Low-temperature fired ceramic and electronic component

Abstract

The present invention provides a low-temperature fired ceramic which contains an after-firing glass component and an oxide of a ceramic crystal component, wherein: the after-firing glass component contains B2O3, SiO2 and an alkaline earth metal oxide; and the proportion of the alkaline earth metal oxide contained in the after-firing glass component is 10 mol% or less.

Description

Low-temperature fired ceramics and electronic components

[0001] The present invention relates to low-temperature co-fired ceramics and electronic components.

[0002] As a ceramic material for a ceramic multilayer wiring board, a glass ceramic material (LTCC material) that can be fired at a low temperature is known.

[0003] For example, Patent Document 1 discloses RO-Al ２ O ３ -B ２ O ３ -SiO ２ (wherein RO is one or more of the group consisting of MgO, CaO, SrO, BaO, and ZnO), and ２ O ３ are all in the range of 1 to 25 mol%, and SiO ２ / B ２ O ３ The glass composition for low-temperature fired substrates has a mol % ratio of 1.3 or less, and a glass ceramic in which the glass composition for low-temperature fired substrates contains an aggregate.

[0004] Japanese Patent Application Laid-Open No. 2004-26529

[0005] In order to reduce the dielectric loss of glass ceramics, it is necessary to reduce the content of alkali metal oxides and alkaline earth metal oxides in the glass of the fired body. However, Patent Document 1 only specifies that the RO content of the glass before firing is 25 mol% or less, but does not specify the composition of the fired body, so it is not necessarily possible to reduce the dielectric loss.

[0006] One of the reasons why the specifications in Patent Document 1 are insufficient to reduce dielectric loss is that crystals containing alkaline earth metal oxides may precipitate from the glass during firing, in which case the content of alkaline earth metal oxides in the fired glass is lower than the content of alkaline earth metal oxides in the glass before firing.

[0007] Another reason is that the ceramics that are mixed with the glass before firing are often made of alkaline earth metal oxides (e.g., Ba). ２ Ti９ O ２０ ), which may dissolve in the glass during firing. In this case, the content of alkaline earth metal oxides in the fired glass is higher than the content of alkaline earth metal oxides in the glass before firing.

[0008] From these findings, it is believed that in order to reduce the dielectric loss, it is necessary to specify the alkaline earth metal oxide contained in the glass component of the fired body. In light of the above, an object of the present invention is to provide a low-temperature fired ceramic having a low dielectric loss.

[0009] The low-temperature fired ceramic of the present invention is a low-temperature fired ceramic containing a fired glass component and an oxide of a ceramic crystalline component, and the fired glass component is B ２ O ３ , SiO ２ and alkaline earth metal oxides, and the proportion of the alkaline earth metal oxides contained in the fired glass component is 10 mol % or less.

[0010] The electronic component of the present invention comprises the low-temperature co-fired ceramic of the present invention.

[0011] According to the present invention, it is possible to provide a low-temperature co-fired ceramic having a small dielectric loss.

[0012] Fig. 1 is a cross-sectional view schematically showing an example of a multilayer ceramic electronic component as an electronic component of the present invention, and Fig. 2 is a cross-sectional view schematically showing a multilayer green sheet (unfired state) produced in the process of manufacturing the multilayer ceramic electronic component in Fig. 1.

[0013] The low-temperature co-fired ceramic and electronic component of the present invention will be described below. Note that the present invention is not limited to the following configurations and may be modified as appropriate without departing from the gist of the present invention. In addition, a combination of multiple individual preferred configurations described below also constitutes the present invention.

[0014] The low-temperature co-fired ceramic of the present invention is a fired body obtained by firing a low-temperature co-fired ceramic (LTCC) material, which is a glass ceramic material that can be sintered at a firing temperature of 1000° C. or less.

[0015] The low-temperature fired ceramic of the present invention contains a fired glass component and oxides of ceramic crystal components. ２ O ３ , SiO ２ and alkaline earth metal oxides. The proportion of alkaline earth metal oxides contained in this fired glass component is 10 mol % or less. In the low-temperature fired ceramic of the present invention, the proportion of alkaline earth metal oxides contained in the fired glass component is specified to be a small proportion, so that the low-temperature fired ceramic can be made to have low dielectric loss.

