JP4249690B2 - High frequency dielectric ceramics and laminates - Google Patents

Description

  The present invention relates to a high frequency dielectric ceramic having a high Q value in a high frequency region such as a microwave and a millimeter wave, and a laminated body. For example, the present invention relates to various types used in a high frequency region such as a microwave and a millimeter wave. The present invention relates to high-frequency dielectric ceramics and laminates that can be used for resonator materials, MIC dielectric substrate materials, dielectric waveguide materials, dielectric layers of multilayer ceramic capacitors, and the like.

  2. Description of the Related Art Conventionally, dielectric ceramics are widely used for dielectric resonators, MIC dielectric substrates, waveguides, and the like in high frequency regions such as microwaves and millimeter waves. In recent years, with the development and spread of mobile communications such as mobile phones, the demand for dielectric ceramics as materials for electronic circuit boards and electronic components is increasing.

  In the simultaneous firing of dielectric ceramics and internal conductors in electronic circuit boards and electronic parts, the firing temperature of conventional dielectric ceramics is as high as 1100 ° C. or higher, so the conductor material has a relatively high melting point. Pt, Pd, W, Mo, etc. were used. Since these high melting point conductor materials have a large conduction resistance, the conventional electronic circuit board has a problem that the Q value of the resonance circuit and the inductance is reduced, and the transmission loss of the conductor line is increased.

Therefore, in order to solve such problems, low-temperature fired dielectric ceramics that can be fired simultaneously with Ag, Cu, etc. having a low conduction resistance have been proposed. For example, the dielectric ceramic composition previously filed by the present applicant is made of MgO, CaO, TiO ₂ and B ₂ O ₃ , Li ₂ CO ₃ , and is formed at a relatively low temperature of 900 to 1050 ° C. with Ag, Excellent characteristics that can be fired at the same time as an inner conductor such as Cu, the dielectric constant εr of the dielectric ceramic is 18 or more, the Q value at a measurement frequency of 7 GHz is 2000 or more, and the temperature coefficient τf of the resonance frequency is within ± 40 ppm / ° C. The high-frequency electronic component can be reduced in size and performance (see Patent Document 1).
JP-A-8-208330

  However, since the dielectric ceramic composition disclosed in JP-A-8-208330 has a high sintering temperature and the shrinkage start temperature in sintering is as high as 845 to 960 ° C., the shrinkage behavior with the conductor material. There are problems such as poor matching, and the fired substrate and electronic parts are warped and distorted.

  That is, as a conductor, there is a conductor mainly composed of Ag and / or Cu, for example, a conductor obtained by adding a metal such as a glass component, a ceramic component, Pt, or Pd to Ag, Cu, or Ag, Cu. Since these conductors have a shrinkage start temperature of about 650 ° C. at the highest at the time of firing, there is a large difference from the shrinkage start temperature of the dielectric ceramic composition, thereby causing problems such as deformation of the substrate and the like. there were.

  The present invention has been made in view of the above problems, and can further reduce the firing temperature, lower the shrinkage start temperature, and can approach the shrinkage start temperature of the conductor, and is mainly composed of Ag or Cu. An object of the present invention is to provide a dielectric ceramic for high frequency and a laminate capable of suppressing warpage and distortion even when fired simultaneously with a conductor.

The dielectric ceramic for high frequency of the present invention comprises 100 parts by weight of a low-loss ceramic filler, and a grain boundary phase-forming component containing B, alkali metal, Si and alkaline earth metal with respect to 100 parts by weight of the low-loss ceramic filler A high frequency dielectric ceramic having a Qf value expressed by a product of a Q value and a measurement frequency thereof is 20000 [GHz] or more, which is obtained by firing a composition comprising 5 to 30 parts by weight. things, the composition formula by molar ratio, relative to _(1-x) when expressed as MgTiO ₃ · xCaTiO 3, principal component 1 00 parts by weight of said x satisfies 0 ≦ x ≦ 0.2, wherein 3-20 parts by weight of B in terms _{of B} 2 _{O 3,} wherein 1 to 10 parts by weight of Li in Li ₂ CO ₃ terms as the alkali metal, the 0.01-5 parts by weight of Si in terms of SiO _2, the alkaline earth Be, Mg as similar metals , Together with at least one of Ca and Ba containing 0.1 to 5 parts by weight in terms of oxide, the M n contains 0.1 to 3 parts by weight MnO ₂ translated to further the main component 100 parts by weight characterized in that it comprises Te.

