JP2018008863A - Dielectric ceramic material and dielectric ceramic composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dielectric ceramic material that can be sintered at low temperature, and has excellent dielectric properties and high thermal conductivities.SOLUTION: A dielectric ceramic material contains aluminum oxide and a sintering aid (titanium, copper, niobium, and silver components), and has a bulk density of 3.8 g/cmor more, wherein in an X-ray diffraction, a corundum phase shows a highest peak intensity and rutile phase shows a second highest peak intensity.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a dielectric ceramic material and a dielectric ceramic composition, and a dielectric ceramic material and a dielectric that enable low-temperature sintering of the dielectric ceramic material, good dielectric properties, and high thermal conductivity. The object is to provide a ceramic composition.

  Conventionally, multilayer ceramic substrates for mounting semiconductor ICs, etc. are roughly classified into high temperature firing type HTCC (High Temperature Co-fired Ceramics) and low temperature firing type LTCC (Low Temperature Co-fired Ceramics) based multilayer ceramic substrates. it can.

In addition, as basic characteristics required for dielectric ceramics used for the HTCC and LTCC multilayer ceramic substrates, the dielectric ceramic has a dielectric constant according to the application, and a dielectric loss tan δ is small (quality factor Q and resonance frequency). Qf value, which is the product of f, is large), and the temperature coefficient τ _{f of the} resonance frequency is close to zero (−0.5 times the temperature coefficient τ _ε of relative permittivity and −1 times the linear expansion coefficient α) The added thing is close to zero).

Now, the base material of the HTCC-based multilayer ceramic substrate is made of inorganic powder having heat resistance such as Al ₂ O ₃ , AlN, BeO, SiC-BeO. These ceramic materials are produced by mixing and molding the inorganic powder as a main component and then firing at a high temperature of 1300 ° C. or higher. For this reason, Mo or W having a high melting point is used as a conductor material for wiring formed inside the HTCC multilayer ceramic substrate. However, Mo and W have a drawback of low conductivity as a conductor. On the other hand, Ag and Cu, which have high conductivity and are inexpensive, have low melting points of about 961 ° C. and about 1084 ° C., respectively, and are melted by firing at the firing temperature of the HTCC-based multilayer ceramic substrate and used as wiring conductors for inner layers. I can't. Further, the high sintering temperature requires a high-temperature firing furnace or an ultra-high temperature firing furnace, so that the equipment cost increases and the energy cost inevitably increases, resulting in a product price increase.

  On the other hand, the demand for lower resistance of the conductor of the multilayer ceramic substrate increases with the demand for module parts in the high frequency range. In order to satisfy these demands, ceramic raw materials such as alumina and forsterite are used at a temperature at which Ag and Cu do not melt. What can be sintered is an LTCC multilayer ceramic substrate. This LTCC-based multilayer ceramic substrate is also called a low-temperature fired multilayer ceramic substrate, and can be fired at a low temperature by mixing a sintering aid such as a glass material having a low melting point into the ceramic raw material (base material). For example, there are alumina + lead borosilicate glass system, cordierite + borosilicate glass system, and various other composition systems.

  The insulator material having these compositions is adjusted so that it can be fired at a temperature of 1000 ° C. or less in order to allow simultaneous firing with a metal having high conductivity such as Ag or Cu. As a result, high conductivity Ag and Cu can be used as an internal conductor, and this LTCC multilayer ceramic substrate (low temperature fired multilayer ceramic substrate) is currently the mainstream as a multilayer ceramic substrate capable of realizing high-density mounting used in a high frequency range. It is becoming.

  However, LTCC materials using these glasses contain a large amount of sintering aids such as glass with low thermal conductivity (generally 50% by weight or more of the total amount), so that the high thermal conductivity and high strength inherent in ceramics such as alumina are high. The feature of good dielectric properties is hampered. In particular, when the thermal conductivity of the ceramic multilayer substrate decreases, when a power amplifier module or the like is produced by mounting a semiconductor element with large heat generation such as a power amplifier at high density, the temperature rises remarkably and cannot be used practically. . This tendency is particularly remarkable in portable electronic devices and the like that are strongly required to be downsized.

  On the other hand, LTCC materials have been developed that enable low-temperature firing while suppressing the amount of low melting point sintering aid added as much as possible and taking advantage of the inherent high thermal conductivity of ceramics.

