Electronic component

Abstract

Inhibiting peeling of plating film. In an electronic component having a ceramic main body and an external electrode, the external electrode includes a resin layer containing a conductive powder and a plating film formed on the resin layer in direct contact with the resin layer, the plating film is formed of a metal having a face-centered cubic structure, and F of formula (1) is 0.20 or more and 0.50 or less. F = (P - P0) / (1 - P0) … (1), P0 and P are obtained from formula (2) and formula (3) below. P0 = I0(111) / {I0(111) + I0(200) + I0(220)} … (2), P = I(111) / {I(111) + I(200) + I(220)} … (3), I0(111), I0(200), I0(220) are diffraction intensities of (111) plane, (200) plane and (220) plane obtained from known powder X-ray diffraction data of the metal constituting the plating film, and I(111), I(200), I(220) are diffraction intensities of (111) plane, (200) plane and

Description

Technical Field

[0001] This invention relates to electronic components. Background Technology

[0002] Electronic components such as positive temperature coefficient thermistors generally have external electrodes, which are formed by stacking a conductive layer at the end of a ceramic body with a metal coating formed by electrolytic plating, electroless plating, or the like. The coating can be formed in one or more layers. In one example of a two-layer coating, the first coating in contact with the conductive layer is a nickel coating for the purpose of improving heat resistance, etc., and the second coating covering the first coating is a tin coating for the purpose of improving solderability.

[0003] Furthermore, in the installed electronic components, cracks may occur in the ceramic body due to impact, thermal stress, etc. To prevent this, Patent Document 1 proposes a solution where a conductive epoxy thermosetting resin layer containing metal powder (hereinafter sometimes referred to as "resin layer") is provided between the baking electrode and the plating layer in the external electrode of the electronic component. The resin layer functions as a stress-absorbing layer, suppressing the formation of cracks in the ceramic body.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 11-162771 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] In external electrodes that include a resin layer, as in Patent Document 1, there is a risk of coating peeling off from the resin layer. If the coating peels off, there is a danger that poor contact may occur inside the external electrode, causing electronic components to malfunction.

[0009] Patent document 1 does not study the peeling of the coating formed on the resin layer.

[0010] The present invention was made against the background of the above situation, and its object is to suppress the peeling of the coating in an electronic component having an external electrode having a coating on a resin layer.

[0011] Solution for solving the problem

[0012] According to one aspect of the present invention, an electronic component is provided, the electronic component comprising a ceramic body and external electrodes disposed at an end of the ceramic body, wherein,

[0013] The external electrode includes a resin layer containing conductive powder and a coating formed on the resin layer in direct contact with the resin layer.

[0014] The coating is formed from a metal with a face-centered cubic structure.

[0015] Regarding the coating, F, calculated using the following formula (1), is 0.20 or more and 0.50 or less:

[0016] F=(P-P0) / (1-P0)···(1)

[0017] In equation (1), P0 and P are obtained from equations (2) and (3) below.

[0018] P0=I0(111) / {I0(111)+I0(200)+I0(220)}···(2)

[0019] P=I(111) / {I(111)+I(200)+I(220)}···(3)

[0020] In equation (2), I0(111), I0(200), and I0(220) are the diffraction intensities of the (111), (200), and (220) planes, respectively, obtained from known powder X-ray diffraction data of the metal constituting the coating.

[0021] In equation (3), I(111), I(200) and I(220) are the diffraction intensities of the (111), (200) and (220) planes obtained from the X-ray diffraction pattern of the coating, respectively.

[0022] The effects of the invention

[0023] According to the present invention, peeling of the coating formed on the resin layer can be suppressed. Attached Figure Description

[0024] Figure 1 This is a schematic cross-sectional view of the electronic component in Embodiment 1.

[0025] Figure 2 This is a schematic cross-sectional view of the electronic component in Embodiment 2. Detailed Implementation

[0026] The inventors of this invention conducted in-depth research to suppress the peeling of coatings in electronic components having external electrodes comprising a resin layer and a coating formed on the resin layer in direct contact with the resin layer. They then discovered that improving the orientation of the metallic material constituting the coating could suppress coating peeling, thus completing this invention.

[0027] The reason for this effect is not yet determined, but it can be speculated to be due to the mechanism described below.

[0028] In the rotary drum plating method, a common method in the manufacture of electronic components, the coating film is formed simultaneously with the impact force generated by rotation, which flattens the surface of the coating. However, this planarization process leads to disordered growth of the coating, resulting in a coating with misaligned crystal orientations (i.e., inconsistent crystallinity). Furthermore, this disordered growth can potentially create defects in metal bonding within the coating. In such cases, the adhesion between the resin layer and the coating is weak, and the coating itself has low strength. Therefore, the coating is prone to peeling off at the resin layer-coating interface or due to internal damage.

[0029] Therefore, the inventors of this invention believe that the crystallinity of the coating, and consequently the crystallinity of the conductive powder within the coating and resin layer, helps to suppress coating peeling, and have further investigated this. As a result, the inventors of this invention optimized the plating bath and plating conditions, causing the coating to grow with a strong orientation toward a specific face ((111) face), thereby forming a coating with a regular crystal structure. With such a coating, it is believed that the tight adhesion between the resin layer and the coating can be improved, and the strength of the coating itself is also increased, thereby suppressing coating peeling.

