CN117897785A

CN117897785A - Electronic component

Info

Publication number: CN117897785A
Application number: CN202280059582.3A
Authority: CN
Inventors: 大岛知也; 星野悠太; 山田耕市; 佐佐木美希; 中野充
Original assignee: Murata Manufacturing Co Ltd
Current assignee: Murata Manufacturing Co Ltd
Priority date: 2021-11-09
Filing date: 2022-08-31
Publication date: 2024-04-16
Also published as: WO2023084878A1

Abstract

The present invention relates to an electronic component. The electronic component (10) is provided with a substrate (20), two first internal electrodes (41) as wiring lines, a glass film (50), and a first base electrode (61A). The first internal electrode (41) is located inside the base body (20). The glass film (50) covers the outer surface (21) of the substrate (20). The first base electrode (61A) is electrically connected to the first internal electrode (41) and partially covers the glass film (50). A part of the glass film (50) covered with the first base electrode (61A) is set as a covered part (AC), and a part which is not covered with the first base electrode (61A) and is more than 10 mu m away from the outer edge of the first base electrode (61A) is set as an uncovered part (AU). In this case, the thickness of the covered portion (AC) is greater than the thickness of the uncovered portion (AU).

Description

Electronic component

Technical Field

The present invention relates to an electronic component.

Background

The electronic component described in patent document 1 includes a substrate, an internal electrode, a glass film, and an external electrode. The internal electrode is located inside the substrate. The glass film covers the outer surface of the substrate. The external electrode partially covers the glass film. The external electrode is electrically connected to the internal electrode.

Patent document 1: japanese patent application laid-open No. 2010-027804

In the electronic component described in patent document 1, moisture and gas may permeate into the external electrode depending on the use environment. If the moisture or the like reaches the boundary between the external electrode and the glass film, it is difficult to discharge the moisture or the like into the atmosphere, and the moisture remains at the boundary between the external electrode and the glass film for a long period of time. Although the glass film is a material through which no water or the like passes, it is difficult to prevent moisture or the like from reaching the substrate if exposed to moisture or the like for a long period of time.

Disclosure of Invention

In order to solve the above problems, the present invention provides an electronic component comprising: a base; wiring, which is located in the base; a glass film covering an outer surface of the substrate; and a base electrode electrically connected to the wiring and partially covering the glass film, wherein when a portion of the glass film covered with the base electrode is a covered portion and a portion which is not covered with the base electrode and is spaced from an outer edge of the base electrode by more than 10 μm is an uncovered portion, a thickness of the covered portion is greater than a thickness of the uncovered portion.

According to the above structure, even if moisture or the like reaches the boundary between the glass film and the base electrode, the thickness of the glass film is large, so that the moisture or the like can be suppressed from reaching the base. In addition, even if moisture adheres to the non-coated portion of the glass film, the moisture volatilizes into the atmosphere. That is, the uncoated region is unlikely to be continuously exposed to moisture for a long period of time. Therefore, even if the thickness of the glass film at the non-coating portion is relatively small, it is possible to sufficiently prevent moisture or the like from reaching the substrate.

Can inhibit moisture from reaching the substrate.

Drawings

Fig. 1 is a perspective view of an electronic component.

Fig. 2 is a side view of an electronic component.

Fig. 3 is a cross-sectional view taken along line 3-3 of fig. 2.

Fig. 4 is an enlarged cross-sectional view of the wrapping.

Fig. 5 is an enlarged cross-sectional view of the non-covered region.

Fig. 6 is an enlarged cross-sectional view of the boundary portion.

Fig. 7 is an explanatory diagram for explaining a method of manufacturing an electronic component.

Fig. 8 is an explanatory diagram for explaining a method of manufacturing an electronic component.

Fig. 9 is an explanatory diagram for explaining a method of manufacturing an electronic component.

Fig. 10 is an explanatory diagram for explaining a method of manufacturing an electronic component.

Fig. 11 is an explanatory diagram for explaining a method of manufacturing an electronic component.

Fig. 12 is an explanatory diagram for explaining a method of manufacturing an electronic component.

Fig. 13 is an enlarged cross-sectional view of a part covered with an electronic component according to a modification.

Detailed Description

One embodiment of an electronic component

An embodiment of the electronic component will be described below with reference to the drawings. In addition, the drawings may show components in an enlarged scale for easy understanding. The dimensional ratios of the constituent elements may be different from the actual ones or from those in other drawings.

(regarding the monolithic structure)

As shown in fig. 1, the electronic component 10 is, for example, a surface-mounted negative-characteristic thermistor component mounted on a circuit board or the like. Further, the negative characteristic thermistor member has a characteristic that the resistance value decreases when the temperature increases.

The electronic component 10 includes a base 20. The base 20 has a substantially quadrangular prism shape and has a central axis CA. Hereinafter, the axis extending along the central axis CA is referred to as a first axis X. One of axes orthogonal to the first axis X is set as a second axis Y. The axis orthogonal to the first axis X and the second axis Y is set as a third axis Z. One of the directions along the first axis X is defined as a first positive direction X1, and the direction opposite to the first positive direction X1 among the directions along the first axis X is defined as a first negative direction X2. One of the directions along the second axis Y is defined as a second positive direction Y1, and the direction opposite to the second positive direction Y1 among the directions along the second axis Y is defined as a second negative direction Y2. One of the directions along the third axis Z is defined as a third positive direction Z1, and the direction opposite to the third positive direction Z1 among the directions along the third axis Z is defined as a third negative direction Z2.

