination of two or more of the individual desirable configurations described below also constitutes the present invention.

[0011] (Electronic Component) First, an electronic component according to an embodiment of the present invention will be described. Fig. 1 is a perspective view schematically showing an example of an electronic component according to an embodiment of the present invention.

[0012] The electronic component 1 shown in FIG. 1 is a small chip-type electronic component (surface-mounted electronic component), and includes an element body 10 and external electrodes 21 and 22 provided on the element body 10 .

[0013] The size of the electronic component 1 is not particularly limited, but may be, for example, a size larger than 1005 size, 1005 size, 0603 size, 0402 size, 0201 size, or the like.

[0014] There are no particular limitations on the specific type of electronic component 1. Specific examples include multilayer ceramic electronic components such as a multilayer ceramic capacitor, a multilayer coil, a multilayer thermistor, a multilayer varistor, a multilayer LC filter, and a multilayer piezoelectric filter.

[0015] In this case, the element body 10 is preferably made of a laminate in which at least one of dielectric ceramic layers, magnetic ceramic layers, piezoelectric ceramic layers, and semiconductor ceramic layers is laminated with internal electrode layers as internal conductors.

[0016] Furthermore, the electronic component 1 does not have to be a laminated component as described above. Specific examples of such a component include a silicon capacitor, a ferrite coil, and an inductor made of a composite material of metal powder and resin.

[0017] The base body 10 includes a dielectric layer 11 and an internal conductor (internal electrode layer, not shown in Figure 1), and has a top surface 10a and a bottom surface 10b that face each other in a height direction T, a first side surface 10c and a second side surface 10d that face each other in a length direction L that is perpendicular to the height direction T, and a third side surface 10e and a fourth side surface 10f that face each other in a width direction W that is perpendicular to the height direction T and the length direction L.

[0018] Although the element body 10 has a substantially rectangular parallelepiped outer shape, the corners and ridges may be rounded. A corner is a portion where three faces of the element body 10 intersect, and a ridge is a portion where two faces of the element body 10 intersect.

[0019] The electronic component 1 is mounted on a mounting board so that the bottom surface 10b faces the mounting surface of the mounting board. In other words, the bottom surface 10b is the mounting surface.

[0020] The areas of the top surface 10a and the bottom surface 10b may be substantially the same as or different from the areas of the third side surface 10e and the fourth side surface 10f, and the areas of the first side surface 10c and the second side surface 10d may be substantially the same as or different from the areas of the third side surface 10e and the fourth side surface 10f.

[0021] Except for the exposed portions of the internal conductors, the surface of the element body 10 is made up of a dielectric layer 11, which is an insulating layer.

[0022] The dielectric layer 11 can be formed of, for example, a dielectric material (oxide). The dielectric material can be appropriately selected depending on the type of electronic component 1, and examples thereof include ceramic materials such as dielectric ceramic materials, magnetic ceramic materials, piezoelectric ceramic materials, and semiconductor ceramic materials.

[0023] Examples of dielectric ceramic materials include those containing a main component such as barium titanate, calcium titanate, strontium titanate, barium calcium titanate, or calcium zirconate. When the electronic component 1 contains any of the above dielectric ceramic materials as the main component, it can function as a multilayer ceramic capacitor. However, depending on the desired characteristics of the multilayer ceramic capacitor, it is also possible to use a material containing a minor component, such as an Mg compound, an Mn compound, an Si compound, an Al compound, a V compound, an Ni compound, or a rare earth compound, in a content less than that of the main component.

[0024] The magnetic ceramic material may be, for example, a material containing a ferrite ceramic material as a main component. When a magnetic ceramic material is used, the electronic component 1 can function as a laminated coil.

[0025] Specific examples of piezoelectric ceramic materials include PZT (lead zirconate titanate) ceramic materials, etc. When a piezoelectric ceramic material is used, the electronic component 1 can function as a multilayer piezoelectric filter.

[0026] Specific examples of semiconducting ceramic materials include spinel-based ceramic materials, etc. When a semiconducting ceramic material is used, the electronic component 1 can function as a multilayer thermistor.

[0027] The external electrodes 21 and 22 are provided on the surface of the element body 10 .

[0028] The external electrode 21 is provided on the first side surface 10c of the element body 10. In Fig. 1, the external electrode 21 is provided from the first side surface 10c to each of the top surface 10a, the bottom surface 10b, the third side surface 10e, and the fourth side surface 10f of the element body 10. The external electrode 21 is electrically connected to the internal conductor exposed from the element body 10 at the first side surface 10c.

[0029] The external electrode 22 is provided on the second side surface 10d of the element body 10. In Fig. 1, the external electrode 22 is provided from the second side surface 10d to each of the top surface 10a, the bottom surface 10b, the third side surface 10e, and the fourth side surface 10f of the element body 10. The external electrode 22 is electrically connected to the internal conductor exposed from the element body 10 at the second side surface 10d.