[0030] The electronic components of embodiments of the present invention will now be described with reference to the accompanying drawings.

[0031] [Implementation Method 1]

[0032] Figure 1 This is a schematic cross-sectional view of the electronic component 10A according to Embodiment 1 of the present invention. Figure 1 The example of the electronic component 10A shown is a positive temperature coefficient (or positive characteristic, PTC) thermistor.

[0033] The electronic component 10A includes a ceramic body 20A and external electrodes located at the ends of the ceramic body 20A.

[0034] Electronic component 10A has at least one external electrode. Figure 1 The positive temperature coefficient thermistor shown has a pair of external electrodes 30 and 40 located at both ends of the ceramic body 20A.

[0035] The external electrodes 30 and 40 include at least resin layers 32 and 42 containing conductive powder and coatings 33 and 43 formed on the resin layers 32 and 42 in direct contact with them. The external electrodes 30 and 40 may also include a base layer 31 and 41 disposed between the end faces 21A and 22A of the ceramic body 20A and the resin layers 32 and 42, and a second coating 34 and 44 covering the coatings 33 and 43.

[0036] The inventors of this invention conducted in-depth research and found that, in order to suppress the peeling of the coatings 33 and 43 formed on the resin layers 32 and 42, the following approach is effective: the coatings 33 and 43 are formed from a metal having a face-centered cubic structure, and the (111) plane is preferentially oriented regarding the crystal structure orientation of the coatings 33 and 43. The orientation of the (111) plane of the coatings 33 and 43 is indicated by the value of F, which is defined by the following formula (1). By making the value of F obtained for the coatings 33 and 43 0.20 or more and 0.50 or less, the tightness of the adhesion between the resin layers 32 and 42 and the coatings 33 and 43 is increased, and internal damage to the coatings 33 and 43 is less likely to occur. Therefore, it is believed that the peeling of the coatings 33 and 43 can be suppressed.

[0037] F=(P-P0) / (1-P0)···(1)

[0038] In equation (1), P0 and P are obtained from equations (2) and (3) below.

[0039] P0=I0(111) / {I0(111)+I0(200)+I0(220)}···(2)

[0040] P=I(111) / {I(111)+I(200)+I(220)}···(3)

[0041] In equation (2), I0(111), I0(200), and I0(220) are the diffraction intensities of the (111), (200), and (220) planes, respectively, obtained from known powder X-ray diffraction data of the metal constituting the coating.

[0042] In equation (3), I(111), I(200) and I(220) are the diffraction intensities of the (111), (200) and (220) planes obtained from the X-ray diffraction pattern of the coating, respectively.

[0043] Known powder X-ray diffraction data for I0(111), I0(200), and I0(220) can be obtained from the ICDD database.

[0044] Regarding I(111), I(200), and I(220), these were derived from the diffraction patterns obtained by measuring coatings 33 and 43 using an XRD diffraction apparatus. The two-dimensional X-ray diffraction image obtained using a two-dimensional detector was converted into a one-dimensional profile, and the diffraction intensity values ​​of the peaks on each orientation plane were determined using the obtained one-dimensional profile. The diffraction intensity values ​​were then used as relative intensities with the maximum intensity set to 100.

[0045] As an XRD diffraction device, a micro-area X-ray diffraction device can be used, such as the Bruker AXS D8 DISCOVER.

[0046] Furthermore, since XRD diffraction measurements of the coatings 33 and 43 on the electronic component 10A are required, when the coatings 33 and 43 are covered by the second coatings 34 and 44, the XRD diffraction of the coatings 33 and 43 is measured after the second coatings 34 and 44 are removed to expose the coatings 33 and 43. Regarding the removal of the second coatings 34 and 44, for example, there are methods that use solvents that selectively dissolve only the second coatings 34 and 44 to dissolve and remove them.

[0047] The value of F obtained by using equations (1) to (3) is an indicator of the orientation of the (111) facet of the material constituting the coatings 33 and 43. Equations (1) to (3) are explained in detail below.

[0048] As a definition of the "degree of orientation" of a predetermined orientation plane, the Lotgering factor f is known. The Lotgering factor f is calculated by the intensity of X-rays diffracted from the predetermined orientation plane (for convenience, denoted as (xyz)) using the following equation (4).

[0049] f=(p-p0) / (1-p0)···(4)

[0050] In equation (4), p0 is a value based on the powder X-ray diffraction data known about the substance being the object, and p is a value based on the X-ray diffraction pattern of the object substance, which are obtained by equations (5) and (6) below, respectively.

[0051] p0=I0(xyz) / ΣI0(hkl)···(5)

[0052] p=I(xyz) / ΣI(hkl)···(6)

[0053] In equations (5) and (6), h, k, and l are integers including 0.

[0054] In equation (5), ΣI0(hkl) refers to the sum of the diffraction intensities (usually relative intensities with the maximum intensity set to 100) of the peaks of all planes obtained from powder X-ray diffraction data known about the material to be targeted, and I0(xyz) refers to the value of the diffraction intensities (as above) of the peaks of a predetermined orientation plane (xyz) obtained from powder X-ray diffraction data known about the material to be targeted.

