JP2011069808A - Measuring method of sintered density of ceramic sintered compact - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a measuring method of a sintered density of a ceramic sintered compact which can determine the sintered density of the ceramic sintered compact in a short time, and measuring efficiently the sintered density, even when the size of the ceramic sintered compact is very small, or when the ceramic sintered compact includes a member made of a material other than ceramics such as an internal conductor. <P>SOLUTION: This method includes following steps: (a) a ceramic sintered compact is prepared, which has open pores, the same composition as a test sample which is an object whose sintered density is to be measured, and a revealed sintered density, and its specific surface area is measured by a BET method, and a calibration curve showing a relation between the sintered density and the specific surface area is generated; (b) the specific surface area of the ceramic sintered compact including the open pores which is the test sample is measured by the BET method; and (c) the sintered density of the test sample is determined by using the calibration curve. The sintered density of the ceramic sintered compact including a member made of a material other than ceramics such as the internal conductor is measured by the method. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for measuring the density (sintering density) of a ceramic sintered body. Specifically, the sintered density of the ceramic sintered body can be efficiently measured. The present invention relates to a method for measuring a sintered density of a ceramic sintered body capable of efficiently measuring the sintered density even when a member made of a material other than the above, such as an internal conductor, is provided.

For example, multilayer coil parts using magnetic ceramics, multilayer capacitors using dielectric ceramics, etc., are divided into individual elements from a mother multilayer body in which ceramic green sheets are laminated, and then fired under predetermined conditions. The ceramic is produced by sintering, and the sinterability of the ceramic is an important factor in expressing the intended characteristics.
That is, a ceramic electronic component composed of ceramics such as a multilayer coil component and a multilayer capacitor can obtain a product having desired characteristics by surely sintering the ceramic.

  Therefore, in the manufacturing process of these ceramic electronic components, it is important to manage the sinterability of the ceramic sintered body constituting the ceramic electronic component.

By the way, the following methods are generally used as a method for measuring and managing the sinterability of the ceramic sintered body in the manufacturing process of the ceramic electronic component.
(1) A method of examining the particle size of ceramic particles, the size of pores contained in the ceramic sintered body, and the like by an image processing method such as SEM observation of the ceramic surface and cross section.
(2) A method of examining the firing shrinkage rate by measuring the dimensions of ceramic electronic components.
(3) A method for obtaining the density of the ceramic sintered body by the Archimedes method. In this method, the dry weight of the sample is measured, boiled with pure water for a predetermined time (for example, 3 hours), and then cooled to room temperature (because the water density changes when the water temperature changes during the measurement). ), Measure the weight in water, then remove the water droplets on the surface, measure the saturated water weight, and check the content ratio of the bubbles, from the dry weight, the weight in water, and the content ratio of the bubbles, ceramic sintered body This is a method for determining the sintering density and determining the sinterability.

  As described above, there are various methods for measuring and managing the sinterability of the ceramic sintered body. In the case of the image processing method (1), the measurement error increases due to the difference in analysis conditions. There is a problem that it is easy.

  In the case of the above method (2), the smaller the ceramic electromagnetic component is, the smaller the absolute value of the dimension that shrinks by firing, which is easily affected by variations and measurement errors when cutting into individual components. There is a problem that it is difficult to perform high management.

  On the other hand, the Archimedes method of (3) is a method that can determine the sintered density of the ceramic sintered body and can accurately determine the sinterability of the ceramic sintered body. There is a problem that it is necessary to carry out and takes time. Further, there is a problem that it is difficult to measure the saturated water weight (confirmation of removal of water droplets on the surface) when the ceramic part is downsized. Furthermore, if the ceramic sintered body contains a member (substance) made of a material other than ceramic, such as an internal electrode, there is a problem that the sintered density of the ceramic itself cannot be measured.

  The present invention solves the above-mentioned problems, and it is possible to obtain the sintered density of the ceramic sintered body in a short time, and when the size of the ceramic sintered body is very small, Provided is a method for measuring the sintered density of a ceramic sintered body capable of measuring the sintered density of the ceramic itself even when the body includes a member made of a material other than ceramic, such as an internal conductor. For the purpose.

