JP4404622B2 - Defect evaluation method of multilayer ceramic element and manufacturing method of multilayer ceramic electronic component - Google Patents

Description

  The present invention relates to a defect evaluation method for a multilayer ceramic element and a method for manufacturing a multilayer ceramic electronic component, and in particular, a multilayer ceramic element formed by alternately laminating ceramic layers and conductor layers exists in the element. The present invention relates to a method for producing a multilayer ceramic electronic component in which defects such as voids are evaluated using a high-frequency microscope, and only a non-defective product is transferred to the next process except for a multilayer ceramic element having a defect exceeding a specified value.

  A laminated ceramic element in which ceramic layers and conductor layers are alternately laminated is formed by laminating a plurality of ceramic green sheets on which conductor patterns are formed, pressing and integrating them, and then degreasing and firing. For example, an external electrode connected to the conductor layer is formed on a side surface of the multilayer ceramic element to manufacture a multilayer ceramic electronic component.

  The above-described multilayer ceramic elements and multilayer ceramic electronic components are subjected to various characteristic evaluations and appearance inspections in these manufacturing processes, and only non-defective products satisfying desired characteristics are shipped.

  In such an inspection process, in particular, a high-frequency microscope has conventionally been suitably used as an apparatus for evaluating defects such as voids that exist inside a multilayer ceramic element and cause characteristic deterioration (for example, Patent Document 1).

In this evaluation method using a high-frequency microscope, a multilayer ceramic element immersed in water is subjected to a high-frequency incident and a reflected wave, which is a response wave, is analyzed to detect defects such as voids that are air layers in the element. The presence and the size of can be evaluated.
JP-A-5-36567

  In recent years, as the ceramic layer has become thinner, multilayered, and miniaturized, the demand for higher quality of the element has become stricter, and stricter pass / fail judgment is required. The need to sort by

  However, in the evaluation method described in Patent Document 1, a high frequency is incident on the laminated ceramic element in which ceramic layers and conductor layers are alternately laminated, so that the incident high frequency is internal. There is a problem in that it is attenuated by the conductor layer, an appropriate reflected wave cannot be detected, and the size of the defect existing inside the multilayer ceramic element cannot be obtained accurately.

  Accordingly, an object of the present invention is to provide a method for evaluating a defect of a multilayer ceramic element capable of accurately evaluating the size of a defect present in the multilayer ceramic element and a method for manufacturing a multilayer ceramic electronic component incorporating the defect evaluation method. To do.

  The defect evaluation method for a multilayer ceramic element according to the present invention is to irradiate a high frequency from a probe to a defect present in a multilayer ceramic element in which ceramic layers and conductor layers are alternately stacked, and to reflect the reflected wave. A defect evaluation method for a multilayer ceramic element that evaluates the size of the defect from the magnitude of an echo signal that is detected and measured, wherein a frequency of a high frequency irradiated from the probe is 50 MHz or more, and the probe is It is characterized by being directed parallel to the conductor layer.

  That is, according to the present invention, for a laminated ceramic element in which ceramic layers and conductor layers are alternately laminated, a high frequency is applied in a direction parallel to the conductor layer, whereby the conductor crossing the ceramic layer in the thickness direction is obtained. Since there is no layer, the high frequency propagates only in the ceramic layer, so the attenuation of the high frequency can be suppressed, so that an appropriate reflected wave can be detected, thereby reducing the size of the defects existing inside the multilayer ceramic element. Accurate measurement evaluation. In addition, the defect which becomes object by the evaluation method of this invention means components other than the component which comprises a space | gap or an element. The high frequency in the present invention is represented by ultrasonic waves.

  The defect evaluation method for the multilayer ceramic element is characterized in that the number of conductor layers is 200 or more. By using the defect evaluation method of the present invention that irradiates a high frequency in a direction parallel to the conductor layer of the multilayer ceramic element, even if there are many conductor layers inside the element, signal attenuation by the conductor layer can be suppressed and detected.

  The defect evaluation method for a multilayer ceramic element is characterized in that the multilayer thickness is larger than the maximum width of the conductor layer. According to the defect evaluation method of the present invention, it can be suitably used for a sample having a laminate thickness larger than the width of the conductor layer or the ceramic layer, regardless of the number of conductor layers constituting the laminate element.