[0055] In the XRD diffraction pattern of a material with a face-centered cubic structure, the diffraction intensities of the peaks belonging to the (111), (200), and (220) planes are significant. Therefore, the inventors of this invention simplified the definition of the Roglin factor f, which requires the diffraction intensities of the peaks on all planes, and obtained a factor F similar to the Roglin factor only from the diffraction intensities of the peaks on the (111), (200), and (220) planes. That is, the above-mentioned equations (1) to (3) for obtaining the factor F were determined by modifying equations (4) to (6) used to obtain the Roglin factor f. The inventors of this invention found that the values ​​of F for the coatings 33 and 43 obtained from equations (1) to (3) are meaningful as indicators for knowing the tightness of the adhesion between the resin layers 32 and 42 and the coatings 33 and 43.

[0056] The value of F can be greater than -1 and less than 1, indicating that the closer it is to 1, the higher the orientation of the (111) facet of the coating 33 and 43.

[0057] As described above, in this invention, the F value of the coatings 33 and 43 is 0.20 or higher and 0.50 or lower. If the F value is less than 0.20, the adhesion between the resin layers 32 and 42 and the coatings 33 and 43 is insufficient. If the F value exceeds 0.50, although the adhesion between the resin layers 32 and 42 and the coatings 33 and 43 increases, coatings 33 and 43 with high orientation must be formed, which imposes strict constraints on production conditions and thus increases manufacturing costs.

[0058] The value of F is preferably 0.23 or higher and 0.48 or lower, more preferably 0.25 or higher and 0.45 or lower.

[0059] The metal having a face-centered cubic structure constituting the coatings 33 and 43 is preferably at least one selected from the group consisting of Ni, Au, Cu, Ag, Pt, Pd and Al.

[0060] The thickness of the coatings 33 and 43 is sufficient to protect the end faces 21A and 22A of the ceramic body 20A of the electronic component 10A from the influence of the reflow soldering atmosphere. For example, in the case of Ni coating, a thickness of 2μm or more and 10μm or less is preferred.

[0061] When the external electrodes 30 and 40 also have a second coating 34 and 44 covering the coating 33 and 43, it is preferable that the second coating 34 and 44 is at least one selected from the group consisting of Sn, Au, Cu and Pd.

[0062] The thickness of the second coating 34 and 44 only needs to be the thickness of the film that the welding material wets and expands during reflow soldering. For example, in the case of Sn coating, an average film thickness of 0.5 μm or more and 5.0 μm or less is preferred.

[0063] The film thicknesses of coatings 33 and 43, and the second coatings 34 and 44, were measured by performing fluorescence X-ray analysis on the samples with each coating exposed on the outermost surface and applying the obtained X-ray intensities to a calibration line. The calibration line was obtained by performing fluorescence X-ray analysis on standard samples with known film thicknesses and plotting the relationship between the obtained X-ray intensities and film thicknesses using a regression equation. The film thickness of the coatings in the standard samples with known film thicknesses was measured using the following method: Multiple standard samples with varying film thicknesses due to intentional changes in coating conditions were prepared. These standard samples were cross-sectionally ground, and electron microscopy or scanning ion microscopy images of the cross-sections were obtained to measure the film thickness of the coatings on the standard samples.

[0064] The resin layers 32 and 42 of the external electrodes 30 and 40 function as stress-absorbing layers, suppressing cracks in the ceramic body 20A caused by external impacts, thermal stress, etc. The resin layers 32 and 42 comprise conductive powder and resin material. The conductive powder dispersed within the resin material makes the resin layers 32 and 42 conductive.

[0065] Regarding the conductive powder contained in resin layers 32 and 42, metal powder is preferred. Particularly preferred is at least one metal powder selected from the group consisting of Ag, Au, Ni, Cu, Pt, Pd, and Al. These metals have a face-centered cubic structure, similar to the metals constituting coatings 33 and 43, thus resulting in better crystallinity consistency between the metal powder exposed on the surfaces of resin layers 32 and 42 and the coatings 33 and 43 formed on the surfaces of resin layers 32 and 42. Therefore, it is expected to promote the oriented growth of coatings 33 and 43. Furthermore, it is also expected to improve the adhesion between coatings 33 and 43 and resin layers 32 and 42.

[0066] Thermosetting resins and UV-curable resins are preferred as resin materials contained in resin layers 32 and 42, with thermosetting resins exhibiting excellent heat resistance being particularly preferred. Suitable thermosetting resins include epoxy resins, phenolic resins, polyurethane resins, silicone resins, and polyimide resins. Epoxy resins are particularly preferred due to their excellent heat resistance, moisture resistance, and tight adhesion. One type of resin material can be used alone, or a mixture of two or more. A curing agent can also be included along with the thermosetting resin. When epoxy resin is used as the base resin, known compounds such as phenolic compounds, amines, acid anhydrides, and imidazoles can be used as curing agents.

[0067] This invention is particularly effective in small chip-type electronic components 10A. This is because, in small chip-type electronic components 10A, the contact area between the resin layers 32, 42 and the coatings 33, 43 is small, making tight adhesion between the resin layers 32, 42 and the coatings 33, 43 especially important. For example, this invention is applicable to electronic components 10A with a length of 0.6 mm or more and 1.0 mm or less, and a width of 0.3 mm or more and 0.5 mm or less (equivalent to 0603 to 1005 specifications).