The inventors have made various studies to solve the above problems, and the density of the ceramic constituting the ceramic sintered body (sintering density) is the specific surface area of the ceramic when the ceramic includes open pores. Knowing that there is a correlation, the present invention was completed through further experiments and studies.
That is, the method for measuring the sintered density of the ceramic sintered body of the present invention is:
A method for measuring a sintered density of a ceramic sintered body having open pores,
(a) The ceramic sintered body having the open pores and containing the open pores whose sintered density is to be measured has the same composition as the ceramic, the sintered density is known, and the sintered density is within a predetermined range. Preparing a plurality of ceramic sintered bodies made different from each other, measuring their specific surface area by the BET method, and creating a calibration curve representing the relationship between the sintered density and the specific surface area;
(b) a step of measuring a specific surface area of a ceramic sintered body including open pores whose sintered density is to be measured by a BET method;
(c) From the value of the specific surface area measured in the step (b), using the calibration curve, obtaining a sintered density of the ceramic sintered body including the open pores, .

  The method for measuring the sintered density of the ceramic sintered body of the present invention can also be applied when the ceramic sintered body includes a member made of a material other than ceramic.

  Further, the method for measuring the sintered density of the ceramic sintered body of the present invention can be suitably applied when the ceramic sintered body is a multilayer ceramic element including an internal conductor inside the ceramic multilayer body. It is.

  Further, the present invention can be applied particularly suitably when the ceramic sintered body constitutes a multilayer ceramic coil component including a coil internal conductor inside the ceramic multilayer body.

The present invention is particularly significant when the ceramic sintered body has a volume of 1 mm ³ or less.

  The method for measuring the sintered density of the ceramic sintered body according to the present invention comprises: (a) a ceramic sintered body (test sample) having open pores (open pores) and including open pores whose sintered density is to be measured; Prepare a plurality of ceramic sintered bodies with the same ceramic composition, known sintered density, and different sintered densities within a predetermined range, and measure their specific surface area by the BET method. A step of creating a calibration curve representing the relationship between the sintered density and the specific surface area, and (b) a step of measuring the specific surface area of the ceramic sintered body containing open pores, which is the test sample, by the BET method, c) a step of obtaining a sintered density of the test sample using a calibration curve. From the specific surface area of the test sample measured by the BET method, the sintering of the ceramic sintered body using the calibration curve described above is provided. Since the density is calculated, the conventional Archimedes method is used. Remote short time can be obtained a sintered density of the ceramic sintered body.

  In the present invention, the sintered density of the ceramic sintered body is a state in which pores are included in the ceramic volume constituting a sintered body (ceramic sintered body) obtained by firing a ceramic laminate or the like. Density (bulk density). That is, according to the present invention, as described below, even when an internal conductor or the like is provided, the sintering density of the ceramic itself constituting the ceramic sintered body can be efficiently reduced without being affected by such influence. It can be measured well.

Further, the present invention uses a correlation between the specific surface area of the ceramic related to the open pores contained in the ceramic constituting the ceramic sintered body and the density of the ceramic (sintered density). Therefore, it is necessary that the ceramic constituting the ceramic sintered body includes open pores.
The ratio of the open pores contained in the ceramic is such that the water absorption rate is 0.1% by weight or more when the water absorption rate is the water rate when all the open pores contained in the ceramic are filled with water. It is desirable that the ratio be

  The mechanism by which the sintered density of the ceramic can be determined according to the present invention is as follows. That is, the open pores (open pores) existing in the ceramic constituting the ceramic sintered body are proportional to the sintered density in the case of ceramics having the same composition (the higher the sintered density, the fewer open pores) . There is a correlation between the ratio of open pores contained in the ceramic and the “specific surface area of the ceramic”. Therefore, by measuring the specific surface area by the BET method, the sintered density can be quickly obtained from a calibration curve prepared in advance and representing the relationship between the sintered density of the ceramic and the specific surface area.

  In the Archimedes method, if the ceramic sintered body includes a member (substance) made of a material other than ceramic, such as an internal electrode, the sintered density of the ceramic itself cannot be measured. By applying, for example, when a ceramic sintered body is provided with a material (substance) other than ceramic, such as an internal conductor disposed inside or an external electrode disposed on the surface, The sintered density of the sintered body can be measured.

That is, the specific surface area (SSA) measured by the BET method includes the surface area of the ceramic sintered body and the surface area of the open pores. Among these, since the surface area of the ceramic sintered body does not change even if the sintered density changes, the change in the specific surface area (SSA) becomes the change in the amount of open pores. Therefore, even a ceramic sintered body containing a substance other than ceramic can obtain information with relatively high accuracy regarding the sintered density from the specific surface area (SSA) measured by the BET method.
However, if the proportion of the non-ceramic member contained in the ceramic sintered body becomes too large, the measurement accuracy of the sintered density is lowered. Therefore, the proportion of the non-ceramic member contained in the ceramic sintered body is usually 30% by weight. % Or less is desirable.
If only the external electrode is provided, it is possible to measure the sintered density of the ceramic itself by the Archimedes method before forming the external electrode, but it has an internal conductor that is fired simultaneously with the ceramic. The method of the present invention is particularly meaningful because the sintered density of the ceramic itself cannot be measured by the Archimedes method.

