JP4697231B2 - Ceramic electronic components - Google Patents

Description

  The present invention relates to a ceramic electronic component that needs to identify the orientation of the component from the viewpoint of assembly and mounting, and more particularly to a ceramic electronic component such as a trimmer capacitor in which an internal conductor is unevenly distributed.

  FIG. 7 is a schematic sectional view showing a conventional trimmer capacitor. As shown in FIG. 7, the trimmer capacitor 500 includes a ceramic sintered body 503 in which a plurality of ceramic layers 502 are laminated, and an internal structure that is disposed between the ceramic layers 502 and drawn to the side surface of the ceramic sintered body 503. A stator 501 including a conductor 504 and external conductors 505a and 505b formed on the side surface of the ceramic sintered body 503 is provided. A metal rotor 507 is disposed on the upper portion of the stator 501, and terminal electrodes 508 and protrusions 509 formed on the lower portion of the rotor 507 are in contact with the upper surface of the ceramic sintered body 503. The rotor 507 is covered with a metal cover 511 via a spring washer 510. A terminal 512 formed by extending a part of the metal cover 511 is electrically connected to the external conductor 505 b on the side surface of the ceramic sintered body 503. A through hole 513 is provided in the metal cover 511, and a driver is inserted into the driver groove 514 formed in the rotor 507 through the through hole 513.

  In the trimmer capacitor 500, a capacitance is formed between the internal conductor 504 and the terminal electrode 508. However, if the ceramic sintered body is turned upside down, a desired capacitance cannot be formed. Therefore, when joining the ceramic sintered body 503 and the metal cover 511, a mark (marker) for identifying the upper and lower sides of the ceramic sintered body 503 is required.

In order to solve such a problem, in Patent Document 1, a ceramic paste containing TiO ₂ and Mn ₃ O ₄ is printed and baked between ceramic layers to form a marker, and the upper and lower sides of the ceramic electronic component are identified. It has been proposed to do.
Japanese Utility Model Publication No. 7-47862

  However, in Patent Document 1, the marker formed between the ceramic layers and the internal electrode formed between the ceramic layers are arranged so as to overlap in the stacking direction of the ceramic layers. For this reason, the location where the marker and the internal electrode overlap with each other becomes thicker than other portions, which may cause structural defects in the ceramic sintered body. In addition, the coloring component diffuses from the marker to the ceramic layer during baking and reaches the internal electrode, which may reduce the reliability of the ceramic electronic component.

  In order to suppress the diffusion of the coloring component, it is possible to form a marker on the surface of the ceramic sintered body after producing the ceramic sintered body. In this case, it is also described in Patent Document 1. As shown, problems such as mounting defects may occur.

  The present invention solves the above-described problem, and can identify the directionality of the ceramic electronic component by the marker formed inside, and can suppress the diffusion of the coloring component from the marker and is reliable. An object of the present invention is to provide a ceramic electronic component that does not deteriorate.

A ceramic electronic component according to the present invention includes a ceramic sintered body in which a plurality of ceramic layers containing La oxide and Ti oxide are laminated, one main surface, the other main surface, and a side surface, and the ceramic layer An inner conductor arranged between the layers and drawn out to the side surface of the ceramic sintered body, and an outer conductor formed on the side surface of the ceramic sintered body and electrically connected to the inner conductor, Mn oxide and Fe oxide are converted into MnCO ₃ equivalent and Fe ₂ O ₃ equivalent, respectively, between the layers of the ceramic layers and from the midpoint of the thickness of the ceramic sintered body to the one main surface side of the ceramic sintered body. The black ceramic layer is contained so as to have a weight ratio of 3: 2 to 1: 3, and the inner conductor and the black ceramic layer are arranged in the stacking direction of the ceramic layers. Te, characterized in that it is arranged so as not heavy.

The inner conductor, that is disposed on the other main surface of the ceramic sintered body from the midpoint of the thickness of the ceramic sintered body.

  In the ceramic electronic component according to the present invention, a terminal electrode is provided outside the ceramic sintered body so as to contact the other main surface of the ceramic sintered body and to face the internal conductor. It may be.

