JP2008074679A - Multilayer ceramic component and its production method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer ceramic component excellent in withstand voltage characteristics and its production method. <P>SOLUTION: The method for production of the multilayer ceramic component includes a process of laminating the non-sintered ceramic layers and non-sintered conductor layers. The non-sintered ceramic layer contains glass powders (SiO<SB>2</SB>-B<SB>2</SB>O<SB>3</SB>-Al<SB>2</SB>O<SB>3</SB>-CaO-based glass or the like) having D90 of ≤8 μm, and also inorganic filler powders (alumina, calcium titanate or the like) having D90 of ≤4.5 μm. The multilayer ceramic component 1 contains glass and an inorganic filler, and has the ceramic layers 111 to 116 in which pores 2 are formed. The thickness (t) of the ceramic layer is ≥10 μm but ≤120 μm. The maximum diameter of the pore in the ceramic layer is ≤7.5 μm, and the number of pores having the maximum diameter of ≥4 μm is ≤t/5.5 in the cross section of t×t square in a laminating direction. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a ceramic multilayer component and a manufacturing method thereof. More specifically, the present invention relates to a ceramic multilayer component having excellent withstand voltage characteristics and a method for manufacturing the same.

In the following Patent Document 1, by controlling the average particle size of the whole powder to be 2.5 μm or less, the maximum diameter of the void can be suppressed to 30% or less of the thickness of the ceramic layer, and the dielectric breakdown voltage can be reduced. It is disclosed that it can be increased.
In Patent Document 2 below, high-strength wiring is achieved by controlling the correlation of 10% particle size (D10), average particle size (D50), and 90% particle size (D90) of the whole powder to a predetermined range. It is disclosed that a substrate is obtained.
Further, in the following Patent Document 3 ([0035] etc.), a glass powder having an average particle diameter (D50) of 0.1 to 5 μm and a filler powder having an average particle diameter (D50) of 0.1 to 5 μm are used. Thus, it is disclosed that the maximum diameter of pores formed in the obtained low-temperature fired ceramic can be suppressed to 10 μm or less.

JP 2004-228411 A JP 2003-165765 A JP 2004-231454 A

However, as shown in Patent Document 1, it is difficult to make the average particle size of the whole powder to be 2.5 μm or less, and the cost becomes very high. On the other hand, there is a problem that the dielectric breakdown voltage obtained is not sufficient at 23 V at the maximum in the thickness of the ceramic layer of 25 μm. Further, as shown in Patent Document 2, it is difficult to make the average particle size of the glass powder 5 μm or less, similarly to Patent Document 1, and there is a problem that the cost is very high. Furthermore, as shown in Patent Document 3, even if the correlation is reached, sufficient voltage resistance may not be obtained.
The present invention has been made in view of the above, and an object of the present invention is to provide a ceramic multilayer component having excellent withstand voltage characteristics and a method for manufacturing the same.

The present inventors diligently studied about the presence of a ceramic layer having a specifically low withstand voltage characteristic. As a result, when the pores formed in the ceramic layer after firing are large, or even if the pores are relatively small, they are continuously present, and as a result, a sufficient insulation distance cannot be secured in these portions. It has been found that the withstand voltage characteristics may be deteriorated.
Furthermore, as shown in the above-mentioned patent documents and the like, these types of pores can generally be suppressed to some extent by reducing the average particle size of the powder used, but the glass powder is pulverized to a small diameter of 3 μm or less. It was difficult, and even if it could be done, it turned out to be very expensive. Therefore, when the particle size control of these powders to be used was examined in detail, it was found that pores can be effectively suppressed and a withstand voltage characteristic of 250 V or higher can be obtained without excessive pulverization. The present invention has been completed.

