Chip-type electronic component

Abstract

Provided is a chip-type electronic component configured such that a large change in the electric characteristics can be suppressed after the chip-type electronic component is reflow-mounted. This chip-type electronic component comprises: a ceramic element body comprising a semiconductor ceramic material comprising an oxide containing Ti and Ba; and a solid metal electrode that is formed on an end of the ceramic element body, and that makes ohmic contact with the ceramic element body. The chip-type electronic component satisfies the following formula (1), and the film stress of the solid metal electrode is 140 MPa or more.　Formula (1) A / V ≧ 3.3 (mm2 / mm3) Here, A (mm2) is the surface area of the solid metal electrode, and V (mm3) is the volume of the ceramic element body.

Description

Technical Field

[0001] The present invention relates to chip-type electronic components, and particularly to chip-type electronic components including semiconductor ceramics.

Background Art

[0002] Some ceramics are known to exhibit the piezoresistive effect in which the resistance value changes by applying stress. For example, ceramics such as La 1-X Sr X MnO 3 , BaTiO 3 etc. have the property that the resistance changes according to the magnitude of strain and stress (piezoresistive effect) (for example, Patent Document 1). The perovskite-type manganese oxide La 1-X Sr X MnO 3 shows a relatively high piezoresistive effect at room temperature when X = 0.25, and the resistivity changes by 7% when strained at 150 MPa. Also, in ceramics such as semiconductor BaTiO 3 , a giant piezoresistive effect appears.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, miniaturization of chip-type electronic components including ceramic bodies has been progressing. However, due to the miniaturization of chip-type electronic components, the electrical characteristics of chip-type electronic components may change before and after reflow mounting. In particular, in the case of chip-type electronic components using semiconductor ceramics, for example, positive temperature coefficient (PTC) thermistors using semiconductor BaTiO 3 ceramics, the resistance of the chip-type electronic components may change significantly before and after reflow mounting.

[0005] Therefore, the present invention is directed to chip-type electronic components before reflow mounting, and aims to provide a configuration capable of suppressing a large change in electrical characteristics after the chip-type electronic components are reflow-mounted.

Means for Solving the Problems

[0006] According to one gist of the present invention, a ceramic body including semiconductor ceramics made of an oxide containing Ti and Ba, a chip-type electronic component including a solid metal electrode formed at an end of the ceramic body and in ohmic contact with the ceramic body, the chip-type electronic component satisfies the following formula (1), a chip-type electronic component is provided in which the film stress of the solid metal electrode is 140 MPa or more. A / V≧3.3(mm 2 / mm 3 )···(1) Here, A (mm 2 ) is the surface area of the solid metal electrode, and V (mm 3 ) is the volume of the ceramic body.

Effects of the Invention

[0007] According to the chip-type electronic component of the present invention, changes in electrical characteristics before and after reflow mounting can be suppressed.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0009] In chip-type electronic components using semiconductor ceramics such as positive temperature coefficient (PTC) thermistors, with miniaturization, the electrical characteristics (e.g., resistance) of the chip-type electronic components before and after reflow mounting may change significantly. As a result of intensive research on the cause of such resistance changes, the inventors have found for the first time that the film stress of the solid metal electrodes formed on the surface of the ceramic body of the chip-type electronic component changes before and after reflow mounting, and this change in film stress causes the resistance change of the chip-type electronic component. By further research, the inventors have obtained a surprising finding that by increasing the film stress of the solid metal electrodes to a certain extent in the electronic component 10 before reflow mounting, the resistance change rate of the electronic component 10 before and after reflow mounting can be suppressed to a low level, and thus the present invention has been completed.

[0010] [Embodiment 1] FIG. 1 is a schematic cross-sectional view of a chip-type electronic component 10 (hereinafter sometimes simply referred to as "electronic component 10") according to Embodiment 1 of the present invention. The electronic component 10 includes a ceramic body 20 and solid metal electrodes 31 and 41 formed at the ends of the ceramic body 20.

[0011] The ceramic body 20 includes semiconductor ceramics made of an oxide containing Ti and Ba. The composition of the semiconductor ceramics includes a perovskite-type compound containing Ba, Ca, Sr, and Ti as main components, and further preferably includes at least one selected from R (R is at least one selected from Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu), Mn, and Si.