  The terminal electrode may be provided so as to be slidably in contact with the other main surface of the ceramic sintered body.

  The ceramic layer may be made of a dielectric, and a capacitor may be formed between the internal conductor and the terminal electrode.

In the present invention, the marker is a black ceramic layer containing Mn oxide and Fe oxide in a weight ratio of 3: 2 to 1: 3 in terms of MnCO ₃ and Fe ₂ O ₃ , respectively. Mn oxide and Fe oxide contained in the black ceramic layer react with La oxide and Ti oxide contained in the adjacent ceramic layer, and as a result, LaFe ₄ is formed at the interface between the black ceramic layer and the ceramic layer. Ti ₆ O ₁₉ phase is formed. Since the LaFe ₄ Ti ₆ O ₁₉ phase itself is black, it assists the color development of the black ceramic layer and plays a role in preventing the coloring component from diffusing into the ceramic layer.

In addition, when Mn oxide and Fe oxide are contained so as to have a weight ratio of 3: 2 to 1: 3 in terms of MnCO ₃ and Fe ₂ O ₃ , respectively, an appropriate color is exhibited and ceramic firing is performed. It is also possible to prevent warping of the body.

It is the schematic sectional drawing and schematic bottom view which show the stator which comprises some trimmer capacitors in Embodiment 1. FIG. It is a schematic sectional drawing which shows the trimmer capacitor using the stator 101 shown in FIG. It is the schematic sectional drawing and schematic bottom view which show the stator which comprises some trimmer capacitors in Embodiment 2. FIG. It is a schematic sectional drawing which shows the trimmer capacitor using the stator 201 shown in FIG. 3 is a schematic cross-sectional view showing a ceramic sintered body used in Experimental Example 1. FIG. 6 is a schematic cross-sectional view showing an unfired ceramic laminate used in Experimental Example 2. FIG. It is a schematic sectional drawing which shows the conventional trimmer capacitor.

Explanation of symbols

100 Trimmer capacitor (ceramic electronic component)
DESCRIPTION OF SYMBOLS 101 Stator 102 Ceramic layer 103 Ceramic sintered body 104 Inner conductor 105a, 105b Outer conductor 106 Black ceramic layer 200 Trimmer capacitor (ceramic electronic component)
201 Stator 202 Ceramic layer 203 Ceramic sintered body 204a, 204b Inner conductor 205a, 205b Outer conductor 206 Black ceramic layer 303 Ceramic sintered body 304 Inner conductor 306 Black ceramic layer

(Embodiment 1)
FIG. 1 is a schematic cross-sectional view and a schematic bottom view showing a stator constituting a part of the trimmer capacitor in the present embodiment. As shown in FIG. 1, the stator 101 includes a ceramic sintered body 103 in which a plurality of ceramic layers 102 are laminated, and an internal conductor that is disposed between the ceramic layers 102 and is drawn out to the side surface of the ceramic sintered body 103. 104, the outer conductor 105a formed on the side surface of the ceramic sintered body 103 and electrically connected to the inner conductor 104, and the side surface opposite to the side surface on which the outer conductor 105a is formed in the ceramic sintered body 103. And an outer conductor 105b and a black ceramic layer 106 disposed between the ceramic layers 102.

The ceramic layer 102 contains La oxide and Ti oxide. As such a ceramic, for example, a CaO—La ₂ O ₃ —TiO ₂ —Nd ₂ O ₃ ceramic, a BaO—TiO ₂ —La ₂ O ₃ —Nd ₂ O ₃ ceramic, or the like can be used.

  The inner conductor 104 is disposed so as not to overlap the black ceramic layer 106 in the stacking direction of the ceramic layers 102. For this reason, it is suppressed that the part with which the internal conductor 104 and the black ceramic layer 106 have overlapped becomes thick locally, and the structural defect of the ceramic sintered compact 103 can be prevented.

  Further, as shown in FIG. 1, the internal conductor 104 is preferably arranged on the bottom surface side of the ceramic sintered body 103 from the midpoint of the thickness (distance from the top surface to the bottom surface) of the ceramic sintered body 103. This makes it easier to form a capacitance in a trimmer capacitor described later.