That is, the present invention is as follows.
(1) A method for producing a ceramic multilayer component comprising: a laminating step of laminating an unsintered ceramic layer and an unsintered conductor layer to obtain an unsintered ceramic multilayer component; and a firing step of firing the unsintered ceramic multilayer component. And
The unfired ceramic layer contains a glass powder having a 90% particle size of 8 μm or less in a particle size distribution, and an inorganic filler powder having a 90% particle size of 4.5 μm or less in the particle size distribution. Production method.
(2) The method for producing a ceramic multilayer component according to (1), wherein the content of the glass powder is 40 to 85% by volume when the total of the glass powder and the inorganic filler powder is 100% by volume. .
(3) glass constituting the glass _{powder, SiO 2 -B 2 O 3 -Al} 2 O 3 -CaO based glass in the above (1) or (2) The method of producing ceramic multilayer part according to.
(4) A ceramic multilayer component comprising a ceramic layer containing glass and an inorganic filler and having pores formed therein,
The ceramic layer has a thickness t of 10 μm to 120 μm,
In the ceramic layer, the number of pores having a maximum diameter of 7.5 μm or less and a maximum diameter of 4 μm or more is t / 5.5 or less in a t × t square cross section in the stacking direction. A ceramic multilayer part characterized by being.
(5) The ceramic multilayer component according to (4), wherein the pore has an R / r of 1.4 or less when the major axis of the pore is R and the minor axis is r.

According to the method for producing a ceramic multilayer component of the present invention, a ceramic multilayer component capable of effectively suppressing the size and number of pores formed in the ceramic layer and obtaining excellent withstand voltage characteristics can be obtained.
When the total of the glass powder and the inorganic filler powder is 100% by volume, when the content of the glass powder is 40 to 85% by volume, a ceramic multilayer part having particularly excellent withstand voltage characteristics can be obtained. . In general, when the amount of glass powder used is large, pores due to good sintering and insufficient firing are unlikely to occur, but when overfired, spherical pores due to glass foaming tend to occur. However, in the present invention, the size and number of pores formed can be suppressed even in such a range.
When the glass constituting the glass powder is SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —CaO glass, in addition to the above effects, it can be fired at a lower temperature and suppresses the reaction with the inorganic filler. Therefore, the firing temperature can be adjusted widely.

The ceramic multilayer component of the present invention does not have a large pore having a maximum diameter exceeding 7.5 μm, and the number of pores having a diameter of 4 μm or more is extremely small. For this reason, pores are not formed on the front and back of the ceramic layer. Therefore, particularly when used in a situation where conductor layers are provided on the front and back sides of the ceramic layer, current leakage between the layers of the ceramic layer hardly occurs, and excellent withstand voltage characteristics can be exhibited.
When the major axis R and minor axis r of the pore are R / r ≦ 1.4, the pores are sufficiently fired and have particularly excellent withstand voltage characteristics.

The present invention will be described in detail below.
[1] Manufacturing method of ceramic multilayer component The manufacturing method of a ceramic multilayer component according to the present invention includes a lamination step of laminating an unfired ceramic layer and an unfired conductor layer to obtain an unfired ceramic multilayer component, and the unfired ceramic multilayer component. A method for producing a ceramic multilayer part comprising:
The unfired ceramic layer contains glass powder having a 90% particle size of 8 μm or less in the particle size distribution and an inorganic filler powder having a 90% particle size of 4.5 μm or less in the particle size distribution.

The “lamination step” is a step of obtaining an unfired ceramic multilayer component by laminating an unfired ceramic layer and an unfired conductor layer.
The “unfired ceramic layer” is a layer containing glass powder and inorganic filler powder, and is a layer that is fired to become a ceramic layer.
The “glass powder” is a powder that is baked to become glass. Further, this glass powder has a 90% particle size (hereinafter also simply referred to as “D90”) in the particle size distribution of 8 μm or less. When D90 exceeds 8 μm and D90 of the inorganic filler powder exceeds 4.5 μm, the maximum diameter of the pores suddenly increases and the number of pores also increases. For this reason, the withstand voltage of 250 V or more may not be obtained.
D90 of glass powder should just be 8 micrometers or less, and although it does not specifically limit, it can be 7.7 micrometers or less, Furthermore, it can be 6.1 micrometers or less. However, it is very difficult to reduce D90 to 5.0 μm or less by a method that can be normally used (ie, vibration mill, ball mill, jet mill, etc.). Therefore, D90 is preferably 5.5 to 8 μm, preferably 5.6 to 7.7 μm, and more preferably 5.7 to 6.1 μm.

In addition to the above D90, D10 is preferably 2.5 μm or less, more preferably 2.0 μm or less, and particularly preferably 0.3 to 1.7 μm. Further, in addition to D90 and D10, the average particle size (D50) is preferably 5.0 μm or less, more preferably 4.5 μm or less, and particularly preferably 2.3 to 4.0 μm. preferable. These preferable ranges of D10 to D90 can be a combination of each.
Further, the correlation between the particle sizes of the glass powder is preferably such that D10 / D50 is 0.10 to 0.45 (more preferably 0.13 to 0.45, still more preferably 0.13 to 0.17). . Moreover, it is preferable that D90 / D50 is 1.8-2.3.

