JP2014096474A - Multilayer ceramic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable multilayer ceramic capacitor the surface direction of an internal electrode of which can be known.SOLUTION: A multilayer ceramic capacitor 10 comprises a ceramic dielectric 12 including an effective part 16 having an internal electrode 14, and an ineffective part 18 not having an internal electrode. At both ends of the ceramic dielectric 12, external electrodes 30 connected with the internal electrode 14 are formed. On the side face of the ceramic dielectric 12 at both ends of the internal electrode 14, protrusions 20 having a height of 5-20 μm are provided. When the number of the internal electrodes 14 is n, the thickness between two internal electrodes arranged on the outermost side, out of a plurality of the internal electrodes 14, is Ti, and the thickness between the two internal electrodes 14 arranged on the outermost side, out of a plurality of the internal electrodes 14, and the side face of the ceramic dielectric facing them is To, Ti/(n-1) is 0.6-5.0 μm, and following relationship is satisfied; To=30-140 μm.

Description

  The present invention relates to a multilayer ceramic capacitor.

  The multilayer ceramic capacitor is arranged so as to face a rectangular parallelepiped ceramic dielectric, an internal electrode drawn out at both ends of the ceramic dielectric, and an internal electrode drawn out at both ends of the ceramic dielectric. It is comprised with the external electrode connected. When this multilayer ceramic capacitor is mounted on a circuit board, the mounting surface of the circuit board and the surface direction of the internal electrode are arranged in parallel depending on the orientation of the multilayer ceramic capacitor, or the mounting surface of the circuit board and the surface direction of the internal electrode May be arranged so as to be orthogonal to each other. The value of the stray capacitance generated due to such a positional relationship between the circuit board mounting surface and the internal electrodes may fluctuate and affect the characteristics of the multilayer ceramic capacitor.

  Therefore, when mounting a multilayer ceramic capacitor on a circuit board, if the surface orientation of the internal electrode is aligned in advance so that the positional relationship between the mounting surface of the circuit board and the main surface of the internal electrode is the same, the multilayer ceramic capacitor Capacitor variation in characteristics can be reduced. However, when the multilayer ceramic capacitor has a square cross section, it is difficult to distinguish the surface direction of the internal electrode from the appearance of the multilayer ceramic capacitor. Therefore, if a display mark that indicates the surface direction of the internal electrode is formed on the side surface of the multilayer ceramic capacitor when the multilayer ceramic capacitor is manufactured, the surface direction of the internal electrode of the multilayer ceramic capacitor can be grasped. The multilayer ceramic capacitor can be mounted on the circuit board in a state where the positional relationship with the internal electrodes is kept constant.

  When forming a display mark at the time of manufacturing a multilayer ceramic capacitor, for example, by forming a protruding display mark with porcelain paste on the surface of the dielectric before firing, and firing the dielectric and the display mark simultaneously, A dielectric having projecting display marks can be obtained. And a multilayer ceramic capacitor is produced by forming an external electrode in the both ends of a dielectric material (refer to patent documents 1). In this way, if a projecting display mark is formed on the side surface of the dielectric so that the surface direction of the inner electrode of the multilayer ceramic capacitor can be specified, the projecting display mark is imaged with a camera or the like, and the inner electrode Can be identified.

JP-A-57-72313

  However, in order to form a projecting display mark with a ceramic paste as in Patent Document 1 on a multilayer ceramic capacitor, a printing process for printing the display mark on the mother laminate, and a drying process for drying the printed ceramic paste. There is a problem that productivity is reduced.

  SUMMARY OF THE INVENTION Therefore, a main object of the present invention is to provide a multilayer ceramic capacitor having a display mark which can know the surface direction of an internal electrode and does not impair productivity.

  The present invention relates to a rectangular parallelepiped ceramic dielectric, a plurality of internal electrodes arranged so as to oppose each other inside the ceramic dielectric, and to the internal electrodes at both ends of the ceramic dielectric. A multilayer ceramic capacitor including an external electrode to be connected, the multilayer ceramic capacitor comprising a protrusion formed by pressure on a side surface of a ceramic dielectric.