  For example, gold, silver, copper, palladium, silver / palladium alloy, nickel, or the like can be used as the internal electrode 104.

  For example, gold, silver, palladium, or a silver / palladium alloy can be used as the outer conductors 105a and 105b.

  The black ceramic layer 106 functions as a marker indicating the upper and lower sides of the ceramic sintered body 103. Since it is black, even if the ceramic sintered body 103 is made of a dark ceramic such as green or brown, it can be identified as a marker. As shown in FIG. 1, the color display of the black ceramic layer 106 can be clearly identified from the bottom surface of the ceramic sintered body 103. Although not shown, the black ceramic layer 106 appears lighter than the color seen from the bottom or not at all from the upper surface of the ceramic sintered body 103. It is possible to determine that the black ceramic layer 106 is located on the bottom surface side (one main surface side) of the ceramic sintered body 103 by the difference in appearance.

The black ceramic layer 106 contains Mn oxide and Fe oxide in a weight ratio of 3: 2 to 1: 3 in terms of MnCO ₃ and Fe ₂ O ₃ , respectively. If there is more Mn oxide and less Fe oxide than this ratio, the ceramic sintered body 103 is deformed, or the black ceramic layer 106 is also identified from the upper surface of the ceramic sintered body 103 due to excessive diffusion of the Mn component. There is a fear. On the other hand, when the amount of Mn oxide is less than this ratio and the amount of Fe oxide is increased, black color development becomes too strong, and this also may cause the black ceramic layer 106 to be identified from the upper surface of the ceramic sintered body 103. .

  The stator 101 is manufactured as follows, for example. First, a ceramic slurry in which ceramic powder, an organic binder, and a solvent are mixed is formed into a sheet shape, and a ceramic green sheet constituting the ceramic layer 102 is manufactured after firing.

  Next, a metal powder, an organic binder, and a solvent are mixed to produce a conductive paste constituting the internal conductor 104 after firing, and printed on the ceramic green sheet. Further, ceramic powder containing La oxide and Ti oxide, an organic binder, and a solvent are mixed to produce a ceramic paste constituting the black ceramic layer 106 after firing, and printed on the ceramic green sheet. At this time, the ratio of the ceramic powder in the ceramic paste is preferably 30 to 70% by weight. If it is less than 30% by weight, the color may not be sufficiently developed. If it exceeds 70% by weight, it may be difficult to produce a paste.

  Next, ceramic green sheets are laminated to produce an unfired ceramic laminate. Next, the unfired ceramic laminate is fired to obtain a fired ceramic laminate. Next, a metal powder, an organic binder, and a solvent are mixed to produce a conductive paste constituting the external conductors 105a and 105b after firing, and the conductive paste is baked on the side surface of the fired ceramic laminate to external conductors. 105a and 105b are formed.

  FIG. 2 is a schematic sectional view showing a trimmer capacitor using the stator 101 shown in FIG. As shown in FIG. 2, in the trimmer capacitor 100, a metal rotor 107 is disposed on the upper portion of the stator 101, and the terminal electrode 108 and the protrusion 109 formed on the lower portion of the rotor 107 are connected to one main surface of the ceramic sintered body 103. It touches. The rotor 107 is covered with a metal cover 111 via a spring washer 110. A terminal 112 formed by extending a part of the metal cover 111 is electrically connected to the external conductor 105 b on the side surface of the ceramic sintered body 103. A through hole 113 is provided in the metal cover 111, and a driver is inserted into the driver groove 114 formed in the rotor 107 through the through hole 113.

  In the trimmer capacitor 100, a capacitance is formed between the inner conductor 104 and the terminal electrode 108, and the capacitance is changed by adjusting the rotation of the rotor 107 with a driver.

  When the trimmer capacitor 100 is manufactured, the metal cover 111, the spring washer 110, the rotor 107, and the stator 101 are placed in this order from the bottom, and the external electrode 105a and the terminal 112 are soldered. At this time, if the stator 101 is placed upside down, a desired capacity cannot be formed. Therefore, the stator 101 is placed with the other main surface on which the black ceramic layer 106 can be identified facing upward.