  The composition of the glass which comprises the said glass powder is not specifically limited. That is, for example, examples of the glass include glass containing Si and alkaline earth metal elements such as Ca, Mg, and Ba. This glass may contain Al. Furthermore, alkali metal elements such as Na and K may be contained. The glass may be glass containing B, glass containing Pb, or the like. The glass is preferably a borosilicate glass containing Si and B, more preferably a borosilicate glass containing Si, B and Al, and particularly preferably a borosilicate glass containing Si, B, Al and Ca.

Examples of the borosilicate glass containing Si, B, Al, and Ca include SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —CaO-based glass. As this SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —CaO-based glass, one or two kinds of glass consisting only of oxides of four kinds of elements of Si, B, Al and Ca, and other oxides are used. A glass containing at least seeds may be mentioned. Examples of the other oxides include oxides of alkaline earth metal elements (Mg, Ba, and Sr) excluding Zn and Ca.

Although the content of each element in the _{SiO 2 -B 2 O 3 -Al 2} O 3 -CaO based glass is not particularly limited, and containing at least Si, B, Al, Ca and _{O, SiO 2, B 2 O} 3 Assuming that the total of Al ₂ O ₃ and CaO is 100 mol%, Si is 20 to 40 mol% in terms of SiO ₂ , B is 15 to 30 mol% in terms of B ₂ O ₃ , and Al is in terms of Al ₂ O ₃ It is preferable that 10-25 mol% and Ca are 10-25 mol% in CaO conversion. Furthermore, when the entire SiO ₂ —B ₂ O ₃ —AL ₂ O ₃ —CaO glass is 100 mol%, the total of SiO ₂ , B ₂ O ₃ , Al ₂ O ₃ and CaO is 85 mol% or more. Some glasses are preferred. Further, when this glass contains other oxides, the other oxides are converted to oxides when the total of SiO ₂ , B ₂ O ₃ , Al ₂ O ₃ and CaO is 100 mol% ( ZnO, MgO, BaO, SrO, etc.) is preferably 5 to 15 mol%.

When SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —CaO-based glass is used, since it can be fired at a lower temperature, it has low resistance and low melting point metal (Cu, Ag, Au, etc.). Co-firing is easy, and in particular, co-firing can be performed at a low temperature of 1000 ° C. or lower. Furthermore, the SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —CaO-based glass is a glass and inorganic glass that is fired even when an inorganic filler having a high relative dielectric constant such as CaTiO ₃ and TiO ₂ is used as the inorganic filler. The reaction with the filler is sufficiently suppressed, and the firing temperature can be widely adjusted.

  The “inorganic filler powder” is a powder made of an inorganic material that is contained in the unfired ceramic layer and is contained in the ceramic layer after firing (however, the particles constituting the powder have a spherical particle shape) And those that are elliptical, columnar, and fibrous). In the ceramic layer in the fired ceramic multilayer part, the inorganic filler powder is usually contained dispersed as an inorganic filler in the glass using the glass as a matrix. The inorganic filler powder may change (composition, state, etc.) before and after firing, but usually hardly changes before and after firing. However, a part of the glass may be deposited through baking and consequently contained as an inorganic filler.

This inorganic filler powder has a D90 in the particle size distribution of 4.5 μm or less. When D90 exceeds 4.5 μm and D90 of the glass powder exceeds 8 μm, the maximum diameter of the pores suddenly increases and the number of pores also increases. For this reason, the withstand voltage of 250 V or more may not be obtained.
D90 of an inorganic filler powder should just be 4.5 micrometers or less, and although it does not specifically limit, it can be 4.0 micrometers or less, Furthermore, it can be 3.5 micrometers or less. However, it is very difficult to reduce D90 to 1.5 μm or less by a method that can be normally used (ie, vibration mill, ball mill, jet mill, etc.). Therefore, D90 is preferably 1.8 to 4.5 μm, and can be 1.9 to 3.5 μm. Each of these numerical ranges can be combined with each numerical range of D90 of the glass powder.