Patent Document 1 discloses an oxide ceramic material in which CuO and Nb ₂ O ₅ are simultaneously added to an alumina (Al ₂ O ₃ ) -based base material.

Patent Document 2 discloses a ceramic multilayer substrate produced by alternately laminating an inorganic oxide layer and an electrode layer mainly composed of silver, and integrally firing at a temperature of 940 ° C. or lower. A layer is made of a ceramic composition, and CuO, TiO ₂ , Nb ₂ O ₅ , and Ag ₂ O are included as subcomponents of the ceramic composition, and the composition of the subcomponents is defined.

Further, Non-Patent Document 1 discloses that alumina (Al ₂ O ₃ ) is added with glass made of Bi ₂ O ₃ , ZnO, B ₂ O ₃ , SiO ₂ and sintered at 850 ° C., As LTCC, a high thermal conductivity of 7.2 W / mK is obtained.

JP 2004-256384 A JP 2006-261170 A

I. J. et al. Induja et al. , Ceramics International, 41 (2015), 13572-13581.

However, the dielectric ceramic materials created by Patent Documents 1 and 2 and Non-Patent Document 1 have a problem that the dielectric properties are not good, although low temperature sintering of 1000 ° C. or lower can be achieved. . In particular, the temperature coefficient τ _{f of the} resonance frequency takes a negative value (the temperature coefficient τ _{ε of the} dielectric constant takes a positive value), and the absolute values thereof are greatly different from zero.

The dielectric ceramic material of the present invention solves the above-mentioned problem. In the dielectric ceramic material, the dielectric ceramic composition as a raw material of the dielectric ceramic material is composed of aluminum oxide and a sintering aid, The sintering aid contains titanium, copper, niobium, and silver components, the bulk density of the dielectric ceramic material is 3.8 g / cm ³ or more, and the corundum phase is the most in X-ray diffraction on the dielectric ceramic material. The dielectric ceramic material is characterized in that it exhibits a high peak intensity and the rutile phase exhibits the next highest peak intensity.

  According to the present invention, while maintaining low-temperature sinterability and high thermal conductivity equivalent to those of conventional dielectric ceramic materials, it is possible to achieve better dielectric properties than the conventional one, and high thermal conductivity, high strength, and dielectric properties. An LTCC material having excellent characteristics can be realized.

The figure which showed the X-ray-diffraction pattern by the CuK alpha ray of the dielectric ceramic material in Example 1 of this invention (sample number 1, 2, 5, 15, 18, 20) Schematic cross-sectional view showing a method for manufacturing a ceramic electronic component produced using a dielectric ceramic composition according to an embodiment of the present invention Schematic cross-sectional view of a ceramic electronic component produced using the dielectric ceramic composition according to one embodiment of the present invention The figure which showed the X-ray-diffraction pattern by the CuK alpha ray of the dielectric ceramic material in Example 1 of this invention (sample numbers 32-35)

  Hereinafter, a dielectric ceramic material and a dielectric ceramic composition of the present invention will be described with reference to the drawings.

  2 (a) to 2 (c) are schematic cross-sectional views for explaining a method for manufacturing a ceramic electronic component produced using a dielectric ceramic material and a dielectric ceramic composition according to an embodiment of the present invention. FIG. 3 is a schematic cross-sectional view of a ceramic electronic component manufactured by the manufacturing method.

  In the present embodiment, a ceramic multilayer substrate in which capacitors, coils, and transmission lines are incorporated in the inner layer of the ceramic multilayer substrate will be described as an example of the dielectric ceramic composition layer.

  First, 79.4 to 93.2% by weight of alumina (aluminum oxide) having an average particle diameter of 0.01 to 10 μm as a main component for producing a dielectric ceramic composition layer, 6.8 to 20.6% by weight of a sintering aid composition having an average particle size of 0.01 to 10 μm is blended.

The sintering aid composition contains titanium, copper, niobium, and silver components, and the total content of the titanium components in the sintering aid is 51 to 81% by weight in terms of oxide, and the copper component Is 4 to 10% by weight in terms of oxide, and the content of the niobium component in the sintering aid is 6 to 16% by weight in terms of oxide. The content of the total silver component in the sintering aid is 9 to 23% by weight in terms of oxide. The sintering aid composition is composed of CuO, TiO ₂ , Nb ₂ O ₅ , and Ag ₂ O, but is not limited to the oxides, oxides having different valences, nitrates, acetates, complexes, etc. A metal component can be mix | blended as various compounds of these.