  In addition, in the case of a laminated coil component having a structure in which an inner conductor for coil formation is disposed via a ceramic layer, the sintered state of the ceramic sintered body has characteristics such as the impedance value and stability of the laminated coil component. In particular, it is necessary to accurately measure and manage the firing state. In this case, the ceramic sintered body is coiled inside the ceramic laminate. In the case of constituting a multilayer ceramic coil component provided with an internal conductor, it is particularly significant that the sintered density of the ceramic sintered body can be accurately measured.

In the Archimedes method, when the size of the ceramic sintered body is reduced, it becomes difficult to confirm whether or not water droplets on the surface have been removed, and an accurate saturated weight cannot be obtained. However, the present invention is applied. Thus, the sintered density of a ceramic sintered body having a volume of 1 mm ³ or less (for example, a multilayer ceramic chip having a length of 0.6 mm, a width of 0.3 mm, and a thickness of 0.3 mm) can be accurately measured.

It is side surface sectional drawing which shows the structure of the ceramic sintered compact by which a sintering density is measured by the method of the Example of this invention. It is a disassembled perspective view which shows the structure of the ceramic sintered compact by which a sintering density is measured by the method of the Example of this invention. FIG. 3 is a front sectional view showing a laminated coil component formed by disposing external electrodes on the ceramic sintered body of FIGS. 1 and 2. It is a figure which shows the calibration curve showing the relationship between the sintered density of a ceramic sintered compact, and a specific surface area.

  Hereinafter, the present invention will be described in more detail with reference to embodiments of the present invention.

[1] Production of Ceramic Sintered Body with Inner Conductor In this example, Fe ₂ O ₃ was 48.0 mol%, ZnO was 29.5 mol%, NiO was 14.5 mol%, and CuO was 8.0 mol%. After the magnetic ceramic raw materials blended at a ratio were wet mixed, calcination was performed. The obtained calcined product was wet pulverized into a ceramic slurry, and then the ceramic slurry was molded to obtain a ceramic green sheet. The ceramic green sheet formed with the internal conductor pattern (coil conductor pattern for the coil) formed by forming a via hole and printing the conductive paste for forming the internal conductor is not formed on the obtained ceramic green sheet. After the ceramic green sheets for the outer layer region were laminated, they were pressure-bonded and cut into a predetermined size to produce an unfired ceramic laminate.

  And by firing this ceramic laminate under different temperature conditions, a plurality of ceramic sintered bodies having different sintered states (for example, the dimensions are 2.0 mm in length, 1.0 mm in width, 1. mm in thickness). 0 mm multilayer ceramic chip) was produced.

  1 is a side sectional view schematically showing the structure of the ceramic sintered body produced as described above, FIG. 2 is an exploded perspective view, and FIG. 3 is for forming external electrodes on the ceramic sintered body. It is front sectional drawing which shows the laminated coil component obtained by these.

  That is, the ceramic sintered body 3 shown in FIG. 1 and FIG. 2 is provided with a plurality of internal conductors 2 arranged via the magnetic ceramic layer 1 and interlayer-connected via the via holes 6 and the internal conductors 2. The outer layer 1a is not provided, and the spiral coil 4 is provided inside.

3 has a pair of external electrodes 5a and 5b that are electrically connected to both ends 4a and 4b of the spiral coil 4 at both ends of the ceramic sintered body 3 shown in FIGS. It is formed by arrange | positioning.
In addition, the ratio of the non-ceramic member (internal conductor) in the ceramic sintered compact 3 which was produced as mentioned above and was equipped with the helical coil 4 inside is 30 weight% or less.

[2] Production of ceramic sintered body not provided with internal conductor Ceramic green sheet which is the same as that used for producing ceramic sintered body including the above internal conductor, and does not have internal conductor pattern An unsintered ceramic sintered body (laminated ceramic chip) cut to a predetermined size using a green sheet is prepared, and in the same manner as in [1] above, under different temperature conditions (the same temperature as in [1] above) Fired under a certain condition), a plurality of ceramic sintered bodies having different sintered states (for example, the dimension is long) A multilayer ceramic chip having a thickness of 2.0 mm, a width of 1.0 mm, and a thickness of 1.0 mm was produced.