[0030] Fig. 2 is a cross-sectional view schematically showing an example of a cross section taken along line AA of the electronic component shown in Fig. 1. Note that in Fig. 2, the internal conductor of element body 10 is omitted.

[0031] 2, the external electrodes 21, 22 have, as an underlying electrode film, a baked electrode layer 23 of copper or silver provided on the element body 10. Specifically, the baked electrode layer 23 is an electrode formed by baking a copper or silver paste material containing a glass component.

[0032] The external electrodes 21, 22 may have a resin electrode layer provided on the element body 10 as an underlying electrode film instead of the baked electrode layer 23. The resin electrode layer contains a conductive component and a resin component. The conductive component contains, as a main component, a simple metal such as silver, copper, nickel, or tin, or an alloy containing at least one of these metals. The resin component contains, as a main component, an epoxy resin, a phenolic resin, or the like. The resin electrode layer can be formed using, for example, a conductive paste such as silver paste.

[0033] The external electrodes 21, 22 also have a so-called plating film (plating layer) formed by plating on the baked electrode layer 23 (or a resin electrode layer; the same applies below). Specifically, the external electrodes 21, 22 have a Ni plating film 24 provided to cover the baked electrode layer 23, and a Sn plating film 26 provided as an outermost layer to cover the Ni plating film 24.

[0034] In the present invention, the external electrodes may be disposed on only part of the surface of the element body, and there are no particular limitations on their location. For example, they may be disposed only on the bottom surface of the element body, or they may be disposed so as to cover part of one of the side surfaces of the element body and extend from that side surface to cover part of the bottom surface (L-shaped in cross section), or they may be disposed so as to cover part or all of one of the side surfaces of the element body and extend from that side surface to cover part of the top surface and part of the bottom surface (C-shaped in cross section).

[0035] In the present invention, the number of external electrodes is not particularly limited, and it is sufficient that at least one external electrode is provided for the element body. For example, four external electrodes may be provided for the element body (four terminals), or six external electrodes may be provided for the element body (six terminals).

[0036] FIG. 3 is a cross-sectional view schematically showing another example of the cross section of the electronic component shown in FIG. 1 taken along line AA, in which the electronic component is a multilayer ceramic capacitor.

[0037] In this case, the element body 10 is a laminate in which dielectric ceramic layers 12 as dielectric layers 11 and internal electrode layers 13 and 14 as internal conductors are stacked.

[0038] The internal electrode layer 13 is extended to a first side surface 10 c of the element body 10 and connected to an external electrode 21 , and the internal electrode layer 14 is extended to a second side surface 10 d of the element body 10 and connected to an external electrode 22 .

[0039] The dielectric ceramic layer 12 can be obtained by forming a dielectric slurry containing a dielectric ceramic material and an organic solvent into a sheet.

[0040] The internal electrode layers 13 and 14 can be obtained by printing an electrode paste containing a conductive component. The internal electrode layers 13 and 14 are preferably Ni electrode layers that use Ni as the conductive component.

[0041] Moreover, the Ni electrode layer may be replaced with an Ag electrode layer, a Pd electrode layer, or a Cu electrode layer.

[0042] Fig. 4 is a plan view schematically showing an example of the surface of the element body of the electronic component shown in Fig. 1. Fig. 5 is a cross-sectional view schematically showing an example of the cross section of the electronic component shown in Fig. 4 taken along line BB.

[0043] As shown in Figure 4, element body 10 has grain boundaries 30 on its surface that have lower resistance than particle surfaces 40. As shown in Figure 5, these low-resistance grain boundaries 30 can function to some extent as conductive paths, making it possible to improve the antistatic properties of the surface of element body 10. As a result, it is possible to prevent foreign matter such as processing debris, dust, and paper fibers from adhering to the surfaces of electronic components 1 near external electrodes 21 and 22, and to prevent electronic components 1 from adhering to each other. Therefore, gas generation during reflow, a decrease in adhesion, and adhesion between electronic components 1 can be suppressed.

[0044] However, the resistance values ​​of the particle surface 40 and the grain boundary 30 are both 10 ６ However, the presence of the grain boundaries 30, which have a lower resistance than the particle surfaces 40, improves the antistatic properties compared to the case where the low-resistance grain boundaries 30 are substantially absent. For example, the resistance of the particle surfaces 40 is 2 to 10 times the resistance of the low-resistance grain boundaries 30. ３ It may be twice as expensive.

[0045] In this specification, the resistance value means electrical resistivity.