  In this way, the display mark of the multilayer ceramic capacitor has a protruding portion formed by pressurization, so that a printing process and a drying process are not required and productivity is high.

  Further, in such a multilayer ceramic capacitor, the height of the protruding portion formed by pressurization is 5 μm to 20 μm, and the dielectric is two internal electrodes arranged on the outermost side among the plurality of internal electrodes. And an ineffective portion between two inner electrodes arranged on the outermost side of the plurality of inner electrodes and a side surface of the dielectric facing the inner electrode, and the thickness of the ineffective portion is To Then, To = 30 to 140 μm, where the thickness of the effective portion is Ti and the number of internal electrodes is n, n = 100 to 700, and Ti / (n−1) = 0.6 to 5 It is preferably in the range of 0.0 μm.

  Since this multilayer ceramic capacitor has an ineffective portion To of 30 to 140 μm, a number n of internal electrodes of 100 to 700, and Ti / (n−1) = 0.6 to 5.0 μm, a small and large capacity is possible. Even if the protrusions are formed by pressurization, the internal electrodes are difficult to bend, or even if they are bent, the distance between the internal electrodes is large, and therefore there is a highly reliable protrusion that is unlikely to cause a short circuit defect. It becomes a multilayer ceramic capacitor.

  According to the present invention, since the protruding portion on the side surface of the ceramic dielectric is formed by pressurization, the productivity of the multilayer ceramic capacitor is high. Moreover, even if the protruding portion is formed by pressurization, it is possible to obtain a highly reliable multilayer ceramic capacitor in which short-circuit failure is unlikely to occur. Further, the surface direction of the internal electrode can be known by detecting the protruding portion due to pressurization. Therefore, when mounting the multilayer ceramic capacitor on the mounting surface of the circuit board, etc., it is possible to mount the multilayer ceramic capacitor on the circuit board in consideration of the positional relationship between the circuit board and the internal electrodes in the ceramic dielectric. it can.

  The above-described object, other objects, features, and advantages of the present invention will become more apparent from the following description of embodiments for carrying out the invention with reference to the drawings.

It is a perspective view which shows the multilayer ceramic capacitor of this invention. FIG. 2 is an illustrative sectional view showing an internal structure of the multilayer ceramic capacitor shown in FIG. 1. FIG. 2 is an illustrative view showing a shape of a protruding portion of the multilayer ceramic capacitor shown in FIG. 1. FIG. 3 is an illustrative view showing one process for manufacturing the multilayer ceramic capacitor shown in FIGS. 1 and 2. It is an illustration figure which shows the process of pressurizing the mother laminated body obtained through the process shown in FIG. It is an illustration figure which shows the mode of the recessed part formed in the metal mold | die in the process shown in FIG. It is an illustration figure which shows the process of forming an external electrode in the ceramic dielectric obtained through the process shown in FIG. FIG. 2 is an illustrative view showing a state in which the multilayer ceramic capacitor shown in FIG. 1 is mounted on a substrate. It is a graph which shows the preferable range of a multilayer ceramic capacitor in the coordinate system which took space | interval Ti / (n-1) between internal electrodes on the horizontal axis, and took thickness To of the ineffective part on the vertical axis. FIG. 6 is a side view showing another example of the multilayer ceramic capacitor shown in FIG. 1. FIG. 6 is a side view showing still another example of the multilayer ceramic capacitor shown in FIG. 1. It is a side view which shows another example of the multilayer ceramic capacitor shown in FIG.

  FIG. 1 is a perspective view showing a multilayer ceramic capacitor of the present invention. As the dimensions in the length direction, width direction, and height direction of the multilayer ceramic capacitor 10 shown in FIG. 1, there are multilayer ceramic capacitors of various dimensions as shown in Table 1. It can also be applied to ceramic capacitors.

  The multilayer ceramic capacitor 10 includes a rectangular parallelepiped ceramic dielectric 12. The cross-sectional shape including the width direction and the height direction of the ceramic dielectric 12 may be square or rectangular. In addition, square shape points out that the ratio of the dimension of the width direction and the dimension of a height direction is the range of 0.75-1.25. A plurality of internal electrodes 14 are formed in the ceramic dielectric 12 so as to face each other, and these internal electrodes 14 are alternately drawn out to the opposing end faces of the ceramic dielectric 12.