  Furthermore, after blending 50 to 300 parts by weight of water with respect to 100 parts by weight of the ceramic dielectric composition and performing ball mill mixing for 12 to 72 hours using high-purity alumina of 1 to 5 mmφ as a dispersion medium, The slurry made of the ceramic composition is taken out from the ball mill and dried.

  Next, 5 to 15 parts by weight of a resin binder such as PVB, 40 to 120 parts by weight of a dispersion medium such as butyl acetate or alcohol, and 2 or more plasticizers such as DBP or BBP with respect to 100 parts by weight of the ceramic composition after drying. 12 parts by weight, and if necessary, a small amount of an antifoaming agent and a dispersing agent are blended, and ball mill dispersion using high-purity alumina of 10 mmφ is performed for 12 to 72 hours to produce a ceramic slurry.

  Next, the obtained ceramic slurry is applied to a predetermined thickness on a carrier film such as a PET film which has been subjected to a mold release treatment by a sheet molding machine such as a die coating apparatus, and then dried in a drying furnace, and then dried as shown in FIG. The ceramic green sheet 201 which is a ceramic dielectric composition layer shown in FIG.

  Next, the ceramic green sheet 201 is punched at a predetermined position by punching or laser processing as necessary, and then a hole is formed using a conductive paste mainly composed of Ag or Cu by screen printing or the like. A via electrode 202 is formed by filling and applying into the opened via hole.

  Thereafter, the wiring electrode 203 having the designed circuit pattern is formed on the ceramic green sheet 201 by a screen printing method or the like using a conductive paste mainly composed of Ag, Ag—Pd, or Cu.

  Next, the ceramic green sheets 201 each having wiring electrodes 203 printed and formed are stacked and pressed while being aligned so as to have a predetermined design as shown in FIG. A laminate 204 in which inorganic material composition layers and electrode layers are alternately laminated as shown in FIG. The size of the laminated body 204 is usually 50 to 200 mm □, and the laminated body 204 can produce a number of predetermined ceramic multilayer substrates 301 in a matrix.

  Further, the capacitor 205 can be incorporated by disposing the wiring electrode 203 having a predetermined area on the inner layer portion of the laminate 204 so as to face each other with the ceramic green sheet 201 therebetween. Furthermore, it is possible to incorporate a capacitor 205 having a larger capacity by stacking the wiring electrodes 203.

  It is also possible to incorporate a spiral coil 207 through a via electrode 202 in which the wiring electrode 203 is formed on the ceramic green sheet 201. By incorporating these capacitor 205 and coil 207, a ceramic multilayer substrate 301 capable of high-density mounting can be realized.

  Next, a surface layer electrode 206 is formed on the laminate 204 using a conductive paste mainly composed of silver. After that, the laminate 204 is pressed with a predetermined pressure in the vertical direction of the laminate 204, and the laminate 204 is laminated and pressure-bonded.

In addition, it is preferable to perform the temperature at the time of this lamination | stacking and pressurization at normal temperature-100 degreeC, and pressure is 20-1000 kgf / cm < ² >.

  Then, the laminated body 204 laminated and pressure-bonded is cut into pieces, and the separated laminated body 204 is subjected to binder removal treatment at a temperature of 350 to 650 ° C.

  Next, as a firing step, firing is performed at a maximum holding temperature of 850 to 1050 ° C. (850 to 950 ° C. when the conductor is Ag, 850 to 1050 ° C. when the conductor is Cu), and a holding time of 0 to 100 hours at the maximum temperature. Do. As for the firing atmosphere, air is used in the case of co-firing with Ag, and nitrogen is used in the case of co-firing with Cu. However, if necessary, nitrogen, oxygen, or a mixed gas of nitrogen and oxygen, argon, etc. Firing can be performed in various oxygen partial pressure atmospheres.

The bulk density of the dielectric ceramic material produced by the firing is 3.8 g / cm ³ or more, which is 95% of the theoretical density of 4.0 g / cm ³ of alumina, that is, the relative density is 95% or more. It is important that In general, it is known that a ceramic material having a relative density of 95% or more has almost no open pores and is highly reliable.