The outer surface 21 of the base 20 has 6 planar flats 22. The term "surface" of the substrate 20 as used herein refers to a surface that can be observed as a surface when the entire substrate 20 is observed. That is, for example, even if there are minute irregularities or steps which are not known without magnifying a part of the substrate 20 with a microscope or the like, the substrate is expressed as a flat surface or a curved surface. The 6 planes 22 extend in mutually different orientations. The 6 planes 22 are roughly divided into a first end face 22A facing the first positive direction X1, a second end face 22B facing the first negative direction X2, and four side faces 22C. The four side surfaces 22C are a surface facing the third positive direction Z1, a surface facing the third negative direction Z2, a surface facing the second positive direction Y1, and a surface facing the second negative direction Y2, respectively.

The outer surface 21 of the base body 20 has 12 boundary surfaces 23. The boundary surface 23 comprises a curved surface present at the boundary of adjacent planes 22 with each other. That is, the boundary surface 23 includes, for example, a curved surface formed by chamfering the corners forming the adjacent flat surfaces 22.

The outer surface 21 of the base 20 has 8 spherical corner faces 24. The corner surface 24 is a boundary portion of the adjacent three flat surfaces 22 with each other. In other words, the corner surface 24 comprises a curved surface at the point where the three boundary surfaces 23 meet. That is, the corner surface 24 includes, for example, a curved surface formed by chamfering the corners formed by the adjacent three flat surfaces 22. In fig. 1 and 2, the surface of a glass film 50 described later is regarded as the same as the outer surface 21 of the substrate 20 and is given the same reference numerals.

As shown in fig. 2, the dimension of the base 20 along the first axis X is larger than the dimension along the third axis Z. In addition, as shown in fig. 1, the dimension of the base 20 along the first axis X is larger than the dimension along the second axis Y. The material of the base 20 is a semiconductor. Specifically, the material of the base 20 is a ceramic obtained by firing a metal oxide containing at least one of Mn, fe, ni, co, ti, ba, al and Zn.

As shown in fig. 3, the electronic component 10 includes two first internal electrodes 41 and two second internal electrodes 42 as wirings. The first internal electrode 41 and the second internal electrode 42 are embedded in the substrate 20.

The material of the first internal electrode 41 is a conductive material. For example, the material of the first internal electrode 41 is palladium. The material of the second internal electrode 42 is the same as that of the first internal electrode 41.

The first internal electrode 41 has a rectangular plate shape. The main surface of the first internal electrode 41 is orthogonal to the second axis Y. The second internal electrode 42 has a rectangular plate shape similar to the first internal electrode 41. The main surface of the second internal electrode 42 is orthogonal to the second axis Y, similarly to the first internal electrode 41.

The dimension of the first internal electrode 41 along the first axis X is smaller than the dimension of the base 20 along the first axis X. As shown in fig. 1, the dimension of the first internal electrode 41 along the third axis Z is approximately two thirds of the dimension of the base 20 along the third axis Z. The dimensions of the second internal electrodes 42 in each direction are the same as those of the first internal electrodes 41.

As shown in fig. 3, the first internal electrode 41 and the second internal electrode 42 are located at mutually different positions in the direction along the second axis Y. That is, the first internal electrode 41, the second internal electrode 42, the first internal electrode 41, and the second internal electrode 42 are arranged in this order from the side surface 22C facing the second positive direction Y1 toward the second negative direction Y2. In the present embodiment, the distances between the internal electrodes in the direction along the second axis Y are equal.

As shown in fig. 1, both the two first internal electrodes 41 and the two second internal electrodes 42 are located at the center of the base 20 in the direction along the third axis Z. On the other hand, as shown in fig. 3, the first internal electrode 41 is located near the first positive direction X1. The second internal electrode 42 is located near the first negative direction X2.

Specifically, the end of the first internal electrode 41 on the first positive direction X1 side coincides with the end of the base 20 on the first positive direction X1 side. The end of the first internal electrode 41 on the first negative direction X2 side is located inside the base 20, and does not reach the end of the base 20 on the first negative direction X2 side. On the other hand, the end of the second internal electrode 42 on the first negative direction X2 side coincides with the end of the base 20 on the first negative direction X2 side. The end of the second internal electrode 42 on the first positive direction X1 side is located inside the base 20, and does not reach the end of the base 20 on the first positive direction X1 side.

The electronic component 10 includes a glass film 50. The glass film 50 covers the outer surface 21 of the substrate 20. In the present embodiment, the glass film 50 covers all areas of the outer surface 21 of the substrate 20. The glass film 50 is made of glass. In this embodiment, the glass is composed of silica.