  As shown in FIG. 2, the ceramic dielectric 12 includes an effective portion 16 that generates capacitance and an ineffective portion 18 that does not generate capacitance. A plurality of internal electrodes 14 are formed in the effective portion 16 so as to face each other. Adjacent internal electrodes 14 are formed in the ceramic dielectric 12 so as to face each other with a part of the internal electrode 14 in between. The plurality of internal electrodes 14 are alternately drawn out to two different end faces of the ceramic dielectric 12 facing each other. The internal electrode 14 is formed of a conductive paste such as Ni or Cu, for example. The effective portion 16 is a part of the ceramic dielectric 12 and is a range sandwiched between the two internal electrodes 14 at both ends of the stacked internal electrodes 14. Here, the thickness of the effective portion 16 is set in a range of 220 to 440 μm. The number of internal electrodes 14 is set to 429 to 437. The ineffective portion 18 is a portion between the two internal electrodes 14 at both ends of the plurality of internal electrodes 14 and the side surface of the ceramic dielectric 12 opposite thereto, that is, outside the effective portion 16 of the ceramic dielectric 12. The internal electrode 14 is not formed in this portion. Here, the thickness of the invalid portion 18 is set in a range of 30 to 140 μm.

  For example, in the case of a monolithic ceramic capacitor 10 having a chip size of 1.0 mm × 0.5 mm × 0.5 mm (including dimensional tolerance ± 10%), the design values are 40 μm thick for the ineffective portion 18, 420 μm thick for the effective portion 16, The number of internal electrodes 14 is 435, and the thickness between adjacent internal electrodes 14 is 1.0 μm.

  Furthermore, the number of internal electrodes 14 is n, the thickness between the two inner electrodes 14 arranged on the outermost side of the plurality of internal electrodes 14, that is, the thickness of the effective portion is Ti, and the plurality of internal electrodes 14 When the thickness between the two inner electrodes 14 arranged on the outermost side and the side surface of the ceramic dielectric 12 opposite thereto, that is, the thickness of the ineffective portion is To, these values are 0.6 μm ≦ Ti / (N−1), 30 μm ≦ To is set to be satisfied. Satisfying these relationships is that the multilayer ceramic capacitor is polished to half the dimension in the length direction so that the surface in the width direction and the height direction becomes a section, and the section is imaged with a camera. This is confirmed by measuring the number of internal electrodes 14 in the image, the thickness of the effective portion 16, and the thickness of the ineffective portion 18. In addition, it is preferable to perform an ion milling process so that the polishing surface does not cause polishing sagging of the internal electrode 14.

  Linear protrusions 20 are formed on the outer side surface of the invalid portion 18, that is, on the two opposite side surfaces of the ceramic dielectric 12 in the surface direction of the internal electrode 14. A width direction (W direction) is a length direction (L direction) connecting both ends of the ceramic dielectric 12 and a direction perpendicular to the height direction (H direction) of the ceramic dielectric 12 which is the surface direction of the internal electrode 14. The protrusion 20 is formed along the W direction at the center in the L direction.

  As shown in FIG. 3, the projecting portion 20 includes two slope portions 20a inclined in the L direction of the ceramic dielectric 12 and a top portion 20b formed so as to connect the slope portions 20a. Including. The projecting portion 20 is formed by the two inclined surface portions 20a so that the width gradually decreases from the side surface of the ceramic dielectric 12 toward the top portion 20b. The top portion 20 b is formed substantially parallel to the side surface of the ceramic dielectric 12. Therefore, although the cross-sectional shape of the projecting portion 20 is substantially trapezoidal, the transition portion from the side surface of the ceramic dielectric 12 to the slope portion 20a and the transition portion from the slope portion 20a to the top portion 20b are respectively It is formed into a rounded shape. The shape of the protruding portion 20 does not necessarily have the inclined surface portion 20a, and may be a linear protruding portion having a cross-sectional shape such as a square or a rectangle.