  In the present embodiment, the dielectric ceramic is exemplified as the material constituting the ceramic layer 102. However, the ceramic layer 102 may be composed of a resistor, a semiconductor ceramic, or the like. In this case, only the structure shown in FIG. 1 can function as a chip resistor or a chip thermistor. At this time, the black ceramic layer 106 functions as a marker for identifying the upper and lower sides when the board is mounted. Further, when the ceramic layer 102 is formed of a resistor, it can function as a variable resistor if the structure shown in FIG. 2 is adopted.

(Embodiment 2)
FIG. 3 is a schematic cross-sectional view and a schematic bottom view showing a stator that constitutes a part of the trimmer capacitor in the present embodiment. As shown in FIG. 3, the stator 201 includes a ceramic sintered body 203 in which a plurality of ceramic layers 202 are laminated, and an internal conductor that is disposed between the ceramic layers 202 and drawn out to the side surface of the ceramic sintered body 203. 204a and 204b, outer conductors 205a and 205b formed on the side surfaces of the ceramic sintered body 203 and electrically connected to the inner conductors 204a and 204b, respectively, and a black ceramic layer 206 disposed between the ceramic layers 202 .

  The stator in the present embodiment is different from that in the first embodiment in the arrangement of the internal electrode and the black ceramic layer. Other configurations are the same as those of the first embodiment, and the description thereof is omitted.

  FIG. 4 is a schematic sectional view showing a trimmer capacitor using the stator 201 shown in FIG. As shown in FIG. 4, in the trimmer capacitor 200, a metal rotor 207 is disposed on the upper portion of the stator 201, and the terminal electrode 208 and the protrusion 209 formed on the lower portion of the rotor 207 are connected to one main surface of the ceramic sintered body 203. It touches. The rotor 207 is covered with a metal cover 211 via a spring washer 210. The metal cover 211 is provided with a through hole 213, and a driver is inserted into the driver groove 214 formed in the rotor 207 through the through hole 213.

  In the trimmer capacitor 200, a capacitance is formed between the inner conductors 204a and 204b and the terminal electrode 208, and the capacitance is changed by rotating the rotor 207 with a screwdriver.

  The trimmer capacitor in this embodiment is different from that in the first embodiment in the arrangement of internal electrodes, the arrangement of black ceramic layers, the structure of the rotor, the structure of the metal cover, and the location where the capacitance is formed. Other configurations are the same as those of the first embodiment, and the description thereof is omitted.

  In the present embodiment, the dielectric ceramic is exemplified as the material constituting the ceramic layer 202. However, the ceramic layer 202 may be composed of a resistor, a semiconductor ceramic, or the like. In this case, only the structure shown in FIG. 3 can function as a chip resistor or a chip thermistor. At this time, the black ceramic layer 206 functions as a marker for identifying the upper and lower sides when the board is mounted. Further, when the ceramic layer 202 is formed of a resistor, it can function as a variable resistor if the structure shown in FIG. 3 is adopted.

Experimental example 1

  In this experimental example, the influence of the composition of the black ceramic layer was verified.

First, as a ceramic powder, a CaO—La ₂ O ₃ —TiO ₂ —Nd ₂ O ₃ ceramic powder (green color after firing) was prepared. Next, the ceramic powder was mixed with a solvent (ethyl acetate) and an organic binder (acrylic resin) to produce a ceramic slurry, which was then formed into a sheet shape by a doctor blade to produce a ceramic green sheet having a thickness of 20 μm.

  Next, Pd powder as a metal powder, α-terpineol as a solvent, and ethylcellulose as an organic binder were prepared, and these were mixed to prepare an internal conductor paste.

Next, MnCO ₃ , Fe ₂ O ₃ , and an organic vehicle were weighed so as to have the composition shown in Table 1 below, and a ceramic paste for a black ceramic layer was produced. Α-Terpineol was used as the solvent contained in the organic vehicle, and ethylcellulose was used as the organic binder.