[0016] Among the components contained in low-temperature co-fired ceramics, the post-fired glass component has a large dielectric loss, while the oxides of the ceramic crystal component have a small dielectric loss. Since the dielectric loss of the post-fired glass component is dominant in the dielectric loss of low-temperature co-fired ceramics, it is important to reduce the dielectric loss of the post-fired glass component. Therefore, the dielectric loss of low-temperature co-fired ceramics can be reduced by specifying a small proportion of alkaline earth metal oxides in the post-fired glass component. The alkaline earth metal oxides contained in the pre-fired glass component of low-temperature co-fired ceramic (LTCC) materials precipitate outside the glass during firing, thereby reducing the proportion of alkaline earth metal oxides in the post-fired glass component. Precipitating alkaline earth metal oxides outside the glass during firing allows low-temperature co-fired ceramics with low dielectric loss to be obtained.

[0017] The proportion of alkaline earth metal oxides contained in the fired glass component is preferably 8.0 mol% or less, more preferably 6.0 mol% or less, and may be 0.1 mol% or more.

[0018] The proportion of alkaline earth metal oxide contained in the glass component after firing can be obtained by measuring powder XRD (X-ray diffraction measurement) of the low-temperature fired ceramic (fired body) at a scan speed as low as 0.2 deg / min, and determining the composition of the glass component by Rietveld analysis.

[0019] When measuring samples of a commercialized fired body, the composition of the glass component can be determined by measuring the glass region identified by STEM and electron beam diffraction of the exfoliated sample using WDS (wavelength dispersive X-ray analysis). Electron beam diffraction can also identify the crystalline phases present.

[0020] Examples of alkaline earth metal oxides contained in the fired glass component include MgO, CaO, SrO, and BaO, with BaO being preferred. The fired glass component may further contain TiO. ２ After firing, the glass component preferably contains BaO and TiO. ２ When the composition contains the above, the dielectric constant can be particularly increased and the dielectric loss can be reduced.

[0021] After firing, the glass component contains Al ２ O ３ It is preferable that the compound does not contain B. ２ O ３ and SiO ２ Other than that, Al ２ O ３ When the glass composition is used as a glass ceramic material that can be fired at a low temperature, the glass composition is mixed with ceramic and fired. In order to increase the dielectric constant of the glass ceramic, Ba, which has a high dielectric constant and a small temperature change in the dielectric constant, is used. ２ Ti ９ O ２０ It is preferable to use ceramics such as Al. ２ O ３ When it contains as a component, Al ２ O ３ Ba ２ Ti ９ O ２０ It cannot be used because it reacts with ceramics such as Al and decomposes. ２ O ３ It is preferable that it does not contain

[0022] Furthermore, it is preferable that the fired glass component does not contain alkali metal oxides. By not containing alkali metal oxides in the fired glass component, a low-temperature fired ceramic with low dielectric loss can be obtained. If the fired glass component contains alkali metal oxides, the proportion of alkali metal oxides contained in the fired glass component is preferably 0.1 mol% or less.

[0023] From the above, the glass component after firing is B ２ O ３ , SiO ２ , BaO and TiO ２ It is preferable that the glass component contains B after firing and does not contain other oxides. ２ O ３ , SiO ２ , BaO and TiO ２ The preferred ratios are as follows: ２ O ３ :21 mol% or more, 65 mol% or less SiO ２ : 24 mol% or more, 62 mol% or less BaO: 0.1 mol% or more, 10 mol% or less TiO ２ : 0.1 mol% or more, 10 mol% or less

[0024] The oxides of the ceramic crystal components include Ba ２ Ti ９ O ２０ It is preferable that the compound contains Ba. ２ Ti ９ O ２０ By including the compound, it is possible to obtain a low-temperature co-fired ceramic having a high dielectric constant and a small temperature change in the dielectric constant.

[0025] Ba contained in low-temperature fired ceramics ２ Ti ９ O ２０ The proportion of is preferably 55% by weight or more, more preferably 60% by weight or more, even more preferably 70% by weight or more, and particularly preferably 80% by weight or more.