  The laminate of the present invention is a laminate having a conductor mainly composed of Ag and / or Cu inside and / or on the surface of a dielectric substrate formed by laminating a plurality of dielectric layers, wherein the dielectric layer comprises: A dielectric ceramic for high frequency according to claim 1 or 2.

  According to the present invention, since the firing temperature can be set to 920 ° C. or less and the shrinkage start temperature can be set to 830 ° C. or less, it can be fired simultaneously with a conductor metal such as Ag or Cu. The warpage and distortion of the substrate caused by the mismatch are suppressed, and since the Qf value is 20000 or more in the high frequency region, the electronic component and the substrate can be reduced in size and performance.

High-frequency dielectric ceramic of the present invention, the main component is, when representing the formula by molar ratio _{(1-x) MgTiO 3 ·} xCaTiO 3, it is desirable that x satisfies 0 ≦ x ≦ 0.2 . Here, x is set to 0 ≦ x ≦ 0.2 because when x exceeds 0.2 mol, the temperature coefficient τf of the resonance frequency becomes too large on the plus side. In particular, from the viewpoint of the temperature coefficient τf of the resonance frequency of the dielectric ceramic, x is preferably 0.03 ≦ x ≦ 0.13. Further, in the MgTiO ₃ and CaTiO _3, be in the range of Mg / Ti ratio or Ca / Ti ratio is 0.9 to 1.1, can be used as the main component of the ceramic of the present invention.

In the high frequency dielectric ceramic according to the present invention, B is ₃ to 20 parts by weight in terms of B ₂ O ₃ with respect to 100 parts by weight of the main component, and Li is 1 to 10 in terms of Li ₂ CO ₃ as an alkali metal. parts, 0.01-5 parts by weight of Si in terms of SiO _2, further Be alkaline earth metals, Mg, Ca, 0.1 to 5 parts by weight of at least one alkaline earth metal oxide converted among Ba In addition, it contains 0.1 to 3 parts by weight of Mn in terms of MnO ₂ with respect to 100 parts by weight of the main component .

Here, B is contained in an amount of 3 to 20 parts by weight in terms of B ₂ O ₃ when B is less than 3 parts by weight, it does not sinter even at 1100 ° C., and at the same time as a conductor mainly composed of Ag or Cu. This is because when firing is impossible and, on the contrary, the amount exceeds 20 parts by weight, the ratio of the glass phase in the sintered body increases and the Q value decreases. Therefore, it is desirable to contain 5 to 15 parts by weight in terms of B ₂ O ₃ from the viewpoint of maintaining sinterability and obtaining a high Q value. Examples of the B-containing compound include metal boron, B ₂ O ₃ , collimite, CaB ₂ O ₄ , borosilicate glass, borosilicate alkali glass, and borosilicate alkaline earth glass.

  Moreover, the alkali metal was contained in an amount of 1 to 10 parts by weight in terms of alkali metal carbonate, and when the content was less than 1 part by weight, it was not sintered even at 1100 ° C. This is because simultaneous firing cannot be performed, and conversely, when the amount exceeds 10 parts by weight, the crystal phase changes and the Q value decreases. From the viewpoint of the Q value of the dielectric ceramic, 4 to 9 parts by weight is desirable. Examples of the alkali metal include Li, Na, and K. Among these, Li is particularly desirable. Examples of the alkali metal-containing compound include carbonates and oxides of the above alkali metals.

Furthermore, Si is contained in an amount of 0.01 to 5 parts by weight in terms of SiO ₂ when the content is less than 0.01 parts by weight, the shrinkage start temperature in the sintering process of the dielectric ceramic is about 840 ° C. This is because the addition effect cannot be obtained. On the other hand, if it exceeds 5 parts by weight, the relative dielectric constant εr or the Q value decreases. From the viewpoint of the relative dielectric constant εr or Q value of the dielectric ceramic, 0.5 to 3 parts by weight is desirable. Examples of the Si-containing compound include SiO ₂ and MgSiO ₃ .

  The alkaline earth metal contains at least one of Be, Mg, Ca, and Ba in an amount of 0.1 to 5 parts by weight in terms of alkaline earth metal oxide. When these are less than 0.1 parts by weight, the shrinkage start temperature in the sintering process of the dielectric ceramic is higher than 830 ° C., and the addition effect cannot be obtained. On the other hand, when the amount exceeds 5 parts by weight, the temperature coefficient τf of the resonance frequency of the dielectric ceramic becomes too large on the plus side. In particular, from the viewpoint of the sinterability of the dielectric ceramic and the temperature coefficient τf of the resonance frequency, the total amount is preferably 0.5 to 3.5 parts by weight.