[0068] Regarding the electronic component 10A suitable for application embodiment 1, in addition to the positive temperature coefficient thermistor described above, there are also chip-type ceramic electronic components such as negative temperature coefficient (or negative characteristic, NTC) thermistors, varistors, and capacitors. Furthermore, in these electronic components, the material constituting the ceramic body 20A is selected according to the desired characteristics.

[0069] With Figure 1 The manufacturing method of electronic component 10A in Embodiment 1 will be described using a positive temperature coefficient thermistor with the structure shown as an example.

[0070] (Production of ceramic body 20A)

[0071] The ceramic body 20A is formed, for example, from BaTiO3, CaTiO3, SrTiO3, CaZrO3, (BaSr)TiO3, Ba(ZrTi)O3 and (BiZn)Nb2O7.

[0072] exist Figure 1In the fabrication of the ceramic body 20A shown, firstly, predetermined amounts of ceramic raw materials such as BaCO3, TiO2, PbO, SrCO3, and CaCO3, semiconductor agents such as Sm2O3 and Er2O3, sintering aids such as SiO2, and characteristic modifiers such as MnO2 are weighed out to serve as the raw materials for the ceramic body 20A. The weighed raw materials, along with a portion of partially stabilized zirconia (PSZ) grinding media (hereinafter also referred to as PSZ balls) and pure water, are fed into a ball mill for wet mixing and grinding. The resulting mixture is then pre-sintered at a predetermined temperature (e.g., 1000℃~1200℃) to obtain pre-sintered powder.

[0073] After adding organic binder, dispersant, and pure water to the obtained pre-fired powder and mixing them, the mixture is dried to granulate it. A molded body is obtained by shaping the granules. The molded body is then degreased and debinded, and sintered at a predetermined temperature (1200℃~1400℃) and a predetermined atmosphere to obtain a ceramic body 20A.

[0074] (Formation of basal layers 31 and 41)

[0075] like Figure 1 As shown, a base layer 31, 41 covering the end faces 21A, 22A of the ceramic body 20A can also be formed after the ceramic body 20A is manufactured.

[0076] The base layers 31 and 41 are appropriately selected from materials that have ohmic properties similar to the ceramic body 20A. For example, they can be formed from metallic materials and oxides such as Ag, Zn, Cr, Ni, Cu, Ti, W, V, Au, and Al.

[0077] The substrate layers 31 and 41 are formed by various thin film formation methods (sputtering, vapor deposition, etc.), various printing methods, or impregnation methods. When the substrate layers 31 and 41 are formed using various printing or impregnation methods, the substrate layers 31 and 41 can be obtained by baking a conductive paste. The baking temperature of the conductive paste is, for example, 500°C to 900°C.

[0078] (Formation of resin layers 32 and 42)

[0079] Resin layers 32 and 42 containing conductive powder are formed at the ends of the ceramic body 20A.

[0080] The resin layers 32 and 42 are formed by curing a fluid resin electrode paste. The resin electrode paste contains conductive powder and resin raw materials. After the resin electrode paste is applied to the ends of the ceramic body 20 in a manner that covers the base layers 31 and 41, the resin raw materials in the resin electrode paste are cured.

[0081] The conductive powder contained in the resin electrode paste is the same conductive powder contained in the resin layers 32 and 42 of the electronic component 10A. That is, regarding the conductive powder contained in the resin electrode paste, metal powder is preferred, and at least one metal powder selected from the group consisting of Ag, Au, Ni, Cu, Pt, Pd and Al is particularly preferred.

[0082] The resin raw material contained in the resin electrode paste is a resin material that forms the resin layer 32, 42 of the electronic component 10A. Specifically, the resin raw material contained in the resin electrode paste is preferably a thermosetting resin before curing or a UV-curable resin before curing, and a thermosetting resin with excellent heat resistance is particularly preferred. For the thermosetting resin raw material, resin raw materials such as epoxy resin, phenolic resin, polyurethane resin, silicone resin, and polyimide resin are suitable, and epoxy resin raw materials are particularly preferred. Liquid resin raw materials are preferred. One or more resin raw materials can be used alone. It is preferable to use a curing agent together with the thermosetting resin raw material. When using epoxy resin as the base resin, known compounds such as phenolic, amine, acid anhydride, and imidazole compounds can be used as curing agents.

[0083] The preferred amount of conductive powder is 70 parts by weight or more and 90 parts by weight or less, relative to 10 parts by weight or more and 30 parts by weight of resin material.

[0084] (Formation of coatings 33 and 43)

[0085] Forming coatings (first coatings) 33 and 43 that are in direct contact with resin layers 32 and 42.

[0086] The coatings 33 and 43 are formed of a metal having a face-centered cubic structure. Preferably, as described above, the metal having a face-centered cubic structure is at least one selected from the group consisting of Ni, Au, Cu, Ag, Pt, Pd and Al.

[0087] Coatings 33 and 43 can be formed using known plating methods such as centrifugal force and electrolytic cell plating.