[0012] The solid metal electrodes 31 and 41 are in ohmic contact with the ceramic body 20. That is, the solid metal electrodes 31 and 41 are formed of a solid metal material that provides ohmic properties with the ceramic body 20 and are in direct contact with the surface of the ceramic body 20. As the solid metal material that provides ohmic properties with the ceramic body 20, for example, Cr, NiCr alloy, Al, and Zn-Ag (ohmic Ag) are suitable.

[0013] The electronic component 10 may further include a protective layer that covers the solid metal electrodes 31 and 41. In the example shown in FIG. 1, the protective layer is composed of four layers: conductive solid metal layers 32 and 42, conductive resin layers 33 and 43, first plating layers 34 and 44, and second plating layers 35 and 45. The conductive solid metal layers 32 and 42 are disposed between the solid metal electrodes 31 and 41 and the conductive resin layers 33 and 43. The conductive resin layers 33 and 43 are disposed between the conductive solid metal layers 32 and 42 and the plating layers (the first plating layers 34 and 44 and the second plating layers 35 and 45).

[0014] Note that the solid metal electrode 31, the conductive solid metal layer 32, the conductive resin layer 33, the first plating layer 34, and the second plating layer 35 can be regarded as constituting the first external electrode 30 of the electronic component 10. Similarly, the solid metal electrode 41, the conductive solid metal layer 42, the conductive resin layer 43, the first plating layer 44, and the second plating layer 45 can be regarded as constituting the second external electrode 40 of the electronic component 10.

[0015] The electronic component 10 of the present invention satisfies the following formula (1). A / V≧3.3(mm 2 / mm 3 )···(1) Here, A (mm 2 ) is the surface area of the solid metal electrodes 31 and 41, and V (mm 3 ) is the volume of the ceramic body 20.

[0016] Formula (1) is for the volume V (mm 3) with respect to the surface area A (mm of the solid metal electrodes 31 and 41 2 ). The smaller the electronic component 10, the larger the value of A / V. Although it also varies depending on the formation range of the solid metal electrodes 31 and 41, for example, in the case of chip size 0603 in millimeters, if the solid metal electrodes 31 and 41 are formed only on the end faces 21 and 22 on both sides of the ceramic body 20, A / V can be approximately 3.3 mm 2 / mm 3 . The volume V (mm of the ceramic body 20 3 ) and the surface area A (mm of the solid metal electrodes 31 and 41 2 ) will be described in detail later.

[0017] In the state of the electronic component 10 of the present invention before reflow mounting, the film stress of the solid metal electrodes 31 and 41 is 140 MPa or more. Thereby, the resistance change rate of the electronic component 10 before and after reflow mounting can be suppressed to be low (for example, less than 10%). The mechanism by which the resistance change rate can be suppressed by controlling the film stress of the solid metal electrodes 31 and 41 to be high will be described below.

[0018] The solid metal electrodes 31 and 41 that are in ohmic contact with the ceramic body 20 are in direct contact with the surface of the ceramic body 20. If there is residual stress (film stress) inside the solid metal electrodes 31 and 41, the surface layer portion of the ceramic body 20 receives stress proportional to the magnitude of the film stress.

[0019] When the electronic component 10 is reflow-mounted, the solid metal electrodes 31 and 41 are affected by the heat during reflow mounting, and the film stress changes. Due to this change in film stress, the stress received by the surface layer portion of the ceramic body 20 changes, and the resistance of the ceramic body 20 changes due to the piezoresistive effect. Although the change in the stress received by the surface layer portion of the ceramic body 20 is minute, this stress change becomes apparent due to the miniaturization of the electronic component 10, and the resistance change of the ceramic body 20 becomes significant.

[0020] According to the research of the present inventors, it has been clarified that when the general reflow temperature (130°C to 300°C) is applied, the film stress of the solid metal electrodes 31 and 41 becomes about 500 MPa. Further, it has been found that when the film stress of the solid metal electrodes 31 and 41 before reflow mounting is close to 500 MPa, the resistance change rate before and after reflow mounting becomes small. From this, the inventors have discovered that by increasing the film stress of the solid metal electrodes 31 and 41 in the electronic component 10 before reflow mounting (more specifically, making it close to the film stress of the solid metal electrodes 31 and 41 after reflow mounting), the resistance change rate before and after reflow mounting can be made extremely small.