In addition to D90, D10 is preferably 2.0 μm or less, more preferably 1.5 μm or less, and particularly preferably 0.1 to 1.3 μm. Furthermore, in addition to D90 and D10, the average particle size (D50) is preferably 3.0 μm or less, more preferably 2.5 μm or less, and particularly preferably 0.7 to 2.0 μm. preferable. These preferable ranges of D10 to D90 can be a combination of each.
Furthermore, as for the correlation of each particle size of inorganic filler powder, it is preferable that D10 / D50 is 0.05-0.65. Moreover, it is preferable that D90 / D50 is 1.5-4.3.

The type of the material constituting the inorganic filler powder is not particularly limited. For example, alumina, alkali metal titanate (magnesium titanate, calcium titanate, strontium titanate, barium titanate, etc.), cordierite, mullite. , Titania, zirconia, garnite, forsterite, wollastonite, anorthite, enstatite, diopsite, akermanite, gelenite and spinel. One kind of these materials may be contained, or two or more kinds thereof may be contained. Further, for example, a powder of a solid solution such as two or more metal oxides of CaTiO ₃ and LaAlO ₃ can be used.

Among the materials constituting these inorganic filler powders, it is preferable to use at least one of alumina, alkaline earth metal titanate, cordierite and mullite. In particular, when SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —CaO glass is used as the glass powder, it can be fired at a low temperature, and the reaction between the glass and the inorganic filler can be suppressed. For this reason, in particular, the firing temperature can be adjusted widely, and excellent dielectric properties can be obtained. Further, the relative dielectric constant of the material constituting the inorganic filler powder is not particularly limited and is preferably set appropriately depending on the purpose of use of the ceramic multilayer component, but is usually 35 or more and 65 or more. Preferably, it is 90 or more.

  When the total of the glass powder and inorganic filler powder contained in the unfired ceramic layer is 100% by volume, the content of each is not particularly limited, but the glass powder content may be 40 to 85% by volume. preferable. That is, the content of the inorganic filler powder is 15 to 60% by volume. 41-82 volume% is preferable and, as for content of this glass powder, 55-80 volume% is more preferable. 18-59 volume% is preferable and, as for content of an inorganic filler powder, 20-45 volume% is more preferable. If the content of the glass powder is in the above range, the green body can be fired in a low temperature range of 1000 ° C. or lower, and the obtained voltage resistance can be 250 V or higher.

  The green ceramic layer can contain other components besides the glass powder and the inorganic filler powder. Examples of other components include a binder, a plasticizer, a solvent, a colorant, a leveling agent, an antifoaming agent, and a dispersing agent. These may use only 1 type and may use 2 or more types together. The method for producing the unfired ceramic layer is not particularly limited, but usually a ceramic slurry containing glass powder and inorganic filler powder is formed into a sheet by a known thinning method such as a doctor blade method and a slip cast method, and then, This sheet can be obtained by drying.

  The “unfired conductor layer” is a layer that is fired to become a conductor layer. This unsintered conductor layer may be a layer that changes before and after firing, or may be a layer that does not change. That is, for example, it is a layer containing a conductor powder composed of a conductor component and an organic vehicle (containing at least one of a binder, a plasticizer, a solvent, and the like). It may be an unfired conductor layer that becomes a conductor layer by fusing. Further, it may be an unfired conductor layer (no change before and after firing) composed only of a patterned conductor component. Among these, the former is preferable from the viewpoint of workability.

  The “lamination” may be performed in any way, and is not particularly limited. It is only necessary that the unfired ceramic layer and the unfired conductor layer are laminated so as to have a desired lamination order. The unfired ceramic layer is fired to become a ceramic layer (insulating layer) in the ceramic multilayer component. On the other hand, the unfired conductor layer is fired to become a conductor layer in the ceramic multilayer component. Usually, since the ceramic layers and the conductor layers are alternately stacked, the unfired ceramic layers and the unfired conductor layers are also alternately stacked. That is, for example, an unfired ceramic multilayer component may be obtained by laminating a laminate in which one unfired ceramic layer and one unfired conductor layer are laminated. Also, one unfired conductor layer is laminated on one unfired ceramic layer, then one unfired ceramic layer is laminated on the unfired conductor layer, and then this unfired ceramic layer An unfired ceramic multilayer component may be obtained by sequentially laminating a single unfired conductor layer on top. Moreover, it is preferable to perform thermocompression bonding at the time of lamination.