[0026] The oxide of the ceramic crystal component is Ba. ２ Ti ９ O ２０and further including BaTi(BO ３ ) ２ ,BaTi ５ O １１ , Ba ２ TiSi ２ O ８ , and TiO ２ Among the oxides of the ceramic crystal components, TiO ２ The oxides of ceramic crystal components other than TiO have the property that the dielectric constant increases as the temperature rises. ２ has the property that the dielectric constant decreases as the temperature rises. ２ For oxides of ceramic crystal components other than TiO ２ By adding a predetermined amount of TiO, the characteristics of the low-temperature co-fired ceramic can be adjusted so that the dielectric constant does not change with temperature. ２ can be used to adjust the temperature change of the properties of low-temperature fired ceramics. ２ represents the TiO contained in the glass component after firing. ２ can be distinguished from.

[0027] BaTi(BO) as an oxide of ceramic crystalline component contained in low-temperature fired ceramics ３ ) ２ ,BaTi ５ O １１ , Ba ２ TiSi ２ O ８ , and TiO ２ The preferred ratios are as follows: BaTi(BO ３ ) ２ : 0% by weight or more and 20% by weight or less BaTi ５ O １１ : 0% by weight or more and 20% by weight or less Ba ２ TiSi ２ O ８ : 0% by weight or more and 20% by weight or less TiO ２ : 0.1% by weight or more, 20% by weight or less

[0028] The proportions of the fired glass component and the oxides of the ceramic crystal component contained in the low-temperature fired ceramic are not particularly limited, but the proportion of the fired glass component contained in the low-temperature fired ceramic can be 2.0 wt % or more and 30.0 wt % or less, and the proportion of the oxides of the ceramic crystal component can be 70.0 wt % or more and 98.0 wt % or less.

[0029] The relative density of low-temperature co-fired ceramics is preferably 90% or more, and more preferably 95% or more. Relative density refers to the density measured by Archimedes' method divided by the true density. If the relative density is less than 90%, a decrease in insulation properties may occur. If the relative density is 95% or more, a decrease in insulation properties does not empirically occur. Furthermore, the low-temperature co-fired ceramics preferably has a relative dielectric constant of 15 or more, and a Q value, which is the reciprocal of the dielectric loss, of 1000 or more. The dielectric loss is preferably 0.001 or less. The relative dielectric constant and dielectric loss of low-temperature co-fired ceramics can be measured as the relative dielectric constant and dielectric loss at 3 GHz using a perturbation method.

[0030] The electronic component of the present invention includes the low-temperature co-fired ceramic of the present invention. Examples of the electronic component of the present invention include a laminate including a plurality of low-temperature co-fired ceramic layers made of the low-temperature co-fired ceramic of the present invention, and a multilayer ceramic electronic component including a multilayer ceramic substrate using the laminate and a chip component mounted on the ceramic substrate. Because the electronic component of the present invention includes a low-temperature co-fired ceramic layer made of the low-temperature co-fired ceramic of the present invention, it has a high dielectric constant and low dielectric loss.

[0031] The laminate having a plurality of low-temperature co-fired ceramic layers made of the low-temperature co-fired ceramic of the present invention can be used, for example, in a ceramic multilayer substrate for communication or a laminated dielectric filter. The electronic component of the present invention has a high dielectric constant, small dielectric loss, and a high Q value, and is therefore particularly suitable as an electronic component for use in the millimeter wave band.

[0032] Fig. 1 is a cross-sectional view schematically showing an example of a multilayer ceramic electronic component as an electronic component of the present invention. As shown in Fig. 1, the electronic component 2 includes a laminate 1 formed by laminating a plurality of low-temperature co-fired ceramic layers 3 (five layers in Fig. 1), and chip components 13 and 14 mounted on the laminate 1. The laminate 1 also serves as a multilayer ceramic substrate.

[0033] The low-temperature co-fired ceramic layer 3 is a fired body made of the low-temperature co-fired ceramic of the present invention. Therefore, the laminate 1 formed by stacking a plurality of low-temperature co-fired ceramic layers 3, the multilayer ceramic substrate using the laminate 1, and the electronic component 2 including chip components 13, 14 mounted on the multilayer ceramic substrate (laminate 1) are all electronic components of the present invention. The compositions of the plurality of low-temperature co-fired ceramic layers 3 may be the same or different, but are preferably the same.