[0088] The plating bath can utilize known plating baths. When the metal having a face-centered cubic structure is Ni, for example, there are matte nickel baths, Watt's baths, sulfamic acid baths, Woodstrike baths, and perchlorate baths.

[0089] By appropriately controlling the plating conditions of coatings 33 and 43, it is possible to form coatings 33 and 43 with an F value of 0.20 or higher and 0.50 or lower, which serves as an indicator of orientation.

[0090] (Formation of the second coating 34 and 44)

[0091] It can also form a second coating 34, 44 covering the coatings 33, 43.

[0092] As described above, preferably, the second coating 34, 44 is at least one selected from the group consisting of Sn, Au, Cu and Pd.

[0093] The second coatings 34 and 44 are formed using known plating methods such as centrifugal force or electrolytic cell plating. The plating bath can be any known plating bath; for example, in the case of Sn plating, acidic baths and alkaline baths can be used. As an acidic bath, sulfuric acid baths, methanesulfonic acid baths, etc., can be used.

[0094] The manufacturing method of electronic component 10A of Embodiment 1 of the present invention has been described above using a positive temperature coefficient thermistor as an example. However, other electronic components can also be appropriately manufactured based on the description in this specification.

[0095] [Implementation Method 2]

[0096] The electronic component of Embodiment 2 differs from that of Embodiment 1 in that it has internal electrodes inside the ceramic body; otherwise, the structure is the same as that of Embodiment 1. The electronic component of Embodiment 2 will be described focusing on its differences from Embodiment 1.

[0097] Figure 2 This is a schematic cross-sectional view of the electronic component 10B according to Embodiment 2 of the present invention. Figure 2 An example of the electronic component 10B shown is a positive temperature coefficient thermistor with internal electrodes 71 and 72.

[0098] The electronic component 10B includes a ceramic body 20B and external electrodes disposed at the ends of the ceramic body 20B. In embodiment 2, the electronic component 10B also includes internal electrodes 71 and 72 inside the ceramic body 20B.

[0099] Furthermore, the structure of the external electrode is the same as in Embodiment 1, so the description is omitted.

[0100] The ceramic body 20B is composed of multiple ceramic layers 200. The multiple ceramic layers 200 and internal electrodes 71 and 72 are alternately stacked to form a laminate 80. The internal electrode 71 is exposed from one end face 21B of the ceramic body 20B, and the internal electrode 72 is exposed from the other end face 22B of the ceramic body 20B. The base layers 31 and 41 of the external electrodes 30 and 40 formed at the ends of the ceramic body 20B are in contact with the internal electrodes 71 and 72 exposed from the end faces 21B and 22B of the ceramic body 20B.

[0101] Regarding the electronic component 10B suitable for application embodiment 2, in addition to the positive temperature coefficient thermistor described above, there are also chip-type ceramic electronic components such as negative temperature coefficient (or negative characteristic, NTC) thermistors, varistors, and capacitors, and the electronic component has internal electrodes.

[0102] For example Figure 2 The manufacturing method of electronic component 10B in Embodiment 2 will be described using a positive temperature coefficient thermistor with internal electrodes 71 and 72 as an example.

[0103] (Making of ceramic body 20B)

[0104] In the fabrication of the ceramic body 20B, the pre-fired powder of the raw material is first prepared using the same steps as the ceramic body 20A in Embodiment 1, and then the pre-fired powder is used to form a laminate 80.

[0105] The ceramic body 20B is formed, for example, from BaTiO3, CaTiO3, SrTiO3, CaZrO3, (BaSr)TiO3, Ba(ZrTi)O3 and (BiZn)Nb2O7.

[0106] The materials used to form the internal electrodes 71 and 72 are not particularly limited as long as they are conductive. Examples include Ag, Cu, Pt, Ni, Al, Pd, and Au, with Ag, Cu, and Ni being particularly preferred.

[0107] First, predetermined amounts of ceramic raw materials such as BaCO3, TiO2, PbO, SrCO3, and CaCO3, semiconductor agents such as Sm2O3 and Er2O3, sintering aids such as SiO2, and property modifiers such as MnO2 are weighed out to serve as the raw materials for the ceramic body 20B. The weighed raw materials, along with a portion of partially stabilized zirconia (PSZ) grinding media (hereinafter also referred to as PSZ balls) and pure water, are fed into a ball mill for wet mixing and grinding. The resulting mixture is then pre-sintered at a predetermined temperature (e.g., 1000℃~1200℃) to obtain pre-sintered powder.

[0108] Organic binder is added to the obtained pre-fired powder, and the mixture is wet-mixed to form a slurry. This slurry is then shaped using a scraper method or similar technique to produce a ceramic green body of the desired thickness. Next, a conductive paste for internal electrodes is coated onto the surface of the ceramic green body to form an internal electrode pattern. The conductive paste for internal electrodes can be prepared, for example, by dispersing metal powder and organic binder in an organic solvent. The paste can be applied, for example, using screen printing. A predetermined number of ceramic green bodies with the internal electrode pattern formed are stacked, and then the upper and lower parts are clamped and pressed together using ceramic green bodies without the internal electrode pattern, thereby producing a laminate. After cutting the laminate to a predetermined size, degreasing and debinding treatments are performed. The laminate is then sintered at a predetermined temperature (1200°C to 1400°C) and a predetermined atmosphere to obtain a laminate 80 having a laminated structure including a ceramic body 20B (multiple ceramic layers 200) and internal electrodes 71 and 72.