  In the above-described defect evaluation method for a multilayer ceramic element, the echo signal is obtained by detecting the entire depth direction excluding the surface region viewed from the incident direction of the ceramic layer. In this evaluation method, it is possible to cover most defects inside the sample while removing the surface reflection by assuming that the echo signal is the entire depth direction excluding the surface region viewed from the incident direction of the ceramic layer.

In the defect evaluation method for the multilayer ceramic element, the defect size is evaluated as follows:
(A) Using a multilayer ceramic element in which a defect having a known size is artificially formed as a standard sample, a standard echo height EHstd with respect to the defect Vstd in the standard sample is measured. Determining the relationship between the echo height EHstd and the actual defect size DVstd;
(B) The standard sample echo obtained in (a) is extracted when the echo height measured for the defect Vsamp in the multilayer ceramic element as the sample is 10% or more of the echo height EHstd of the standard sample. And a step of determining the magnitude DVsamp of the defect Vsamp of the sample from the relationship between the height EHstd and the actual defect size DVstd.

  In the present invention, the relationship between the echo height by the high frequency signal and the size of the actual defect is obtained in advance using a standard sample containing a defect of known size, and the standard sample is referred to and compared with the actual defect. Since a method for obtaining the defect size of the sample is employed, a more accurate defect size can be evaluated. The defect size in the present invention means, for example, the maximum diameter in the direction perpendicular to the high-frequency irradiation direction of the voids existing in the ceramic layer.

  In the defect evaluation method for the multilayer ceramic element, the relationship between the standard echo height EHstd and the actual defect size DVstd is DVstd / EHstd = 0.5 to 1.5. And By performing the conversion of the specified range, the actual defect size can be evaluated with higher accuracy.

  Further, the defect evaluation method for the multilayer ceramic element is characterized by evaluating a ceramic layer having a defect size of 200 μm or less. In other words, the defect evaluation method of the present invention enables highly accurate evaluation even when the defect size is as small as 200 μm or less.

  In the defect evaluation method for a multilayer ceramic element, the ceramic layer has a surface roughness (Ra) of 2 μm or less and a porosity of 5% or less.

  That is, the attenuation of echo reflection can be reduced by setting the surface roughness (Ra) to 2 μm or less in the ceramic layer that irradiates high frequency in the evaluation method of the present invention. Moreover, by setting the porosity to 5% or less, scattering due to adjacent defects can be suppressed, and the accuracy of the evaluation value of one defect size can be increased.

The manufacturing method of the multilayer ceramic electronic component of the present invention includes: (a) a step of firing a multilayer body formed by alternately stacking ceramic green sheets and conductor patterns to form a multilayer ceramic element;
(B) For the multilayer ceramic element, the multilayer ceramic element is evaluated by the multilayer ceramic element defect evaluation method according to any one of claims 1 to 3, and a defect having a defect size of 200 μm or less is detected. A step of selecting a laminated ceramic element having,
(C) forming an external electrode on the surface of the selected multilayer ceramic element.

  And by adopting the above-mentioned defect evaluation method in the manufacturing process of multilayer ceramic electronic components, it is possible to evaluate non-destructive and highly accurate defects such as internal voids that cannot be understood only by visual inspection, and this is a good product The rate can be increased.

  That is, in the present invention, when evaluating defects such as voids existing inside the multilayer ceramic element in a non-destructive manner, by irradiating the high frequency in the same direction as the plane of the laminated ceramic layer or conductor layer, Since there is no conductor layer that crosses the ceramic layer in the transmitting direction, the attenuation of the high-frequency signal by the metal component such as the conductor layer is suppressed, whereby the defect size can be evaluated with higher accuracy.

  In addition, such a defect evaluation method is adopted in the manufacturing process of the multilayer ceramic electronic component, for example, product evaluation after the formation of the multilayer ceramic element, except for a product having a defect larger than a specified size, By incorporating it into the manufacturing process so as to select only non-defective products, it is possible to improve the yield of final products that are shipped by forming external electrodes or the like on the surface of the multilayer ceramic element.