  Next, an internal conductor paste or a black ceramic layer paste was printed on a predetermined ceramic green sheet, and a plurality of ceramic green sheets were laminated to produce an unfired ceramic laminate.

  Next, the unfired ceramic laminate was fired in an air atmosphere and the firing temperature was 1240 ° C. (kept for 2 hours) to prepare ceramic sintered body samples 1 to 11 shown in Table 1 below.

  FIG. 5 is a schematic cross-sectional view showing a ceramic sintered body in this experimental example. As shown in FIG. 5, the ceramic sintered body 303 includes an inner conductor 304 and a black ceramic layer 306 inside. In FIG. 5, the ceramic layers are not shown one by one for convenience.

  The dimension of each sample of the ceramic sintered body was 4.9 mm × 4.8 mm × 1.2 mm. Moreover, in each sample, the black ceramic layer was arrange | positioned in the position of 0.02 mm from the upper surface of the ceramic sintered compact.

  Next, color development, permeability and warpage were evaluated for each sample. The results are shown in Table 1.

  Regarding color development, the case where the black ceramic layer could be identified visually from the bottom surface (one main surface) of the ceramic sintered body was evaluated as ◯, and the case where the black ceramic layer could not be identified as x.

  As for the permeability, the case where the black ceramic layer could not be visually identified from the upper surface (the other main surface) of the ceramic sintered body was evaluated as ◯, and the case where the black ceramic layer was identified as x.

  Regarding the warpage, the difference in height between the side surface and the center of the ceramic sintered body was evaluated as ◯, and when the height difference was 0.5 mm or more as x.

  As can be seen from Table 1, for Samples 4 to 10, good results were obtained in any of color development, permeability and warpage. On the other hand, samples 1 to 3 were poorly evaluated for permeability and warpage because the Mn component was excessively added. Moreover, about the sample 11, since the Fe component was added excessively, black color development became too strong. From this, the evaluation of permeability was bad.

Experimental example 2

  In this experimental example, the influence of the formation position of the black ceramic layer was verified.

First, as the ceramic powder, CaO—La ₂ O ₃ —TiO ₂ —Nd ₂ O ₃ ceramic powder (shown green after firing) and BaO—TiO ₂ —La ₂ O ₃ —Nd ₂ O ₃ ceramic powder. (Shown brown after firing). Using these ceramic powders, two types of ceramic green sheets having a thickness of 20 μm were produced in the same manner as in Experimental Example 1.

  Next, a ceramic paste for a black ceramic layer having the same composition as Sample 5 prepared in Experimental Example 1 was prepared, and this ceramic paste was printed on each of two types of ceramic green sheets. The coating thickness of the ceramic paste was 5 μm.

  In this experimental example, a plurality of unfired ceramic laminates were produced by changing the lamination position of the ceramic green sheets on which the ceramic paste for the black ceramic layer was printed. FIG. 6 is a schematic cross-sectional view showing an unfired ceramic laminate used in this experimental example. As shown in FIG. 6, the unfired ceramic laminate 403 includes a ceramic paste 406 for the black ceramic layer inside, but the internal conductor is not formed because it has nothing to do with this experiment. In FIG. 6, the ceramic green sheets are not shown one by one for convenience.

  As shown in FIG. 6, in the thickness direction of the unfired ceramic laminate 403, the distance from the upper surface 403a to the black ceramic layer ceramic paste 406 is X (μm), and from the black ceramic layer ceramic paste 406 to the bottom surface 403b. Was set to Y (μm). The unfired ceramic laminate 403 had a thickness of 1.2 mm.

  In FIG. 6, for the sake of convenience, the distance to the middle point in the thickness direction of the ceramic paste 406 for the black ceramic layer is illustrated, but actually, the ceramic green sheet up to the portion where the black ceramic layer ceramic paste 406 is formed is illustrated. The number of sheets was counted, and the distance X was determined by multiplying the thickness of the ceramic green sheet (50 μm). Further, Y is a distance obtained by subtracting X from the total thickness of 1200 μm.