[0046] Here, the surface of the element body 10 on which the grain surfaces 40 and grain boundaries 30 exist refers to the surface of the dielectric layer 11, excluding the exposed surfaces of the internal conductors. That is, the dielectric layer 11 of the element body 10 is composed of numerous crystal grains, and at the boundaries between the crystal grains, there are grain boundaries (grain boundary layers) with lower resistance than the crystal grains. Therefore, the entire surface of the dielectric layer 11 has fine irregularities due to the crystal grains and grain boundaries. Furthermore, the above-mentioned low-resistance grain boundaries 30 also exist at the boundaries between the crystal grains on the surface of the dielectric layer 11. That is, as shown in FIG. 4 , the surface of the element body 10 (dielectric layer 11) has low-resistance grain boundaries 30 and grain surfaces 40 corresponding to the crystal grains. The grain surfaces 40 exist in each region surrounded by the grain boundaries 30.

[0047] The element body 10 is polished with very fine abrasive powder having an average particle size of less than 0.1 mm in a fine polishing step described below. This fine polishing makes it possible to thicken (enlarge) the grain boundary layer on the surface of the dielectric layer 11. Therefore, many low-resistivity grain boundaries 30 are present on the surface of the element body 10 (dielectric layer 11).

[0048] Specifically, low-resistivity grain boundaries 30 are present preferably in an amount of 1% or more, more preferably 5% or more, and even more preferably 10% or more per unit area on the surface of element body 10. Grain boundaries 30 are present preferably in an amount of 50% or less, and more preferably 30% or less per unit area on the surface of element body 10.

[0049] The resistance value R1 of the low-resistance grain boundary 30 is preferably 30% or less, more preferably 10% or less, and even more preferably 1% or less of the resistance value R2 of the particle surface 40. The resistance value R1 of the low-resistance grain boundary 30 is preferably 0.00001% or more, more preferably 0.0001% or more of the resistance value R2 of the particle surface 40.

[0050] The low-resistance grain boundaries 30 may be ubiquitous on the surface of the element body 10 (dielectric layer 11) as shown in Fig. 4 or may be locally unevenly distributed on the surface of the element body 10 (dielectric layer 11), but the grain boundaries 30 are preferably present in the vicinity of the external electrodes 21, 22 on the surface of the element body 10. In other words, the grain boundaries 30 are preferably present in at least the regions adjacent to the external electrodes 21, 22 on the surface of the dielectric layer 11 that are not covered by the external electrodes 21, 22. This makes it possible to more reliably electrically connect the low-resistance grain boundaries 30 to the external electrodes 21, 22, thereby further improving the antistatic properties of the surface of the element body 10.

[0051] The low-resistance grain boundary 30 preferably exists within a range of 10 μm (more preferably, 2 μm) from the external electrode 21 or 22. The grain boundary 30 may also exist locally only in the vicinity of the external electrodes 21, 22.

[0052] 4 shows the top surface 10a of the element body 10, but the low-resistance grain boundaries 30 may be ubiquitous or locally distributed on the other bottom surface 10b, first side surface 10c, second side surface 10d, third side surface 10e, and fourth side surface 10f, except for the exposed surfaces of the internal conductors. The low-resistance grain boundaries 30 are preferably present at least in regions of the surface of the element body 10 (the top surface 10a, bottom surface 10b, first side surface 10c, second side surface 10d, third side surface 10e, and fourth side surface 10f) that are not covered by the external electrodes 21 and 22.

[0053] Furthermore, in the electronic component of the present invention, the low-resistivity grain boundaries and particle surfaces present on the surface of the element body, and their physical properties such as resistance values, can be detected using, for example, a scanning probe microscope (SPM, which is synonymous with an atomic force microscope (AFM) in a broad sense) or a scanning electrochemical cell microscope (SECCM).

[0054] Fig. 6 is a plan view schematically showing another example of the surface of the element body of the electronic component shown in Fig. 1. Fig. 7 is a cross-sectional view schematically showing an example of the cross section of the electronic component shown in Fig. 6 taken along line CC.

[0055] As shown in Figure 6, the electronic component 1 preferably has a glass layer 50 that extends from the external electrode 21 to the particle surfaces 40 and low-resistance grain boundaries 30 near the external electrode 21. The glass layer 50 can protect the particle surfaces 40 and the low-resistance grain boundaries 30, i.e., the antistatic layer. Furthermore, the presence of the glass layer 50 that covers the grain boundaries 30 can prevent abnormal growth of plating on the surface of the element body 10 when a plating film is formed on the baked electrode layer 23. This is because plating tends to deposit preferentially on the exposed low-resistance grain boundaries 30.

[0056] Similarly, it is preferable that the glass layer 50 extends from the external electrode 22 to the particle surfaces 40 and the low-resistance grain boundaries 30 in the vicinity of the external electrode 22. Although the aspects of the glass layer 50 in relation to the external electrode 21 will be described below in some cases, these aspects can also be applied to the relationship with the external electrode 22.