  FIG. 1 is a schematic view of a high-frequency flaw detector. As shown in FIG. 1, the measurement of the defect size of the internal defect by high-frequency flaw detection is performed with a high frequency focused by an acoustic lens (not shown) from a probe that includes a transmitter and a scanner and repeatedly applies a pulse voltage. A reflected wave (reflected sound) reflected by a sample immersed in a solvent (for example, in pure water) and returned is output as a voltage to the receiver.

  In the detector, in order to process the reflected wave of the defect to be visualized, the peak value is output as a DC voltage through a detection circuit having a receiver. While the AD conversion of the DC voltage is executed during the operation, the conversion value is arithmetically processed and then stored in the memory to display the operation video. The display monitors the reflected wave and can observe the echo of the defect in addition to the transmitted wave. The detector has a screening and data processing mechanism associated with the display. The sample that has been evaluated is moved to the case-by-case replacement device to replace the sample and prepare for the next evaluation.

  FIG. 2 is an explanatory diagram showing a state in which a multilayer ceramic element is subjected to high-frequency flaw detection. According to the defect evaluation method of the multilayer ceramic element of the present invention, a high frequency is irradiated from the probe 9 to the defect 7 existing in the multilayer ceramic element 5 in which the ceramic layers 1 and the conductor layers 3 are alternately laminated. A method of evaluating the size of the defect 7 from the magnitude of an echo signal measured by detecting the reflected wave 13, and in particular, the probe 9 is directed parallel to the conductor layer 3. And

  That is, when the incident direction of the high frequency is parallel to the conductor layer 3, the reflection from the conductor layer 3 is reduced, and the reflectance of the defect 7 can be maximized. Therefore, even when the size of the defect 7 is small Detection is possible.

  FIG. 3 is a schematic diagram showing the traveling directions of high-frequency incident waves and reflected waves incident from the probe 9 on the sample surface. As shown in FIG. 3, a high frequency is incident from the surface of the sample toward the inside from a probe 9 provided above the sample.

  Here, the frequency of the probe 9 is preferably 50 MHz or higher, particularly 75 MHz or higher, and more preferably 100 MHz or higher. When the frequency of the high frequency output is increased to 50 MHz or higher in this way, the converged beam diameter is reduced, and the size of the defect 7 is reduced. The focus accuracy can be increased, and the defect 7 having a small size can be easily detected.

  The high-frequency beam diameter is preferably larger than the size of the defect 7, but is preferably smaller than the thickness of the ceramic layer 1 that is the distance between the conductor layers 3. Thereby, the reflected wave 13 can be detected without the intensity of the echo signal being saturated with respect to the target defect. Further, the reflected wave 13 from the conductor layer 3 can be removed by making the beam diameter smaller than the thickness of the ceramic layer 1. It is more desirable that the pitch of the probe 9 is less than the diameter of the converged beam, particularly ½ or less.

  FIG. 4 is a schematic diagram of an echo for a defect obtained as an output waveform of a high-frequency microscope. As shown in FIG. 4, when the echo is focused on the reflection source due to the defect 7 inside the sample, a strong reflection echo 12 is obtained. In FIG. 4, the echo height represents the magnitude of the defect in the same direction as the high-frequency traveling direction irradiated from the probe, while the echo width represents the defect in the high-frequency traveling direction irradiated from the probe 9. On the other hand, it represents the size in the vertical direction. In addition, since the reflected wave 13 from the surface itself generate | occur | produces in the surface of the sample to evaluate, it is desirable to detect the echo in the whole depth direction except the surface part.

  FIG. 5 is a schematic diagram showing the traveling directions of high-frequency incident waves and reflected waves incident from a probe onto a sample surface having a surface roughness (Ra).

  When the high frequency is incident on the sample, it is reflected by the surface roughness and density difference of the sample and the conductor layer 3 and foreign matter having different transmittances. However, if the incident angle of the high frequency is vertical, the reflectance is the highest. Thus, the reflected wave 12 due to the internal defect 7 can be easily detected.

  For this reason, the thickness of the surface region is preferably evaluated excluding the thickness region of 50 μm or more.

  Further, the surface roughness (Ra) of the ceramic layer 1 irradiated with the high frequency is preferably 2 μm or less, particularly preferably 1 μm or less. For the surface roughness (Ra), a value measured according to JIS B 1601 is used.