  The “firing step” is a step of firing the unfired ceramic multilayer component. That is, it is a step of simultaneously firing the unfired ceramic layer and the unfired conductor layer. The firing temperature in this firing step is not particularly limited, but is usually 1000 ° C. or lower. Furthermore, 800-950 degreeC is preferable and 800-900 degreeC is more preferable. The firing atmosphere is not particularly limited, but can be set depending on the type of metal constituting the conductor layer. That is, for example, when a metal that is not easily oxidized (such as a noble metal) is used, it can be fired in an oxidizing atmosphere such as an air atmosphere. On the other hand, when a metal (such as Cu) that is easily oxidized is used, it can be fired in an inert atmosphere composed of an inert gas such as nitrogen and argon, or in a reducing atmosphere containing a small amount of hydrogen. The firing time (time for maintaining the firing temperature) is not particularly limited, but is usually 5 to 30 minutes, and preferably 10 to 25 minutes.

  In the manufacturing method of the present invention, other steps can be provided in addition to the laminating step and the firing step. The degreasing process is mentioned as another process. That is, when an organic vehicle is contained in the unfired ceramic layer, the unfired ceramic layer is usually heated to remove the organic vehicle, and then the firing is performed. The heating temperature and time for degreasing can be set according to the type and content of the organic vehicle. For example, the heating temperature can be 150 to 600 ° C., particularly 200 to 500 ° C., and the heating time can be 1 to 10 hours, particularly 2 to 7 hours. Moreover, this degreasing process may be performed continuously with the baking process or may be provided as a separate process.

[2] Ceramic multilayer component The ceramic multilayer component of the present invention is a ceramic multilayer component comprising a ceramic layer containing glass and an inorganic filler and having pores formed therein,
The ceramic layer has a thickness t of 10 μm to 120 μm,
In the ceramic layer, the number of pores having a maximum diameter of 7.5 μm or less and a maximum diameter of 4 μm or more is t / 5.5 or less in a t × t square cross section in the stacking direction. It is characterized by being.

The ceramic layer constituting the ceramic multilayer component of the present invention contains glass and an inorganic filler. Of these, glass is usually glass obtained by melting the glass powder by firing. Therefore, the glass type and the content ratio with the inorganic filler can be applied as they are in the glass powder. Moreover, the inorganic filler contained in the ceramic layer is an inorganic filler in which the inorganic filler powder contained in the unfired ceramic layer is contained through a firing step, and usually does not change before and after firing. Therefore, the kind of inorganic filler, the content ratio with glass, and the like can be applied as they are in the inorganic filler powder.
In addition, the ceramic layer that has undergone the firing process may contain an inorganic filler in which the glass powder contained in the unfired ceramic layer is precipitated during the firing process. When the whole powder is taken as 100% by volume, it is 5% by volume or less.

Moreover, although the thickness of the said ceramic layer is not specifically limited, Usually, it is 120 micrometers or less, 10-90 micrometers is preferable, 15-60 micrometers is more preferable, 20-45 micrometers is especially preferable. Although it may exceed 120 μm, in this range, it is not necessary to control the particle size, and sufficient withstand voltage characteristics can be obtained. The thickness of the ceramic layer usually means the thickness of the ceramic layer interposed between conductor layers.
Further, this ceramic layer may constitute all of the ceramic portion constituting the ceramic multilayer component or only a part thereof. That is, for example, the ceramic multilayer component may include only one ceramic layer, and a plurality of ceramic layers (a plurality of ceramic layers when fired after laminating directly unfired ceramic layers of the same composition) Layers may be integrated).

  The ceramic multilayer component of the present invention is not particularly limited except that the ceramic multilayer component includes the ceramic layer, but usually includes a conductor layer. When the conductor layer is provided, the arrangement is not particularly limited, but it is preferable that at least the ceramic layer is interposed between the conductor layers. It is because the effect of using the ceramic layer is easily exhibited by having such a structure. Furthermore, the conductor layer can be a conductor layer co-fired with the ceramic layer. That is, the ceramic multilayer component of the present invention can include the ceramic layer and a conductor layer disposed on the front and back of the ceramic layer and co-fired with the unfired ceramic layer. In such a ceramic multilayer component, the effect of the ceramic layer is more easily exhibited.