[0109] (Formation of basal layers 31 and 41)

[0110] like Figure 2 As shown, alternatively, a base layer 31, 41 may be formed after the ceramic body 20B is fabricated, covering the end faces 21B, 22B (end faces of the laminate 80) of the ceramic body 20B. The base layer 31, 41 is electrically connected to the internal electrodes 71, 72 exposed from the end faces 21B, 22B of the ceramic body 20B.

[0111] The method of forming the base layers 31 and 41 is the same as in Embodiment 1, so the description is omitted.

[0112] (Formation of resin layers 32 and 42)

[0113] Resin layers 32 and 42 containing conductive powder are formed at the ends of the ceramic body 20B. The method for forming resin layers 32 and 42 is the same as in Embodiment 1, so the description is omitted.

[0114] (Formation of coatings 33 and 43)

[0115] A coating (first coating) 33 and 43 is formed that is in direct contact with the resin layers 32 and 42. The method for forming the coatings 33 and 43 is the same as in Embodiment 1, so the description is omitted.

[0116] (Formation of the second coating 34 and 44)

[0117] A second coating 34, 44 can also be formed covering the coatings 33, 43. The method for forming the second coating 34, 44 is the same as in Embodiment 1, so the description is omitted.

[0118] The manufacturing method of electronic component 10B according to Embodiment 2 of the present invention has been described above using a positive temperature coefficient thermistor with internal electrodes as an example. However, other electronic components with internal electrodes can also be appropriately manufactured based on the description in this specification.

[0119] Example

[0120] The present invention will be described in detail below through embodiments, but the present invention is not limited to these embodiments.

[0121] [Example 1]

[0122] (Preparation of the object to be plated)

[0123] Prepare the "coating object" for forming the coating.

[0124] A barium titanate semiconductor (hereinafter referred to as the "body") with dimensions of 0.53 mm (L) × 0.27 mm (W) × 0.27 mm (T) was prepared. A substrate layer for obtaining ohmic bonding with the body was formed on the WT side of the body by sputtering. The thickness of the substrate layer was set to 2.5 μm. Next, a resin layer comprising epoxy resin and silver powder was formed on the WT side to cover the substrate layer. This yielded a "plating object" comprising the body, the substrate layer, and the resin layer.

[0125] (Preparation of the first coating and the second coating)

[0126] A nickel plating film is formed on the surface of the resin layer of the object to be plated by electrolytic plating. A Watt's bath is used as the plating bath (pH 4.5, bath temperature 55°C, nickel sulfate 240 g / L–300 g / L, nickel chloride 45 g / L–50 g / L, boric acid 30 g / L–40 g / L). Additionally, metallic nickel is brought into contact with the anode electrode as the nickel source.

[0127] In drum plating, a metallic medium (conductive medium) is used to facilitate electrical conduction between the objects being plated, and resin balls are used to insulate the contents of the agitator drum.

[0128] First, the object to be plated and a conductive medium are placed inside the drum container. A cathode electrode is positioned inside the drum container in contact with the object to be plated and the conductive medium. Then, resin balls for stirring are added inside the drum container. Next, while the drum is rotated and oscillated, a current is passed between the anode and cathode at a predetermined current density for a predetermined time, thereby forming a nickel plating film of the desired thickness on the surface of the resin layer of the object to be plated. In Example 1, the average thickness of the nickel plating film is 6.74 μm.

[0129] Then, a tin plating film (second plating film) is formed on the surface of the nickel plating film by electrolytic deposition. Both acidic and alkaline baths are possible plating baths, but an acidic bath was chosen. A sulfuric acid bath or a methanesulfonic acid bath is used as the acidic bath. Additionally, metallic tin is brought into contact with the anode electrode as the tin source. The same operations as those for forming the nickel plating film were performed for other plating conditions. In Example 1, the average thickness of the tin plating film was 4.37 μm.

[0130] After the tin plating film is formed, the substrate is cleaned with pure water, dried in a constant temperature bath at 85°C for 20 minutes, and then dried at 120°C for 6 hours to prepare the plated sample (sample for measurement).

[0131] (Evaluation of the orientation of nickel plating)

[0132] To measure the orientation of the nickel coating, the tin coating on the measurement sample was removed by solvent dissolution. Furthermore, there were no particular limitations on the solvent as long as it could selectively dissolve tin, but in Example 1, a solvent with boron fluoride as the main component was used. Regarding the measurement sample after the tin coating was removed, micro-area X-ray diffraction measurements were performed on the exposed nickel coating using a Bruker AXS D8 DISCOVER. The two-dimensional X-ray diffraction image obtained using a two-dimensional detector was converted into a one-dimensional profile. The diffraction intensities I(111), I(200), and I(220) of the XRD diffraction peaks on the (111), (200), and (220) planes of the nickel coating were obtained using the values ​​of the diffraction intensity areas of the peaks in the obtained one-dimensional profile. The diffraction intensity values ​​were calculated as relative intensities with the maximum intensity I(111) set to 100.