  External electrodes 30 are formed at both ends in the longitudinal direction of the ceramic dielectric 12 so as to be connected to the drawn internal electrodes 14. The external electrode 30 includes an end face external electrode portion 30a formed on the end face of the ceramic dielectric 12, and a side face external electrode portion 30b formed so as to wrap around four side faces from the end face external electrode portion 30a. The external electrode 30 has an underlying metal layer formed by dipping the end of the ceramic dielectric 12 in an electrode paste and sintering it. The external electrode 30 is formed by performing Ni plating and Sn plating on the base metal layer.

  The multilayer ceramic capacitor 10 described above is manufactured by a method for manufacturing a multilayer ceramic capacitor described below. In order to produce the multilayer ceramic capacitor 10, a ceramic green sheet formed of a ceramic dielectric material is prepared. Then, as shown in FIG. 4, a plurality of rectangular internal electrode patterns 42 are formed on the ceramic green sheet 40 with a conductive paste. The internal electrode pattern 42 is formed by, for example, screen printing or gravure printing.

  Next, a plurality of ceramic green sheets 40 on which the internal electrode pattern 42 is not formed are stacked, and a portion corresponding to the invalid portion 18 is formed. On top of that, a plurality of ceramic green sheets 40 on which the internal electrode patterns 42 are formed are stacked to form a portion corresponding to the effective portion 16. Further, a plurality of ceramic green sheets 40 on which the internal electrode pattern 42 is not formed are stacked, and a portion corresponding to the invalid portion 18 is formed. By stacking the ceramic green sheets 40 in this way, a mother stacked body 44 is formed. For example, when the multilayer ceramic capacitor 10 having a chip size of 1.0 mm × 0.5 mm × 0.5 mm is manufactured, all the ceramic green sheets 40 including the portion corresponding to the effective portion 16 and the portion corresponding to the ineffective portion 18 are included. The number of sheets is 435 (design value).

  After forming the mother laminated body 44, the mother laminated body 44 is pressurized using a flat metal mold | die as a pressurization process of the 1st time. The ceramic clean sheets 40 are pressurized by this first pressurization. Thereafter, as a second pressurizing step, the mother laminate 44 is pressed using a mold 48 in which a linear recess 46 is formed, as shown in FIG. At this time, the resin film 50 is sandwiched between the surface of the mold 48 where the recess 46 is formed and the mother laminate 44. When the mother laminate 44 is pressed in this state, the portion other than the recess 46 of the mold 48 presses the mother laminate strongly, and the vicinity of the surface of the mother laminate 44 corresponding to the position of the recess 46 is directed toward the recess 46. Protruding. At this time, as shown in FIG. 6, the resin film 50 is pushed by the mother laminate 44 and enters the recess 46 of the mold 48, but the resin film 50 is deepest from the end of the recess 46 to the center of the recess 46. The mother laminated body 44 also enters the recess 46 in accordance with the inclination of the resin film 50. As a result, the mother laminate 44 having projecting portions protruding in the same manner as the shape of the projecting portions 20 on the side surfaces of the ceramic dielectric 12 on both main surfaces of the mother laminate 44 is obtained.

  Here, the resin film 50 is rounded and bent at the corners of the recesses 46 and at the deepest part of the recesses 46, and in accordance therewith, protrusions are formed on the mother laminate 44 by pressing. Further, since there is the resin film 50 that bends in this way, the protruding portion can be formed without damaging the mother laminate 44 by the corners of the recess 46.

  Since the mother laminate 44 is cured in advance by being pressed with a flat plate-shaped mold in the first pressurizing step, the mother laminate 44 is added with a mold 48 having a recess 46 in the second pressurizing step. The pressure to press should be higher than the first pressurizing pressure. Further, only the second pressurization step may be performed without performing the first pressurization step. In this case, pressurization of the mother laminated body 44 with the metal mold 48 having the recesses 46 enables the pressurization of the ceramic green sheets 40 and the formation of the projecting portions at the same time.

  The pressed mother laminate 44 is cut into green chips for obtaining individual ceramic dielectrics 12. The cutting method of the mother laminated body 44 may be a cutting with a dicer or a pressing with a pressing blade.