  FIG. 6 is a schematic diagram showing a reflected wave scattering state exerted by the parallelism of adjacent conductor layers and the flatness of the incident surface. The flatness of the surface on which the high frequency of the multilayer ceramic element is irradiated indicates a shape deviation, and is indicated as a value of warpage. For example, if the shape of the element is a rectangular parallelepiped, the surface formed by the four sides constituting the irradiation surface is a virtual plane, and the maximum displacement amount from the virtual plane. In the present invention, the flatness of the incident surface is preferably 100 μm / mm or less, particularly 50 μm / mm or less. The flatness is measured according to JIS B 0621-1981.

  In the evaluation method of the present invention, the high frequency is irradiated in parallel to the conductor layer 3 holding the ceramic layer 1, and the parallelism of the conductor layer 3 indicates an attitude deviation, and the ceramic layer It is the thickness difference in one layer. That is, in the present invention, the thickness difference between the ceramic layers is preferably 10% or less. The parallelism is measured according to JIS B 0621-1981.

  That is, in the present invention, the measurement accuracy of the defect size can be improved by irradiating the sample with a high frequency parallel to the conductor layer 3, but the sample surface or a portion where the conductor layer 3 is curved has a high frequency. Is likely to cause scattering of the reflected wave 12, and the echo height changes, making it impossible to evaluate an accurate defect size.

  The porosity of the sample that is the object of the evaluation method of the present invention is preferably 5% or less, particularly 3% or less in terms of suppressing scattering of the high-frequency reflected wave 12. That is, the multilayer ceramic element 5 as shown in FIG. 2 is a sample with a large echo reflection attenuation. The more voids there are, the higher the frequency is scattered, the greater the attenuation of the reflected wave 12, and the reflection by the defect 7. The wave 12 becomes difficult to detect. The porosity is measured based on JIS R1634.

The defect size evaluation according to the present invention is as follows:
(A) First, a multilayer ceramic element in which a defect having a known size is artificially formed is used as a standard sample, and a standard echo height EHstd with respect to the defect Vstd in the standard sample is measured. The relationship between the actual echo height EHstd and the actual defect size DVstd is obtained.

(B) Next, an echo whose measured height is 10% or more of the echo height EHstd of the standard sample is extracted for the defect Vsamp in the multilayer ceramic element as the sample, and the standard obtained in (a) From the relationship between the echo height EHstd of the sample and the actual defect size DVstd, the size DVsamp of the defect Vsamp of this sample is obtained. The relationship between the standard echo height EHstd and the actual defect size DVstd is DVstd / EHstd = 0.5 to 1.5, and the ratio is preferably 0.8 in view of further improvement in accuracy. It is preferable that the relationship is -1.2 (please confirm). In this case, if the defect echo height is 10% or more of the echo height of the standard sample, the probability of picking up noise can be lowered. In the evaluation of the standard sample, the defect size in both the thickness direction and the in-plane direction of the ceramic layer is obtained.

  Further, the size (maximum diameter) of the defect 7 existing in the ceramic layer in the present invention is preferably 5 μm or more and 20 μm or more depending on the detection limit. On the other hand, if the evaluation method of the present invention is used, even a small defect can be evaluated. Therefore, 100 μm or less, particularly 50 μm or less is more desirable.

  FIG. 7 is an enlarged view of the void existing inside the ceramic layer held by the conductor layer. FIG. 8 is a relationship diagram when the defect size in the thickness direction of the ceramic layer of this sample obtained with reference to the echo height EHstd1 of the standard sample is D1, and the actual defect size is D2. FIG. 9 is a relational diagram when the defect size in the thickness direction of the ceramic layer of this sample obtained with reference to the echo height EHstd1 of the standard sample is V1, and the actual defect size is V2.

  Here, the actual defect size (maximum diameter) in the thickness direction of the ceramic layer 1 in this sample is D2, and the actual defect size (maximum diameter) in the direction parallel to the conductor layer is V2. In addition, the size (maximum diameter) of the defect 7 in the thickness direction of the ceramic layer 1 in this sample, which is obtained on the basis of the echo height of the standard sample, is D1, and the size (maximum diameter) of the defect 7 in the direction parallel to the conductor layer is V1.