[0057] The glass layer 50 may be present at least within a range of 10 μm (more preferably within 2 μm) from the external electrode 21, or may be present only within this range.

[0058] The resistance value of the glass layer 50 is preferably 10 times or more larger than the resistance value of the particle surface 40. ２ That is, when the resistance value of the particle surface 40 is R2 and the resistance value of the glass layer 50 is R3, the resistance value R2 of the particle surface 40 and the resistance value R3 of the glass layer 50 preferably satisfy R3 / R2≧10, and more preferably R3 / R2≧10 ２ This makes it possible to further suppress the plating from spilling onto the surface of element body 10 when forming a plating film on baked electrode layer 23.

[0059] Therefore, it is preferable that the resistance value R1 of the low-resistance grain boundary 30, the resistance value R2 of the grain surface 40, and the resistance value R3 of the glass layer 50 satisfy the relationship R1<R2<R3.

[0060] Specifically, for example, the resistance value R1 of the low-resistance grain boundary 30 is 10 ８ ~10 １４ Ωcm, and the resistance R2 of the particle surface 40 is 10１０ ~10 １６ The resistance R3 of the glass layer 50 may be 10 １２ ~10 １８ It may be Ωcm.

[0061] Furthermore, even if the relatively low-resistance grain boundary 30 is covered by the relatively high-resistance glass layer 50, the grain boundary 30 can be electrically connected to the external electrode 21 under the glass layer 50, thereby ensuring antistatic properties.

[0062] 6 , the glass layer 50 preferably spreads preferentially to the low-resistance grain boundaries 30 rather than to the particle surfaces 40. This makes it possible to further suppress the plating from spilling onto the surface of the element body 10 when forming a plating film on the baked electrode layer 23. More specifically, in this case, the glass layer 50 is present so as to cover the particle surfaces 40 and the low-resistance grain boundaries 30 in the vicinity of the external electrode 21, but in regions further away from the external electrode 21 than that region, the glass layer 50 is present on the low-resistance grain boundaries 30 but may not be substantially present on the particle surfaces 40.

[0063] The thickness of the glass layer 50 may become thinner with increasing distance from the external electrode 21. This more reliably allows the glass layer 50 to spread preferentially to the grain boundaries 30, which have lower resistance than the particle surfaces 40. More specifically, assuming that the thickness of the glass layer 50 on the particle surfaces 40 adjacent to the external electrode 21 is t1, the thickness of the glass layer 50 on the particle surfaces 40 500 nm away from the external electrode 21 is t2, and the thickness of the glass layer 50 on the particle surfaces 40 1 μm away from the external electrode 21 is t3, the thickness of the glass layer 50 is considered to become thinner with increasing distance from the external electrode 21 if t1 > t2 > t3 is satisfied. Here, t1, t2, and t3 are the averages of the thicknesses at any three points on the target particle.

[0064] The glass layer 50 preferably contains at least one of boron, silica, and bismuth, and more preferably contains boron / silicate / bismuth-based glass, which more reliably allows the glass layer 50 to preferentially extend to the grain boundaries 30, which have lower resistance than the grain surfaces 40.

[0065] The external electrode 21 preferably contains 1 wt % or more and 40 wt % or less of a glass component, and more preferably 2 wt % or more and 20 wt % or less of a glass component. The same applies to the external electrode 22. By containing 1 wt % or more of a glass component, it is possible to more reliably ensure that the glass layer 50 spreads preferentially to the grain boundaries 30, which have lower resistance than the particle surfaces 40. On the other hand, by setting the glass component to 40 wt % or less, it is possible to suppress glass floating, which is a phenomenon in which the glass component floats (precipitates) on the surface of the baked electrode layer 23.

[0066] The glass component contained in the external electrodes 21 and 22 preferably contains at least one of boron, silica, and bismuth, and more preferably contains boron / silicate / bismuth-based glass, which allows the glass layer 50 to be formed more reliably.

[0067] 7, the thickness t of the glass layer 50 on the particle surface 41 adjacent to the external electrode 21 is preferably 50% or less, and more preferably 5% or less, of the depth d of the grain boundary 31 adjacent to the external electrode 21. By making the thickness t 50% or less of the depth d, the antistatic effect of the low-resistance grain boundary 30 can be maintained. The thickness t is preferably 3% or more of the depth d.

[0068] 7 , the glass layer 50 preferably exists along the shape of the external electrode 21 in the vicinity of the external electrode 21. That is, in a cross section including the glass layer 50 and the external electrode 21, the glass layer 50 preferably exists along the edge of the external electrode 21 (so as to cover the edge). This can improve the adhesion between the glass layer 50 and the external electrode 21.