[0021] However, the film stress of the solid metal electrodes 31 and 41 also changes depending on the film formation conditions of the solid metal electrodes 31 and 41 (for example, in the case of sputter formation, sputter temperature, sputter time, etc.), various processing treatments (for example, barrel polishing, etc.), and preliminary heat treatment. Therefore, as a result of the inventors' detailed examination of the relationship between the allowable resistance change rate of the electronic component 10 and the film stress of the solid metal electrodes 31 and 41 before reflow mounting, it has been found that if the film stress of the solid metal electrodes 31 and 41 before reflow mounting is controlled to 140 MPa or more, the resistance change rate before and after reflow mounting can be suppressed within an acceptable range (approximately less than 10%) for use in general applications.

[0022] The film stress of the solid metal electrodes 31 and 41 in the electronic component 10 before reflow mounting can be controlled by adjusting the film formation conditions of the solid metal electrodes 31 and 41 (for example, in the case of sputter formation, sputter temperature, sputter time, etc.), the processing treatment of the electronic component 10 (for example, barrel polishing, etc.), and the conditions of preliminary heat treatment, etc.

[0023] The film stress of the solid metal electrodes 31 and 41 is preferably 300 MPa or more, and the resistance change rate before and after reflow mounting can be further reduced. The film stress of the solid metal electrodes 31 and 41 is preferably 490 MPa or less, and it is possible to suppress the occurrence of cracks and peeling in the solid metal electrodes 31 and 41 due to the film stress. In addition, in order to increase the film stress of the solid metal electrodes 31 and 41, it is necessary to control various manufacturing conditions, which may increase the manufacturing cost of the solid metal electrodes 31 and 41. As a result, the manufacturing cost of the electronic component 10 may increase. Therefore, it is more preferable that the film stress is 400 MPa or less, which can suppress the increase in the manufacturing cost of the electronic component 10.

[0024] The film stress of the solid metal electrodes 31 and 41 can be measured by the method described in the examples. In addition, when there is a protective layer covering the solid metal electrodes 31 and 41, before measuring the film stress, the protective layer is removed to expose the solid metal electrodes 31 and 41. The method for removing the protective layer (the conductive solid metal layers 32 and 42, the conductive resin layers 33 and 43, the first plating layer 34 and 44, and the second plating layer 35 and 45) is not particularly limited. For example, there are physical removal and chemical removal as shown below. Examples of the physical removal method include physical etching and barrels. Examples of the chemical removal method include a method of dissolving and removing each layer with a solvent that selectively dissolves the layer. For a layer made of a metal material (the first plating layer 34 and 44, and the second plating layer 35 and 45), for example, it can be dissolved with various acids such as hydrochloric acid, nitric acid, ferric chloride, ammonium sulfate, hydrogen peroxide, sulfuric acid, boric acid, cyanide, hydrofluoric acid, and phosphoric acid. For a layer containing a resin material (the conductive resin layers 32 and 42), for example, it can be dissolved and removed with various organic solvents such as aromatic, ketone, and ether.

[0025] Next, the volume V (mm 3 ) of the ceramic body 20 and the surface area A (mm 2 ) of the solid metal electrodes 31 and 41 will be described in detail.

[0026] Regarding the dimensions of the ceramic body 20, the dimension in the W direction is defined as "width 20W" (mm), the dimension in the L direction is defined as "length 20L" (mm), and the dimension in the T direction is defined as "thickness 20T" (mm) (not shown in the figure). Using each dimension of the ceramic body 20, the volume V of the ceramic body 20 can be obtained as follows. The volume V (mm 3): 20W × 20T × 20L

[0027] The volume V of the ceramic body 20 is 0.001 mm 3 or more and 0.12 mm 3 or less. In such a small-sized ceramic body 20, the effect of suppressing the resistance change rate by controlling the film stress of the solid metal electrodes 31 and 41 is remarkable.