As shown in fig. 3, the electronic component 10 includes a first external electrode 61 and a second external electrode 62. The first external electrode 61 has a first base electrode 61A and a first metal layer 61B. The first base electrode 61A is laminated on a portion including the first end face 22A in the outer surface 21 of the base 20 from above the glass film 50. That is, the first base electrode 61A partially covers the outer surface 21 of the base 20. Specifically, the first base electrode 61A is a 5-sided electrode covering a portion of the first end surface 22A and the first positive direction X1 side of the four side surfaces 22C of the base 20. In the present embodiment, the material of the first base electrode 61A is silver or glass. In addition, the first base electrode 61A is a sintered body. Accordingly, as shown in fig. 4, the first base electrode 61A includes a plurality of voids P as hollows. A part of the glass G in the material constituting the first base electrode 61A is present in the pores P, but at least a part of the pores P is in a state where no hollow such as the glass G is present. Further, a part of the pores P in the first base electrode 61A is in contact with the glass film 50.

As shown in fig. 3, the first metal layer 61B covers the first base electrode 61A from the outside. Therefore, the first metal layer 61B is laminated on the first base electrode 61A. In addition, a portion of the first metal layer 61B protrudes from the first base electrode 61A. That is, a part of the outer edge of the first metal layer 61B directly covers the glass film 50 without sandwiching the first base electrode 61A. Although not shown, the first metal layer 61B has a two-layer structure including a nickel layer and a tin layer in this order from the first base electrode 61A side.

The second external electrode 62 has a second base electrode 62A and a second metal layer 62B. The second base electrode 62A is laminated on a portion including the second end face 22B in the outer surface 21 of the base 20 from above the glass film 50. That is, the second base electrode 62A partially covers the outer surface 21 of the base 20. Specifically, the second base electrode 62A is a 5-sided electrode covering the second end surface 22B of the base 20 and a part of the four side surfaces 22C on the first negative direction X2 side. In the present embodiment, the material of the second base electrode 62A is silver and glass, which is the same as that of the first external electrode 61. The second base electrode 62A is a sintered body, similar to the first base electrode 61A. Therefore, although not shown, the second base electrode 62A includes a plurality of voids P as cavities. A part of the glass in the material constituting the second base electrode 62A is present in the pores P, but at least a part of the pores P is in a state where no hollow such as glass is present. Further, a part of the pores P in the second base electrode 62A is in contact with the glass film 50.

The second metal layer 62B covers the second base electrode 62A from the outside. Therefore, the second metal layer 62B is laminated on the second base electrode 62A. In addition, a portion of the second metal layer 62B protrudes from the second base electrode 62A. That is, a part of the outer edge of the second metal layer 62B directly covers the glass film 50 without interposing the second base electrode 62A. Although not shown, the second metal layer 62B has a two-layer structure including a nickel layer and a tin layer in this order from the second base electrode 62A side, similarly to the first metal layer 61B.

The second external electrode 62 does not reach the first external electrode 61 on the side surface 22C, but is disposed apart from the first external electrode 61 in the direction along the first axis X. Then, the first external electrode 61 and the second external electrode 62 are not laminated on the side surface 22C of the base 20 at the central portion in the direction of the first axis X, and the glass film 50 is exposed. In fig. 1 to 3, the first external electrode 61 and the second external electrode 62 are shown by two-dot chain lines.

As shown in fig. 3, the first external electrode 61 and the first internal electrode 41 are connected at their ends on the first positive direction X1 side via the first through-hole 71 penetrating the glass film 50. Accordingly, the first external electrode 61 is electrically connected to the first internal electrode 41. Further, although the details will be described later, the first through-hole 71 is formed by extending palladium constituting the first internal electrode 41 toward the first external electrode 61 during the manufacturing process of the electronic component 10.

The second external electrode 62 and the end portion of the second internal electrode 42 on the first negative direction X2 side are connected via the second through portion 72 penetrating the glass film 50. Accordingly, the second external electrode 62 is electrically connected to the second internal electrode 42. The second through-hole 72 is also formed by extending palladium constituting the first internal electrode 41 toward the second external electrode 62 during the manufacturing process of the electronic component 10, similarly to the first through-hole 71. In fig. 3, the first internal electrode 41 and the first through-hole portion 71 are illustrated as different members having boundaries, but there is actually no clear boundary between the two. The same applies to the second through portion 72 at this point. In fig. 1, the first through portion 71 is not illustrated.

(regarding the thickness of the glass film)

As shown in fig. 3, the glass film 50 has a covered portion AC, an uncovered portion AU, and a boundary portion AB.

As shown in fig. 4, the coating portion AC is a portion of the glass film 50 covered with the first base electrode 61A or the second base electrode 62A. In fig. 4, a coating portion AC covered with the first base electrode 61A is illustrated. The thickness of the coating portion AC is calculated as follows. First, a cross section perpendicular to the first end surface 22A and the one side surface 22C is photographed by an electron microscope. Next, for the captured image, the range of the coating portion AC in the direction along the outer surface 21 is determined. Within this range, the cross-sectional area of the glass film 50 is calculated by image processing for a measurement range of at least 5 μm or more. Then, the thickness of the coating portion AC is calculated by dividing the cross-sectional area of the glass film 50 in the calculated measurement range by the length as the measurement range. That is, the thickness of the coating portion AC is the average thickness in the measurement range.