In the evaluation method of the present invention, when the size of the defect 7 of the present sample is within the following range with respect to the size of the defect 7 of the standard sample, the highly accurate size evaluation of the present invention can be performed. That is, (1) When the defect size (maximum diameter) in the thickness direction of the ceramic layer 1 in the standard sample is D1, and the size (maximum diameter) of the defect 7 in the same direction for this sample is D2, D2 is 0 of D1. .3 to 1 times the size range,
(2) When the size (maximum diameter) of the defect 7 parallel to the conductor layer 3 in the standard sample is V1, and the size (maximum diameter) of the defect 7 in the same direction for this sample is V2, V2 is 0 of V1. Desirably, the size is in the range of 5 to 1.5 times, particularly 0.8 to 1.2 times.

  In the multilayer ceramic element of the present invention, the number of laminated ceramic layers 1 or conductor layers 3 is preferably 200 or more, particularly 300 or more. As described above, when the number of conductor layers 3 is large, the method in which high frequency is incident in the stacking direction increases the difference in density between the ceramic layer 1 and the conductor layer 3 and the attenuation of high frequency incidence and reflection by the conductor layer 3 itself. Although a clear reflected wave 12 cannot be obtained, in the present invention, since a high frequency is incident on the conductor layer 3 in parallel, attenuation by the conductor layer 3 can be suppressed and a clear reflected wave 12 can be obtained. . Moreover, in this invention, when a lamination | stacking thickness is larger than the width | variety of one side of the conductor layer 3, it is preferable at the point that a high frequency can permeate | transmit to the whole ceramic layer.

The ceramic layer 1 constituting the multilayer ceramic element of the present invention may be any ceramic, but for example, lead zirconate titanate Pb (Zr, Ti) O ₃ (hereinafter abbreviated as PZT), barium titanate BaTiO. A dielectric ceramic material having ₃ as a main component is used, but is not limited thereto.

For the conductor layer 3, for example, a conductive paste mainly composed of Ag, Al, Au, Cu, Ni, Pd, and W, a foil, a plate, a film, a resin, or a net-like material is used, but is not limited thereto. It is not a thing, and any may be sufficient as long as the resistivity is 10 ⁻³ Ωm or less.

  The standard sample used in the evaluation method of the present invention is preferably made of the same material as the ceramic layer constituting the sample, but a SUS material or a steel material may be used. The maximum size of the size in the high frequency incident direction (length in the stacking direction) may be 50 to 200 μm. The shape of the defect 7 is preferably a flat plate shape, but may be a spherical shape.

  Note that the position of the artificial defect existing in the standard sample (depth in the stacking direction from the surface) is set to a position specified in advance because high-frequency focusing can be easily performed on the artificial defect in a short time. That is, it is desirable to set the distance from the surface on which the high frequency is incident, and the position is desirably the center in the depth direction.

  The artificial defect is produced by introducing a defect source having a size specified in advance at a position where the defect is formed and scattering or disappearing by debinding or firing. The material of the artificial defect source can be made of an organic material such as a resin, but may be a carbon material. By using a standard sample having defects artificially formed in this way, a standard echo for a certain defect size can be obtained, and the relationship between the defect size and the standard echo height can be known.

  Subsequently, it is useful to employ the above-described defect evaluation method for multilayer ceramic elements of the present invention in the manufacture of multilayer ceramic electronic components.

That is, the manufacturing method of the multilayer ceramic electronic component of the present invention includes: (a) a step of firing a multilayer body formed by alternately stacking ceramic green sheets and conductor patterns to form a multilayer ceramic element;
(B) With respect to the multilayer ceramic element, the multilayer ceramic element is evaluated by the above-described defect evaluation method of the multilayer ceramic element, and the multilayer ceramic element having the defect 7 having a defect size of 200 μm or less is selected. Process,
(C) forming an external electrode on the surface of the selected multilayer ceramic element.

  That is, with respect to the multilayer ceramic element produced in the step (a), the present evaluation method can be applied to remove a sample having a large-sized defect 7. As a result, the size is 200 μm or less, particularly 100 μm or less. Furthermore, only those having defects 7 of 50 μm or less can be selected, whereby a multilayer ceramic element and a multilayer ceramic electronic component produced using the multilayer ceramic element can be manufactured with a high yield.