[0069] As shown in Figure 7, if the height of the highest point of the glass layer 50 in a portion 51 that follows the shape of the external electrode 21 is H, and the depth of the glass layer 50 at the grain boundary 32 between a first crystal grain 42 adjacent to the external electrode 21 and a second crystal grain 43 located next to the first crystal grain 42 on the opposite side of the external electrode 21 with respect to the first crystal grain 42, is D, the ratio H:D of H to D may be 0.9:1.1 to 1.1:0.9.

[0070] 7 , the glass layer 50 in a portion 51 that follows the shape of the external electrode 21 is preferably larger than the glass layer 50 in a portion 52 that exists on the particle surface 41 adjacent to the external electrode 21. Increasing the amount of the portion 51 that follows the shape of the external electrode 21 in this way makes it possible to strengthen the protection of the antistatic layer and improve the adhesion between the glass layer 50 and the external electrode 21.

[0071] 7 , the maximum thickness Tmax of the glass layer 50 at a portion 51 that follows the shape of the external electrode 21 is preferably 120% or less of the depth d of the grain boundary 31 adjacent to the external electrode 21. The maximum thickness Tmax of the glass layer 50 corresponds to the thickness from the grain boundary 31 adjacent to the external electrode 21 to the highest point of the glass layer 50 at the portion 51 that follows the shape of the external electrode 21.

[0072] 7 , the maximum thickness Tmax of the glass layer 50 at a portion 51 that follows the shape of the external electrode 21 is preferably 10 to 50 times, and more preferably 20 to 30 times, the thickness t of the glass layer 50 on the particle surface 41 adjacent to the external electrode 21. This also makes it possible to enhance the protection of the antistatic layer and improve the adhesion between the glass layer 50 and the external electrode 21.

[0073] The preferred relationships of the dimensions and quantity of the glass layer 50 and grain boundaries described here need only be satisfied in at least one cross section including the glass layer 50 , the external electrode 21 and the element body 10 .

[0074] Furthermore, the thickness t of the glass layer 50, which is compared with the depth d of the grain boundary 31 adjacent to the external electrode 21 and the maximum thickness Tmax of the glass layer 50, is the thickness of the glass layer 50 at a point on the particle surface 41 adjacent to the external electrode 21, that is, at a midpoint between the grain boundary 32 between the first crystal grain 42 and the second crystal grain 43 and the external electrode 21.

[0075] The depth d of the grain boundary 31 and the height H of the highest point of the glass layer 50 are respectively the depth and height based on the position of the highest point of the particle surface 41 adjacent to the external electrode 21 .

[0076] In the electronic component of the present invention, the glass layer present on the surface of the element body and its physical properties such as its resistance value can be detected, for example, by observing a cross section using a transmission electron microscope (TEM) with a focused ion beam (FIB) or by elemental analysis using energy dispersive X-ray fluorescence spectroscopy (EDX).

[0077] (Method for Manufacturing Electronic Component) Next, a method for manufacturing an electronic component according to an embodiment of the present invention will be described, taking as an example a case where a laminated coil is manufactured as the electronic component 1. Fig. 8 shows an example of a manufacturing flow of the method for manufacturing an electronic component according to an embodiment of the present invention.

[0078] First, a magnetic ceramic material and a non-magnetic ceramic material are prepared (S10).

[0079] Next, magnetic ceramic green sheets and non-magnetic ceramic green sheets are prepared from the magnetic ceramic material and the non-magnetic ceramic material, respectively, and a coil conductor pattern is formed on the magnetic ceramic green sheets and / or the non-magnetic ceramic green sheets. These sheets are then stacked to prepare a laminate block (S11).

[0080] Next, the laminated block is divided into individual pieces to produce element bodies (S12).

[0081] Next, a barreling process is performed in which the element body is polished with the first polishing powder to round off the corners and ridges of the element body (S13). This barreling process can be performed by a general wet barrel polishing method.

[0082] The average particle size of the first polishing powder (polishing media) used in this barrel processing step is not particularly limited, but is preferably 100 μm or more and 1 mm or less, and more preferably 200 μm or more and 400 μm or less.

[0083] The polishing time in the barrel treatment step is not particularly limited, but is preferably 5 minutes or more and 120 minutes or less, and more preferably 10 minutes or more and 30 minutes or less.

[0084] The material of the first polishing powder used in the barrel treatment step is not particularly limited, and may be, for example, a ceramic material (e.g., alumina, zirconia), etc. The shape of the first polishing powder is, for example, spherical.

[0085] Next, the barrel-processed body is fired (S14). The firing conditions, such as firing temperature and firing time, are not particularly limited and can be set appropriately.

[0086] Next, the sintered body is polished with a second polishing powder that is finer than the first polishing powder used in the barreling process and has an average particle size of less than 0.1 mm (S15). This fine polishing process can be performed in the same manner as the barreling process, i.e., by wet barrel polishing, except that the average particle size of the polishing powder used is different.