As shown in fig. 5, the non-covered region AU is a region of the glass film 50 that is not covered with any one of the first base electrode 61A and the second base electrode 62A and is spaced apart from both the outer edge of the first base electrode 61A and the outer edge of the second base electrode 62A by more than 10 μm. The thickness of the non-covered region AU is calculated as follows. First, a cross section orthogonal to the one side surface 22C and parallel to the first axis X is photographed by an electron microscope. Next, regarding the captured image, the range of the non-covered region AU in the direction along the outer surface 21 is determined. Within this range, the cross-sectional area of the glass film 50 is calculated by image processing for the measurement range of the same length as when the thickness of the coating portion AC is measured. The measurement range of the non-covered region AU is positioned such that the center of the non-covered region AU in the direction of the first axis X becomes the center of the measurement range of the non-covered region AU in the direction of the first axis X. Then, the thickness of the non-covered region AU is calculated by dividing the cross-sectional area of the glass film 50 in the calculated measurement range by the length as the measurement range. That is, the thickness of the non-covered region AU is the average thickness in the measurement range.

In addition, the boundary portion AB exists in the vicinity of the first base electrode 61A and in the vicinity of the second base electrode 62A. That is, as shown in fig. 6, one of the two boundary portions AB is a portion of the glass film 50 that is not covered with the first base electrode 61A and is not more than 10 μm apart from the outer edge of the first base electrode 61A. In addition, one of the two boundary portions AB is a portion of the glass film 50 that is not covered with the second base electrode 62A and is not more than 10 μm apart from the outer edge of the second base electrode 62A. The thickness of the boundary portion AB is calculated as follows. First, a cross section orthogonal to the one side surface 22C and parallel to the first axis X is photographed by an electron microscope. Next, regarding the captured image, the range of the boundary portion AB in the direction along the outer surface 21 is determined. This range was 10. Mu.m. Within this 10 μm range, the cross-sectional area of the glass film 50 was calculated by image processing. Then, the thickness of the boundary portion AB was calculated by dividing the cross-sectional area of the glass film 50 in the calculated range by the length of the measurement range, that is, 10 μm. That is, the thickness of the boundary portion AB is an average thickness in the whole boundary portion AB.

As shown in fig. 6, the thickness of the covered portion AC is larger than the thickness of the uncovered portion AU. In addition, the thickness of the boundary portion AB is larger than the thickness of the coating portion AC. That is, the thickness of the coating portion AC is smaller than the thickness of the boundary portion AB. The thickness of the non-coating portion AU is 30nm or more. The thickness of the boundary portion AB is 1000nm or less.

The thickness of the coated portion AC has a larger coefficient of variation than the thickness of the uncoated portion AU. That is, in the covered region AC, the surface is uneven compared with the uncovered region AU.

The coefficient of variation of the thickness of each portion was calculated as follows. First, the maximum value of the thickness of the glass film 50 at 5 is measured within the measurement range. Next, within this measurement range, the minimum value of the glass film 50 at 5 is measured. Next, the average value and standard deviation of the thicknesses at the total 10 are calculated. The coefficient of variation is then calculated by dividing the standard deviation by the average of the thicknesses at 10.

(method for manufacturing electronic component)

Next, a method of manufacturing the electronic component 10 will be described.

As shown in fig. 7, the method for manufacturing the electronic component 10 includes a laminate preparation step S11, a rounding step S12, a solvent charging step S13, a catalyst charging step S14, a base charging step S15, a polymer charging step S16, and a metal alkoxide charging step S17. The method for manufacturing the electronic component 10 further includes a film forming step S18, a drying step S19, a conductor coating step S20, a curing step S21, and a plating step S22.

First, when forming the base 20, in the laminate preparation step S11, a laminate is prepared as the base 20 without the boundary surface 23 and the corner surface 24. That is, the laminate is in a rounded state and has a rectangular parallelepiped shape having 6 flat surfaces 22. For example, first, a plurality of ceramic sheets serving as the base 20 are prepared. The sheet is in the shape of a thin plate. The conductive paste to be the first internal electrode 41 is laminated on the sheet. The laminated paste is laminated with a ceramic sheet serving as the base 20. A conductive paste to be the second internal electrode 42 is laminated on the sheet. Thus, the ceramic sheet and the conductive paste are laminated. Then, the laminate is cut to a predetermined size to form an unfired laminate. Then, the unfired laminate is fired at a high temperature to prepare a laminate.

Next, a chamfering step S12 is performed. In the chamfering step S12, a boundary surface 23 and a corner surface 24 are formed with respect to the laminate prepared in the laminate preparation step S11. For example, the corners of the laminate are rounded by roll grinding, thereby forming boundary surfaces 23 having curved surfaces and corner surfaces 24 having curved surfaces. Thereby, the base 20 is formed.

Next, a solvent charging step S13 is performed. As shown in fig. 8, in the solvent charging step S13, 2-propanol is charged into the reaction vessel 81 as the solvent 82.

Next, as shown in fig. 7, a catalyst loading step S14 is performed. As shown in fig. 9, in the catalyst charging step S14, first, stirring of the solvent 82 in the reaction vessel 81 is started. Then, ammonia water is introduced into the reaction vessel 81 as an aqueous solution 83 containing a catalyst. The catalyst in the present embodiment is hydroxide ion, and functions as a catalyst for promoting hydrolysis of the metal alkoxide 85 described later.