[0133] The value of F, which represents the orientation of the (111) facet, was calculated using the following formulas (1) to (3). The value of F for the nickel coating in Example 1 was 47.7% (0.477).

[0134] F=(P-P0) / (1-P0)···(1)

[0135] In equation (1), P0 and P are obtained from equations (2) and (3) below.

[0136] P0=I0(111) / {I0(111)+I0(200)+I0(220)}···(2)

[0137] P=I(111) / {I(111)+I(200)+I(220)}···(3)

[0138] In equation (2), I0(111), I0(200) and I0(220) are the diffraction intensities of the (111), (200) and (220) planes obtained from powder X-ray diffraction data of nickel obtained from the ICDD database, respectively.

[0139] In Equation (3), I(111), I(200) and I(220) are the diffraction intensities of the (111), (200) and (220) planes obtained from XRD diffraction measurements of the nickel coating of the sample.

[0140] In addition, F, representing the orientation of the (200) plane, is obtained using equations (1-2), (2-2), and (3-2). (200) , and are shown in Table 1.

[0141] F (200) =(P (200) -P 0(200) ) / (1-P 0(200) (1-2)

[0142] In equation (1-2), P 0(200) and P (200) It can be obtained from the following equations (2-2) and (3-2).

[0143] P 0(200) =I0(200) / {I0(111)+I0(200)+I0(220)}···(2-2)

[0144] P (200) =I(200) / {I(111)+I(200)+I(220)}···(3-2)

[0145] The I0(111), I0(200), I0(220), I(111), I(200) and I(220) in equations (2-2) and (3-2) are the same as their definitions in equations (2) and (3).

[0146] Furthermore, using equations (1-3), (2-3), and (3-3), the orientation F representing the (220) plane is obtained. (220) , and are shown in Table 1.

[0147] F (220) =(P (220) -P 0(220) ) / (1-P 0(220) (1-3)

[0148] In equation (1-3), P 0(220) and P (220) It can be obtained from the following equations (2-3) and (3-3).

[0149] P 0(220) =I0(220) / {I0(111)+I0(200)+I0(220)}···(2-3)

[0150] P (220) =I(220) / {I(111)+I(200)+I(220)}···(3-3)

[0151] The I0(111), I0(200), I0(220), I(111), I(200) and I(220) in equations (2-3) and (3-3) are the same as their definitions in equations (2) and (3).

[0152] (Evaluation of fixation)

[0153] The adhesion of the nickel plating and resin layer was evaluated using the breaking strength and peeling mode at failure determined by the transverse shear strength test. The plated samples (for measurement) were mounted on a glass cloth substrate epoxy resin substrate (JIS C 6484:2005) of a copper-clad laminate. First, Sn-3Ag-0.5Cu solder paste was screen-printed onto the substrate at a thickness of 200 μm. The measurement samples were placed on the solder paste on the substrate with the WT side (the side with the plating) facing the substrate, and reflow soldered in a nitrogen atmosphere at a maximum temperature of 220°C at room temperature.

[0154] As a method for measuring adhesion strength, similar to JIS 62137-1-2:2010, a push-pull force gauge is used to push the mounted measurement sample from the side, and the strength of the measurement sample when it is peeled off from the substrate is measured.

[0155] In addition, after the measurement sample is peeled off from the substrate, the soldered part of the substrate (the part where the measurement sample is mounted) is observed using a digital microscope and a scanning electron microscope to determine whether the peeling mode is caused by ceramic damage (peeling due to damage to the main body) or by electrode damage (peeling due to damage to the interface between the nickel plating and the resin electrode, or peeling due to damage to the nickel plating itself).

[0156] Ten samples were used for measurement, and ten measurements of adhesion strength and observations of the peeling mode were performed. The average breaking strength was 7.95 N. In the peeling mode, the number of samples with ceramic failure and the number of samples with electrode failure were 10 and 0, respectively.

[0157] [Example 2]

[0158] Except for changing the plating conditions of the nickel plating film to make the F value of the nickel plating film 35.7% (0.357), the plating samples (samples for measurement) were prepared in the same manner as in Example 1, and the adhesion strength was evaluated. In addition, the average film thicknesses of the nickel plating film and the tin plating film were 5.32 μm and 3.16 μm, respectively.

[0159] The average breaking strength of the 10 measurement samples was 6.85 N. In the peeling mode, the number of measurement samples with ceramic failure and the number of measurement samples with electrode failure were 10 and 0, respectively.

[0160] [Example 3]

[0161] Except for changing the plating conditions of the nickel plating film to make the F value of the nickel plating film 25.8% (0.258), the plating samples (for measurement) were prepared in the same manner as in Example 1, and the adhesion strength was evaluated. Furthermore, the average film thicknesses of the nickel plating film and the tin plating film were 7.02 μm and 3.20 μm, respectively.

[0162] The average breaking strength of the 10 measurement samples was 7.43 N. In the peeling mode, the number of measurement samples with ceramic failure and the number of measurement samples with electrode failure were 10 and 0, respectively.