[0087] The average particle size of the second polishing powder (polishing media) used in the fine polishing step is preferably 100 nm or more and 0.1 mm or less, and more preferably 150 nm or more and 80 μm or less.

[0088] In this specification, the average particle size of the first polishing powder and the second polishing powder is calculated by measuring the particle size of a plurality of (e.g., 100) polishing powder particles by physically clamping them with a vernier caliper, or by measuring the particle size in an image obtained with an optical microscope and then taking the arithmetic mean.

[0089] The polishing time in the fine polishing step is not particularly limited, but is preferably 5 minutes or more and 120 minutes or less, and more preferably 10 minutes or more and 30 minutes or less.

[0090] The material of the second polishing powder used in the fine polishing step is not particularly limited, and may be, for example, a ceramic material (e.g., alumina, zirconia), etc. The shape of the second polishing powder is, for example, spherical.

[0091] By carrying out the above barrel processing step, firing step, and fine polishing step in this order, it is possible to expose many low-resistance grain boundaries on the surface of the element body (dielectric layer).

[0092] The fine polishing step may be performed by blasting instead of wet barrel polishing, which allows many low-resistivity grain boundaries to be selectively and locally exposed in desired regions on the surface of the element body (dielectric layer), for example, in the vicinity of regions where external electrodes are to be formed.

[0093] Thereafter, external electrodes are formed on the finely polished surface of the element body (S16).

[0094] More specifically, a baked electrode layer or a resin electrode layer is first formed as a base electrode film. If glass is to flow onto the surface of the element body near the external electrodes, a baked electrode layer is formed as the base electrode film. That is, a copper or silver paste material containing a glass component is applied to a predetermined area on the element body, and then the electrode paste is baked to form a baked electrode layer. During this baking, the glass component in the electrode paste material flows out to the particle surfaces and low-resistance grain boundaries on the element body, with a particular preference for low-resistance grain boundaries, forming a glass layer.

[0095] The electrode paste preferably contains at least one of boron, silica, and bismuth as a glass component, and more preferably contains boron / silica / bismuth-based glass.

[0096] The electrode paste preferably contains 1% by weight or more and 40% by weight or less of a glass component, and more preferably contains 2% by weight or more and 20% by weight or less of a glass component.

[0097] From the viewpoint of allowing the glass to flow preferentially to the grain boundaries with low resistance, the following modes (1) to (5) are preferred.

[0098] (1) Use glass that flows easily into low-resistance grain boundaries (having low glass transition and glass yield points).

[0099] (2) Select heavy glass powder particles. This allows the glass powder to sink to the element body side when the electrode paste is baked. As a result, there is less glass powder on the surface of the electrode paste and more glass powder at the interface between the electrode paste and the element body. This makes it possible to suppress glass floating while increasing glass outflow.

[0100] (3) The temperature during baking of the electrode paste is increased. Specifically, the temperature is preferably 300° C. or higher and 800° C. or lower, and more preferably 500° C. or higher and 700° C. or lower.

[0101] (4) The particle surfaces are hydrophobized except for the grain boundaries.

[0102] (5) The surface of the element is treated with a hydrophilic agent such as plasma to make it easier for the glass to flow out.

[0103] Subsequently, plating films (plating layers), for example, Ni plating film and Sn plating film, are formed in this order on the base electrode film by plating, thereby forming external electrodes.

[0104] In this manner, a laminated coil is manufactured as the electronic component 1 .

[0105] EXAMPLES Hereinafter, examples will be given that more specifically disclose the electronic component and the method for manufacturing the electronic component of the present invention, but the present invention is not limited to these examples.

[0106] Example 1: The electronic component (laminated coil) shown in Figures 4 to 7 was fabricated using the above-described manufacturing method as a sample of the electronic component of Example 1. Specifically, the following steps were performed in this order: magnetic material and non-magnetic material fabrication step (S10), sheet fabrication, coil conductor pattern formation, and laminate block fabrication step (S11), singulation step (S12), barrel processing step (S13), firing step (S14), fine polishing step (S15), and external electrode formation step (S16). Conventional methods were used for steps (S10) to (S13). In step (S10), a ferrite material containing Fe and Zn was used as the magnetic material. In step (S16), a silver electrode layer was formed by baking a silver paste material containing boron / bismuth-based glass as a glass component. The baking temperature for this paste material was 600°C.

[0107] FIG. 9 shows an SPM image of the surface of the element body in the vicinity of the external electrode of the sample of Example 1.