Next, as shown in fig. 7, a substrate loading step S15 is performed. As shown in fig. 10, in the substrate loading step S15, the substrates 20 formed in advance in the rounding step S12 as described above are loaded into the reaction vessel 81.

Next, as shown in fig. 7, a polymer charging step S16 is performed. As shown in fig. 11, in the polymer charging step S16, polyvinylpyrrolidone is charged into the reaction vessel 81 as the polymer 84. Thus, the polymer 84 charged into the reaction vessel 81 is adsorbed on the outer surface 21 of the substrate 20.

Next, as shown in fig. 7, a metal alkoxide charging step S17 is performed. As shown in fig. 12, in the metal alkoxide charging step S17, liquid tetraethylorthosilicate is charged into the reaction vessel 81 as the metal alkoxide 85. In addition, tetraethyl orthosilicate is sometimes also referred to as tetraethoxysilane. In the present embodiment, the amount of the metal alkoxide 85 charged in the metal alkoxide charging step S17 is calculated based on the area of the outer surface 21 of the substrate 20 charged in the substrate charging step S15. Specifically, the number of substrates 20 is calculated by multiplying the amount of the metal alkoxide 85 of each of the substrates 20 required to form the glass film 50 covering the outer surface 21 of the substrate 20.

Next, as shown in fig. 7, a film forming step S18 is performed. In the film forming step S18, the solvent 82 is stirred in the solvent charging step S13 for a predetermined period of time after the metal alkoxide 85 is charged into the reaction vessel 81 in the metal alkoxide charging step S17. In the film forming step S18, the glass film 50 is formed by a liquid phase reaction in the reaction vessel 81.

Next, a drying step S19 is performed. In the drying step S19, after stirring is continued for a predetermined time in the film forming step S18, the substrate 20 is taken out of the reaction vessel 81 and dried. Thus, the sol-like glass film 50 is dried to form a gel-like glass film 50.

Next, a conductor coating step S20 is performed. In the conductor coating step S20, a conductor paste is coated on both of a portion including a portion covering the first end face 22A of the base 20 and a portion including a portion covering the second end face 22B of the base 20, on the surface of the glass film 50. Specifically, the conductor paste is applied as a glass film 50 covering the entire area of the first end face 22A and a part of the four side faces 22C. In addition, the conductor paste is applied as a glass film 50 covering the entire area of the second end face 22B and a part of the four side faces 22C.

Next, a curing step S21 is performed. Specifically, the curing step S21 heats the glass film 50 and the substrate 20 coated with the conductor paste. By this, the water and the polymer 84 are vaporized from the gel-like glass film 50, and as shown in fig. 3, the glass film 50 covering the outer surface 21 of the substrate 20 is fired and cured. At the same time, the first base electrode 61A and the second base electrode 62A are formed by firing the conductor paste applied in the conductor application step S20. Further, by heating the conductor paste, a low-melting point substance among materials constituting glass in the conductor paste diffuses toward the gel-like glass film 50 side. Thus, the thickness of the portion of the glass film 50 covered with the first base electrode 61A and the portion covered with the second base electrode 62A is larger than the uncoated portion AU. In addition, the low-melting point substance of the glass in the conductor paste overflows from the boundary between the glass film 50 and the conductor paste and reaches the boundary portion AB. Since the boundary portion AB is not covered with the first base electrode 61A, the thickness of the boundary portion AB containing the diffused low-melting point substance becomes large, and is fired in this state. As a result, the thickness of the boundary portion AB is larger than the thickness of the coating portion AC. In this way, the base electrode forming step is constituted by the conductor coating step S20 and the curing step S21. As described above, in the present embodiment, the curing step S21 serves not only as a step of curing the glass film 50 but also as a step of sintering the base electrode.

In the present embodiment, during the heating in the curing step S21, palladium contained in the first internal electrode 41 side is attracted to the first base electrode 61A side containing silver due to the rankine effect generated by the difference in diffusion rates between the first internal electrode 41 and the first base electrode 61A. Thus, the first through portion 71 extends from the first internal electrode 41 toward the first base electrode 61A so as to penetrate the glass film 50, and the first internal electrode 41 is connected to the first base electrode 61A. The same applies to the second through-hole 72 connecting the second internal electrode 42 and the second base electrode 62A.

Next, a plating step S22 is performed. Electroplating is performed on the portions of the first base electrode 61A and the second base electrode 62A. Specifically, barrel plating is performed. In barrel plating, a substrate 20 provided with a first base electrode 61A and a second base electrode 62A and a medium are placed in a drum and stirred. Thereby, the first metal layer 61B is formed on the surface of the first base electrode 61A. At the same time, the medium collides with the non-clad portion AU in the glass film 50, whereby the surface of the glass film 50 at the non-clad portion AU is scraped off. Therefore, the thickness of the non-covered region AU becomes small. The irregularities on the surface of the uncoated portion AU are flatter than those before barrel plating. On the other hand, the medium does not collide with the boundary portion AB in the glass film 50 due to interference of the first metal layer 61B. Therefore, the thickness of the boundary portion AB is larger than that of the non-covered portion AU. In addition, the thickness of the boundary portion AB is maintained to be greater than the thickness of the coating portion AC. In addition, a second metal layer 62B is formed on the surface of the second base electrode 62A in the same manner. Although not shown, the first metal layer 61B and the second metal layer 62B are formed into a two-layer structure by plating with both nickel and tin. Thus, the electronic component 10 is formed.