As described above, the temperature coefficient τ _f of the resonance frequency occupies the main item among the dielectric characteristics of the dielectric ceramic material. τ _f of the corundum phase of α-alumina is about −50 ppm / ° C. and takes a negative value. In order to bring this close to zero, it is important that a substance having a positive value of τ _f is present in the fired dielectric ceramic material. Since τ _f of the rutile phase of titanium oxide is about +450 ppm / ° C. and takes a large positive value, τ _f of the entire dielectric ceramic material can be brought close to zero in the presence of a small amount of rutile phase. Titanium oxide is effective as a sintering aid for α-alumina. That is, titanium oxide can realize both the effect of bringing τ _f of the dielectric ceramic material close to zero and the improvement in maintaining sinterability.

Therefore, in X-ray diffraction on the dielectric ceramic material, it is important that the corundum phase exhibits the highest peak intensity and the rutile phase exhibits the next highest peak intensity. According to ICSD (inorganic crystal structure database) 31545, the main peak corresponding to the corundum phase of α-alumina (space group R3c) is 2θ = 35.11 ± 0.20 ° (diffraction index 104). Or 2θ = 43.30 ° (diffraction index 113) or 2θ = 57.42 ° (diffraction index 116). According to ICSD (Inorganic Crystal Structure Database) 39169, a main peak corresponding to the rutile phase of titanium oxide (space group P42 / mnm) appears at 2θ = 27.33 ° (diffraction index 110). Each peak includes a measurement error of ± 0.20 °. Here, the intensity with the highest peak intensity among the three main peaks of the corundum phase of the α-alumina is the highest peak intensity by X-ray diffraction. The next highest peak intensity is the main peak corresponding to the rutile phase of titanium oxide. Of course, other components may be dissolved in the corundum phase of α-alumina and the rutile phase of titanium oxide, and the peak position (2θ) may change, but it should be within the range of ± 0.20 °. When the main peak corresponding to the rutile phase of titanium oxide is higher than the corundum phase main peak of α-alumina, the resonance frequency temperature coefficient τ _f exceeds +60 ppm / ° C., and the absolute value of the resonance frequency temperature coefficient is also α -Be larger than that of alumina.

Furthermore, it is important that the peak of silver niobate (AgNbO ₃ ) is not detected by X-ray diffraction on the dielectric ceramic material. Τ _f of silver niobate is estimated to be −600 ppm / ° C. or less around room temperature to 100 ° C., and takes a large negative value. By this peak is not detected, it appears clearly that tau _f increasing effect of rutile phase titanium oxide as described above.

  According to ICSD (Inorganic Crystal Structure Database) 55646, a main peak corresponding to the orthorhombic phase (space group Pbcm) of silver niobate appears at 2θ = 32.08 ° (diffraction index 114). The peak includes a measurement error of ± 0.20 °. Of course, other components may be dissolved in the silver niobate and the peak position (2θ) may change, but it should be within the range of ± 0.20 °.

  As a result of inventor's earnest study, the fine structure of the dielectric ceramic material after firing was successfully controlled by increasing the content of titanium oxide in the dielectric ceramic composition. Specifically, rutile phase titanium oxide was allowed to remain, and silver niobate could be eliminated. As a result, the dielectric ceramic material has been improved in dielectric properties while maintaining low temperature sintering and high thermal conductivity. This part is a characteristic point of the present invention.

  The relative density of the ceramic multilayer substrate 301 thus prepared is 95% or more. In such a ceramic multilayer substrate 301, by realizing the composition of the dielectric ceramic composition layer, it is possible to maintain the low-temperature sinterability and reduce the holding time while improving the dielectric characteristics, thereby saving energy. In addition, Ag or Cu having excellent conductivity can be used as the main component for the electrode material. Further, the amount of the sintering aid necessary for obtaining sufficient sinterability can be reduced, and it can be brought close to pure alumina. As a result, the thermal conductivity, mechanical strength, and dielectric properties of the dielectric ceramic material can be improved. In particular, with respect to thermal characteristics, a ceramic multilayer substrate 301 having higher thermal conductivity can be realized, and the ceramic multilayer substrate 301 is suitable for a small power amplifier module or the like on which a semiconductor device having high heat generation is mounted and has good dielectric characteristics. Can be provided.