[0034] The laminate 1 may further include a conductor layer. The conductor layer may constitute, for example, a passive element such as a capacitor or an inductor, or may constitute a connecting wiring that electrically connects elements. Such conductor layers include conductor layers 9, 10, and 11, and a via-hole conductor layer 12, as shown in FIG. 1 .

[0035] The conductor layers 9, 10, and 11 and the via-hole conductor layer 12 preferably contain Ag or Cu as a primary component. The use of such low-resistivity metals prevents signal propagation delays associated with higher electrical signal frequencies. Furthermore, the low-temperature co-fired ceramic layer 3 is a sintered body of a low-temperature co-fired ceramic (LTCC) material, and can be formed by co-firing with Ag and Cu. In other words, the electronic component of the present invention preferably incorporates Cu wiring, and preferably incorporates Cu wiring formed by co-firing a low-temperature co-fired ceramic (LTCC) material with Cu.

[0036] The conductor layer 9 is disposed inside the laminate 1. Specifically, the conductor layer 9 is disposed at the interface between the low-temperature co-fired ceramic layers 3.

[0037] The conductor layer 10 is disposed on one of the main surfaces of the laminate 1 .

[0038] The conductor layer 11 is disposed on the other main surface of the laminate 1 .

[0039] The via hole conductor layer 12 is arranged to penetrate the low-temperature co-fired ceramic layer 3, and serves to electrically connect the conductor layers 9 of different layers, electrically connect the conductor layers 9 and 10, and electrically connect the conductor layers 9 and 11.

[0040] The laminate 1 is manufactured, for example, as follows.

[0041] (A) Preparation of glass composition B ２ O ３ , SiO ２ and alkaline earth metal oxides in a predetermined ratio to prepare a glass composition. BaO is preferably used as the alkaline earth metal oxide, and TiO ２ It is preferable to add

[0042] (B) Preparation of Glass Powder The glass composition is melted and the resulting melt is rapidly cooled to prepare cullets. The cullets are coarsely crushed and further crushed in a ball mill or the like to prepare glass powder having a predetermined particle size.

[0043] (C) Preparation of Low Temperature Co-fired Ceramic (LTCC) Material The low temperature co-fired ceramic material is prepared by mixing glass powder and oxides of ceramic crystal components. ２ Ti ９ O ２０ The proportion of glass powder in the low temperature co-fired ceramic (LTCC) material is preferably 20% by weight or more and 40% by weight or less.

[0044] (D) Preparation of Green Sheets A low-temperature co-fired ceramic material is mixed with a binder, a plasticizer, etc. to prepare a ceramic slurry. The ceramic slurry is then cast onto a substrate film (e.g., a polyethylene terephthalate (PET) film) and dried to prepare a green sheet.

[0045] (E) Preparation of Laminated Green Sheets A laminated green sheet (unfired state) is prepared by stacking green sheets. FIG. 2 is a cross-sectional schematic diagram showing a laminated green sheet (unfired state) prepared during the manufacturing process of the laminated ceramic electronic component in FIG. 1. As shown in FIG. 2, a laminated green sheet 21 is formed by stacking multiple green sheets 22 (five in FIG. 2). The green sheets 22 become the low-temperature fired ceramic layers 3 after firing. Conductive layers including conductor layers 9, 10, and 11 and via-hole conductor layers 12 may be formed on the laminated green sheet 21. The conductor layers can be formed by screen printing, photolithography, or the like using a conductive paste containing Ag or Cu.

[0046] (F) Firing of Laminated Green Sheet The laminated green sheet 21 is fired, resulting in a laminate 1 as shown in FIG.

[0047] The firing temperature of the laminated green sheet 21 is not particularly limited as long as it is a temperature at which the low-temperature co-fired ceramic material constituting the green sheet 22 can be sintered, and may be, for example, 1000° C. or lower.

[0048] The firing atmosphere for the laminated green sheet 21 is not particularly limited, but an air atmosphere is preferred when a material that is resistant to oxidation, such as Ag, is used for the conductor layers 9, 10, 11 and the via-hole conductor layer 12, and a low-oxygen atmosphere such as a nitrogen atmosphere is preferred when a material that is resistant to oxidation, such as Cu, is used. The firing atmosphere for the laminated green sheet 21 may also be a reducing atmosphere.