In the ceramic multilayer component of the present invention, the arrangement and the number of each layer are not particularly limited. For example, 10 to 20 ceramic layers are provided, and one conductor layer is provided between each of these ceramic layers, for a total of 9 to 19 It is possible to provide a laminated structure that includes layers (in other words, a conductor layer is embedded between ceramic layers) (may be composed of only this laminated structure).
Furthermore, the ceramic multilayer component is preferably a ceramic multilayer component that is used in a state where a voltage is always applied between the conductor layers constituting the multilayer structure. In such a ceramic multilayer component, the effect of providing the ceramic layer is more easily exhibited.
Examples of such ceramic multilayer parts include wiring boards on which electronic parts are mounted, ceramic packages, antennas, baluns and couplers, LC filters (diplexers, bandpass filters, lowpass filters, and the like).

In addition, although the kind of conductor component which comprises the said conductor layer is not specifically limited, Au, Ag, Cu, Pd, Pt, etc. are mentioned. In addition, other conductor components such as Al, Cr and Ni may be contained. The other conductor component is usually 4.0% by mass or less, preferably 2.5% by mass or less, when the entire conductor layer is 100% by mass.
The details of the unfired ceramic layer and the firing in the present invention can be applied as they are in the manufacturing method.

  In the ceramic multilayer component of the present invention, when the thickness t of the ceramic layer is in the range of 10 to 120 μm, the maximum major axis of the pore is 7.5 μm or less (more 7 μm or less, usually 1 μm or more) in the ceramic layer. It can be. Further, in this ceramic layer, the number of pores having a maximum major axis of 4 μm or more is t / 5.5 or less (usually 0.5 or more) in a t × t square cross section (see FIG. 2) in the stacking direction. can do. That is, for example, when the thickness of the ceramic layer (the thickness of the ceramic portion sandwiched between the conductor layers) t is 25 μm in the cross section of the ceramic layer of the ceramic multilayer component cut in the stacking direction, this cross section (ceramic layer) The pores exceeding 7.5 μm are not recognized in an arbitrary 25 μm × 25 μm square range in the cross section), and even if pores of 4 μm or more are recognized, the number of pores can be 4 or less.

Furthermore, in the ceramic multilayer component of the present invention, even when pores are contained in the ceramic layer, the major axis (maximum dimension) of the pore is R and the minor axis (shortest dimension) is r (see FIG. 2). Further, R / r can be set to 1.4 or less. In other words, the case of “R / r ≦ 1.4” means that the pore has approached a homogeneous spherical shape by being sufficiently fired. Therefore, in spite of sufficient firing, the inevitable pores recognized in the ceramic layer have the above-mentioned form (the maximum major axis is 7.5 μm or less, the maximum major axis is 4 μm or more, the number of pores is t × t / 5.5 or less in a t-square cross section). That is, by controlling the particle size, the size and number of inevitable pores contained in the ceramic layer can be suppressed, and as a result, the withstand voltage characteristics can be improved.
According to the ceramic multilayer component of the present invention, the withstand voltage characteristic measured by the method described later in the examples can be 100 V or more, and more preferably 200 V or more, between the conductor layers insulated by the ceramic layer. In particular, it can be set to 250 V or more.

Examples of the ceramic multilayer component of the present invention include a wiring board on which an electronic component is mounted, a ceramic package, an antenna, a balun, a coupler, an LC filter (a diplexer, a band pass filter, a low pass filter, and the like).
Among these, an example of a ceramic multilayer LC filter is shown in FIG. 1 as an exploded perspective view. The LC filter 1 includes ceramic layers (dielectric ceramic parts) 111, 112, 113, 114, 115, and 116 and conductor layers 121, 122, 123, 124, and 125. These are integrally fired as a single body. Further, 131, 132, 133, 134, 135 and 136 end face conductors are provided. This end face conductor may or may not be cofired with the ceramic layer and the conductor layer.

Hereinafter, the present invention will be specifically described by way of examples.
[1] when an element manufacturing each of the glass powder in terms oxide, 25 wt% of Si in terms of SiO _2, 21 wt% of B in terms _{of B} 2 _{O 3,} 25 mass Al in terms _{of Al} 2 _{O 3} SiO ₂ powder, H ₃ BO ₃ powder, Al ₂ (OH) so as to contain 15% by weight, 17% by weight of Ca in terms of CaO, and 12% by weight of Zn in terms of ZnO (the total of which is 100% by weight). ₃ powders, CaCO ₃ powders and ZnO powders were weighed and mixed with a grinder. Thereafter, the mixture was heated and melted for 3 to 5 hours, and then rapidly cooled by water cooling to prepare glass (glass transition point was 631 ° C.). Thereafter, this glass was pulverized by a ball mill to obtain three types of glass powders having D90 of 8.3 μm, 7.5 μm, and 5.9 μm, respectively.
The particle size distribution is a value measured with a laser diffraction / scattering particle size distribution measuring apparatus (manufactured by Horiba, Ltd., model “LA-750”).