  Next, as shown in FIG. 3, by mounting a semiconductor component 302 such as a power amplifier or LED or a high-capacitance capacitor 303 that is difficult to form on the inner layer on the surface layer of the ceramic multilayer substrate 301 manufactured by the above method, a small size is achieved. The ceramic electronic component can be realized.

  By realizing such a ceramic multilayer substrate 301, for example, the number of thermal vias, which are metal conductor wirings for heat dissipation, can be reduced compared to a conventional power amplifier module, or by using no thermal vias. As the degree of freedom increases and the restrictions on the wiring space are relaxed, the various modules can be further miniaturized, and the communication equipment can be miniaturized and multifunctional.

  Hereinafter, dielectric ceramic materials and dielectric ceramic compositions will be described in detail based on examples. The present invention is not limited to these examples.

As shown in Table 1, 71.1 to 100% by weight of aluminum oxide (Al ₂ O ₃ ) as a base material, and CuO, TiO ₂ , Nb ₂ O ₅ , and Ag ₂ O as a sintering aid total 0.0 ˜28.9 wt% was blended and mixed and dried for 16 hours in a ball mill. A predetermined amount of PVA resin as a binder and water were added to the powder, granulated using a mortar, and after drying, a cylindrical shaped body was prepared by uniaxial pressing at 75 MPa. After the binder was removed from the molded body, firing was performed in the air. The heating rate was 300 ° C./h, the maximum temperature was 860, 900, 940, 980 ° C., or 1300 ° C., the holding time at the maximum temperature was 24 h, and the cooling rate was 300 ° C./h. In this way, 35 types of dielectric ceramic materials of sample numbers 1 to 35 were prepared.

For sample numbers 1 to 20, the weight ratio of the sintering aids other than TiO ₂ (CuO, Nb ₂ O ₅ , Ag ₂ O) is constant, and the sample number 1 is used as a base for the total amount of TiO ₂ sintering aid. The weight percent is increased from 5 to 86%. Sample numbers 2 to 4, 5 to 7, 8 to 10, 11 to 13, 14 to 16, and 17 to 19 have the same composition, and only the firing temperature is changed to 900, 940, and 980 ° C. Sample numbers 2 to 19 are patent examples. Sample numbers 1 and 20 are comparative examples. In particular, sample number 1 is a sample corresponding to Patent Document 2 described in the prior art. The firing temperature of sample number 1 was 860 ° C., and the firing temperature of sample number 20 was 940 ° C. As will be described later, the composition of sample number 1 is also fired at 900, 940, and 980 ° C. (sample number is not given).

For sample numbers 21 to 26, the weight ratio of the sintering aids other than TiO ₂ (CuO, Nb ₂ O ₅ , Ag ₂ O) is constant, and based on the sample number 1 with respect to the total amount of the TiO ₂ sintering aid. The weight percent is increased from 5 to 84%. The firing temperatures of sample numbers 21 to 26 are 860, 860, 900, 900, 900, and 940 ° C., respectively. Although this reason is mentioned later, it is because the optimal calcination temperature which achieved bulk density 3.8g / cm < ³ > or more with each composition was selected. Sample numbers 23 to 25 are patent examples, and sample numbers 21, 22, and 26 are comparative examples. Sample Nos. 27 to 31 are all patent examples, and additional experiments were conducted in order to further ensure the effects of the patent examples.

Sample numbers 32 to 35 are all comparative examples, and the sintering aid is only TiO ₂ . In other words, it does not contain any sintering aid other than TiO ₂ . Sample number 32 indicates that it is only alumina (Al ₂ O ₃ ). Based on Sample No. 32, the weight percentage of the sintering aid to the total amount of the dielectric ceramic composition is increased from 0 to 25.1%. The firing temperature of sample numbers 32 to 35 is 1300 ° C. This is because sufficient sinterability (corresponding to a bulk density of 3.8 g / cm ³ ) could not be obtained at a temperature below 1300 ° C.

Regarding evaluation of the obtained dielectric ceramic materials of sample numbers 1 to 35, bulk density, relative dielectric constant ε _r , Q × f (product of quality factor Q and resonance frequency f), resonance frequency temperature coefficient τ _f , heat conduction The measurement was performed by XRD (X-ray diffraction) measurement using a rate κ and CuKα rays.