[0108] As shown in Figure 9, in the sample of Example 1, which was subjected to the barrel treatment step, firing step, and fine polishing step in this order, it was confirmed that grain boundaries with lower resistance than the particle surfaces existed on the surface of the element body (dielectric layer). Low-resistance grain boundaries were present in 7.7% per unit area on the surface of the element body, and the resistance value of the grain boundaries was 3.8 x 10 compared to the resistance value of the particle surfaces. １４ The resistance value of the grain boundary was 10% of the resistance value of the particle surface.

[0109] Fig. 10 is an image showing the results of TEM-EDX observation and analysis of the surface of the element body near the external electrode of the sample of Example 1, and shows an image in which the ceramic component, which is one component of the dielectric layer, the silver component, which is one component of the electrode paste, and the silicon component, which is one component of the glass component, are mapped onto the TEM image. Fig. 11 is an image in which only the silicon component is mapped onto the image of Fig. 10. In Fig. 10, to make it easier to distinguish between the silver component and the silicon component, the approximate area where the silver component is present is outlined with a solid line and hatched.

[0110] 10 and 11, it was confirmed that in the sample of Example 1, a glass layer was formed on the surface of the element body (dielectric layer), preferentially spreading to the grain boundaries, which have lower resistance than the grain surfaces. The resistance value of the glass layer was 2.6×10 １３ Ω·cm, which was 1000 times larger than the resistance value of the particle surface.

[0111] Fig. 12 is a TEM image showing the results of TEM-EDX observation and analysis of a cross section of the element body near the external electrode of the sample of Example 1. Fig. 13 is an image in which only the silicon component, which is one of the glass components, is mapped in the image of Fig. 12.

[0112] As shown in FIGS. 12 and 13, it was confirmed that the thickness of the glass layer became thinner as it was farther away from the external electrodes.

[0113] The thickness t of the glass layer on the particle surface adjacent to the external electrode was 5% of the depth d of the grain boundary adjacent to the external electrode.

[0114] Furthermore, it was confirmed that the glass layer was present near the external electrode, following the shape of the external electrode, and that the glass layer in the portion following the shape of the external electrode was thicker than the portion of the glass layer present on the particle surface adjacent to the external electrode. Here, if the height of the highest point of the glass layer in the portion following the shape of the external electrode is H and the depth of the glass layer at the grain boundary between the first crystal grain adjacent to the external electrode and the second crystal grain located next to the first crystal grain on the opposite side of the first crystal grain from the external electrode is D, the ratio H:D was 1.1:1. Furthermore, the maximum thickness Tmax of the glass layer in the portion following the shape of the external electrode was 35 times the thickness t of the glass layer on the particle surface adjacent to the external electrode.

[0115] The present specification discloses the following:

[0116] <1> An electronic component comprising: an element body; and external electrodes provided on the element body, the element body having, on its surface, grain boundaries that have a lower resistance than particle surfaces.

[0117] <2> The electronic component according to <1>, wherein the grain boundaries are present in the surface in an amount of 1% or more per unit area.

[0118] <3> The electronic component according to <1> or <2>, wherein the resistance of the grain boundary is 30% or less of the resistance of the particle surface.

[0119] <4> The electronic component according to any one of <1> to <3>, wherein the grain boundary is present on the surface in the vicinity of the external electrode.

[0120] <5> The electronic component according to <4>, further comprising a glass layer extending from the external electrode to the particle surfaces and the grain boundaries in the vicinity of the external electrode.

[0121] <6> The electronic component according to <5>, wherein the glass layer extends preferentially to the grain boundaries rather than to the particle surfaces.

[0122] <7> The electronic component according to <5> or <6>, wherein the thickness of the glass layer decreases with increasing distance from the external electrode.

[0123] <8> The electronic component according to any one of <5> to <7>, wherein the glass layer contains at least one of boron, silica, and bismuth.

[0124] <9> The electronic component according to <8>, wherein the glass layer contains boron / silicate / bismuth-based glass.

[0125] <10> The electronic component according to any one of <5> to <9>, wherein the external electrodes contain a glass component in an amount of 1 wt % or more and 40 wt % or less.

[0126] <11> The electronic component according to any one of <5> to <10>, wherein the resistance value of the glass layer is 10 times or more greater than the resistance value of the particle surface.

[0127] <12> The electronic component according to any one of <5> to <11>, wherein the thickness of the glass layer on the particle surface adjacent to the external electrode is 50% or less of the depth of the grain boundary adjacent to the external electrode.

[0128] <13> The electronic component according to any one of <5> to <12>, wherein the glass layer is present in the vicinity of the external electrode and conforms to the shape of the external electrode.

[0129] <14> The electronic component according to <13>, wherein a ratio H:D of H to D is 0.9:1.1 to 1.1:0.9, where H is a height of the highest point of the glass layer in a portion that follows the shape of the external electrode, and D is a depth of the glass layer at a grain boundary between a first crystal grain adjacent to the external electrode and a second crystal grain that is located adjacent to the first crystal grain on the opposite side of the external electrode with respect to the first crystal grain.