[2] Preparation of inorganic filler powder Alumina powder (purity 99% or more) and calcium titanate powder (purity 97% or more) were each secondarily ground for 10-15 hours using a trommel grinder, and D90 was Four types of alumina powders of 4.6 μm, 4.4 μm, 2.8 μm, and 2.2 μm and three types of calcium titanate powders having D90 of 4.8 μm, 3.0 μm, and 2.4 μm were obtained.

[3] Preparation of green sheet The glass powder obtained in the above [1] and any one of the inorganic filler powders obtained in the above [2] are mixed by a ball mill so that the volume ratio is 70:30. Thus, a mixed powder was obtained. Thereafter, an organic binder (acrylic resin), a plasticizer (dibutyl phthalate), and a solvent (toluene) were added to the mixed powder and kneaded to obtain a slurry. Next, the obtained slurry was formed into a sheet shape so that the thickness after firing was 25 μm, and 22 types of green sheets were obtained.

[4] Manufacture of ceramic multilayer parts Ag paste was printed at a predetermined position of each green sheet obtained in [3] above to a thickness of 15 μm by screen printing. Thereafter, another green sheet of the same kind was laminated on the Ag paste layer by thermocompression bonding. Next, after the Ag paste is printed on the surface of the laminated green sheets in the same manner as described above, another green sheet of the same kind is repeatedly laminated, and the layers of 10 green sheets of the same kind and each green sheet (9 A green ceramic multilayer part having an Ag paste layer formed on the layer) was obtained.
The obtained unsintered ceramic multilayer part was fired at a temperature of 850 ° C. for 15 minutes to obtain 22 types of ceramic multilayer parts using 22 types of green sheets.

[5] Evaluation of withstand voltage characteristics For each of the ceramic multilayer parts obtained in [4] above, the obtained ceramic multilayer was obtained using a dielectric breakdown measuring device (model “SM-8215” manufactured by Toa DKK Corporation). A voltage of 250 V was applied between the signal terminal and the ground terminal of the component, and the presence or absence of current leakage between the capacitor pattern and the ground pattern was confirmed.

[6] Evaluation of pores in cross section Each ceramic multilayer part obtained in the above [4] is cut in the stacking direction of each layer, and then the cross section is polished and magnified 500 times with an electron microscope. The surface was digitally photographed, and in the obtained image, the average value of the number of pores recognized in 10 arbitrarily selected 25 μm × 25 μm squares and the shape of the pores were observed. As illustrated in FIG. 2, when there is a pore (pore 21 in FIG. 2) that includes only a part of the region in the measurement range t × t square in which the number of pores is converted, the maximum length of this pore. Was 4 μm or more, it was converted into one pore and integrated.
These results are shown in Table 1. Further, the explanatory diagrams based on the images obtained by enlarging the cut sections of Experimental Example 1 and Experimental Example 9 500 times with an electron microscope used in this measurement are shown in FIGS. 3 (Experimental Example 9) and FIG. 4 (Experimental Example 1). (The scale in FIGS. 3 and 4 corresponds to a total length of 50 μm).

Incidentally, “*” in the table indicates that it is outside the scope of the present invention.

[7] Evaluation of Ceramic Multilayer Part It is understood that pores having a size exceeding 7.5 μm are recognized in FIG. 4 which is a cross section of Experimental Example 1 (comparative product). It can also be seen that there are many pores in the whole. On the other hand, it can be seen that pores having a size exceeding 7.5 μm are not recognized in FIG. In addition, it can be seen that the number of pores is suppressed to be small as a whole.
In FIG. 3 and FIG. 4, the pore 2 is indicated by an arrow as an example. In addition to these pores, pores exist as can be seen in the figure.