Regarding the evaluation of the bulk density, the values are shown in Table 2. However, the evaluation was good at 3.8 g / cm ³ or more, which is 95% of the theoretical density of 4.0 g / cm ³ of alumina. Although the theoretical density of titanium oxide (rutile phase) is 4.2 g / cm ^3, it is equivalent to the value of alumina and its content is small, so the theoretical density of alumina was used as a reference.

Table 2 shows values for the evaluation of the three dielectric properties (relative permittivity ε _r , Q × f (product of quality factor Q and resonance frequency f), resonance frequency temperature coefficient τ _f ). As noted above, τ _f is particularly focused on this time. A sample having an absolute value lower than the value of the alumina single component of sample number 32 was judged good.

  Regarding the evaluation of the thermal conductivity κ, the one of 7.2 W / mK or more shown in Non-Patent Document 1 was judged to be good.

The evaluation of the XRD measurement was defined as follows. As described above, the main peak corresponding to the corundum phase of α-alumina is 2θ = 35.11 ± 0.20 ° (diffraction index 104) or 2θ = 43.30 ± 0.20 ° (diffraction index 113), 2θ = Appears at 57.42 ± 0.20 ° (diffraction index 116). A main peak corresponding to the rutile phase of titanium oxide appears at 2θ = 27.33 ± 0.20 ° (diffraction index 110). A main peak corresponding to silver niobate (AgNbO ₃ ) appears at 2θ = 32.08 ± 0.20 ° (diffraction index 114). Here, (1) the intensity of the highest peak intensity among the three main peaks of the corundum phase of the α-alumina shows the highest peak intensity by X-ray diffraction, and (2) the second highest after the α-alumina. Three standards were used: the peak intensity was a main peak corresponding to the rutile phase of titanium oxide, and the peak of ( ₃ ) silver niobate (AgNbO ₃ ) was not detected. That is, the case where the above three criteria are satisfied is indicated as “◯”, and the case where the above three criteria are not satisfied is indicated as “X”.

  A result is demonstrated using (Table 2), (FIG. 1), and (FIG. 4).

From the results of sample numbers 1 to 31, the bulk density of all the samples was 3.8 g / cm ³ or more, and had good sinterability at less than 1000 ° C. Moreover, the thermal conductivity of all the samples is 14 W / mK or more, and the dielectric ceramic material fired at less than 1000 ° C. has good thermal characteristics of 7.2 W / mK or more described in Non-Patent Document 1. It was.

Sample No. 1 (Comparative Example) contains 5% by weight of TiO ₂ with respect to the total amount of the sintering aid. Τ _f of this sample was −87 ppm / ° C. and smaller than the value of sample number 32 (alumina single component) −52 ppm / ° C., and the absolute value was large. That is, the dielectric characteristics deteriorated. From the XRD pattern shown in FIG. 1 (a), the peak of TiO ₂ (rutile phase) was not recognized, but the peak of AgNbO ₃ was recognized instead. This is the reason why τ _{f of} sample number 1 deteriorated. Sample No. 1 was obtained at a firing temperature of 860 ° C., but Q × f was 3500 GHz. Attempts were made to measure Q × f of samples fired at 900, 940, and 980 ° C., but the properties were too bad to measure. In other words, it was found that the composition described in Sample No. 1 was extremely inferior in the stability of the dielectric characteristics depending on the firing temperature.

On the other hand, τ _{f of} Sample No. 2 containing 51% by weight of TiO ₂ with respect to the total amount of the sintering aid is −39 ppm / ° C. and larger than the value of Sample No. 32 (alumina single component) −52 ppm / ° C. The value was small. That is, the dielectric characteristics improved. From the XRD pattern shown in FIG. 1 (b), the AgNbO ₃ peak disappeared, and instead a TiO ₂ (rutile phase) peak was observed. This is the reason why τ _{f of} sample number 2 is improved compared to sample numbers 1 and 32. Sample No. 2 was obtained at a firing temperature of 900 ° C., but Q × f was 2900 GHz. Q × f of samples No. 3 and 4 calcined at 940 and 980 ° C. were 3100 and 6500 GHz, respectively, and there was no deterioration of Q × f compared to the composition described in sample No. 1 (rather, the Q × f was increased by increasing the calcining temperature. Xf tended to increase). Further, no significant difference was observed between the samples having the same composition _{depending on} the firing temperature of εr. That is, it was confirmed that the dielectric property was stabilized by the firing temperature by increasing the amount of TiO ₂ .