[3] Measurement of specific surface area A plurality of ceramic sintered bodies produced in the above [1], including the internal conductor, having a ratio of open bubbles of 0.1% by weight or more in terms of water absorption, and having different sintered states ( Multilayer ceramic chip) and a plurality of ceramic sintered bodies produced in [2] above, including no internal conductor, having a ratio of open bubbles of 0.1% by weight or more in terms of water absorption, and having different sintered states ( The specific surface area of the multilayer ceramic chip) was measured.

In measuring the specific surface area, the specific surface area (SSA) was measured by the BET method according to the following procedure using a fully automatic BET specific surface area measuring device Macsorb (HM Model-1201: manufactured by Mountec Co., Ltd.). .
(1) Measurement of cell weight of fully automatic BET specific surface area measuring device
(2) Setting of sample in cell and setting of cell in fully automatic BET specific surface area measuring device
(3) Set of conditions for fully automatic BET specific surface area measuring device
(4) Automatic measurement according to the following process using a fully automatic BET specific surface area measuring device
(a) Degassing at 400 ° C
(b) Cooling
(c) Liquid nitrogen cooling and nitrogen adsorption
(d) Temperature rise to room temperature and nitrogen desorption
(5) Measurement of cell + sample weight In measuring the specific surface area, the time required for each of the above steps (1) to (5) was simultaneously measured and evaluated in the following [7].

[4] Preparation of calibration curve A plurality of sintered ceramics produced in [2] above, including no internal conductor, having a ratio of open bubbles of 0.1% by weight or more in terms of water absorption, and having different sintered states The body was subjected to the following steps by the Archimedes method, and the sintered density of the ceramic sintered body was determined from the dry weight, the weight in water, and the content ratio of bubbles.
(1) Measurement of dry weight
(2) boiling in pure water
(3) Cool to room temperature
(4) Underwater weight measurement
(5) Saturation weight measurement From the relationship between the measured sintered density data and the specific surface area data measured in [3] above, a calibration curve representing the relationship between the two was prepared.
FIG. 4 is a calibration curve showing the relationship between the sintered density and the specific surface area of the ceramic sintered body prepared as described above.

In addition, when calculating | requiring a sintered density by the Archimedes method here, the time which each process of said (1)-(5) requires is measured simultaneously, The comparison data for evaluation of this invention in following [7] It was.
[5] Regarding the sintered density of the ceramic sintered body provided with the internal conductor, the ratio of open bubbles, including the internal conductor, determined in [3] above is 0.1% by weight or more in terms of water absorption, and From the specific surface area values measured for a plurality of ceramic sintered bodies (multilayer ceramic chips) having different sintered states, the sintered density was determined using the calibration curve (FIG. 4) created in [4] above. That is, the sintered density corresponding to the measured specific surface area value is read from the calibration curve in FIG. 4, and the value is set as the sintered density of the ceramic sintered body (test sample) whose sintered density is to be measured. .

  As a result, it was confirmed that the sintered density of the ceramic sintered body including the internal conductor can be measured with high accuracy from the value of the specific surface area measured by the BET method.

  For confirmation, when the specific surface area is measured by the BET method for a ceramic sintered body having an inner conductor and a ceramic sintered body not having an inner conductor, which are fired under the same firing conditions, Approximately the same specific surface area value was obtained. When the sintering density is obtained from the specific surface area value, substantially the same sintering density value is obtained.

  From the above results, it was confirmed that according to the method of the present invention, the sintered density of the ceramic sintered body including the internal conductor can be efficiently measured.

[6] Regarding the sintered density of a ceramic sintered body whose size cannot be determined by the Archimedes method, the size is small and the sintered density cannot be measured by the Archimedes method, the length is 0.6 mm, the width is 0.3 mm, A ceramic sintered body having a thickness of 0.3 mm (the ratio of open bubbles was 0.1% by weight or more in terms of water absorption) was produced.
Then, the specific surface area (SSA) of this ceramic sintered body was measured by the BET method in the same manner as in [3] above.
And the sintered density was calculated | required from the value of the measured specific surface area using the calibration curve (FIG. 4) created by said [4]. That is, the sintered density corresponding to the measured specific surface area value is read from the calibration curve in FIG. 4, and the value is set as the sintered density of the ceramic sintered body (test sample) whose sintered density is to be measured. .
As a result, it is difficult to measure the saturated water weight (confirmation of water droplet removal on the surface), and the Archimedes method cannot practically measure the sintered density. Length 0.6 mm, width 0.3 mm, thickness 0.3 mm It was confirmed that the sintered density of the ceramic sintered body could be measured.
In addition, also when measuring the sintering density of a ceramic sintered compact with a small size, it is desirable that the ratio of non-ceramic members (internal conductors) such as an internal conductor is 30% by weight or less.