  Examples of the alkaline earth metal include Be, Mg, Ca, and Ba, and Ba is preferable among them. Examples of the alkaline earth metal-containing compound include carbonates and oxides of the above alkaline earth metals.

Furthermore, in the high frequency dielectric ceramic of the present invention, 0.1 to 3 parts by weight of Mn in terms of MnO _{2 is} further contained with respect to 100 parts by weight of the main component from the viewpoint of improving the sinterability . The reason why 0.1 to 3 parts by weight of Mn in terms of MnO ₂ is contained is that the addition effect is not obtained when the amount is less than 0.1 part by weight, and the dielectric property is increased when the amount is more than 3 parts by weight. Because it gets worse. It is desirable to contain 1.2 to 1.8 parts by weight of Mn in terms of MnO ₂ .

  The dielectric ceramic for high frequency of the present invention includes 100 parts by weight of a low-loss ceramic filler, and Be, Mg, Ca, Ba as B, alkali metal, Si, and alkaline earth metal with respect to 100 parts by weight of the low-loss ceramic filler. A composition comprising 5 to 30 parts by weight of a grain boundary phase-forming component containing sinter is fired, and the Qf value represented by the product of the Q value and its measurement frequency is 20000 [GHz] or more.

Here, as a low loss ceramic filler, it is desirable that the Qf value of the filler alone is 30000 [GHz] or more. For example, a perovskite-type crystal grains containing at least Mg and Ti represented by the composition formula by molar ratio _{(1-x) MgTiO 3 ·} xCaTiO 3 (0 ≦ x ≦ 0.2) is desirable.

  The grain boundary phase forming component containing B, alkali metal, Si and alkaline earth metal was used, and by using these components, the firing temperature could be 920 ° C. or lower, and the firing shrinkage start temperature This is because the Qf value as a porcelain can be 20000 [GHz] or more.

  The amount of the grain boundary phase forming component is 5 to 30 parts by weight with respect to 100 parts by weight of the low-loss ceramic filler. When the amount is less than 5 parts by weight, the effect of lowering the firing temperature is small. Simultaneous firing with the conductor as the main component becomes impossible, and conversely, when it exceeds 30 parts by weight, the temperature coefficient τf of the resonance frequency of the dielectric ceramic becomes too large on the plus side. In particular, the addition amount is preferably 15 to 25 parts by weight from the viewpoint of the sinterability of the dielectric ceramic and the temperature coefficient τf of the resonance frequency.

The dielectric ceramic for high frequency of the present invention includes, for example, MgTiO ₃ powder, CaTiO ₃ powder, B ₂ O ₃ powder, Li ₂ CO ₃ powder, SiO ₂ powder, MnO ₂ powder, and alkaline earth metal as raw material powder. Oxide (MgO, CaO, BaO) powder was prepared, these were weighed so as to have the above composition ratio, pulverized and mixed with ZrO ₂ balls, this mixed powder was calcined at 650 to 850 ° C., and then again ZrO Crush and mix with _two balls until the pulverized particle size is 2.5 μm or less, and form the calcined powder into a predetermined shape by a known method such as press molding or doctor blade method, and then in the atmosphere, oxygen atmosphere or nitrogen atmosphere In a non-oxidizing atmosphere such as 920 ° C. or less, particularly baked at 870 to 920 ° C. for 0.5 to 2 hours. The raw material powder may be a metal salt such as a hydroxide, carbonate, nitrate, etc. that generates an oxide upon firing.

  Be, Mg, Ca, and Ba as alkaline earth metals are desirably added as glass frit containing B, Li, and Si from the viewpoint of improving sinterability. In this case, the amounts of B, Li, and Si are the total amount of the amount contained in the glass frit and the amount added as a powder.

  In the dielectric ceramic for high frequency of the present invention, Zr, Al, etc. may be mixed in the manufacturing process such as the mixing and pulverizing process of raw materials, or Al, Fe, Hf, Sn, etc. may be included as inevitable impurities of the raw materials. .

In the high frequency dielectric ceramic according to the present invention, for example, MgTiO ₃ and CaTiO ₃ may be main crystal phases as crystal phases, and (Mg, Ti) ₂ (BO ₃ ) O may be precipitated. In addition, Be, Mg, Ca and Ba as alkaline earth metals are dissolved in the A site of MgTiO ₃ and CaTiO ₃ or become glass components to improve the sinterability. Si exists as a glass phase. Furthermore, the high frequency dielectric ceramic of the present invention has an average crystal grain size of 1 to 5 μm.