As a ceramic material, a slurry is prepared by mixing ceramic powder of lead zirconate titanate Pb (Zr, Ti) O ₃ , a binder made of an organic polymer, and a plasticizer, and a ceramic green sheet is formed by a slip casting method. Produced.

  A conductive pattern was formed by screen printing a conductive paste mainly composed of the metal shown in Table 1 serving as a conductive layer on one surface of the ceramic green sheet. Next, ceramic green sheets on which this conductor pattern was formed were laminated, and 1 to 10 ceramic green sheets to which no conductive paste was applied were laminated on the upper and lower surfaces of this laminate. In addition, the number of laminations in Table 1 describes the number of laminations of ceramic layers sandwiched between internal electrodes.

  Next, this multilayer ceramic molded body was placed in a mold and integrated by pressing the mold while heating at 100 ° C. or hot water CIP, and cutting into a size of 3 mm × 3 mm to 20 × 20 mm. Thereafter, the binder was removed at 300 ° C. or higher for 10 hours, and main firing was performed at 900 to 1300 ° C. for 2 hours to obtain a multilayer ceramic element as a multilayer piezoelectric element. The thickness of the fired ceramic layer was 50 to 100 μm, the conductor layer thickness was 2 to 5 μm, and the number of laminated layers was 200 to 500 layers.

  About the obtained sintered body, the surface roughness Ra was changed while the appearance was processed, and the flatness was further changed. In addition, the porosity was measured based on JISR1634, and the value was described.

A multilayer ceramic capacitor was produced as a multilayer ceramic element by the same method using barium titanate BaTiO ₃ as a constituent component of the ceramic layer and using Ni as the conductor layer.

On the other hand, the standard sample has a size of 7 × 7 × 30 mm ³ by the same process as that for producing the multilayer ceramic element mainly composed of lead zirconate titanate Pb (Zr, Ti) O ₃ described above. A standard sample was prepared. The artificial defect of the standard sample was formed by adding an acrylic spherical resin together with an organic binder when forming the ceramic green sheet. About the produced several standard samples, the magnitude | size of the artificial defect was 20-200 micrometers, respectively. The artificial defect was formed at the center of the element. The thickness of the ceramic layer after the firing of the standard sample, the thickness of the conductor layer, and the number of laminated layers were the same as in this sample.

  Next, the defect size was measured using the high frequency microscope (ultrasonic flaw detector) about the produced standard sample and the multilayer ceramic element which is this sample. In the measurement, first, a standard sample was evaluated. In this case, a standard sample is placed on the base of a high-frequency microscope so as to irradiate a high-frequency wave in a direction parallel to the conductor layer, and a defect is formed using a probe with a frequency of 30 to 200 MHz to focus on the depth position. Measured. The beam diameter was set to 10 to 100 μm.

  Subsequently, this sample was evaluated. In the evaluation of this sample, the defect size D1 in the thickness direction of the ceramic layer and the defect size V1 in the in-plane direction of the ceramic layer were determined. Specifically, using a high-frequency probe having the frequency shown in Table 2, the measurement was performed while focusing on a position away from the element surface by a certain distance. With respect to the defect echoes of all the extracted internal defects, an echo having a height higher than that shown in Table 2 with respect to the echo height of the standard sample is extracted, and defect sizes D1 and V1 obtained by high-frequency microscope evaluation are obtained from this echo. It was.

Finally, the laminated ceramic element after the measurement was subjected to cross-sectional polishing, and the actual defect sizes D2 and V2 were measured while observing the corresponding defect under a microscope, and compared with the defect size obtained from the echo.

  From the results of Tables 1 and 2, when using the defect evaluation method of the present invention in which the frequency of the high frequency irradiated from the probe is 50 MHz or more and the probe is measured parallel to the conductor layer, In the range of 0.5 to 1.5.

  In particular, the sample surface roughness is 2 μm or less, the porosity is 5% or less, and the defect size obtained with reference to the defect echo of the standard sample is the relationship between the defect size obtained from the echo and the actual defect size. A certain range of D2 = (0.5 to 0.8) D1 and V2 = (0.8 to 1.2) V1 was entered, and highly accurate evaluation was possible.