[0028] Further, using each dimension (width 20W, length 20L, and thickness 20T) of the ceramic body 20, the area of each of the end faces 21 and 22 of the ceramic body 20 can be obtained as follows. The area of the first end face 21 (mm 2 ): 20W × 20T The area of the second end face 22 (mm 2 ): 20W × 20T

[0029] The surface area A of the solid metal electrodes 31 and 41 means the sum of the total surfaces of the solid metal electrodes 31 and 41. FIGS. 2 and 3 show solid metal electrodes 31 and 41 having different shapes, and the surface area A of each of the solid metal electrodes 31 and 41 will be described.

[0030] FIG. 2 is a schematic partial enlarged cross-sectional view of one end (the first end face 21 side) of the ceramic body 20 of the electronic component 10 shown in FIG. 1. In FIG. 2, the solid metal electrode 31 covers the first end face 21 of the ceramic body 20, but does not cover the side face 23 of the ceramic body 20. In this case, the surface area A21 of the solid metal electrode 31 is substantially equal to the area of the first end face 21. Since the area of the first end face 21 is 20W × 20T, the surface area A21 of the solid metal electrode 31 is 20W × 20T.

[0031] When the solid metal electrode 41 formed at the other end of the ceramic body 20 (the side of the second end face 22 shown in FIG. 1) is the same as the solid metal electrode 31 shown in FIG. 2 (that is, when it covers the second end face 22 of the ceramic body 20 but does not cover the side face 23 of the ceramic body 20), the surface area of the solid metal electrode 41 is substantially equal to the area of the second end face 22. Since the area of the second end face 22 is 20W×20T, the surface area of the solid metal electrode 41 is 20W×20T.

[0032] And since the surface area A of the solid metal electrodes 31 and 41 is the sum of the total surfaces of the solid metal electrodes 31 and 41, the surface area A can be obtained as (20W×20T)+(20W×20T)=(20W×20T)×2.

[0033] FIG. 3 is a schematic partial enlarged cross-sectional view showing an enlarged view of one end (the end face 21 side) of the ceramic body 20 in another form of the electronic component 10. In FIG. 3, the solid metal electrode 31 is different from the solid metal electrode 31 shown in FIG. 2 in that it continuously covers not only the first end face 21 of the ceramic body 20 but also a part of the side face 23 of the ceramic body 20 adjacent to the first end face 21. In FIG. 3, although the conductive solid metal layer 32 is not shown, the conductive solid metal layer 32 may be formed so as to cover only the end face (a plane substantially parallel to the first end face 21 of the ceramic body 20) of the solid metal electrode 31, or the end face and the side face (a plane substantially parallel to the side face 23 of the ceramic body 20).

[0034] In FIG. 3, regarding the surface area of the solid metal electrode 31, the surface area of the plane substantially parallel to the first end face 21 of the ceramic body 20 is denoted as A31, and the surface area of the plane substantially parallel to the side face 23 of the ceramic body 20 is denoted as A32. The surface area of the solid metal electrode 31 is the sum of the surface areas A31 and A32. In FIG. 3, although the solid metal electrode 31 formed on two of the four side faces 23 (the LT faces) of the ceramic body 20 is shown, the solid metal electrode 31 may also be formed on the remaining two faces (the LW faces). In that case, when calculating the surface area of the solid metal electrode 31, it is necessary to add the surface area of the solid metal electrode 31 formed on the LW face.

[0035] When the solid metal electrode 41 formed on the other end portion of the ceramic body 20 (the side of the second end face 22 shown in FIG. 1) is the same as the solid metal electrode 31 shown in FIG. 3 (that is, not only the second end face 22 of the ceramic body 20 but also a part of the side face 23 of the ceramic body 20 adjacent to the second end face 22 is continuously covered), the surface area of the solid metal electrode 41 is, similar to the surface area of the solid metal electrode 31 on the first end face 21 side, the sum of the surface area of a plane substantially parallel to the second end face 22 and the surface area of a plane substantially parallel to the side face 23 of the ceramic body 20.

[0036] And the surface area A of the solid metal electrodes 31 and 41 can be obtained as the sum of the surface area of the solid metal electrode 31 on the first end face 21 side and the surface area of the solid metal electrode 41 on the second end face 22.