Example 1
MgTiO ₃ powder, CaTiO ₃ powder, B ₂ O ₃ powder, alkali metal carbonate powder (Li ₂ CO ₃ ) , SiO ₂ powder, MnO ₂ powder, and alkaline earth oxide powder (purity 99% or more as a raw material ) MgO, CaO, BaO) were weighed so as to have the ratio shown in Table 1 , and wet-mixed for 20 hours in a ball mill using ZrO ₂ balls using pure water as a medium. The mixture was then dried (dehydrated) and calcined at 800 ° C. for 1 hour.

This calcined product was pulverized so that the pulverized particle size was 1.0 μm or less, and was press-molded at a pressure of 1 ton / cm ² into a cylindrical shape having a diameter of 10 mm and a height of 8 mm as a sample for dielectric property evaluation. The sample was fired for 3 hours at the temperature shown in 2 to obtain a cylindrical sample having a diameter of 8 mm and a height of 6 mm.

Evaluation of dielectric characteristics was performed by measuring the relative dielectric constant and Q value at a frequency of 8 GHz by the dielectric cylindrical resonator method using the sample. Table 2 shows the Qf value expressed by the product of the Q value and the measurement frequency f. Furthermore, the temperature coefficient τf [ppm / ° C.] of the resonance frequency in the temperature range of −40 to + 85 ° C. was measured. The results are shown in Table 2 .

From these Tables 1 and 2 , the dielectric ceramic composition of the present invention has a relative dielectric constant of 18 to 20, a Qf value of 20000 [GHz] or more, and a temperature coefficient τf of resonance frequency within ± 40 ppm / ° C. It can be seen that it has excellent dielectric properties, has sintering shrinkage at 760 to 830 ° C., and has excellent sinterability capable of firing at 920 ° C. or lower.

Incidentally, in the column of alkali in Table 1, have been described as L i, which is the meaning of the _Li 2 CO _3, also in the field of alkaline earth, Mg, Ba, has been described as Ca, which, It means MgO, BaO, CaO. Furthermore, sample No. For 4 and 5 , raw material powders with Mg / Ti and Ca / Ti ratios of 1.1 and 0.9, respectively, were used.

The main ingredient high frequency dielectric porcelain, represented by the composition formula by molar ratio _{(1-x) MgTiO 3 ·} xCaTiO 3 (0 ≦ x ≦ 0.2) of the present invention, B, alkali metal, Si, alkaline By containing a predetermined amount of earth metal, the relative dielectric constant is 18 to 40, the Qf value is 20000 [GHz] or more, the firing temperature is 920 ° C. or less, and the shrinkage start temperature is 830 ° C. or less. Is possible.

  Further, in the laminate of the present invention, by using the dielectric ceramic as described above, even when simultaneously fired with a conductor mainly composed of Ag and Cu, it is possible to suppress the occurrence of warpage, distortion, etc. of the laminate, In high frequency regions such as microwaves and millimeter waves, it can be suitably used for resonators, MIC substrates, and waveguides.

Claims (2)

A composition comprising 100 parts by weight of a low loss ceramic filler and 5 to 30 parts by weight of a grain boundary phase forming component containing B, alkali metal, Si and alkaline earth metal with respect to 100 parts by weight of the low loss ceramic filler. A high frequency dielectric ceramic having a Qf value represented by the product of the Q value and its measurement frequency of 20000 [GHz] or more, wherein the composition comprises:
The composition formula by molar ratio is
_{(1-x) MgTiO 3 ·} xCaTiO 3
When expressed with respect to principal component 1 00 parts by weight of said x satisfies 0 ≦ x ≦ 0.2, 3 to 20 parts by weight of said B _B 2 _{O 3} in terms of the Li as the alkali metal 1-10 parts by weight li ₂ CO ₃ terms, 0.01 to 5 parts by weight of the Si SiO ₂ in terms, as the alkaline earth metals Be, Mg, at least one of Ca and Ba in terms of oxide 0 .1-5 parts by weight and further containing 0.1-3 parts by weight of Mn in terms of MnO ₂ with respect to 100 parts by weight of the main component . Inside and / or surface of the dielectric substrate comprising a dielectric layer stacked, a laminate having a conductor composed mainly of Ag and / or Cu, the dielectric layer is a high frequency according to claim 1, wherein A laminate comprising a dielectric ceramic for use.