[0049] The laminated green sheet 21 may be fired while sandwiched between constraining green sheets. The constraining green sheets are made of an inorganic material (e.g., Al) that is substantially not sintered at the sintering temperature of the low-temperature co-fired ceramic material that constitutes the green sheet 22. ２ O ３) as a main component. Therefore, the constraining green sheets do not shrink when the laminated green sheets 21 are fired, and act to suppress shrinkage of the laminated green sheets 21 in the main surface direction. As a result, the dimensional accuracy of the obtained laminate 1 (particularly the conductor layers 9, 10, 11 and the via-hole conductor layer 12) is improved.

[0050] Chip components 13 and 14 may be mounted on the laminate 1 in a state where they are electrically connected to the conductor layer 10. In this way, an electronic component 2 having the laminate 1 is constructed.

[0051] Examples of the chip components 13 and 14 include an LC filter, a capacitor, an inductor, and the like.

[0052] The electronic component 2 may be mounted on a mounting substrate (for example, a motherboard) so as to be electrically connected via the conductor layer 11 .

[0053] The following examples will be given to more specifically disclose the low-temperature co-fired ceramic and electronic device of the present invention, but the present invention is not limited to these examples.

[0054] (A) Preparation of Glass Glass powders G1 to G4 (all in powder form) having the compositions shown in Table 1 were prepared by the following method. First, glass raw material powders were mixed to obtain a glass composition. The glass composition was placed in a Pt crucible and melted at 1600°C for 30 minutes or more in an air atmosphere. The resulting melt was then quenched to prepare cullets. Note that carbonate (BaCO ３ ) was used. ３ ) becomes alkaline earth metal oxide (BaO) upon firing, and Table 1 shows the compounding amounts converted to BaO. The cullet was then coarsely crushed and placed in a container together with ethanol and PSZ balls (diameter: 5 mm) and mixed in a ball mill. By adjusting the crushing time during mixing in the ball mill, a glass powder with a median particle size of 1.0 μm was obtained. Here, "median particle size" refers to the median particle size D50 measured by laser diffraction / scattering.

[0055] (B) Preparation of Green Sheet Next, glass powder and oxides of ceramic crystal components (median particle size 1.0 μm) were mixed in ethanol in a ball mill with the composition shown in Table 2, and then a binder solution and a plasticizer dissolved in an organic solvent were mixed to form a slurry. The slurry was formed on a PET film with a doctor blade and dried at 40°C to obtain a green sheet with a thickness of 50 μm. The glass powder in the green sheet and Ba as oxides of the ceramic crystal components were mixed in a ball mill with the composition shown in Table 2. The binder solution and plasticizer dissolved in an organic solvent were mixed to form a slurry. The slurry was formed on a PET film with a doctor blade and dried at 40°C to obtain a green sheet with a thickness of 50 μm. ２ Ti ９ O ２０ and TiO ２ The weight ratio of the above is shown in Table 2 as "LTCC material before firing [wt %]".

[0056] (C) Preparation and Evaluation of Evaluation Samples To evaluate sinterability, 20 green sheets were cut into 50 mm x 50 mm pieces and stacked, placed in a mold, and pressed using a press. The pressed body was fired in air at 900 °C for 60 minutes. After firing, the density was measured using the Archimedes method, and the relative permittivity and Q value (the reciprocal of the dielectric loss) at 3 GHz were measured using the perturbation method. The measurement conditions were as follows: [Measurement Equipment and Conditions] Network Analyzer: Keysight 8757D Signal Generator: Keysight Synthesized Sweeper 83751 Resonator: Homemade jig (resonant frequency: 3 GHz) Prior to the measurement, the network analyzer and signal generator were connected to measure cable loss. The resonator was also calibrated using a standard substrate (quartz, relative permittivity: 3.73, Q value: 9091 @ 3 GHz, thickness: 0.636 mm).