  Then, as shown in Table 2 below, a plurality of unfired ceramic laminates were produced by laminating ceramic green sheets while changing the distance X. In addition, when producing the unfired ceramic laminate, the same kind of ceramic green sheets was laminated. These unfired ceramic laminates were fired under the same conditions as in Experimental Example 1 to prepare ceramic sintered body samples 21 to 46 shown in Table 2.

In Table 2, the ceramic sintered body A is a green ceramic sintered body produced using CaO—La ₂ O ₃ —TiO ₂ —Nd ₂ O ₃ ceramic powder. The ceramic sintered body B is a brown ceramic sintered body produced using a BaO—TiO ₂ —La ₂ O ₃ —Nd ₂ O ₃ ceramic powder.

  Next, each sample was evaluated for display identifiability and front / back identifiability. The results are shown in Table 2.

  Regarding the display identifiability, ◯ indicates that the black mark could be clearly identified from at least one of the upper surface side or the bottom surface side of the ceramic sintered body, X indicates that the black mark could not be identified, and it was not clear but was generally identifiable. The thing was evaluated as △.

  As for the possibility of distinguishing the front and back, the black mark is darker and clearer when viewed from both the top and bottom sides of the ceramic sintered body and viewed from the main surface side close to the side on which the black ceramic layer is formed. Those that could be identified were evaluated as ◯, those that could not be identified were evaluated as ×, and those that were not clearly identified were generally evaluated as △.

  As can be seen from Table 2, sample No. 30 has a black ceramic layer formed at the midpoint of the thickness of the ceramic sintered body, so it cannot be identified which is darker, that is, which is front or back. It was. In Sample No. 42, a black ceramic layer is formed at the midpoint of the thickness of the ceramic sintered body, and since the distance from the main surface to the black ceramic layer is longer than that in Sample No. 30, the black dot mark itself is Could not be identified.

  Sample numbers 21, 29, 31, and sample numbers 33, 41, 43 are all subject data of the present invention, and the black dot mark can be identified and the front and back sides can be identified. The clearer the distance from the midpoint, the more clearly it was identified.

  In the above-described embodiment, the internal conductor is disposed so as not to overlap the black ceramic layer in the stacking direction of the ceramic layers. However, the black ceramic layer unintentionally extends and extends in the direction perpendicular to the stacking direction, depending on the pressure applied after the green sheets are laminated and the viscosity of the green sheets. It is possible to have overlap. Even in such a case, the effect of the present invention is not impaired even if there is a slight overlap between the inner conductor and the black ceramic layer as long as structural defects do not become apparent when the ceramic sintered body is formed. It is within the scope of the present invention.

Claims (4)

A plurality of ceramic layers containing La oxide and Ti oxide are laminated, and a ceramic sintered body having one main surface, the other main surface, and side surfaces;
An inner conductor disposed between the ceramic layers and drawn out to the side of the ceramic sintered body;
An outer conductor formed on a side surface of the ceramic sintered body and electrically connected to the inner conductor;
With
Mn oxide and Fe oxide are converted into MnCO ₃ equivalent, Fe ₂ O ₃ between the ceramic layers and on one main surface side of the ceramic sintered body from the middle point of the thickness of the ceramic sintered body, respectively. The black ceramic layer to be contained is arranged so as to have a weight ratio of 3: 2 to 1: 3 in terms of conversion,
The inner conductor and the black ceramic layer in the stacking direction of the ceramic layer is disposed so as not heavy,
The inner conductor is characterized in that it is arranged on the other main surface of the ceramic sintered body from the midpoint of the thickness of the ceramic sintered body, ceramic electronic components. The terminal electrode is provided outside the ceramic sintered body so as to be in contact with the other main surface of the ceramic sintered body and opposed to the internal conductor. 2. The ceramic electronic component according to 1. The ceramic electronic component according to claim 2 , wherein the terminal electrode is provided so as to be slidably in contact with the other main surface of the ceramic sintered body. The ceramic layer is a dielectric, serial, characterized in that the capacitance is formed between the inner conductor and the terminal electrode, a ceramic electronic component according to claim 2 or claim 3.

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