Sample Nos. 5, 6, and 7 contain 67% by weight of TiO ₂ with respect to the total amount of sintering aid, Sample Nos. 8, 9, and 10 contain 69% by weight of TiO ₂ with respect to the total amount of sintering aid. 11, 12 and 13 contain 71% by weight of TiO ₂ with respect to the total amount of the sintering aid, and Sample Nos. 14, 15 and 16 contain 76% by weight of TiO ₂ with respect to the total amount of the sintering aid. 18 and 19 contain 81% by weight of TiO ₂ with respect to the total amount of the sintering aid. The τ _f of these samples increases as the content of TiO ₂ increases. For example, τ _{f of} sample numbers 5, 8, 11, 15, and 18 are −8, −6, ± 0, +19, and +42 ppm / ° C., respectively. It was. Further, no significant difference was observed between the samples having the same composition depending on the firing temperature of τ _f . In particular, the absolute value of tau _f in the sample No. 5-13 is below 10 ppm / ° C., showed good dielectric properties. From the XRD patterns of Sample Nos. 5, 15, and 18 shown in FIGS. 1 (c), (d), and (e), respectively, there is no AgNbO ₃ peak and TiO ₂ (rutile phase) peak as in Sample No. 2. Admitted. Also, there was a tendency that with increasing content of TiO ₂ increases the peak intensity of TiO 2 _(rutile phase), the peak intensity of TiO 2 _(rutile phase) was less than the peak intensity of alumina. These are the reasons why good τ _f is obtained. In addition, no significant deterioration was observed due to an increase in the firing temperature of Q × f between samples having the same composition. Rather, Q × f tended to increase with increasing firing temperature. Further, no significant difference was observed between the samples having the same composition _{depending on} the firing temperature of εr.

Sample No. 20 (Comparative Example) contains 86% by weight of TiO ₂ with respect to the total amount of the sintering aid. The absolute value of τ _f of this sample was +99 ppm / ° C. and the absolute value of the sample number 32 (alumina single component) was −52 ppm / ° C. That is, the dielectric characteristics deteriorated. From the XRD pattern shown in FIG. 1 (f), there was no AgNbO ₃ peak and a TiO ₂ (rutile phase) peak, but the TiO ₂ (rutile phase) peak was larger than the peak intensity of alumina, It was the maximum. This is the reason why τ _{f of} sample number 20 deteriorated.

Similar evaluations were made for sample numbers 21-31. Sample numbers 23 to 25 and 27 to 31 (patent examples) contained 58 to 81 wt% of TiO ₂ with respect to the total amount of the sintering aid, and the absolute value of τ _f was a small value of 47 ppm / ° C. or less. In the X-ray diffraction of these samples, there was no AgNbO ₃ peak and a TiO ₂ (rutile phase) peak was observed, and the peak intensity was smaller than that of alumina. Sample numbers 21, 22, and 26 (comparative examples) contained 5, 31, and 84% by weight, respectively, of TiO ₂ with respect to the total amount of the sintering aid, and the absolute value of τ _f was large.

In addition, all of the sample numbers 32-35 which are comparative examples needed baking at 1300 degreeC in order to acquire sufficient sinterability. Further, for sample number 35, a bulk density of 3.8 g / cm ³ could not be obtained. That is, these samples are HTCC and cannot be said to be LTCC. Τ _{f of} Sample Nos. 32, 33, 34, and 35 are −52, −36, −46, and −65 ppm / ° C., respectively, and the weight of the only sintering aid TiO ₂ with respect to the total amount of the dielectric ceramic composition. % Was increased from 0 to 25.1%, but τ _f did not approach zero as in the results of sample numbers 5 to 13 (± 10 ppm / ° C. or less). From the XRD patterns shown in FIGS. 4A to 4D, it was found that a part of the increased amount of TiO ₂ exists as Al ₂ TiO ₅ . According to the equilibrium diagram, Al ₂ TiO ₅ is a compound produced only at 1100 ° C. or higher, and there is expansion (density reduction) at that time. Moreover, τ _f of the Al ₂ TiO ₅ is +79 ppm / ° C., which is considerably smaller than that of TiO ₂ , and these are considered to be the reasons why τ _f did not approach ± 10 ppm / ° C. or less.