[0037] In the case of the solid metal electrodes 31 and 41 having the shape shown in FIG. 3, the dimensions of the solid metal electrodes 31 and 41 on each side face are measured by a microscope or the like, and the surface area is calculated.

[0038] [Manufacturing Method of Chip-Type Electronic Component 10] Regarding the manufacturing method of the electronic component 10 according to Embodiment 1, a PTC thermistor having the structure shown in FIG. 1 will be described as an example.

[0039] (Fabrication of Ceramic Body 20) The ceramic body 20 is made of, for example, a ceramic material obtained by adding a predetermined additive to BaTiO 3 (barium titanate). Examples of the additive include rare earths. The rare earth to be added is typically selected from Sm, Er, and Y, and may also be selected from Nd, La, etc.

[0040] In the fabrication of the ceramic body 20, first, as raw materials for the ceramic body, BaCO 3 , TiO 2 , PbO, SrCO 3 , CaCO 3Weigh a predetermined amount of ceramic raw materials such as these and rare earth additives (semi-conductor agents). As the rare earth additives, oxides of at least one rare earth element selected from Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, etc. may be used. Further, as the raw material of the ceramic green body, in addition to the above-mentioned ceramic raw materials and rare earth additives, property improvers such as Mn 2 O 3 etc., and sintering aids such as SiO 2 etc. may be used. Put the weighed raw materials into a ball mill together with a grinding medium such as partially stabilized zirconia (PSZ) (hereinafter also referred to as PSZ balls) and pure water, and perform wet mixing and grinding. Calcinate the obtained mixture at a predetermined temperature (for example, 1000 to 1200 °C) to obtain a calcined powder.

[0041] Add an organic binder, a dispersant, and pure water to the obtained calcined powder, mix them, and then dry them to granulate. Obtain a molded body by molding the obtained granulated product. Perform a degreasing treatment and a debinding treatment on the molded body, and sinter it at a predetermined temperature (1200 to 1400 °C) and a predetermined atmosphere to obtain a ceramic green body 20A.

[0042] (Formation of solid metal electrodes 31 and 41) As shown in FIGS. 1 to 3, form solid metal electrodes 31 and 41 so as to cover the end portions of the ceramic green body 20 (only the end faces 21 and 22 as shown in FIGS. 1 and 2, or a part of the end faces 21 and 22 and the side face 23 as shown in FIG. 3).

[0043] The solid metal electrodes 31 and 41 are formed of a metal material that can have ohmic contact with the ceramic green body 20, such as a metal material such as Zn, Ni, Al, Cr, V, W, an alloy of these metals and Ag, and an alloy material such as NiCr. In particular, solid metal materials such as Cr, NiCr alloy, Al, and Zn-Ag (ohmic Ag) are suitable.

[0044] The solid metal electrodes 31 and 41 can be formed by known film-forming methods. For example, sputtering method, vapor deposition method, coating method (baking after applying a conductive paste to a predetermined position), dipping method, etc. can be used. For example, Cr film, NiCr alloy film, and Al film are suitable for the sputtering method, and Zn-Ag film (ohmic Ag film) is suitable for the method of baking after coating.

[0045] (Formation of protective layer) A protective layer may be formed so as to cover the solid metal electrodes 31 and 41. In Embodiment 1, the protective layer is composed of four layers: conductive solid metal layers 32 and 42, conductive resin layers 33 and 43, first plating layers 34 and 44, and second plating layers 35 and 45. The formation method of each layer will be described.

[0046] (Conductive solid metal layers 32 and 42) The conductive solid metal layers 32 and 42 are preferably formed from a solid metal material that has high adhesion to the solid metal electrodes 31 and 41 and high weather resistance. Examples of the solid metal material include metal materials such as Ni, Cr, Au, Ag, W, etc. or alloy materials such as NiCr, NiCu, NiV, etc. As the conductive solid metal layers 32 and 42, solid metal material films such as NiCu alloy film, NiV alloy film, and Ag film are particularly preferred.