  Next, the ceramic dielectric 12 having the internal electrode 14 is obtained by firing the green chip. The obtained ceramic dielectric 12 has protrusions 20 on the side surfaces at both ends in the surface direction of the internal electrode 14. Before and after firing, barrel polishing may be performed to round the corners of the green chip or the ceramic dielectric 12. The firing temperature of the green chip is about 1200 to 1300 ° C.

  Further, as shown in FIG. 7, one end of the ceramic dielectric 12 is held by the holder 60, and the other end of the ceramic dielectric 12 is dipped in the electrode paste layer 64 on the base 62 and dried. . Thereafter, the other end is held in the same manner as the one end of the ceramic dielectric 12, and the one end is dipped in the electrode paste layer 64 and dried, so that the electrode paste is attached to both ends of the ceramic dielectric 12. Thereafter, the base electrode is formed by sintering the attached electrode paste. The external electrode 30 is formed by performing Ni plating and Sn plating on the base electrode.

  The multilayer ceramic capacitor 10 obtained in this way is connected to lands 72 formed on the circuit board 70 with solder 74, as shown in FIG. In this case, for example, the external electrode 30 of the multilayer ceramic capacitor 10 is held by the land 72 using a solder paste, and the external electrode 30 is soldered to the land 72 by reflow.

  In this multilayer ceramic capacitor 10, light is irradiated from above the multilayer ceramic capacitor 10 in order to identify the side surface of the ceramic dielectric 12 on which the protrusions 20 are formed, and the side surface of the ceramic dielectric 12 is imaged with a camera. Is done. Here, by providing the projecting portion 20 with the inclined surface portion 20a and the apex portion 20b, the light reflection state differs between the apex portion 20b and the side surfaces of the ceramic dielectric 12 and the inclined surface portion 20a. Therefore, by binarizing the image captured by the camera between the side surface of the ceramic dielectric 12 and the top portion 30b and the slope portion 30a, an image corresponding to the difference in density can be obtained. Next, the presence or absence of the protruding portion 20 is identified based on a preset threshold value.

  In this way, the side surfaces of the ceramic dielectric 12 at both ends in the surface direction of the internal electrode 14 can be reliably identified by having the protrusions 20. Therefore, when the multilayer ceramic capacitor 10 is mounted so that the circuit board 70 and the internal electrode 14 are parallel to each other, it is mounted on the circuit board so that the side surface of the ceramic dielectric 12 having the protrusions 20 is the upper surface. That's fine. When the multilayer ceramic capacitor 10 is mounted so that the circuit board and the internal electrode 14 are orthogonal to each other, the side surface of the ceramic dielectric 12 having the protrusions 20 is orthogonal to the circuit board so that the multilayer ceramic capacitor 10 is mounted. 10 may be implemented.

  In such a multilayer ceramic capacitor 10, when the thickness of the ineffective portion 18 is To, when To is thin, when the mother laminated body 44 is pressed with the mold 48 having the recess 46, the portion corresponding to the recess 46 is internally The electrode pattern 42 may be curved toward the concave portion 46 side. In this case, the ceramic dielectric 12 having the internal electrode 14 curved on the side surface side of the ceramic dielectric 12 in the vicinity of the ineffective portion 18 can be obtained. By setting To to 30 μm or more, the internal electrode 14 The influence of bending can be reduced.

  Further, when the thickness of the effective portion 16 of the multilayer ceramic capacitor 10 is represented by Ti and the number of the internal electrodes 14 is represented by n, the distance between the adjacent internal electrodes 14 in the effective portion 16 is Ti / (n−1). Is calculated by If the internal electrodes 14 are bent due to the influence of the pressurization for forming the protrusions 20, short-circuit defects are likely to occur when the distance between the internal electrodes 14 is smaller than 0.6 μm. By setting the distance between the internal electrodes 14 to 0.6 μm or more, the occurrence rate of short-circuit defects can be suppressed.