(action and Effect of the embodiment)

(1) In the above embodiment, the first base electrode 61A and the second base electrode 62A have innumerable pores P. In addition, fine cracks may be generated in the first base electrode 61A and the second base electrode 62A during and after the manufacturing of the electronic component 10. Therefore, depending on the environment in which the electronic component 10 is used, moisture adhering to the electronic component 10 may infiltrate into the pores P and the inside of the cracks. If the pores P and the cracks reach the glass film 50, the moisture existing in the pores P and the cracks contacts the glass film 50. Further, if a fine crack is generated in the glass film 50, moisture may reach the substrate 20 through the crack.

According to the above embodiment, the thickness of the covered portion AC is greater than the thickness of the uncovered portion AU. Therefore, for example, even if moisture or the like reaches the boundary between the glass film 50 and each base electrode according to the use environment of the electronic component 10, the thickness of the coating portion AC in the glass film 50 is large, and thus the moisture or the like can be suppressed from reaching the base 20. Further, since the first external electrode 61 is not covered at the non-covered portion AU of the glass film 50, moisture is volatilized into the atmosphere even if it adheres. That is, the uncoated region AU is unlikely to be continuously exposed to moisture for a long period of time. Therefore, even if the thickness of the non-coating portion AU in the glass film 50 is relatively small, moisture and the like can be sufficiently prevented from reaching the base 20.

(2) According to the above embodiment, the coefficient of variation of the thickness of the covered portion AC is larger than the coefficient of variation of the thickness of the uncovered portion AU. That is, the coated portion AC of the glass film 50 has a rugged surface compared with the uncoated portion AU. Therefore, the adhesion between the coating portion AC and each base electrode can be improved. As a result, moisture and the like are easily prevented from accumulating between each base electrode and the glass film 50.

(3) According to the above embodiment, each base electrode comprises glass. Therefore, as in the manufacturing method of the embodiment, when the glass in the conductor paste is melted after each base electrode is formed, the low-melting point substance of the glass diffuses into the glass film 50. This makes it easy to form the thickness of the coating portion AC large.

(4) According to the above embodiment, each base electrode is a sintered body containing silver. The sintered body has a plurality of voids P therein. Therefore, moisture and gas are easily accumulated in the pores P in the sintered body, that is, the base electrode. Therefore, the possibility of moisture accumulating at the boundary between the base electrode and the glass film 50 increases. On the premise of such a structure of the base electrode, it is preferable to adopt a structure in which the thickness of the covered region AC is larger than the thickness of the uncovered region AU, in order to effectively suppress moisture or the like from reaching the base 20.

(5) According to the above embodiment, the outer surface 21 of the base 20 is entirely covered with the glass film 50, the first base electrode 61A, or the second base electrode 62A. Therefore, moisture and gas can be prevented from entering the substrate 20 from outside the electronic component 10 in all regions of the outer surface 21.

(6) In the above embodiment, a part of the outer edge of the first metal layer 61B directly covers the glass film 50. The first metal layer 61B has lower adhesion to the glass film 50 than the first base electrode 61A including glass. Therefore, moisture may be impregnated between the outer edge of the first metal layer 61B and the glass film 50, and the glass film 50 may be exposed to moisture for a long period of time. According to the above embodiment, the thickness of the boundary portion AB, which is a portion of the glass film 50 that is highly likely to be directly covered by the first metal layer 61B, is larger than the thickness of the non-covered portion AU. Since the thickness of the boundary portion AB is large, even if moisture is impregnated between the outer edge of the first metal layer 61B and the glass film 50, the moisture can be prevented from reaching the substrate 20. The first metal layer 61B is described as an example, but the same applies to the second metal layer 62B.

(7) According to the above embodiment, the thickness of the boundary portion AB is larger than the thickness of the coating portion AC. That is, the thickness of the coating portion AC is smaller than the thickness of the boundary portion AB. The thickness of the glass film 50 covered with each base electrode is reduced, whereby the electronic component 10 can be prevented from becoming larger as a whole.

(8) According to the above embodiment, in the glass film 50, the thickness of the non-clad portion AU having the smallest thickness among the clad portion AC, the boundary portion AB, and the non-clad portion AU is 30nm or more. Therefore, at the portion not covered by the first base electrode 61A, a sufficient thickness can be ensured to protect the base 20.

(9) According to the above embodiment, in the glass film 50, the thickness of the boundary portion AB having the largest thickness among the clad portion AC, the boundary portion AB, and the unclad portion AU is 1000nm or less. Therefore, the electronic component 10 as a whole can be prevented from becoming large due to the excessive thickness of the boundary portion AB.

< other embodiments >

The above embodiment can be modified as follows. The above-described embodiments and the following modifications can be combined and implemented within a range that is not technically contradictory.

In the above embodiment, the electronic component 10 is not limited to the negative-characteristic thermistor component. For example, if some wiring is provided in the base 20, a thermistor component other than the negative characteristic may be used, or a multilayer capacitor component or an inductor component may be used.