[0047] The conductive solid metal layers 32 and 42 may be formed from the same material as the solid metal electrodes 31 and 41. For example, when a solid metal material that can obtain ohmic properties with the ceramic body 20 has the characteristics required for the solid metal material forming the protective layer (conductive solid metal layers 32 and 42), the conductive solid metal layers 32 and 42 and the solid metal electrodes 31 and 41 may be formed from the same material. When they are formed from the same material, the solid metal electrodes 31 and 41 and the conductive solid metal layers 32 and 42 can be provided as one integrated layer.

[0048] The conductive solid metal layers 32 and 42 are composed of a single-layer film or a multi-layer film and can be formed by known film-forming methods. For example, sputtering, vapor deposition, coating (baking after applying a conductive paste to a predetermined position), dipping, etc. can be used. For example, NiCu alloy films, NiV alloy films, and Ag films are preferably formed by sputtering.

[0049] (Formation of the conductive resin layers 33 and 43) The conductive resin layers 33 and 43 are provided by curing a resin electrode paste having fluidity. The resin electrode paste contains conductive powder and a resin raw material. After applying the resin electrode paste so as to cover the solid metal electrodes 31 and 41 at the ends of the ceramic body 20, the resin raw material in the resin electrode paste is cured. As the conductive powder contained in the resin electrode paste, metal powders such as Ag, Au, Ni, Cu, Pt, Pd, and Al can be used. As the resin raw material contained in the resin electrode paste, for example, resin raw materials such as epoxy resin, phenolic resin, urethane resin, silicone resin, and polyimide resin can be used.

[0050] (Formation of the first plating layers 34 and 44 and the second plating layers 35 and 45) Plating layers (the first plating layers 34 and the second plating layers 35) are formed so as to cover the surfaces of the conductive resin layers 33 and 43. The plating layers preferably have a multi-layer structure including the first plating layers 34 and 44 in contact with the conductive resin layers 33 and 43 and the second plating layers 35 and 45 covering the first plating layers 34 and 44. In this case, after forming the first plating layers 34 and 44 so as to cover the surfaces of the conductive resin layers 33 and 43, the second plating layers 35 and 45 are formed so as to cover the first plating layers 34 and 44.

[0051] The first plating layers 34 and 44 can be formed, for example, by electrolytically plating at least one of Ni and Cu. The second plating layers 35 and 45 can be formed, for example, by electrolytically plating Sn. The first plating layers 34 and 44 and the second plating layers 35 and 45 can be formed by known plating methods, and for example, barrel plating using balls can be used.

[0052] As described above, the manufacturing method of the chip-type electronic component 10 according to Embodiment 1 of the present invention has been described by taking a PTC thermistor as an example. However, other chip-type electronic components can also be appropriately manufactured based on the description in this specification.

Examples

[0053] Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to such examples.

[0054] Measurement samples were prepared according to the following procedure. Note that about 5000 measurement samples can be formed in one production. The film stress of the solid metal electrode in each measurement sample was adjusted to the film stress shown in Table 1 by adjusting the film formation conditions of the solid metal electrode, the conditions of barrel polishing, the preliminary heat treatment conditions, etc.

[0055] (Examples 1 to 5, Comparative Examples 2 and 3) The ceramic body 20 was adjusted by pulverizing and mixing the raw materials of the ceramic body 20, pre-firing, molding, firing, and cutting. The pulverizing and mixing of the raw materials was mainly composed of BaCO 3 , CaCO 3 , SrCO 3 , PbO, TiO 2 , Sm 2 O 3 as a rare earth element, MnO 2 as a property adjusting material, and SiO 2A predetermined amount was mixed, pulverized, and dried. The obtained dried powder was calcined at a maximum temperature of 1200 °C in an air atmosphere. An organic binder, a dispersant, and pure water were added to the obtained calcined powder, and after mixing, it was dried to form granules. The obtained granules were compression-molded. The molded body was subjected to a degreasing treatment and a debinding treatment, and fired at a maximum temperature of 1380 °C. The fired body was cut into a predetermined size to obtain a ceramic green body 20.