  Further, when the height of the protruding portion 20 of the multilayer ceramic capacitor 10 is lower than 5 μm, even if the protruding portion 20 is imaged by a camera, it may not be recognized as a display mark. Further, when the height of the protruding portion 20 is higher than 20 μm, the influence of the curvature on the internal electrode 14 becomes large, and the occurrence rate of short circuit failure cannot be suppressed. Therefore, if the height of the protruding portion 20 is set to 5 to 20 μm, the protruding portion 20 can be recognized as a display mark, and the influence of the bending of the internal electrode 14 can be reduced.

  When the chip size is determined in the multilayer ceramic capacitor 10, if the distance between the internal electrodes 14 in the effective portion 16 is increased in order to suppress the occurrence rate of short-circuit defects, the thickness of the ineffective portion 18 needs to be reduced. Further, when the thickness of the ineffective portion 18 is increased in order to suppress the bending of the internal electrode 14 due to pressurization, the distance between the internal electrodes 14 needs to be reduced. From such a relationship, as shown in FIG. 9, in a coordinate system in which Ti / (n-1) is taken on the horizontal axis and To is taken on the vertical axis, a range where the required capacitance cannot be obtained (A ) And the range where the required capacitance can be obtained is (B), these ranges are separated by a straight line having a negative slope in which To and Ti / (n-1) have a certain relationship. Become. Further, the range (B) is a straight line showing To = 30 μm which is the lowest value of To and a straight line showing Ti / (n−1) = 0.6 μm which is the lowest value of Ti / (n−1). being surrounded.

  In the range (A) in which the invalid portion 18 is thick and the distance between the adjacent internal electrodes 14 is large (A), even if the display mark is a depression or a protruding portion 20 due to pressurization, the influence of the pressurization is not affected. Therefore, the internal electrode 14 is not easily bent, and even if it is bent, the distance between the internal electrodes 14 is sufficiently large, so that a short circuit failure is unlikely to occur. However, since the thickness To of the ineffective portion 18 is large and the distance Ti / (n−1) between the internal electrodes 14 is large, a necessary capacitance cannot be obtained. On the other hand, in the range (B) where the necessary capacitance can be obtained, as in the range (A), when the display mark is formed as a depression by pressurization, Ti / (n−1) is 0.6 μm or more and To is Even if designed at 30 μm or more, the pressure applied by the pressurization is directed toward the inside of the ceramic dielectric 12, and the curvature of the internal electrode 14 is in the direction in which the internal electrodes 14 inside the ceramic dielectric 12 are densely packed. Head. Therefore, the distance between the internal electrodes 14 is reduced, and a short circuit is likely to occur. Further, since the thickness To of the ineffective portion 18 is reduced, the moisture resistance is reduced. However, even in the range (B), if the display mark is the projecting portion 20 due to pressurization, the curvature of the internal electrode 14 can be suppressed, so that the distance between the internal electrodes 14 is also sufficiently maintained. And short circuit defects are unlikely to occur. Moreover, if the height of the projecting portion 20 is 5 to 20 μm, the internal electrode 14 is difficult to bend and a short circuit failure is unlikely to occur. When the display mark is the projecting portion 20, the thickness of the ineffective portion 18 is not reduced, so that moisture in the atmosphere hardly enters between the internal electrodes 14, and moisture resistance is not easily lowered.