  On the other hand, even if the frequency of the high frequency emitted from the probe is the same, when the probe is measured perpendicularly to the conductor layer, the reflected wave is greatly attenuated by the conductor layer, and the defect size obtained from the echo is accurately evaluated. It was not possible (in Table 2, described as having no defects).

It is the schematic of a high frequency (high frequency) flaw detector. It is explanatory drawing which shows the state which carries out the high frequency (high frequency) flaw detection of a multilayer ceramic element. It is the schematic which shows the advancing direction of the high frequency incident wave and reflected wave which injected from the probe with respect to the sample surface. It is a schematic diagram of the echo with respect to the defect obtained as an output waveform of a high frequency microscope. It is the schematic which shows the advancing direction of the high frequency incident wave and reflected wave which injected from the probe with respect to the sample surface which has surface roughness (Ra). It is a schematic diagram which shows the scattering state of the reflected wave which the parallelism of an adjacent conductor layer and the flatness of an incident surface exert. It is an enlarged view of the space | gap which exists in the inside of the ceramic layer pinched by the conductor layer. FIG. 4 is a relationship diagram when the defect size in the thickness direction of the ceramic layer of this sample obtained with reference to the echo height EHstd1 of the standard sample is D1, and the actual defect size is D2. It is a relationship figure when the defect size of the thickness direction of the ceramic layer of this sample calculated | required on the basis of the echo height EHstd1 of a standard sample is set to V1, and an actual defect size is set to V2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Ceramic layer 3 ... Conductor layer 5 ... Multilayer ceramic element 7 ... Defect 9 ... Probe EHstd ... Echo height DVstd of standard sample ... Actual defect of standard sample size

Claims (9)

From the magnitude of the echo signal measured by irradiating a high frequency from a probe to a defect existing inside a multilayer ceramic element in which ceramic layers and conductor layers are alternately stacked, and detecting the reflected wave A defect evaluation method for a multilayer ceramic element for evaluating the size of a defect, characterized in that a frequency of a high frequency irradiated from the probe is 50 MHz or more and the probe is directed parallel to the conductor layer. For evaluating defects in multilayer ceramic elements. 2. The defect evaluation method for a multilayer ceramic element according to claim 1, wherein the number of conductor layers is 200 or more. 3. The defect evaluation method for a multilayer ceramic element according to claim 1, wherein the multilayer thickness is larger than the maximum width of the conductor layer. 4. The method for evaluating defects in a multilayer ceramic element according to claim 1, wherein the echo signal is obtained by detecting the entire depth direction excluding the surface region viewed from the incident direction of the ceramic layer. . Defect size assessment is
(A) Using a multilayer ceramic element in which a defect having a known size is artificially formed as a standard sample, a standard echo height EHstd with respect to the defect Vstd in the standard sample is measured. Determining the relationship between the echo height EHstd and the actual defect size DVstd;
(B) The standard sample echo obtained in (a) is extracted when the echo height measured for the defect Vsamp in the multilayer ceramic element as the sample is 10% or more of the echo height EHstd of the standard sample. The method of obtaining the magnitude DVsamp of the defect Vsamp of the present sample from the relationship between the height EHstd and the actual defect size DVstd. Defect evaluation method for multilayer ceramic elements. 6. The relationship between the echo height EHstd of the standard sample and the actual defect size DVstd is DVstd / EHstd = 0.5 to 1.5. Defect evaluation method for multilayer ceramic elements. The method for evaluating a defect of a multilayer ceramic element according to any one of claims 1 to 6, wherein a ceramic layer having a defect size of 200 µm or less is evaluated. The method for evaluating defects in a multilayer ceramic element according to any one of claims 1 to 7, wherein the ceramic layer has a surface roughness (Ra) of 2 µm or less and a porosity of 5% or less. (A) firing a laminate formed by alternately laminating ceramic green sheets and conductor patterns to form a multilayer ceramic element;
(B) About the multilayer ceramic element, the multilayer ceramic element is evaluated by the multilayer ceramic element defect evaluation method according to any one of claims 1 to 8, and a defect having a defect size of 200 μm or less is detected. A step of selecting a laminated ceramic element having,
And (c) forming an external electrode on the surface of the selected multilayer ceramic element, and producing a multilayer ceramic electronic component.

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