The shape of the base 20 is not limited to the example of the embodiment described above. For example, the base 20 may have a polygonal column shape other than a quadrangular column shape having the central axis CA. The base 20 may be a core of a wound inductor component. For example, the core may be in the shape of a so-called drum core. Specifically, the core may have a columnar roll core portion and flange portions provided at respective end portions of the roll core portion.

The material of the base 20 is not limited to the example of the embodiment. For example, the material of the base 20 may be a composite of a resin and a metal powder.

The outer surface 21 of the base 20 may not have the boundary surface 23 and the corner surface 24. For example, when the boundary between adjacent flat surfaces 22 in the outer surface 21 of the base 20 is not in a chamfered shape, there is no curved surface at the boundary. Therefore, in this case, the boundary surface 23 and the corner surface 24 may not exist.

In the outer surface 21 of the substrate 20, there may be a portion not covered with any one of the glass film 50, the first base electrode 61A, and the second base electrode 62A. For example, a part of the side surface 22C may be covered with an insulating resin or the like different from the glass film 50 instead of the glass film 50. Further, as such an insulating resin, a colored resin for optically recognizing the orientation of the substrate 20, or the like is exemplified.

In the above embodiment, the first internal electrode 41 and the second internal electrode 42 may be formed in such a shape as to ensure electrical conduction with the corresponding first external electrode 61 and second external electrode 62. The number of the first internal electrodes 41 and the second internal electrodes 42 is not limited, and may be one or three or more.

The structure of the first external electrode 61 is not limited to the example of the embodiment described above, as long as it has the first base electrode 61A. For example, the first external electrode 61 may be constituted by only the first base electrode 61A, and the first metal layer 61B may not be constituted by two layers. The same applies to the second external electrode 62.

The material of the first base electrode 61A is not limited to the example of the embodiment described above. For example, the material of the first base electrode 61A may be copper or gold. The material of the first base electrode 61A may not include glass. For example, the material of the first base electrode 61A may be composed of only metal.

The first base electrode 61A may not be a sintered body. For example, the first base electrode 61A may be a single crystal.

In the above embodiment, the combination of the materials of the first internal electrode 41 and the first base electrode 61A is not limited to the combination of palladium and silver. For example, copper and nickel, copper and silver, silver and gold, nickel and cobalt, or a combination of nickel and gold may be used. For example, one of the two may be silver, and the other may be a combination of silver and palladium. For example, one may be palladium, and the other may be a combination of silver and palladium, or one may be copper, and the other may be a combination of silver and palladium. For example, one may be gold, and the other may be a combination of silver and palladium.

Further, according to the combination of the first internal electrode 41 and the first base electrode 61A, the kemel effect may not be obtained in some cases. In this case, for example, the first end surface 22A side of the substrate 20 may be polished before the external electrode forming step, and a part of the glass film 50 may be physically removed to expose the first internal electrode 41. After that, the first internal electrode 41 and the first base electrode 61A can be connected by performing the base electrode forming step. For example, after the first base electrode 61A is formed, the glass film 50 may be formed on the surface including the first base electrode 61A, and the glass film 50 covering the surface of the first base electrode 61A may be removed. In this regard, the same applies to the combination of the materials of the second internal electrode 42 and the second base electrode 62A.

The arrangement position of the first external electrode 61 is not limited to the example of the embodiment described above. For example, the first external electrode 61 may be disposed only on the first end surface 22A and the one side surface 22C. The same applies to the second external electrode 62.

Regarding the glass film 50, at least one of the thickness of the coating portion AC on the first external electrode 61 side and the thickness of the coating portion AC on the second external electrode 62 side may be larger than the thickness of the non-coating portion AU.

Regarding the thickness of the glass film 50, the thickness of the coating portion AC may be larger than the thickness of the non-coating portion AU, and the thickness of the boundary portion AB may be equal to or smaller than the thickness of the coating portion AC. The thickness of the boundary portion AB may be equal to or less than the thickness of the non-covered portion AU. The thickness of the boundary portion AB may be larger than 1000nm, and the thickness of the uncoated portion AU may be smaller than 30nm.

The coefficient of variation in the thickness of the covered region AC may be equal to or less than the coefficient of variation in the thickness of the uncovered region AU. For example, in the case where the first base electrode 61A is formed by sticking a metal foil, the surface of the coating portion AC in the glass film 50 may not be uneven due to diffusion of the low-melting-point substance. In addition, in the case where the first metal layer 61B is plated without using a roller, the surface of the non-covered portion AU is not planarized by the roller. Even in these cases, the coefficient of variation of the thickness of the covered portion AC may be equal to or less than the coefficient of variation of the thickness of the uncovered portion AU, as long as the thickness of the covered portion AC is greater than the thickness of the uncovered portion AU.