  A multilayer ceramic capacitor 10 having a chip size of 1.0 mm × 0.5 mm × 0.5 mm was produced in each of the ranges (A) and (B). To is 20 μm, 30 μm, 100 μm, 140 μm, 150 μm (design values), and Ti / (n−1) is 0.4 μm, 0.6 μm, 2.0 μm, 5.0 μm, 6.0 μm (respectively design values). The display mark was formed by the protruding portion 20 having a height of 1 μm, 5 μm, 10 μm, 20 μm, and 25 μm by pressurization. The occurrence rate of such short-circuit defects in the multilayer ceramic capacitor 10 was examined to determine G / NG. The determination of G / NG of the occurrence rate of short circuit is 30 because the number of parameters is 30 and the rate of occurrence of short circuit of the multilayer ceramic capacitor without protrusions 20 is 4. If it is larger than that, it was judged as NG. The results are shown in the column of the occurrence rate of short circuit failure in Table 2. Further, assuming that the required capacitance is 1 μF, it is determined that G can secure a capacitance of 1 μF or more, and the case where this capacitance cannot be secured is determined as NG. The results are shown in the column. Further, the case where the insulation resistance value did not decrease in a high temperature and high humidity atmosphere was determined as G, and the case where the insulation resistance value decreased was determined as NG. The results are shown in the moisture resistance column of Table 2. When all the conditions of short-circuit defect occurrence rate, capacitance, and moisture resistance are G, the overall judgment is G, and when one condition is NG, the overall judgment is NG. In addition, the number n of the internal electrodes 14 is appropriately selected within a range of 100 to 700 so that a necessary capacitance can be obtained. When the height of the protrusion 20 is 1 μm, which is smaller than 5 μm, the presence or absence of the display mark cannot be identified by the camera. Further, when the height of the protruding portion was 25 μm or more, which was larger than 20 μm, the occurrence rate of short-circuit failure due to the internal electrode 14 being curved increased. From the above, the height of the protrusion is 5.0 to 20 μm, and when To = 30 to 140 μm and Ti / (n−1) = 0.6 to 5.0 μm, the required capacitance is required. In addition, the multilayer ceramic capacitor 10 can be obtained, which is highly reliable even if there is a protruding portion due to pressurization and can identify the presence or absence of the display mark by the protruding portion 20.

  Here, as a comparative example, a case where the display mark is formed by a depression by pressurization rather than by a projection by pressurization is given. The evaluation was performed under the same conditions as those of the multilayer ceramic capacitor in which the protrusions were formed, except that the display mark was formed with a 20 μm deep recess. When the occurrence rate of short-circuit defects of the multilayer ceramic capacitor 10 was examined, in the range (B), the occurrence rate of short-circuit defects was higher than that of the multilayer ceramic capacitor 10 in which no display mark was formed. Therefore, the internal electrode 14 is bent inward by the pressurization depression, and the distance between the internal electrodes 14 is shortened. As a result, a short circuit failure occurs and the reliability is lowered. Further, in the range (A), a short circuit failure due to the pressurization depression did not occur, but the required capacitance could not be obtained.

  In such a multilayer ceramic capacitor 10, as shown in FIG. 10, a plurality of protruding portions 20 may be formed side by side in the length direction of one side surface of the ceramic dielectric 12. Further, the protrusion 20 may be formed along the length direction of the ceramic dielectric 12. At this time, as shown in FIG. 11, the protrusions 20 may be formed so as to connect the external electrodes 30 with the shortest distance, or as shown in FIG. The protruding portion 20 may be formed. When the multilayer ceramic capacitor 10 is imaged with a camera, the sensing area is set and the imaging is performed. However, like these multilayer ceramic capacitors 10, a projecting portion other than the central portion in the length direction of the ceramic dielectric 12 is used. By forming 20, the protruding portion 20 can be detected even if the sensing area is displaced from the side surface of the multilayer ceramic capacitor.

DESCRIPTION OF SYMBOLS 10 Multilayer ceramic capacitor 12 Ceramic dielectric material 14 Internal electrode 16 Effective part 18 Invalid part 20 Projection part 30 External electrode

Claims (2)

Cuboid ceramic dielectric,
A plurality of internal electrodes arranged so as to face each other inside the ceramic dielectric and drawn to both end faces of the ceramic dielectric, and external electrodes connected to the internal electrodes at both ends of the ceramic dielectric A multilayer ceramic capacitor,
A multilayer ceramic capacitor comprising a protruding portion formed by pressure on a side surface of the ceramic dielectric. The height of the protrusion formed by the pressurization is 5 to 20 μm,
The ceramic dielectric includes an effective portion between the two inner electrodes arranged on the outermost side of the plurality of internal electrodes, and the two inner parts arranged on the outermost side of the plurality of internal electrodes. An ineffective portion between the electrode and the side surface of the dielectric material facing the electrode;
When the thickness of the invalid portion is To, To = 30 to 140 μm, the thickness of the effective portion is Ti, and the number of internal electrodes is n, n = 100 to 700, and Ti / (n−1) = The multilayer ceramic capacitor according to claim 1, wherein the multilayer ceramic capacitor is in a range of 0.6 to 5.0 μm.

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