[0163] [Comparative Example 1]

[0164] Except for changing the plating conditions of the nickel coating to make the F value of the nickel coating 1.96% (0.0196), the plated samples (for measurement) were prepared in the same manner as in Example 1, and the adhesion strength was evaluated. Furthermore, the average film thicknesses of the nickel and tin coatings were 6.21 μm and 3.57 μm, respectively.

[0165] The average breaking strength of the 10 measurement samples was 4.53 N. In the peeling mode, the number of measurement samples with ceramic failure and the number of measurement samples with electrode failure were 3 and 7, respectively.

[0166] [Comparative Example 2]

[0167] Except for changing the plating conditions of the nickel coating to make the F value of the nickel coating 5.02% (0.0502), the plated samples (for measurement) were prepared in the same manner as in Example 1, and the adhesion strength was evaluated. Furthermore, the average film thicknesses of the nickel and tin coatings were 5.78 μm and 3.34 μm, respectively.

[0168] The average breaking strength of the 10 measurement samples was 3.97 N. In the peeling mode, the number of measurement samples with ceramic failure and the number of measurement samples with electrode failure were 3 and 7, respectively.

[0169] [Comparative Example 3]

[0170] Except for changing the plating conditions of the nickel coating to make the F value of the nickel coating -1.16% (-0.0116), the plated samples (for measurement) were prepared in the same manner as in Example 1, and the adhesion strength was evaluated. Furthermore, the average film thicknesses of the nickel and tin coatings were 5.19 μm and 3.37 μm, respectively.

[0171] The average breaking strength of the 10 measurement samples was 5.04 N. In the peeling mode, the number of measurement samples with ceramic breakage and the number of measurement samples with electrode breakage were 2 and 8, respectively.

[0172] [Comparative Example 4]

[0173] Except for changing the plating conditions of the nickel plating film to make the F value of the nickel plating film -10.9% (-0.109), the plating samples (samples for measurement) were prepared in the same manner as in Example 1, and the adhesion strength was evaluated. In addition, the average film thicknesses of the nickel plating film and the tin plating film were 5.54 μm and 3.22 μm, respectively.

[0174] The average breaking strength of the 10 measurement samples was 4.67 N. In the peeling mode, the number of measurement samples with ceramic breakage and the number of measurement samples with electrode breakage were 3 and 7, respectively.

[0175] Table 1 summarizes the results of Examples 1-3 and Comparative Examples 1-4. For the plated samples (measurement samples) with an F value representing the orientation of the (111) of the nickel plating film of 20.0% or more and 50.0% or less (0.20 or more and 0.50 or less), the destructive strength after welding was high. Furthermore, in the evaluation of the peeling mode, no samples exhibited electrode damage (peeling due to interface damage between the nickel plating film and the resin electrode, or peeling due to damage to the nickel plating film itself). This confirms that by increasing the orientation of the (111) of the nickel plating film to make the F value 0.20 or more and 0.50 or less, peeling of the nickel plating film can be suppressed, thereby improving the adhesion strength between the nickel plating film and the resin layer.

[0176] [Table 1]

[0177]

[0178] This application claims priority based on Japanese Patent Application No. 2021-141837, filed on August 31, 2021, the contents of which are incorporated herein by reference in their entirety.

[0179] Explanation of reference numerals in the attached figures

[0180] 10. Electronic component; 20. Ceramic body; 200. Ceramic layer; 21, 22. End face of ceramic body; 30, 40. External electrode; 31, 41. Substrate layer; 32, 42. Resin layer; 33, 43. Coating; 34, 44. Second coating; 71, 72. Internal electrode; 80. Laminated body.

Claims

1. An electronic component comprising a ceramic body and external electrodes disposed at an end of the ceramic body, wherein... The external electrode includes a resin layer containing conductive powder and a coating formed on the resin layer in direct contact with the resin layer. The coating is formed from a metal with a face-centered cubic structure. Regarding the coating, F, calculated using the following formula (1), is 0.20 or more and 0.50 or less: F=(P-P0) / (1-P0)···(1) In equation (1), P0 and P are obtained from the following equations (2) and (3): P0=I0(111) / {I0(111)+I0(200)+I0(220)}···(2) P=I(111) / {I(111)+I(200)+I(220)}···(3) In equation (2), I0(111), I0(200), and I0(220) are the diffraction intensities of the (111), (200), and (220) planes, respectively, obtained from known powder X-ray diffraction data of the metal constituting the coating. In equation (3), I(111), I(200) and I(220) are the diffraction intensities of the (111), (200) and (220) planes obtained from the X-ray diffraction pattern of the coating, respectively.

2. The electronic component according to claim 1, wherein, The metal having a face-centered cubic structure is at least one selected from the group consisting of Ni, Au, Cu, Ag, Pt, Pd and Al.

3. The electronic component according to claim 1 or 2, wherein, The conductive powder is a metal powder.

4. The electronic component according to any one of claims 1 to 3, wherein, The resin layer comprises a thermosetting resin.

5. The electronic component according to any one of claims 1 to 4, wherein, The external electrode also includes a second coating covering the coating.

6. The electronic component according to any one of claims 1 to 5, wherein, The electronic component has a length of 0.6 mm or more and 1.0 mm or less, and a width of 0.3 mm or more and 0.5 mm or less.

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