In addition, for example, in the electronic component 110 of the modification shown in fig. 13, the glass film 150 has a pure glass layer 151 and a diffusion layer 152. A pure glass layer 151 is laminated on the outer surface 21 at the clad part AC. Here, the material of the first base electrode 61A is silver and glass. The glass of the first base electrode 61A contains alkali metal and alkaline earth metal as additives. On the other hand, the pure glass layer 151 does not contain a metal component of the first base electrode 61A. Therefore, in this modification, the pure glass layer 151 does not contain silver, alkali metal, and alkaline earth metal. Specifically, the pure glass layer 151 is composed of only silica. The minimum thickness of the coating portion AC in the glass film 150 is 10nm or more. Further, the minimum thickness is calculated as follows. First, a cross section perpendicular to the first end surface 22A and the one side surface 22C is photographed by an electron microscope. Next, in the captured image, a portion where the thickness of the glass film 150 is minimum is determined. Then, the thickness of the determined portion is measured on the image. The thickness thus measured was taken as the minimum thickness of the clad portion AC in the glass film 150.

It is assumed that the entire glass film contains the metal component of the first base electrode 61A. In this case, in the curing step S21 of the manufacturing step, the metal component in the glass film enters inside the outer surface 21 of the base 20. More specifically, the case where the metal component contained in the glass film is silver and the matrix 20 contains manganese is exemplified. In this case, the crystal structure in the vicinity of the outer surface 21 in the matrix 20 changes from a state composed of manganese and oxygen to a state in which silver is also added. Thus, silver entering the matrix 20 is confined in the matrix 20. Further, since silver diffuses in the glass film, silver entering the base 20 is connected to silver in the conductor paste via silver in the glass film. Therefore, the silver in the conductor paste is also restrained on the substrate 20 side via the silver in the glass film, respectively. As a result, silver in the conductor paste is difficult to aggregate in the curing step S21. If silver of the conductor paste is less likely to aggregate, the sintering time may be long.

In this regard, according to the electronic component 110 of the modification example described above, the pure glass layer 151 does not contain the metal component of the first base electrode 61A. That is, silver does not enter the vicinity of the outer surface 21 in the interior of the base 20. Therefore, in the curing step S21 of the manufacturing step, even if silver serving as the first base electrode 61A diffuses into the glass film 150, the silver does not enter the crystal structure layer of the substrate 20 and is not confined to the substrate 20 side. Therefore, as described above, the silver of the conductor paste does not easily move due to the origin of the layer. Therefore, silver of the conductor paste is less likely to aggregate and is less likely to be sintered, and thus the sintering time can be prevented from becoming excessively long.

In the electronic component 110 according to the modification example, the pure glass layer 151 is composed of only silicon dioxide. Therefore, even if the additive is contained in the first base electrode 61A, excessive diffusion of alkali metal and alkaline earth metal, which are components of the additive, into the glass film 150 can be prevented.

In the electronic component 110 according to the modification, the minimum thickness of the coating portion AC in the glass film 150 is 10nm or more. Therefore, in the curing step S21 of the manufacturing step, if the metal component contained in the conductor paste diffuses a corresponding amount into the glass film 150, the pure glass layer 151 containing no metal component is also present in a part of the outer surface 21 side. Therefore, the pure glass layer 151 is easily and stably manufactured.

In the electronic component 110 according to the modification shown in fig. 13, if the glass film 150 includes the pure glass layer 151, the minimum thickness of the coating portion AC of the glass film 150 may be less than 10nm.

In the electronic component 110 of the modification shown in fig. 13, the pure glass layer 151 is not limited to only silicon dioxide. For example, in the case where the glass of the glass film 150 contains boron oxide as a main component, the pure glass layer 151 may be only boron oxide.

In the electronic component 110 according to the modification shown in fig. 13, the glass film 150 may be constituted by only the pure glass layer 151.

Description of the reference numerals

10. 110 … electronic components; 20 … base; 21 … outer surface; 41 … first inner electrode; 42 … second inner electrode; 50. 150 … glass film; 61 … first external electrode; 62 … second external electrode; 71 … first through portion; 72 … second through portion; 81 … reaction vessel; 82 … solvent; 83 … in water; 84 … polymer; 85 … metal alkoxide; 151 … pure glass layer.

Claims

1. An electronic component, comprising:

a base;

wiring inside the substrate;

a glass film covering an outer surface of the substrate; and

a base electrode electrically connected to the wiring and partially covering the glass film,

when the part of the glass film covered by the base electrode is a covered part and the part which is not covered by the base electrode and is more than 10 μm away from the outer edge of the base electrode is an uncovered part,

the thickness of the coating part is larger than that of the non-coating part.

2. The electronic component according to claim 1, wherein,

the thickness variation coefficient of the covered portion is larger than that of the uncovered portion.

3. The electronic component according to claim 1 or 2, wherein,

the base electrode comprises glass.

4. The electronic component according to any one of claim 1 to 3, wherein,

the base electrode is a sintered body containing silver.

5. The electronic component according to any one of claims 1 to 4, wherein,

the outer surface is entirely covered with the glass film or the base electrode.

6. The electronic component according to any one of claims 1 to 5, wherein,

the glass film has a pure glass layer that does not contain a metal component of the base electrode,

the pure glass layer is laminated on the outer surface of the cladding portion.

7. The electronic component according to claim 6, wherein,

the pure glass layer consists of silica only.

8. The electronic component according to claim 6 or 7, wherein,

the minimum thickness of the coating portion in the glass film is 10nm or more.