[0056] Solid metal electrodes 31, 41 (Cr films) and conductive solid metal layers 32, 42 (multilayer films of NiCu alloy films and Ag films) were formed in this order so as to cover only both end faces 21, 22 of the ceramic green body 20. Each film was formed by sputtering. As the sputtering apparatus, CS-S manufactured by ULVAC was used, and the film thickness was adjusted by adjusting the sputtering time according to the film type under the flow of argon gas at an absolute pressure of less than 1 Pa and a sputtering output of 200 W. Table 1 shows the types of materials of the solid metal electrodes 31, 41 and the film thicknesses of the solid metal electrodes 31, 41 used in each of the examples and comparative examples.

[0057] (Example 6, Comparative Example 1) Solid metal electrodes 31, 41 were formed by the dip method so as to cover only both end faces 21, 22 of the ceramic green body 20 prepared in the same manner as in Example 1. By dipping the end face 21 of the ceramic green body 20 into a paste containing Ag-Zn, it was applied and dried at 180 °C. The end face 22 was also dipped, applied, and dried in the same manner to obtain a dried body in which Ag-Zn films (ohmic Ag films) were formed on both end faces. This dried body was passed through a belt furnace at a maximum temperature of 600 °C to bake the solid metal electrodes 31, 41 onto the ceramic green body 20. Table 1 shows the film thicknesses of the solid metal electrodes 31, 41 used in each of Example 6 and Comparative Example 1.

[0058] The ceramic substrates 20 used in Examples 1 to 6 and Comparative Examples 1 to 3 were in a quadrangular prism shape and had the following dimensions (equivalent to 0603 chips). · Length 20L: 0.60 mm · Width 20W: 0.28 mm · Thickness 20T: 0.28 mm

[0059] Since the solid metal electrodes 31 and 41 were formed only on both end faces 21 and 22 (corresponding to the WT surface) of the ceramic body 20, the surface area A (mm 2 ) of the solid metal electrodes 31 and 41 was (20W × 20T) × 2 = (0.28 mm × 0.28 mm) × 2 = 0.1568 mm 2 . The volume V (mm 3 ) of the ceramic body 20 was 20W × 20T × 20L = 0.28 mm × 0.28 mm × 0.60 mm = 0.04704 mm 3 . From these values, A / V was obtained and listed in Table 1.

[0060] (Measurement of film stress) The film stress of the solid metal electrode was measured using the sin 2 ψ-2θ method by X-ray diffraction. This measurement method is excellent in terms of high reproducibility. As the XRD diffractometer, a micro X-ray diffractometer can be used. In the examples, D8 DISCOVER manufactured by BRUKER axs was used. CuKα rays were used as the X-ray source. In each of the examples and comparative examples, 3 samples were randomly selected from about 5000 prepared measurement samples and used for measurement.

[0061] The sin 2 ψ method by the micro X-ray diffractometer is a method for determining the film stress by measuring a specific diffraction peak. The method for selecting a specific diffraction peak is as follows. Select one diffraction peak of "any crystal plane" of "a certain crystal phase". In order to confirm the strain amount while tilting the measurement sample, a diffraction peak on the high-angle side that is sensitive to the strain of the crystal phase is desirable. Select a diffraction peak that does not overlap with the diffraction peaks of other crystal planes and has a clear (i.e., strong) peak top that serves as an index of the interplanar spacing.

[0062] In the examples and comparative examples, the diffraction lines of Cr(220) for the Cr film, NiCr(222) for the NiCr alloy film, and Ag(222) for the ohmic Ag electrode were measured.

[0063] The film stress of the solid metal electrode is obtained from the following formula (2). σ = K·∂(2θ) / ∂(sin 2 ψ)···(2) Here, K is the stress constant, which is obtained by the following formula (3). K = E / ν···(3) Here, E is the Young's modulus of the material constituting the solid metal electrode, and ν is the Poisson's ratio of the material constituting the solid metal electrode.

[0064] When obtaining the film stress of the examples and comparative examples, the following values were used for the Young's modulus E and the Poisson's ratio ν. These values are known values described in the Science Yearbook, various documents, etc. NiCr alloy: E / ν = 29400 MPa / 0.21 Cr: E / ν = 82700 MPa / 0.367 Ohmic Ag: E / ν = 214000 MPa / 0.31 From the results of micro X-ray diffraction, the film stress of the solid metal electrode of the measurement sample was calculated. The average value of the film stress values obtained from 3 measurement samples was calculated and shown as "Film stress of solid metal electrode" in Table 1.