Thus, when the results of the sample numbers 1 to 35 are summarized, the bulk density of the dielectric ceramic material produced by firing the dielectric ceramic composition at 980 ° C. or less is 3.8 g / cm ³ or more. In a sample in which the corundum phase of alumina shows the highest peak intensity and the rutile phase of titanium oxide shows the next highest peak intensity in X-ray diffraction on the dielectric ceramic material, good dielectric properties and high thermal conductivity It was clarified in this example that the Further, since the peak of AgNbO ₃ is not observed in the X-ray diffraction of the dielectric ceramic material, the value of the resonance frequency temperature coefficient τ _f can be made close to zero with a smaller amount of TiO ₂ content. . Furthermore, by firing the dielectric ceramic composition at less than 961 ° C., which is the melting point of Ag, simultaneous firing with Ag having low electrical resistance is possible.

  In order to obtain a dielectric ceramic material having the good dielectric properties and high thermal conductivity, the dielectric ceramic composition used as a raw material is made of an aluminum oxide and a sintering aid. And the total content of the aluminum oxide in the dielectric ceramic composition is 79.4 to 93.2% by weight, and the total content of the sintering aid is in the dielectric ceramic composition Is 6.8 to 20.6% by weight in terms of oxide, and the sintering aid contains titanium, copper, niobium, and silver components, and the total content of the titanium components occupies the sintering aid. It is 51 to 81% by weight in terms of oxide, the content of the copper component in the sintering aid is 4 to 10% by weight in terms of oxide, and the total of the niobium component is the sintering aid. Contained in the agent It is important that the total content of the silver component in the sintering aid is 9 to 23% by weight in terms of oxide, in terms of oxide. It was revealed in

  The present invention is a dielectric ceramic material and a dielectric ceramic composition that enable low-temperature sintering, good dielectric properties, and high thermal conductivity. By using the present invention, Ag or Cu having low electrical resistance can be obtained. It is useful as a substrate for ceramic electronic components that are built in as conductors and have high heat dissipation and good dielectric properties, on which a heat-generating semiconductor such as a power amplifier or LED is mounted.

DESCRIPTION OF SYMBOLS 201 Ceramic green sheet 202 Via electrode 203 Wiring electrode 204 Laminated body 205 Capacitor 206 Surface layer electrode 207 Coil 301 Ceramic multilayer substrate 302 Semiconductor components, such as a power amplifier and LED 303 High capacity capacitor components

Claims (4)

In the dielectric ceramic material, the dielectric ceramic composition as a raw material of the dielectric ceramic material is composed of aluminum oxide and a sintering aid, and the sintering aid contains titanium, copper, niobium, and a silver component, The bulk density of the dielectric ceramic material is 3.8 g / cm ³ or more, the X-ray diffraction on the dielectric ceramic material shows the highest peak intensity in the corundum phase, and the rutile phase shows the next highest peak intensity. A dielectric ceramic material characterized by 2. The dielectric ceramic material according to claim 1, wherein a peak of silver niobate (AgNbO ₃ ) is not detected by X-ray diffraction on the dielectric ceramic material in the dielectric ceramic material.   The dielectric ceramic material according to any one of claims 1 and 2, wherein in the dielectric ceramic material, a firing temperature of the dielectric ceramic composition is lower than a melting point of silver.   In the dielectric ceramic composition, the dielectric ceramic composition is composed of aluminum oxide and a sintering aid, and a total content of the aluminum oxide in the dielectric ceramic composition is 79.4 to 93.2 wt. The content of the sintering aid in the dielectric ceramic composition is 6.8 to 20.6% by weight in terms of oxide, and the sintering aid is composed of titanium, copper, and niobium. In addition, the content of the silver component, and the total content of the titanium component in the sintering aid is 51 to 81% by weight in terms of oxide, and the total content of the copper component is in the sintering aid. It is 4 to 10% by weight in terms of oxide, the content of the niobium component in the sintering aid is 6 to 16% by weight in terms of oxide, and the total of the silver component is the sintering aid. The percentage content of the agent in terms of oxide ~ 23 dielectric ceramic composition, wherein the percentages by weight.