[0057] The fired body was then pulverized and the true density of the powder was measured. The relative density (%) was calculated by dividing the density measured by the Archimedes method by the true density. Furthermore, to analyze the composition of the fired body, the powder XRD of the fired body was measured at a scan speed as low as 0.2 deg / min, and the proportion of the fired glass component contained in the fired body and the composition of the fired glass component were determined by Rietveld analysis. To determine the composition, it was assumed that the total amount of oxide of each element remained unchanged before and after firing. The oxide composition of the ceramic crystal component contained in the fired body was also determined. These results are shown in Tables 2 and 3.

[0058]

[0059]

[0060]

[0061] The low-temperature-fired ceramics of Samples S2, S3, and S5 had a post-fired glass component containing alkaline earth metal oxides (BaO percentage shown in Table 3) of 10 mol% or less, and correspond to the low-temperature-fired ceramics of the present invention. These samples all had high Q values, indicating that they were low-temperature-fired ceramics with low dielectric loss. Furthermore, all samples had high dielectric constants. Furthermore, all samples had high relative densities of 95% or more, indicating no deterioration in insulation.

[0062] The present specification discloses the following:

[0063] The present disclosure (1) is a low-temperature fired ceramic containing a fired glass component and an oxide of a ceramic crystalline component, and the fired glass component is B ２ O ３ , SiO ２ and alkaline earth metal oxides, and the proportion of the alkaline earth metal oxides contained in the glass component after firing is 10 mol % or less.

[0064] The present disclosure (2) is the low-temperature fired ceramic according to the present disclosure (1), in which the alkaline earth metal oxide contained in the fired glass component is BaO.

[0065] In the present disclosure (3), the fired glass component further contains TiO ２ The low-temperature co-fired ceramic according to the present disclosure (1) or (2) includes:

[0066] The present disclosure (4) is that the oxide of the ceramic crystal component is Ba ２ Ti ９ O ２０ and any combination of any of the present disclosure (1) to (3).

[0067] The present disclosure (5) is directed to the Ba contained in the low-temperature fired ceramic.２ Ti ９ O ２０ The low-temperature co-fired ceramic according to the present disclosure (4), wherein the ratio of

[0068] The present disclosure (6) further provides that the oxide of the ceramic crystal component is BaTi(BO ３ ) ２ ,BaTi ５ O １１ , Ba ２ TiSi ２ O ８ , and TiO ２ The low-temperature co-fired ceramic according to the present disclosure (4) or (5) contains at least one selected from the group consisting of:

[0069] The present disclosure (7) is an electronic component comprising a low-temperature co-fired ceramic in any combination with any of the present disclosures (1) to (6).

[0070] The present disclosure (8) is the electronic component according to the present disclosure (7) having built-in Cu wiring.

[0071] REFERENCE SIGNS LIST 1 Laminate 2 Electronic component 3 Low-temperature fired ceramic layer 9, 10, 11 Conductor layer 12 Via-hole conductor layer 13, 14 Chip component 21 Laminated green sheet 22 Green sheet

Claims

1. a low-temperature-fired ceramic containing a fired glass component and an oxide of a ceramic crystalline component; The fired glass component is B ２ O ３ , SiO ２ and an alkaline earth metal oxide, but not containing Li 2 O, wherein the proportion of the alkaline earth metal oxide contained in the glass component after firing is 10 mol % or less.

2. 2. The low-temperature fired ceramic according to claim 1, wherein the alkaline earth metal oxide contained in the fired glass component is BaO.

3. The fired glass component further contains TiO ２ The low-temperature co-fired ceramic according to claim 1 or 2, comprising:

4. The oxide of the ceramic crystal component is Ba. ２ Ti ９ O ２０ The low-temperature co-fired ceramic according to claim 1 or 2, comprising:

5. Ba contained in the low-temperature co-fired ceramic ２ Ti ９ O ２０ 5. The low-temperature co-fired ceramic according to claim 4, wherein the ratio of is 55% by weight or more.

6. The oxide of the ceramic crystal component may further include BaTi(BO ３ ) ２ ,BaTi ５ O １１ , Ba ２ TiSi ２ O ８ , and TiO ２ The low-temperature co-fired ceramic according to claim 4, comprising at least one selected from the group consisting of:

7. An electronic component comprising the low-temperature co-fired ceramic according to claim 1 or 2.

8. 8. The electronic component according to claim 7, further comprising a Cu wiring.