[7] Time required for measurement of sintered density As described above, the specific surface area (SSA) measured in the above [3] is measured by the BET method, and the sintering density is determined from the value. Table 1 shows the time required and the total time.
Table 2 shows the time required for each step and the total time when the sintered density is obtained by the Archimedes method investigated in [4] above.

  From Tables 1 and 2, the specific surface area measurement by the BET method does not require boiling for a long time as in the case of measuring the sintering density by the Archimedes method, so the sintering density is measured by the Archimedes method. Compared to the case, it was confirmed that the time required to measure the sintered density by the method of the present invention was shortened to about 1/4.

  As described above, according to the method for measuring the sintered density of the ceramic sintered body according to the present invention, it is possible to measure the sintered density in a shorter time than when the sintered density is measured by the Archimedes method. Become. In the Archimedes method, the sintered density of a ceramic sintered body having a small size (for example, a length of 0.6 mm, a width of 0.3 mm, a thickness of 0.3 mm, etc.) or a ceramic sintered body including an internal conductor is used. However, according to the method of the present invention, as described above, the sintered density of the ceramic itself can be efficiently measured even when the ceramic sintered body includes an internal conductor.

  In the above embodiment, the case where the ceramic sintered body is a multilayer ceramic element constituting a multilayer coil component has been described as an example. However, the ceramic sintered body capable of measuring the sintered density by applying the present invention is described. The bonded body is not limited to this, but for measuring the sintered density of a ceramic sintered body produced in the manufacturing process of various ceramic electronic parts such as multilayer ceramic capacitors, LC composite parts, ceramic piezoelectric parts, and resistive elements. The present invention can be widely applied.

In the above embodiment, the ceramic constituting the ceramic sintered body is described as an example in which the ceramic is a ferrite ceramic formed by firing a raw material containing Fe ₂ O _3, ZnO, NiO, CuO. The present invention can be widely applied when measuring the sintered density of a ceramic sintered body made of various ceramics such as a dielectric ceramic, a piezoelectric ceramic, and a resistor ceramic.
Also, in the above examples, a plurality of ceramic sintered bodies having different sintered states are produced by firing at different temperature conditions. However, the mixing conditions, pulverization conditions, calcination conditions, and pressure bonding after lamination of ceramic raw materials are produced. It is also possible to produce a plurality of ceramic sintered bodies having different sintered states by changing the conditions of each process such as the conditions.

  The present invention is not limited to the above embodiment in other points as well. The types of members (for example, internal conductors) made of a material other than the ceramic provided in the ceramic sintered body, the arrangement thereof, the ceramic Various applications and modifications can be made within the scope of the invention with respect to specific types of analyzers used to measure the specific surface area of the sintered body.

DESCRIPTION OF SYMBOLS 1 Magnetic ceramic layer 1a Outer layer 2 Internal conductor 3 Ceramic sintered body (magnetic ceramic element)
4 Helical coils 4a, 4b Both ends of the helical coil 5a, 5b External electrode 6 Via hole

Claims (5)

A method for measuring a sintered density of a ceramic sintered body having open pores,
(a) The ceramic sintered body having the open pores and containing the open pores whose sintered density is to be measured has the same composition as the ceramic, the sintered density is known, and the sintered density is within a predetermined range. Preparing a plurality of ceramic sintered bodies made different from each other, measuring their specific surface area by the BET method, and creating a calibration curve representing the relationship between the sintered density and the specific surface area;
(b) a step of measuring a specific surface area of a ceramic sintered body including open pores whose sintered density is to be measured by a BET method;
(c) From the value of the specific surface area measured in the step (b), using the calibration curve, obtaining a sintered density of the ceramic sintered body including the open pores, A method for measuring the sintered density of a ceramic sintered body.   The method for measuring a sintered density of a ceramic sintered body according to claim 1, wherein the ceramic sintered body includes a member made of a material other than ceramic.   2. The method for measuring a sintered density of a ceramic sintered body according to claim 1, wherein the ceramic sintered body is a laminated ceramic element having an inner conductor inside a ceramic laminated body.   2. The measurement of the sintered density of the ceramic sintered body according to claim 1, wherein the ceramic sintered body constitutes a multilayer ceramic coil component including a coil inner conductor inside the ceramic laminated body. Method. The method for measuring a sintered density of a ceramic sintered body according to any one of claims 1 to 4, wherein the ceramic sintered body has a volume of 1 mm ³ or less.

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