[0130] <15> The electronic component according to <13> or <14>, wherein the glass layer in the portion following the shape of the external electrode is thicker than the glass layer in the portion present on the particle surface adjacent to the external electrode.

[0131] <16> The electronic component according to any one of <13> to <15>, wherein the maximum thickness of the glass layer in the portion following the shape of the external electrode is 10 to 50 times the thickness of the glass layer on the surface of a particle adjacent to the external electrode.

[0132] <17> A method for manufacturing an electronic component, comprising: a barrel processing step of polishing an element body with first abrasive powder to round off corners and ridges of the element body; a firing step of firing the barrel-processed element body; and a fine polishing step of polishing the fired element body with second abrasive powder that is finer than the first abrasive powder and has an average particle size of less than 0.1 mm.

[0133] <18> The method for manufacturing an electronic component according to <17>, further comprising an external electrode forming step of forming external electrodes on the finely polished surface of the element body.

[0134] REFERENCE SIGNS LIST 1 Electronic component 10 Body 10a Top surface 10b Bottom surface 10c First side surface 10d Second side surface 10e Third side surface 10f Fourth side surface 11 Dielectric layer 12 Dielectric ceramic layer 13, 14 Internal electrode layer 21, 22 External electrode 23 Baked electrode layer (base electrode film) 24 Ni plating film 26 Sn plating film 30 Low-resistance grain boundary 31, 32 Grain boundary 40, 41 Particle surface 42 First crystal grain 43 Second crystal grain 50 Glass layer 51 Portion of glass layer following the shape of external electrode 52 Portion of glass layer present on particle surface adjacent to external electrode

Claims

1. An electronic component comprising an element body and external electrodes provided on the element body, the element body having grain boundaries on its surface that have a lower resistance than the grain surfaces.

2. The electronic component according to claim 1, wherein the grain boundaries are present in an amount of 1% or more per unit area of ​​the surface.

3. An electronic component according to claim 1 or 2, wherein the resistance of the grain boundary is 30% or less of the resistance of the particle surface.

4. An electronic component according to any one of claims 1 to 3, wherein the grain boundary is present on the surface in the vicinity of the external electrode.

5. The electronic component according to claim 4, further comprising a glass layer extending from said external electrodes to said grain surfaces and said grain boundaries in the vicinity of said external electrodes.

6. The electronic component according to claim 5, wherein the glass layer extends preferentially to the grain boundaries rather than to the grain surfaces.

7. The electronic component according to claim 5 or 6, wherein the thickness of the glass layer decreases with increasing distance from the external electrodes.

8. The electronic component according to any one of claims 5 to 7, wherein the glass layer contains at least one of boron, silica, and bismuth.

9. The electronic component of claim 8, wherein the glass layer comprises a boron / silicate / bismuth-based glass.

10. An electronic component according to any one of claims 5 to 9, wherein the external electrodes contain a glass component in an amount of 1% by weight or more and 40% by weight or less.

11. The electronic component according to any one of claims 5 to 10, wherein the resistance value of the glass layer is at least 10 times greater than the resistance value of the particle surface.

12. An electronic component according to any one of claims 5 to 11, wherein the thickness of the glass layer on the particle surfaces adjacent to the external electrodes is 50% or less of the depth of the grain boundaries adjacent to the external electrodes.

13. The electronic component according to any one of claims 5 to 12, wherein the glass layer is present in the vicinity of the external electrodes and conforms to the shape of the external electrodes.

14. The electronic component according to claim 13, wherein the ratio H:D is 0.9:1.1 to 1.1:0.9, where H is the height of the highest point of the glass layer in a portion that follows the shape of the external electrode, and D is the depth of the glass layer at the grain boundary between a first crystal grain adjacent to the external electrode and a second crystal grain that is located adjacent to the first crystal grain on the opposite side of the external electrode from the first crystal grain.

15. An electronic component according to claim 13 or 14, wherein the glass layer in the portion following the shape of the external electrode is greater than the glass layer in the portion present on the particle surface adjacent to the external electrode.

16. An electronic component according to any one of claims 13 to 15, wherein the maximum thickness of the glass layer in the portion that follows the shape of the external electrode is 10 times or more and 50 times or less the thickness of the glass layer on the particle surface adjacent to the external electrode.

17. A method for manufacturing electronic components, comprising: a barrel processing step in which an element body is polished with a first polishing powder to round off corners and ridges of the element body; a firing step in which the barrel processed element body is fired; and a fine polishing step in which the fired element body is polished with a second polishing powder that is finer than the first polishing powder and has an average particle size of less than 0.1 mm.

18. The method for manufacturing an electronic component according to claim 17, further comprising an external electrode forming step of forming external electrodes on the finely polished surface of the element body.

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