  Furthermore, from the results of Table 1, in Experimental Example 1 and Experimental Example 13, D90 of the glass powder exceeds 8 μm and D90 of the inorganic filler powder exceeds 4.5 μm. As a result, the maximum pore diameter is 18.2 μm or 17.6 μm, and the number of pores of 4 μm or more is 12 or 10. In Experimental Example 2 and Experimental Example 14, D90 of the inorganic filler powder is less than 4.5 μm, but D90 of the glass powder exceeds 8 μm. As a result, the maximum pore diameter is 13.7 μm or 15.4 μm, and the number of pores of 4 μm or more is 9 or 10. In Experimental Example 3 and Experimental Example 15, D90 of the glass powder is less than 8 μm, but D90 of the inorganic filler powder exceeds 4.5 μm. As a result, the maximum pore diameter is 10.5 μm or 11.9 μm, and the number of pores of 4 μm or more is 6 or 5. Further, in Experimental Example 7 and Experimental Example 18, D90 of the glass powder is less than 8 μm and as small as 2.8 μm, but D90 of the inorganic filler powder exceeds 4.5 μm. As a result, the maximum pore diameter is 8.1 μm or 9.3 μm, and the number of pores of 4 μm or more is five. None of these had a voltage resistance of 250V. That is, it can be seen that even if only one of the glass powder and the inorganic filler powder is small, the size and number of pores cannot be suppressed. Further, as a result, it can be seen that sufficient voltage resistance cannot be obtained. Moreover, it turns out that this tendency is not related to the kind of inorganic filler.

  In contrast, in Experimental Examples 4-6, Experimental Examples 8-12, Experimental Examples 16-17, and Experimental Examples 19-22, D90 of the glass powder is 8 μm or less and D90 of the inorganic filler powder is 4.5 μm or less. It is. As a result, the maximum pore diameter is suppressed to 7.3 μm or less, and the number of pores of 4 μm or more is suppressed to 4 or less. That is, it can be seen that by controlling the powder particle size to be equal to or less than a predetermined value, the size and number of pores can be remarkably effectively suppressed regardless of the type of the inorganic filler. In addition, even if powders of particles that are somewhat large are used, by setting the particle sizes of both powders to a predetermined value or less, it is possible to provide extremely high withstand voltage performance of 250 V or more.

  The present invention is widely used in the field of electronic equipment. That is, for example, LC filters (ceramic multilayer LC filters, diplexers, bandpass filters, lowpass filters, etc.), wiring boards on which electronic components are mounted, multilayer boards incorporating passive components such as ceramic packages, antennas, baluns, and couplers Etc.

It is a disassembled perspective view of LC filter which is an example of the ceramic multilayer component of this invention. It is explanatory drawing explaining the pore contained in a ceramic layer. It is explanatory drawing by the image obtained by enlarging the cross section of the ceramic multilayer component of this invention (experimental example 9) 500 times. It is explanatory drawing by the image obtained by enlarging the cross section of the ceramic multilayer component of a comparative product (Experimental example 1) 500 times.

Explanation of symbols

  1; LC filter (ceramic multilayer part), 110, 111, 112, 113, 114, 115 and 116; ceramic layer, 120, 121, 122, 123, 124 and 125; conductor layer, 131, 132, 133, 134, 135 and 136; end face conductors, 2; pores.

Claims (5)

A method for producing a ceramic multilayer component comprising: a lamination step of laminating an unfired ceramic layer and an unfired conductor layer to obtain an unfired ceramic multilayer component; and a firing step of firing the unfired ceramic multilayer component,
The unfired ceramic layer contains a glass powder having a 90% particle size of 8 μm or less in a particle size distribution, and an inorganic filler powder having a 90% particle size of 4.5 μm or less in the particle size distribution. Production method.   The method for producing a ceramic multilayer part according to claim 1, wherein the content of the glass powder is 40 to 85% by volume when the total of the glass powder and the inorganic filler powder is 100% by volume. _{Glass, SiO 2 -B 2 O 3 -Al} 2 O 3 method for producing a ceramic multilayer component according to claim 1 or 2 which is -CaO based glass constituting the glass powder. A ceramic multilayer component comprising a ceramic layer containing glass and an inorganic filler and having pores formed therein,
The ceramic layer has a thickness t of 10 μm to 120 μm,
In the ceramic layer, the number of pores having a maximum diameter of 7.5 μm or less and a maximum diameter of 4 μm or more is t / 5.5 or less in a t × t square cross section in the stacking direction. A ceramic multilayer part characterized by being.   5. The ceramic multilayer component according to claim 4, wherein the pore has an R / r of 1.4 or less when the major axis of the pore is R and the minor axis is r.