[0065] (Evaluation of resistance change rate) In order to pseudo-reproduce the reflow mounting, the measurement sample was put into a constant temperature bath at 230°C for 30 minutes. The resistance of the measurement sample before pseudo-mounting (before heat treatment) and the resistance of the measurement sample after pseudo-mounting (after heat treatment) were measured, and the change rate of the resistance value after heating with respect to the resistance value before heating (resistance change rate) was measured. First, the room temperature resistance value of the sample before pseudo-mounting (before heat treatment) was measured. Next, the sample was mounted on the mounting substrate using solder paste for pseudo-mounting (heat treatment). For the sample after pseudo-mounting (after heat treatment), the room temperature resistance value was measured.

[0066] A glass epoxy resin substrate (FR-4) was used as the implementation substrate, and Sn-3.0Ag-0.5Cu M705-GRN360-K2KJ-V manufactured by Senju Metal Industry Co., Ltd. was used as the solder paste. As the resistance measuring instrument, a commercially available digital multimeter was used. In the examples, an R6451A digital multimeter manufactured by ADVANTEST was used, but similar measurement results can be obtained with other digital multimeters. In the resistance measurement, for the sample before pseudo-implementation, the digital multimeter was brought into contact with both electrodes (positive electrode, negative electrode) of the sample for measurement, and for the sample after pseudo-implementation, the digital multimeter was brought into contact with the substrate wiring for measurement.

[0067] Ten samples were randomly selected from the approximately 5000 fabricated measurement samples and used for measurement. For each individual sample, the resistance value Ri before implementation and the resistance value Rf after implementation were measured, and the resistance change rate was obtained using the following formula (4). Resistance change rate (%) = (Rf / Ri - 1) × 100 ··· (4) The resistance change rate was determined for each of the 10 measurement samples, and their average value was calculated and shown as "Resistance change rate" in Table 1.

[0068]

Table 1

[0069] In Examples 1 to 6 where the film stress of the solid metal electrode before heat treatment was 140 MPa or more, the resistance change rate after heat treatment was less than 10%. On the other hand, in Comparative Examples 1 to 3 where the film stress of the solid metal electrode before heat treatment was less than 140 MPa, the resistance change rate after heat treatment was 10% or more.

[0070] This application claims priority based on Japanese Patent Application No. 2021-197184 filed in Japan on December 3, 2021, and the entire contents of its description are incorporated herein by reference.

Explanation of Reference Signs

[0071] 10 chip-type electronic components 20 Ceramic body 21, 22 End faces of the ceramic body 23 Side face of the ceramic body 30, 40 External electrodes 31, 41 Solid metal electrodes 32, 33 Conductive solid metal layers 33, 43 Conductive resin layers 34, 44 First plating layer 35, 45 Second plating layer

Claims

1. A chip-type electronic component comprising a ceramic body including semiconductor ceramics made of an oxide containing Ti and Ba, and a solid metal electrode formed at an end of the ceramic body and in ohmic contact with the ceramic body, wherein the chip-type electronic component satisfies the following formula (1), and the film stress of the solid metal electrode is 140 MPa or more. A / V ≥ 3.3 (mm ２ / mm ３ )...(1) Here, A (mm ２ ), is the surface area of the solid metal electrode, and V (mm ３ ) is the volume of the ceramic green body.

2. The chip-type electronic component according to claim 1, wherein the film stress of the solid metal electrode is 490 MPa or less.

3. The volume V of the ceramic body is 0.001 mm ３ or more and 0.12 mm ３ or less. The chip-type electronic component according to claim 1 or 2.

4. The chip-type electronic component according to claim 1 or 2, wherein the solid metal electrode covers an end face of the ceramic body.

5. The chip-type electronic component according to claim 4, wherein the solid metal electrode continuously covers from an end face of the ceramic body to a part of a side face of the ceramic body adjacent to the end face.

6. The chip-type electronic component according to claim 1 or 2, wherein the composition of the semiconductor ceramics contains a perovskite-type compound containing Ba, Ca, Sr, and Ti as main components, and further contains R (R is at least one selected from Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu), Mn, and Si.

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